WIP: Implemented support for QOI G-code thumbnail format as requested

by the RepRapFirmware team due to their low RAM budget for decompression.
Bundled the QOI image compression library.

also squashed with "follow-up", "Fixing perl unit tests", and some fixes for superslicer

resources/ui_layout/printer_fff.ui

@@ -50,6 +50,7 @@ group:Thumbnails
 		setting:label$:label_width$1:thumbnails_color
 	end_line
 	line:Thumbnail options
+		setting:thumbnails_format
 		setting:thumbnails_with_bed
 		setting:thumbnails_end_file
 	end_line

src/CMakeLists.txt

@@ -14,6 +14,8 @@ add_subdirectory(Shiny)
 add_subdirectory(semver)
 add_subdirectory(libigl)
 add_subdirectory(hints)
+add_subdirectory(qoi)
+add_subdirectory(jpeg-compressor)
 
 # Adding libnest2d project for bin packing...
 add_subdirectory(libnest2d)

src/jpeg-compressor/CMakeLists.txt

@@ -0,0 +1,9 @@
+# PrusaSlicer specific CMake
+
+cmake_minimum_required(VERSION 2.8.12)
+project(jpeg-compressor)
+
+add_library(jpeg-compressor STATIC
+    jpge.h
+    jpge.cpp
+)

src/jpeg-compressor/README.md

@@ -0,0 +1,15 @@
+** jpeg-compressor is a C++ JPEG compression/fuzzed low-RAM JPEG decompression codec.**
+
+For more information go to https://github.com/richgel999/jpeg-compressor
+
+THIS DIRECTORY CONTAINS THE TWO FILES:
+
+jpge.h
+jpge.cpp
+
+TAKEN FROM
+
+master branch
+
+ON 03 FEB 2022.
+

src/jpeg-compressor/jpge.cpp

@@ -0,0 +1,1076 @@
+// jpge.cpp - C++ class for JPEG compression. Richard Geldreich <richgel99@gmail.com>
+// Supports grayscale, H1V1, H2V1, and H2V2 chroma subsampling factors, one or two pass Huffman table optimization, libjpeg-style quality 1-100 quality factors.
+// Also supports using luma quantization tables for chroma.
+//
+// Released under two licenses. You are free to choose which license you want:
+// License 1: 
+// Public Domain
+//
+// License 2:
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// v1.01, Dec. 18, 2010 - Initial release
+// v1.02, Apr. 6, 2011 - Removed 2x2 ordered dither in H2V1 chroma subsampling method load_block_16_8_8(). (The rounding factor was 2, when it should have been 1. Either way, it wasn't helping.)
+// v1.03, Apr. 16, 2011 - Added support for optimized Huffman code tables, optimized dynamic memory allocation down to only 1 alloc.
+//                        Also from Alex Evans: Added RGBA support, linear memory allocator (no longer needed in v1.03).
+// v1.04, May. 19, 2012: Forgot to set m_pFile ptr to NULL in cfile_stream::close(). Thanks to Owen Kaluza for reporting this bug.
+//                       Code tweaks to fix VS2008 static code analysis warnings (all looked harmless).
+//                       Code review revealed method load_block_16_8_8() (used for the non-default H2V1 sampling mode to downsample chroma) somehow didn't get the rounding factor fix from v1.02.
+// v1.05, March 25, 2020: Added Apache 2.0 alternate license
+
+#include "jpge.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <malloc.h>
+
+#define JPGE_MAX(a,b) (((a)>(b))?(a):(b))
+#define JPGE_MIN(a,b) (((a)<(b))?(a):(b))
+
+namespace jpge {
+
+	static inline void* jpge_malloc(size_t nSize) { return malloc(nSize); }
+	static inline void jpge_free(void* p) { free(p); }
+
+	// Various JPEG enums and tables.
+	enum { M_SOF0 = 0xC0, M_DHT = 0xC4, M_SOI = 0xD8, M_EOI = 0xD9, M_SOS = 0xDA, M_DQT = 0xDB, M_APP0 = 0xE0 };
+	enum { DC_LUM_CODES = 12, AC_LUM_CODES = 256, DC_CHROMA_CODES = 12, AC_CHROMA_CODES = 256, MAX_HUFF_SYMBOLS = 257, MAX_HUFF_CODESIZE = 32 };
+
+	static uint8 s_zag[64] = { 0,1,8,16,9,2,3,10,17,24,32,25,18,11,4,5,12,19,26,33,40,48,41,34,27,20,13,6,7,14,21,28,35,42,49,56,57,50,43,36,29,22,15,23,30,37,44,51,58,59,52,45,38,31,39,46,53,60,61,54,47,55,62,63 };
+	static int16 s_std_lum_quant[64] = { 16,11,12,14,12,10,16,14,13,14,18,17,16,19,24,40,26,24,22,22,24,49,35,37,29,40,58,51,61,60,57,51,56,55,64,72,92,78,64,68,87,69,55,56,80,109,81,87,95,98,103,104,103,62,77,113,121,112,100,120,92,101,103,99 };
+	static int16 s_std_croma_quant[64] = { 17,18,18,24,21,24,47,26,26,47,99,66,56,66,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99 };
+
+	// Table from http://www.imagemagick.org/discourse-server/viewtopic.php?f=22&t=20333&p=98008#p98008
+	// This is mozjpeg's default table, in zag order.
+	static int16 s_alt_quant[64] = { 16,16,16,16,17,16,18,20,20,18,25,27,24,27,25,37,34,31,31,34,37,56,40,43,40,43,40,56,85,53,62,53,53,62,53,85,75,91,74,69,74,91,75,135,106,94,94,106,135,156,131,124,131,156,189,169,169,189,238,226,238,311,311,418 };
+
+	static uint8 s_dc_lum_bits[17] = { 0,0,1,5,1,1,1,1,1,1,0,0,0,0,0,0,0 };
+	static uint8 s_dc_lum_val[DC_LUM_CODES] = { 0,1,2,3,4,5,6,7,8,9,10,11 };
+	static uint8 s_ac_lum_bits[17] = { 0,0,2,1,3,3,2,4,3,5,5,4,4,0,0,1,0x7d };
+	static uint8 s_ac_lum_val[AC_LUM_CODES] =
+	{
+	  0x01,0x02,0x03,0x00,0x04,0x11,0x05,0x12,0x21,0x31,0x41,0x06,0x13,0x51,0x61,0x07,0x22,0x71,0x14,0x32,0x81,0x91,0xa1,0x08,0x23,0x42,0xb1,0xc1,0x15,0x52,0xd1,0xf0,
+	  0x24,0x33,0x62,0x72,0x82,0x09,0x0a,0x16,0x17,0x18,0x19,0x1a,0x25,0x26,0x27,0x28,0x29,0x2a,0x34,0x35,0x36,0x37,0x38,0x39,0x3a,0x43,0x44,0x45,0x46,0x47,0x48,0x49,
+	  0x4a,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5a,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0x6a,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7a,0x83,0x84,0x85,0x86,0x87,0x88,0x89,
+	  0x8a,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9a,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7,0xa8,0xa9,0xaa,0xb2,0xb3,0xb4,0xb5,0xb6,0xb7,0xb8,0xb9,0xba,0xc2,0xc3,0xc4,0xc5,
+	  0xc6,0xc7,0xc8,0xc9,0xca,0xd2,0xd3,0xd4,0xd5,0xd6,0xd7,0xd8,0xd9,0xda,0xe1,0xe2,0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9,0xea,0xf1,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8,
+	  0xf9,0xfa
+	};
+	static uint8 s_dc_chroma_bits[17] = { 0,0,3,1,1,1,1,1,1,1,1,1,0,0,0,0,0 };
+	static uint8 s_dc_chroma_val[DC_CHROMA_CODES] = { 0,1,2,3,4,5,6,7,8,9,10,11 };
+	static uint8 s_ac_chroma_bits[17] = { 0,0,2,1,2,4,4,3,4,7,5,4,4,0,1,2,0x77 };
+	static uint8 s_ac_chroma_val[AC_CHROMA_CODES] =
+	{
+	  0x00,0x01,0x02,0x03,0x11,0x04,0x05,0x21,0x31,0x06,0x12,0x41,0x51,0x07,0x61,0x71,0x13,0x22,0x32,0x81,0x08,0x14,0x42,0x91,0xa1,0xb1,0xc1,0x09,0x23,0x33,0x52,0xf0,
+	  0x15,0x62,0x72,0xd1,0x0a,0x16,0x24,0x34,0xe1,0x25,0xf1,0x17,0x18,0x19,0x1a,0x26,0x27,0x28,0x29,0x2a,0x35,0x36,0x37,0x38,0x39,0x3a,0x43,0x44,0x45,0x46,0x47,0x48,
+	  0x49,0x4a,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5a,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0x6a,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7a,0x82,0x83,0x84,0x85,0x86,0x87,
+	  0x88,0x89,0x8a,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9a,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7,0xa8,0xa9,0xaa,0xb2,0xb3,0xb4,0xb5,0xb6,0xb7,0xb8,0xb9,0xba,0xc2,0xc3,
+	  0xc4,0xc5,0xc6,0xc7,0xc8,0xc9,0xca,0xd2,0xd3,0xd4,0xd5,0xd6,0xd7,0xd8,0xd9,0xda,0xe2,0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9,0xea,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8,
+	  0xf9,0xfa
+	};
+
+	// Low-level helper functions.
+	template <class T> inline void clear_obj(T& obj) { memset(&obj, 0, sizeof(obj)); }
+
+	const int YR = 19595, YG = 38470, YB = 7471, CB_R = -11059, CB_G = -21709, CB_B = 32768, CR_R = 32768, CR_G = -27439, CR_B = -5329;
+	static inline uint8 clamp(int i) { if (static_cast<uint>(i) > 255U) { if (i < 0) i = 0; else if (i > 255) i = 255; } return static_cast<uint8>(i); }
+
+	static inline int left_shifti(int val, uint32 bits)
+	{
+		return static_cast<int>(static_cast<uint32>(val) << bits);
+	}
+
+	static void RGB_to_YCC(uint8* pDst, const uint8* pSrc, int num_pixels)
+	{
+		for (; num_pixels; pDst += 3, pSrc += 3, num_pixels--)
+		{
+			const int r = pSrc[0], g = pSrc[1], b = pSrc[2];
+			pDst[0] = static_cast<uint8>((r * YR + g * YG + b * YB + 32768) >> 16);
+			pDst[1] = clamp(128 + ((r * CB_R + g * CB_G + b * CB_B + 32768) >> 16));
+			pDst[2] = clamp(128 + ((r * CR_R + g * CR_G + b * CR_B + 32768) >> 16));
+		}
+	}
+
+	static void RGB_to_Y(uint8* pDst, const uint8* pSrc, int num_pixels)
+	{
+		for (; num_pixels; pDst++, pSrc += 3, num_pixels--)
+			pDst[0] = static_cast<uint8>((pSrc[0] * YR + pSrc[1] * YG + pSrc[2] * YB + 32768) >> 16);
+	}
+
+	static void RGBA_to_YCC(uint8* pDst, const uint8* pSrc, int num_pixels)
+	{
+		for (; num_pixels; pDst += 3, pSrc += 4, num_pixels--)
+		{
+			const int r = pSrc[0], g = pSrc[1], b = pSrc[2];
+			pDst[0] = static_cast<uint8>((r * YR + g * YG + b * YB + 32768) >> 16);
+			pDst[1] = clamp(128 + ((r * CB_R + g * CB_G + b * CB_B + 32768) >> 16));
+			pDst[2] = clamp(128 + ((r * CR_R + g * CR_G + b * CR_B + 32768) >> 16));
+		}
+	}
+
+	static void RGBA_to_Y(uint8* pDst, const uint8* pSrc, int num_pixels)
+	{
+		for (; num_pixels; pDst++, pSrc += 4, num_pixels--)
+			pDst[0] = static_cast<uint8>((pSrc[0] * YR + pSrc[1] * YG + pSrc[2] * YB + 32768) >> 16);
+	}
+
+	static void Y_to_YCC(uint8* pDst, const uint8* pSrc, int num_pixels)
+	{
+		for (; num_pixels; pDst += 3, pSrc++, num_pixels--) { pDst[0] = pSrc[0]; pDst[1] = 128; pDst[2] = 128; }
+	}
+
+	// Forward DCT - DCT derived from jfdctint.
+	enum { CONST_BITS = 13, ROW_BITS = 2 };
+#define DCT_DESCALE(x, n) (((x) + (((int32)1) << ((n) - 1))) >> (n))
+#define DCT_MUL(var, c) (static_cast<int16>(var) * static_cast<int32>(c))
+#define DCT1D(s0, s1, s2, s3, s4, s5, s6, s7) \
+  int32 t0 = s0 + s7, t7 = s0 - s7, t1 = s1 + s6, t6 = s1 - s6, t2 = s2 + s5, t5 = s2 - s5, t3 = s3 + s4, t4 = s3 - s4; \
+  int32 t10 = t0 + t3, t13 = t0 - t3, t11 = t1 + t2, t12 = t1 - t2; \
+  int32 u1 = DCT_MUL(t12 + t13, 4433); \
+  s2 = u1 + DCT_MUL(t13, 6270); \
+  s6 = u1 + DCT_MUL(t12, -15137); \
+  u1 = t4 + t7; \
+  int32 u2 = t5 + t6, u3 = t4 + t6, u4 = t5 + t7; \
+  int32 z5 = DCT_MUL(u3 + u4, 9633); \
+  t4 = DCT_MUL(t4, 2446); t5 = DCT_MUL(t5, 16819); \
+  t6 = DCT_MUL(t6, 25172); t7 = DCT_MUL(t7, 12299); \
+  u1 = DCT_MUL(u1, -7373); u2 = DCT_MUL(u2, -20995); \
+  u3 = DCT_MUL(u3, -16069); u4 = DCT_MUL(u4, -3196); \
+  u3 += z5; u4 += z5; \
+  s0 = t10 + t11; s1 = t7 + u1 + u4; s3 = t6 + u2 + u3; s4 = t10 - t11; s5 = t5 + u2 + u4; s7 = t4 + u1 + u3;
+
+	static void DCT2D(int32* p)
+	{
+		int32 c, * q = p;
+		for (c = 7; c >= 0; c--, q += 8)
+		{
+			int32 s0 = q[0], s1 = q[1], s2 = q[2], s3 = q[3], s4 = q[4], s5 = q[5], s6 = q[6], s7 = q[7];
+			DCT1D(s0, s1, s2, s3, s4, s5, s6, s7);
+			q[0] = left_shifti(s0, ROW_BITS); q[1] = DCT_DESCALE(s1, CONST_BITS - ROW_BITS); q[2] = DCT_DESCALE(s2, CONST_BITS - ROW_BITS); q[3] = DCT_DESCALE(s3, CONST_BITS - ROW_BITS);
+			q[4] = left_shifti(s4, ROW_BITS); q[5] = DCT_DESCALE(s5, CONST_BITS - ROW_BITS); q[6] = DCT_DESCALE(s6, CONST_BITS - ROW_BITS); q[7] = DCT_DESCALE(s7, CONST_BITS - ROW_BITS);
+		}
+		for (q = p, c = 7; c >= 0; c--, q++)
+		{
+			int32 s0 = q[0 * 8], s1 = q[1 * 8], s2 = q[2 * 8], s3 = q[3 * 8], s4 = q[4 * 8], s5 = q[5 * 8], s6 = q[6 * 8], s7 = q[7 * 8];
+			DCT1D(s0, s1, s2, s3, s4, s5, s6, s7);
+			q[0 * 8] = DCT_DESCALE(s0, ROW_BITS + 3); q[1 * 8] = DCT_DESCALE(s1, CONST_BITS + ROW_BITS + 3); q[2 * 8] = DCT_DESCALE(s2, CONST_BITS + ROW_BITS + 3); q[3 * 8] = DCT_DESCALE(s3, CONST_BITS + ROW_BITS + 3);
+			q[4 * 8] = DCT_DESCALE(s4, ROW_BITS + 3); q[5 * 8] = DCT_DESCALE(s5, CONST_BITS + ROW_BITS + 3); q[6 * 8] = DCT_DESCALE(s6, CONST_BITS + ROW_BITS + 3); q[7 * 8] = DCT_DESCALE(s7, CONST_BITS + ROW_BITS + 3);
+		}
+	}
+
+	struct sym_freq { uint m_key, m_sym_index; };
+
+	// Radix sorts sym_freq[] array by 32-bit key m_key. Returns ptr to sorted values.
+	static inline sym_freq* radix_sort_syms(uint num_syms, sym_freq* pSyms0, sym_freq* pSyms1)
+	{
+		const uint cMaxPasses = 4;
+		uint32 hist[256 * cMaxPasses]; clear_obj(hist);
+		for (uint i = 0; i < num_syms; i++) { uint freq = pSyms0[i].m_key; hist[freq & 0xFF]++; hist[256 + ((freq >> 8) & 0xFF)]++; hist[256 * 2 + ((freq >> 16) & 0xFF)]++; hist[256 * 3 + ((freq >> 24) & 0xFF)]++; }
+		sym_freq* pCur_syms = pSyms0, * pNew_syms = pSyms1;
+		uint total_passes = cMaxPasses; while ((total_passes > 1) && (num_syms == hist[(total_passes - 1) * 256])) total_passes--;
+		for (uint pass_shift = 0, pass = 0; pass < total_passes; pass++, pass_shift += 8)
+		{
+			const uint32* pHist = &hist[pass << 8];
+			uint offsets[256], cur_ofs = 0;
+			for (uint i = 0; i < 256; i++) { offsets[i] = cur_ofs; cur_ofs += pHist[i]; }
+			for (uint i = 0; i < num_syms; i++)
+				pNew_syms[offsets[(pCur_syms[i].m_key >> pass_shift) & 0xFF]++] = pCur_syms[i];
+			sym_freq* t = pCur_syms; pCur_syms = pNew_syms; pNew_syms = t;
+		}
+		return pCur_syms;
+	}
+
+	// calculate_minimum_redundancy() originally written by: Alistair Moffat, alistair@cs.mu.oz.au, Jyrki Katajainen, jyrki@diku.dk, November 1996.
+	static void calculate_minimum_redundancy(sym_freq* A, int n)
+	{
+		int root, leaf, next, avbl, used, dpth;
+		if (n == 0) return; else if (n == 1) { A[0].m_key = 1; return; }
+		A[0].m_key += A[1].m_key; root = 0; leaf = 2;
+		for (next = 1; next < n - 1; next++)
+		{
+			if (leaf >= n || A[root].m_key < A[leaf].m_key) { A[next].m_key = A[root].m_key; A[root++].m_key = next; }
+			else A[next].m_key = A[leaf++].m_key;
+			if (leaf >= n || (root < next && A[root].m_key < A[leaf].m_key)) { A[next].m_key += A[root].m_key; A[root++].m_key = next; }
+			else A[next].m_key += A[leaf++].m_key;
+		}
+		A[n - 2].m_key = 0;
+		for (next = n - 3; next >= 0; next--) A[next].m_key = A[A[next].m_key].m_key + 1;
+		avbl = 1; used = dpth = 0; root = n - 2; next = n - 1;
+		while (avbl > 0)
+		{
+			while (root >= 0 && (int)A[root].m_key == dpth) { used++; root--; }
+			while (avbl > used) { A[next--].m_key = dpth; avbl--; }
+			avbl = 2 * used; dpth++; used = 0;
+		}
+	}
+
+	// Limits canonical Huffman code table's max code size to max_code_size.
+	static void huffman_enforce_max_code_size(int* pNum_codes, int code_list_len, int max_code_size)
+	{
+		if (code_list_len <= 1) return;
+
+		for (int i = max_code_size + 1; i <= MAX_HUFF_CODESIZE; i++) pNum_codes[max_code_size] += pNum_codes[i];
+
+		uint32 total = 0;
+		for (int i = max_code_size; i > 0; i--)
+			total += (((uint32)pNum_codes[i]) << (max_code_size - i));
+
+		while (total != (1UL << max_code_size))
+		{
+			pNum_codes[max_code_size]--;
+			for (int i = max_code_size - 1; i > 0; i--)
+			{
+				if (pNum_codes[i]) { pNum_codes[i]--; pNum_codes[i + 1] += 2; break; }
+			}
+			total--;
+		}
+	}
+
+	// Generates an optimized offman table.
+	void jpeg_encoder::optimize_huffman_table(int table_num, int table_len)
+	{
+		sym_freq syms0[MAX_HUFF_SYMBOLS], syms1[MAX_HUFF_SYMBOLS];
+		syms0[0].m_key = 1; syms0[0].m_sym_index = 0;  // dummy symbol, assures that no valid code contains all 1's
+		int num_used_syms = 1;
+		const uint32* pSym_count = &m_huff_count[table_num][0];
+		for (int i = 0; i < table_len; i++)
+			if (pSym_count[i]) { syms0[num_used_syms].m_key = pSym_count[i]; syms0[num_used_syms++].m_sym_index = i + 1; }
+		sym_freq* pSyms = radix_sort_syms(num_used_syms, syms0, syms1);
+		calculate_minimum_redundancy(pSyms, num_used_syms);
+
+		// Count the # of symbols of each code size.
+		int num_codes[1 + MAX_HUFF_CODESIZE]; clear_obj(num_codes);
+		for (int i = 0; i < num_used_syms; i++)
+			num_codes[pSyms[i].m_key]++;
+
+		const uint JPGE_CODE_SIZE_LIMIT = 16; // the maximum possible size of a JPEG Huffman code (valid range is [9,16] - 9 vs. 8 because of the dummy symbol)
+		huffman_enforce_max_code_size(num_codes, num_used_syms, JPGE_CODE_SIZE_LIMIT);
+
+		// Compute m_huff_bits array, which contains the # of symbols per code size.
+		clear_obj(m_huff_bits[table_num]);
+		for (int i = 1; i <= (int)JPGE_CODE_SIZE_LIMIT; i++)
+			m_huff_bits[table_num][i] = static_cast<uint8>(num_codes[i]);
+
+		// Remove the dummy symbol added above, which must be in largest bucket.
+		for (int i = JPGE_CODE_SIZE_LIMIT; i >= 1; i--)
+		{
+			if (m_huff_bits[table_num][i]) { m_huff_bits[table_num][i]--; break; }
+		}
+
+		// Compute the m_huff_val array, which contains the symbol indices sorted by code size (smallest to largest).
+		for (int i = num_used_syms - 1; i >= 1; i--)
+			m_huff_val[table_num][num_used_syms - 1 - i] = static_cast<uint8>(pSyms[i].m_sym_index - 1);
+	}
+
+	// JPEG marker generation.
+	void jpeg_encoder::emit_byte(uint8 i)
+	{
+		m_all_stream_writes_succeeded = m_all_stream_writes_succeeded && m_pStream->put_obj(i);
+	}
+
+	void jpeg_encoder::emit_word(uint i)
+	{
+		emit_byte(uint8(i >> 8)); emit_byte(uint8(i & 0xFF));
+	}
+
+	void jpeg_encoder::emit_marker(int marker)
+	{
+		emit_byte(uint8(0xFF)); emit_byte(uint8(marker));
+	}
+
+	// Emit JFIF marker
+	void jpeg_encoder::emit_jfif_app0()
+	{
+		emit_marker(M_APP0);
+		emit_word(2 + 4 + 1 + 2 + 1 + 2 + 2 + 1 + 1);
+		emit_byte(0x4A); emit_byte(0x46); emit_byte(0x49); emit_byte(0x46); /* Identifier: ASCII "JFIF" */
+		emit_byte(0);
+		emit_byte(1);      /* Major version */
+		emit_byte(1);      /* Minor version */
+		emit_byte(0);      /* Density unit */
+		emit_word(1);
+		emit_word(1);
+		emit_byte(0);      /* No thumbnail image */
+		emit_byte(0);
+	}
+
+	// Emit quantization tables
+	void jpeg_encoder::emit_dqt()
+	{
+		for (int i = 0; i < ((m_num_components == 3) ? 2 : 1); i++)
+		{
+			emit_marker(M_DQT);
+			emit_word(64 + 1 + 2);
+			emit_byte(static_cast<uint8>(i));
+			for (int j = 0; j < 64; j++)
+				emit_byte(static_cast<uint8>(m_quantization_tables[i][j]));
+		}
+	}
+
+	// Emit start of frame marker
+	void jpeg_encoder::emit_sof()
+	{
+		emit_marker(M_SOF0);                           /* baseline */
+		emit_word(3 * m_num_components + 2 + 5 + 1);
+		emit_byte(8);                                  /* precision */
+		emit_word(m_image_y);
+		emit_word(m_image_x);
+		emit_byte(m_num_components);
+		for (int i = 0; i < m_num_components; i++)
+		{
+			emit_byte(static_cast<uint8>(i + 1));                                   /* component ID     */
+			emit_byte((m_comp_h_samp[i] << 4) + m_comp_v_samp[i]);  /* h and v sampling */
+			emit_byte(i > 0);                                   /* quant. table num */
+		}
+	}
+
+	// Emit Huffman table.
+	void jpeg_encoder::emit_dht(uint8* bits, uint8* val, int index, bool ac_flag)
+	{
+		emit_marker(M_DHT);
+
+		int length = 0;
+		for (int i = 1; i <= 16; i++)
+			length += bits[i];
+
+		emit_word(length + 2 + 1 + 16);
+		emit_byte(static_cast<uint8>(index + (ac_flag << 4)));
+
+		for (int i = 1; i <= 16; i++)
+			emit_byte(bits[i]);
+
+		for (int i = 0; i < length; i++)
+			emit_byte(val[i]);
+	}
+
+	// Emit all Huffman tables.
+	void jpeg_encoder::emit_dhts()
+	{
+		emit_dht(m_huff_bits[0 + 0], m_huff_val[0 + 0], 0, false);
+		emit_dht(m_huff_bits[2 + 0], m_huff_val[2 + 0], 0, true);
+		if (m_num_components == 3)
+		{
+			emit_dht(m_huff_bits[0 + 1], m_huff_val[0 + 1], 1, false);
+			emit_dht(m_huff_bits[2 + 1], m_huff_val[2 + 1], 1, true);
+		}
+	}
+
+	// emit start of scan
+	void jpeg_encoder::emit_sos()
+	{
+		emit_marker(M_SOS);
+		emit_word(2 * m_num_components + 2 + 1 + 3);
+		emit_byte(m_num_components);
+		for (int i = 0; i < m_num_components; i++)
+		{
+			emit_byte(static_cast<uint8>(i + 1));
+			if (i == 0)
+				emit_byte((0 << 4) + 0);
+			else
+				emit_byte((1 << 4) + 1);
+		}
+		emit_byte(0);     /* spectral selection */
+		emit_byte(63);
+		emit_byte(0);
+	}
+
+	// Emit all markers at beginning of image file.
+	void jpeg_encoder::emit_markers()
+	{
+		emit_marker(M_SOI);
+		emit_jfif_app0();
+		emit_dqt();
+		emit_sof();
+		emit_dhts();
+		emit_sos();
+	}
+
+	// Compute the actual canonical Huffman codes/code sizes given the JPEG huff bits and val arrays.
+	void jpeg_encoder::compute_huffman_table(uint* codes, uint8* code_sizes, uint8* bits, uint8* val)
+	{
+		int i, l, last_p, si;
+		uint8 huff_size[257];
+		uint huff_code[257];
+		uint code;
+
+		int p = 0;
+		for (l = 1; l <= 16; l++)
+			for (i = 1; i <= bits[l]; i++)
+				huff_size[p++] = (char)l;
+
+		huff_size[p] = 0; last_p = p; // write sentinel
+
+		code = 0; si = huff_size[0]; p = 0;
+
+		while (huff_size[p])
+		{
+			while (huff_size[p] == si)
+				huff_code[p++] = code++;
+			code <<= 1;
+			si++;
+		}
+
+		memset(codes, 0, sizeof(codes[0]) * 256);
+		memset(code_sizes, 0, sizeof(code_sizes[0]) * 256);
+		for (p = 0; p < last_p; p++)
+		{
+			codes[val[p]] = huff_code[p];
+			code_sizes[val[p]] = huff_size[p];
+		}
+	}
+
+	// Quantization table generation.
+	void jpeg_encoder::compute_quant_table(int32* pDst, int16* pSrc)
+	{
+		int32 q;
+		if (m_params.m_quality < 50)
+			q = 5000 / m_params.m_quality;
+		else
+			q = 200 - m_params.m_quality * 2;
+		for (int i = 0; i < 64; i++)
+		{
+			int32 j = *pSrc++; j = (j * q + 50L) / 100L;
+			*pDst++ = JPGE_MIN(JPGE_MAX(j, 1), 255);
+		}
+	}
+
+	// Higher-level methods.
+	void jpeg_encoder::first_pass_init()
+	{
+		m_bit_buffer = 0; m_bits_in = 0;
+		memset(m_last_dc_val, 0, 3 * sizeof(m_last_dc_val[0]));
+		m_mcu_y_ofs = 0;
+		m_pass_num = 1;
+	}
+
+	bool jpeg_encoder::second_pass_init()
+	{
+		compute_huffman_table(&m_huff_codes[0 + 0][0], &m_huff_code_sizes[0 + 0][0], m_huff_bits[0 + 0], m_huff_val[0 + 0]);
+		compute_huffman_table(&m_huff_codes[2 + 0][0], &m_huff_code_sizes[2 + 0][0], m_huff_bits[2 + 0], m_huff_val[2 + 0]);
+		if (m_num_components > 1)
+		{
+			compute_huffman_table(&m_huff_codes[0 + 1][0], &m_huff_code_sizes[0 + 1][0], m_huff_bits[0 + 1], m_huff_val[0 + 1]);
+			compute_huffman_table(&m_huff_codes[2 + 1][0], &m_huff_code_sizes[2 + 1][0], m_huff_bits[2 + 1], m_huff_val[2 + 1]);
+		}
+		first_pass_init();
+		emit_markers();
+		m_pass_num = 2;
+		return true;
+	}
+
+	bool jpeg_encoder::jpg_open(int p_x_res, int p_y_res, int src_channels)
+	{
+		m_num_components = 3;
+		switch (m_params.m_subsampling)
+		{
+		case Y_ONLY:
+		{
+			m_num_components = 1;
+			m_comp_h_samp[0] = 1; m_comp_v_samp[0] = 1;
+			m_mcu_x = 8; m_mcu_y = 8;
+			break;
+		}
+		case H1V1:
+		{
+			m_comp_h_samp[0] = 1; m_comp_v_samp[0] = 1;
+			m_comp_h_samp[1] = 1; m_comp_v_samp[1] = 1;
+			m_comp_h_samp[2] = 1; m_comp_v_samp[2] = 1;
+			m_mcu_x = 8; m_mcu_y = 8;
+			break;
+		}
+		case H2V1:
+		{
+			m_comp_h_samp[0] = 2; m_comp_v_samp[0] = 1;
+			m_comp_h_samp[1] = 1; m_comp_v_samp[1] = 1;
+			m_comp_h_samp[2] = 1; m_comp_v_samp[2] = 1;
+			m_mcu_x = 16; m_mcu_y = 8;
+			break;
+		}
+		case H2V2:
+		{
+			m_comp_h_samp[0] = 2; m_comp_v_samp[0] = 2;
+			m_comp_h_samp[1] = 1; m_comp_v_samp[1] = 1;
+			m_comp_h_samp[2] = 1; m_comp_v_samp[2] = 1;
+			m_mcu_x = 16; m_mcu_y = 16;
+		}
+		}
+
+		m_image_x = p_x_res; m_image_y = p_y_res;
+		m_image_bpp = src_channels;
+		m_image_bpl = m_image_x * src_channels;
+		m_image_x_mcu = (m_image_x + m_mcu_x - 1) & (~(m_mcu_x - 1));
+		m_image_y_mcu = (m_image_y + m_mcu_y - 1) & (~(m_mcu_y - 1));
+		m_image_bpl_xlt = m_image_x * m_num_components;
+		m_image_bpl_mcu = m_image_x_mcu * m_num_components;
+		m_mcus_per_row = m_image_x_mcu / m_mcu_x;
+
+		if ((m_mcu_lines[0] = static_cast<uint8*>(jpge_malloc(m_image_bpl_mcu * m_mcu_y))) == NULL) return false;
+		for (int i = 1; i < m_mcu_y; i++)
+			m_mcu_lines[i] = m_mcu_lines[i - 1] + m_image_bpl_mcu;
+
+		if (m_params.m_use_std_tables)
+		{
+			compute_quant_table(m_quantization_tables[0], s_std_lum_quant);
+			compute_quant_table(m_quantization_tables[1], m_params.m_no_chroma_discrim_flag ? s_std_lum_quant : s_std_croma_quant);
+		}
+		else
+		{
+			compute_quant_table(m_quantization_tables[0], s_alt_quant);
+			memcpy(m_quantization_tables[1], m_quantization_tables[0], sizeof(m_quantization_tables[1]));
+		}
+
+		m_out_buf_left = JPGE_OUT_BUF_SIZE;
+		m_pOut_buf = m_out_buf;
+
+		if (m_params.m_two_pass_flag)
+		{
+			clear_obj(m_huff_count);
+			first_pass_init();
+		}
+		else
+		{
+			memcpy(m_huff_bits[0 + 0], s_dc_lum_bits, 17);    memcpy(m_huff_val[0 + 0], s_dc_lum_val, DC_LUM_CODES);
+			memcpy(m_huff_bits[2 + 0], s_ac_lum_bits, 17);    memcpy(m_huff_val[2 + 0], s_ac_lum_val, AC_LUM_CODES);
+			memcpy(m_huff_bits[0 + 1], s_dc_chroma_bits, 17); memcpy(m_huff_val[0 + 1], s_dc_chroma_val, DC_CHROMA_CODES);
+			memcpy(m_huff_bits[2 + 1], s_ac_chroma_bits, 17); memcpy(m_huff_val[2 + 1], s_ac_chroma_val, AC_CHROMA_CODES);
+			if (!second_pass_init()) return false;   // in effect, skip over the first pass
+		}
+		return m_all_stream_writes_succeeded;
+	}
+
+	void jpeg_encoder::load_block_8_8_grey(int x)
+	{
+		uint8* pSrc;
+		sample_array_t* pDst = m_sample_array;
+		x <<= 3;
+		for (int i = 0; i < 8; i++, pDst += 8)
+		{
+			pSrc = m_mcu_lines[i] + x;
+			pDst[0] = pSrc[0] - 128; pDst[1] = pSrc[1] - 128; pDst[2] = pSrc[2] - 128; pDst[3] = pSrc[3] - 128;
+			pDst[4] = pSrc[4] - 128; pDst[5] = pSrc[5] - 128; pDst[6] = pSrc[6] - 128; pDst[7] = pSrc[7] - 128;
+		}
+	}
+
+	void jpeg_encoder::load_block_8_8(int x, int y, int c)
+	{
+		uint8* pSrc;
+		sample_array_t* pDst = m_sample_array;
+		x = (x * (8 * 3)) + c;
+		y <<= 3;
+		for (int i = 0; i < 8; i++, pDst += 8)
+		{
+			pSrc = m_mcu_lines[y + i] + x;
+			pDst[0] = pSrc[0 * 3] - 128; pDst[1] = pSrc[1 * 3] - 128; pDst[2] = pSrc[2 * 3] - 128; pDst[3] = pSrc[3 * 3] - 128;
+			pDst[4] = pSrc[4 * 3] - 128; pDst[5] = pSrc[5 * 3] - 128; pDst[6] = pSrc[6 * 3] - 128; pDst[7] = pSrc[7 * 3] - 128;
+		}
+	}
+
+	void jpeg_encoder::load_block_16_8(int x, int c)
+	{
+		uint8* pSrc1, * pSrc2;
+		sample_array_t* pDst = m_sample_array;
+		x = (x * (16 * 3)) + c;
+		for (int i = 0; i < 16; i += 2, pDst += 8)
+		{
+			pSrc1 = m_mcu_lines[i + 0] + x;
+			pSrc2 = m_mcu_lines[i + 1] + x;
+			pDst[0] = ((pSrc1[0 * 3] + pSrc1[1 * 3] + pSrc2[0 * 3] + pSrc2[1 * 3] + 2) >> 2) - 128; pDst[1] = ((pSrc1[2 * 3] + pSrc1[3 * 3] + pSrc2[2 * 3] + pSrc2[3 * 3] + 2) >> 2) - 128;
+			pDst[2] = ((pSrc1[4 * 3] + pSrc1[5 * 3] + pSrc2[4 * 3] + pSrc2[5 * 3] + 2) >> 2) - 128; pDst[3] = ((pSrc1[6 * 3] + pSrc1[7 * 3] + pSrc2[6 * 3] + pSrc2[7 * 3] + 2) >> 2) - 128;
+			pDst[4] = ((pSrc1[8 * 3] + pSrc1[9 * 3] + pSrc2[8 * 3] + pSrc2[9 * 3] + 2) >> 2) - 128; pDst[5] = ((pSrc1[10 * 3] + pSrc1[11 * 3] + pSrc2[10 * 3] + pSrc2[11 * 3] + 2) >> 2) - 128;
+			pDst[6] = ((pSrc1[12 * 3] + pSrc1[13 * 3] + pSrc2[12 * 3] + pSrc2[13 * 3] + 2) >> 2) - 128; pDst[7] = ((pSrc1[14 * 3] + pSrc1[15 * 3] + pSrc2[14 * 3] + pSrc2[15 * 3] + 2) >> 2) - 128;
+		}
+	}
+
+	void jpeg_encoder::load_block_16_8_8(int x, int c)
+	{
+		uint8* pSrc1;
+		sample_array_t* pDst = m_sample_array;
+		x = (x * (16 * 3)) + c;
+		for (int i = 0; i < 8; i++, pDst += 8)
+		{
+			pSrc1 = m_mcu_lines[i + 0] + x;
+			pDst[0] = ((pSrc1[0 * 3] + pSrc1[1 * 3] + 1) >> 1) - 128; pDst[1] = ((pSrc1[2 * 3] + pSrc1[3 * 3] + 1) >> 1) - 128;
+			pDst[2] = ((pSrc1[4 * 3] + pSrc1[5 * 3] + 1) >> 1) - 128; pDst[3] = ((pSrc1[6 * 3] + pSrc1[7 * 3] + 1) >> 1) - 128;
+			pDst[4] = ((pSrc1[8 * 3] + pSrc1[9 * 3] + 1) >> 1) - 128; pDst[5] = ((pSrc1[10 * 3] + pSrc1[11 * 3] + 1) >> 1) - 128;
+			pDst[6] = ((pSrc1[12 * 3] + pSrc1[13 * 3] + 1) >> 1) - 128; pDst[7] = ((pSrc1[14 * 3] + pSrc1[15 * 3] + 1) >> 1) - 128;
+		}
+	}
+
+	void jpeg_encoder::load_quantized_coefficients(int component_num)
+	{
+		int32* q = m_quantization_tables[component_num > 0];
+		int16* pDst = m_coefficient_array;
+		for (int i = 0; i < 64; i++)
+		{
+			sample_array_t j = m_sample_array[s_zag[i]];
+			if (j < 0)
+			{
+				if ((j = -j + (*q >> 1)) < *q)
+					*pDst++ = 0;
+				else
+					*pDst++ = static_cast<int16>(-(j / *q));
+			}
+			else
+			{
+				if ((j = j + (*q >> 1)) < *q)
+					*pDst++ = 0;
+				else
+					*pDst++ = static_cast<int16>((j / *q));
+			}
+			q++;
+		}
+	}
+
+	void jpeg_encoder::flush_output_buffer()
+	{
+		if (m_out_buf_left != JPGE_OUT_BUF_SIZE)
+			m_all_stream_writes_succeeded = m_all_stream_writes_succeeded && m_pStream->put_buf(m_out_buf, JPGE_OUT_BUF_SIZE - m_out_buf_left);
+		m_pOut_buf = m_out_buf;
+		m_out_buf_left = JPGE_OUT_BUF_SIZE;
+	}
+
+	void jpeg_encoder::put_bits(uint bits, uint len)
+	{
+		m_bit_buffer |= ((uint32)bits << (24 - (m_bits_in += len)));
+		while (m_bits_in >= 8)
+		{
+			uint8 c;
+#define JPGE_PUT_BYTE(c) { *m_pOut_buf++ = (c); if (--m_out_buf_left == 0) flush_output_buffer(); }
+			JPGE_PUT_BYTE(c = (uint8)((m_bit_buffer >> 16) & 0xFF));
+			if (c == 0xFF) JPGE_PUT_BYTE(0);
+			m_bit_buffer <<= 8;
+			m_bits_in -= 8;
+		}
+	}
+
+	void jpeg_encoder::code_coefficients_pass_one(int component_num)
+	{
+		if (component_num >= 3) return; // just to shut up static analysis
+		int i, run_len, nbits, temp1;
+		int16* src = m_coefficient_array;
+		uint32* dc_count = component_num ? m_huff_count[0 + 1] : m_huff_count[0 + 0], * ac_count = component_num ? m_huff_count[2 + 1] : m_huff_count[2 + 0];
+
+		temp1 = src[0] - m_last_dc_val[component_num];
+		m_last_dc_val[component_num] = src[0];
+		if (temp1 < 0) temp1 = -temp1;
+
+		nbits = 0;
+		while (temp1)
+		{
+			nbits++; temp1 >>= 1;
+		}
+
+		dc_count[nbits]++;
+		for (run_len = 0, i = 1; i < 64; i++)
+		{
+			if ((temp1 = m_coefficient_array[i]) == 0)
+				run_len++;
+			else
+			{
+				while (run_len >= 16)
+				{
+					ac_count[0xF0]++;
+					run_len -= 16;
+				}
+				if (temp1 < 0) temp1 = -temp1;
+				nbits = 1;
+				while (temp1 >>= 1) nbits++;
+				ac_count[(run_len << 4) + nbits]++;
+				run_len = 0;
+			}
+		}
+		if (run_len) ac_count[0]++;
+	}
+
+	void jpeg_encoder::code_coefficients_pass_two(int component_num)
+	{
+		int i, j, run_len, nbits, temp1, temp2;
+		int16* pSrc = m_coefficient_array;
+		uint* codes[2];
+		uint8* code_sizes[2];
+
+		if (component_num == 0)
+		{
+			codes[0] = m_huff_codes[0 + 0]; codes[1] = m_huff_codes[2 + 0];
+			code_sizes[0] = m_huff_code_sizes[0 + 0]; code_sizes[1] = m_huff_code_sizes[2 + 0];
+		}
+		else
+		{
+			codes[0] = m_huff_codes[0 + 1]; codes[1] = m_huff_codes[2 + 1];
+			code_sizes[0] = m_huff_code_sizes[0 + 1]; code_sizes[1] = m_huff_code_sizes[2 + 1];
+		}
+
+		temp1 = temp2 = pSrc[0] - m_last_dc_val[component_num];
+		m_last_dc_val[component_num] = pSrc[0];
+
+		if (temp1 < 0)
+		{
+			temp1 = -temp1; temp2--;
+		}
+
+		nbits = 0;
+		while (temp1)
+		{
+			nbits++; temp1 >>= 1;
+		}
+
+		put_bits(codes[0][nbits], code_sizes[0][nbits]);
+		if (nbits) put_bits(temp2 & ((1 << nbits) - 1), nbits);
+
+		for (run_len = 0, i = 1; i < 64; i++)
+		{
+			if ((temp1 = m_coefficient_array[i]) == 0)
+				run_len++;
+			else
+			{
+				while (run_len >= 16)
+				{
+					put_bits(codes[1][0xF0], code_sizes[1][0xF0]);
+					run_len -= 16;
+				}
+				if ((temp2 = temp1) < 0)
+				{
+					temp1 = -temp1;
+					temp2--;
+				}
+				nbits = 1;
+				while (temp1 >>= 1)
+					nbits++;
+				j = (run_len << 4) + nbits;
+				put_bits(codes[1][j], code_sizes[1][j]);
+				put_bits(temp2 & ((1 << nbits) - 1), nbits);
+				run_len = 0;
+			}
+		}
+		if (run_len)
+			put_bits(codes[1][0], code_sizes[1][0]);
+	}
+
+	void jpeg_encoder::code_block(int component_num)
+	{
+		DCT2D(m_sample_array);
+		load_quantized_coefficients(component_num);
+		if (m_pass_num == 1)
+			code_coefficients_pass_one(component_num);
+		else
+			code_coefficients_pass_two(component_num);
+	}
+
+	void jpeg_encoder::process_mcu_row()
+	{
+		if (m_num_components == 1)
+		{
+			for (int i = 0; i < m_mcus_per_row; i++)
+			{
+				load_block_8_8_grey(i); code_block(0);
+			}
+		}
+		else if ((m_comp_h_samp[0] == 1) && (m_comp_v_samp[0] == 1))
+		{
+			for (int i = 0; i < m_mcus_per_row; i++)
+			{
+				load_block_8_8(i, 0, 0); code_block(0); load_block_8_8(i, 0, 1); code_block(1); load_block_8_8(i, 0, 2); code_block(2);
+			}
+		}
+		else if ((m_comp_h_samp[0] == 2) && (m_comp_v_samp[0] == 1))
+		{
+			for (int i = 0; i < m_mcus_per_row; i++)
+			{
+				load_block_8_8(i * 2 + 0, 0, 0); code_block(0); load_block_8_8(i * 2 + 1, 0, 0); code_block(0);
+				load_block_16_8_8(i, 1); code_block(1); load_block_16_8_8(i, 2); code_block(2);
+			}
+		}
+		else if ((m_comp_h_samp[0] == 2) && (m_comp_v_samp[0] == 2))
+		{
+			for (int i = 0; i < m_mcus_per_row; i++)
+			{
+				load_block_8_8(i * 2 + 0, 0, 0); code_block(0); load_block_8_8(i * 2 + 1, 0, 0); code_block(0);
+				load_block_8_8(i * 2 + 0, 1, 0); code_block(0); load_block_8_8(i * 2 + 1, 1, 0); code_block(0);
+				load_block_16_8(i, 1); code_block(1); load_block_16_8(i, 2); code_block(2);
+			}
+		}
+	}
+
+	bool jpeg_encoder::terminate_pass_one()
+	{
+		optimize_huffman_table(0 + 0, DC_LUM_CODES); optimize_huffman_table(2 + 0, AC_LUM_CODES);
+		if (m_num_components > 1)
+		{
+			optimize_huffman_table(0 + 1, DC_CHROMA_CODES); optimize_huffman_table(2 + 1, AC_CHROMA_CODES);
+		}
+		return second_pass_init();
+	}
+
+	bool jpeg_encoder::terminate_pass_two()
+	{
+		put_bits(0x7F, 7);
+		flush_output_buffer();
+		emit_marker(M_EOI);
+		m_pass_num++; // purposely bump up m_pass_num, for debugging
+		return true;
+	}
+
+	bool jpeg_encoder::process_end_of_image()
+	{
+		if (m_mcu_y_ofs)
+		{
+			if (m_mcu_y_ofs < 16) // check here just to shut up static analysis
+			{
+				for (int i = m_mcu_y_ofs; i < m_mcu_y; i++)
+					memcpy(m_mcu_lines[i], m_mcu_lines[m_mcu_y_ofs - 1], m_image_bpl_mcu);
+			}
+
+			process_mcu_row();
+		}
+
+		if (m_pass_num == 1)
+			return terminate_pass_one();
+		else
+			return terminate_pass_two();
+	}
+
+	void jpeg_encoder::load_mcu(const void* pSrc)
+	{
+		const uint8* Psrc = reinterpret_cast<const uint8*>(pSrc);
+
+		uint8* pDst = m_mcu_lines[m_mcu_y_ofs]; // OK to write up to m_image_bpl_xlt bytes to pDst
+
+		if (m_num_components == 1)
+		{
+			if (m_image_bpp == 4)
+				RGBA_to_Y(pDst, Psrc, m_image_x);
+			else if (m_image_bpp == 3)
+				RGB_to_Y(pDst, Psrc, m_image_x);
+			else
+				memcpy(pDst, Psrc, m_image_x);
+		}
+		else
+		{
+			if (m_image_bpp == 4)
+				RGBA_to_YCC(pDst, Psrc, m_image_x);
+			else if (m_image_bpp == 3)
+				RGB_to_YCC(pDst, Psrc, m_image_x);
+			else
+				Y_to_YCC(pDst, Psrc, m_image_x);
+		}
+
+		// Possibly duplicate pixels at end of scanline if not a multiple of 8 or 16
+		if (m_num_components == 1)
+			memset(m_mcu_lines[m_mcu_y_ofs] + m_image_bpl_xlt, pDst[m_image_bpl_xlt - 1], m_image_x_mcu - m_image_x);
+		else
+		{
+			const uint8 y = pDst[m_image_bpl_xlt - 3 + 0], cb = pDst[m_image_bpl_xlt - 3 + 1], cr = pDst[m_image_bpl_xlt - 3 + 2];
+			uint8* q = m_mcu_lines[m_mcu_y_ofs] + m_image_bpl_xlt;
+			for (int i = m_image_x; i < m_image_x_mcu; i++)
+			{
+				*q++ = y; *q++ = cb; *q++ = cr;
+			}
+		}
+
+		if (++m_mcu_y_ofs == m_mcu_y)
+		{
+			process_mcu_row();
+			m_mcu_y_ofs = 0;
+		}
+	}
+
+	void jpeg_encoder::clear()
+	{
+		m_mcu_lines[0] = NULL;
+		m_pass_num = 0;
+		m_all_stream_writes_succeeded = true;
+	}
+
+	jpeg_encoder::jpeg_encoder()
+	{
+		clear();
+	}
+
+	jpeg_encoder::~jpeg_encoder()
+	{
+		deinit();
+	}
+
+	bool jpeg_encoder::init(output_stream* pStream, int width, int height, int src_channels, const params& comp_params)
+	{
+		deinit();
+		if (((!pStream) || (width < 1) || (height < 1)) || ((src_channels != 1) && (src_channels != 3) && (src_channels != 4)) || (!comp_params.check())) return false;
+		m_pStream = pStream;
+		m_params = comp_params;
+		return jpg_open(width, height, src_channels);
+	}
+
+	void jpeg_encoder::deinit()
+	{
+		jpge_free(m_mcu_lines[0]);
+		clear();
+	}
+
+	bool jpeg_encoder::process_scanline(const void* pScanline)
+	{
+		if ((m_pass_num < 1) || (m_pass_num > 2)) return false;
+		if (m_all_stream_writes_succeeded)
+		{
+			if (!pScanline)
+			{
+				if (!process_end_of_image()) return false;
+			}
+			else
+			{
+				load_mcu(pScanline);
+			}
+		}
+		return m_all_stream_writes_succeeded;
+	}
+
+	// Higher level wrappers/examples (optional).
+#include <stdio.h>
+
+	class cfile_stream : public output_stream
+	{
+		cfile_stream(const cfile_stream&);
+		cfile_stream& operator= (const cfile_stream&);
+
+		FILE* m_pFile;
+		bool m_bStatus;
+
+	public:
+		cfile_stream() : m_pFile(NULL), m_bStatus(false) { }
+
+		virtual ~cfile_stream()
+		{
+			close();
+		}
+
+		bool open(const char* pFilename)
+		{
+			close();
+			m_pFile = fopen(pFilename, "wb");
+			m_bStatus = (m_pFile != NULL);
+			return m_bStatus;
+		}
+
+		bool close()
+		{
+			if (m_pFile)
+			{
+				if (fclose(m_pFile) == EOF)
+				{
+					m_bStatus = false;
+				}
+				m_pFile = NULL;
+			}
+			return m_bStatus;
+		}
+
+		virtual bool put_buf(const void* pBuf, int len)
+		{
+			m_bStatus = m_bStatus && (fwrite(pBuf, len, 1, m_pFile) == 1);
+			return m_bStatus;
+		}
+
+		uint get_size() const
+		{
+			return m_pFile ? ftell(m_pFile) : 0;
+		}
+	};
+
+	// Writes JPEG image to file.
+	bool compress_image_to_jpeg_file(const char* pFilename, int width, int height, int num_channels, const uint8* pImage_data, const params& comp_params)
+	{
+		cfile_stream dst_stream;
+		if (!dst_stream.open(pFilename))
+			return false;
+
+		jpge::jpeg_encoder dst_image;
+		if (!dst_image.init(&dst_stream, width, height, num_channels, comp_params))
+			return false;
+
+		for (uint pass_index = 0; pass_index < dst_image.get_total_passes(); pass_index++)
+		{
+			for (int i = 0; i < height; i++)
+			{
+				const uint8* pBuf = pImage_data + i * width * num_channels;
+				if (!dst_image.process_scanline(pBuf))
+					return false;
+			}
+			if (!dst_image.process_scanline(NULL))
+				return false;
+		}
+
+		dst_image.deinit();
+
+		return dst_stream.close();
+	}
+
+	class memory_stream : public output_stream
+	{
+		memory_stream(const memory_stream&);
+		memory_stream& operator= (const memory_stream&);
+
+		uint8* m_pBuf;
+		uint m_buf_size, m_buf_ofs;
+
+	public:
+		memory_stream(void* pBuf, uint buf_size) : m_pBuf(static_cast<uint8*>(pBuf)), m_buf_size(buf_size), m_buf_ofs(0) { }
+
+		virtual ~memory_stream() { }
+
+		virtual bool put_buf(const void* pBuf, int len)
+		{
+			uint buf_remaining = m_buf_size - m_buf_ofs;
+			if ((uint)len > buf_remaining)
+				return false;
+			memcpy(m_pBuf + m_buf_ofs, pBuf, len);
+			m_buf_ofs += len;
+			return true;
+		}
+
+		uint get_size() const
+		{
+			return m_buf_ofs;
+		}
+	};
+
+	bool compress_image_to_jpeg_file_in_memory(void* pDstBuf, int& buf_size, int width, int height, int num_channels, const uint8* pImage_data, const params& comp_params)
+	{
+		if ((!pDstBuf) || (!buf_size))
+			return false;
+
+		memory_stream dst_stream(pDstBuf, buf_size);
+
+		buf_size = 0;
+
+		jpge::jpeg_encoder dst_image;
+		if (!dst_image.init(&dst_stream, width, height, num_channels, comp_params))
+			return false;
+
+		for (uint pass_index = 0; pass_index < dst_image.get_total_passes(); pass_index++)
+		{
+			for (int i = 0; i < height; i++)
+			{
+				const uint8* pScanline = pImage_data + i * width * num_channels;
+				if (!dst_image.process_scanline(pScanline))
+					return false;
+			}
+			if (!dst_image.process_scanline(NULL))
+				return false;
+		}
+
+		dst_image.deinit();
+
+		buf_size = dst_stream.get_size();
+		return true;
+	}
+
+} // namespace jpge

src/jpeg-compressor/jpge.h

@@ -0,0 +1,173 @@
+// jpge.h - C++ class for JPEG compression.
+// Public Domain or Apache 2.0, Richard Geldreich <richgel99@gmail.com>
+// Alex Evans: Added RGBA support, linear memory allocator.
+#ifndef JPEG_ENCODER_H
+#define JPEG_ENCODER_H
+
+namespace jpge
+{
+	typedef unsigned char  uint8;
+	typedef signed short   int16;
+	typedef signed int     int32;
+	typedef unsigned short uint16;
+	typedef unsigned int   uint32;
+	typedef unsigned int   uint;
+
+	// JPEG chroma subsampling factors. Y_ONLY (grayscale images) and H2V2 (color images) are the most common.
+	enum subsampling_t { Y_ONLY = 0, H1V1 = 1, H2V1 = 2, H2V2 = 3 };
+
+	// JPEG compression parameters structure.
+	struct params
+	{
+		inline params() : m_quality(85), m_subsampling(H2V2), m_no_chroma_discrim_flag(false), m_two_pass_flag(false), m_use_std_tables(false) { }
+
+		inline bool check() const
+		{
+			if ((m_quality < 1) || (m_quality > 100)) return false;
+			if ((uint)m_subsampling > (uint)H2V2) return false;
+			return true;
+		}
+
+		// Quality: 1-100, higher is better. Typical values are around 50-95.
+		int m_quality;
+
+		// m_subsampling:
+		// 0 = Y (grayscale) only
+		// 1 = YCbCr, no subsampling (H1V1, YCbCr 1x1x1, 3 blocks per MCU)
+		// 2 = YCbCr, H2V1 subsampling (YCbCr 2x1x1, 4 blocks per MCU)
+		// 3 = YCbCr, H2V2 subsampling (YCbCr 4x1x1, 6 blocks per MCU-- very common)
+		subsampling_t m_subsampling;
+
+		// Disables CbCr discrimination - only intended for testing.
+		// If true, the Y quantization table is also used for the CbCr channels.
+		bool m_no_chroma_discrim_flag;
+
+		bool m_two_pass_flag;
+
+		// By default we use the same quantization tables as mozjpeg's default. 
+		// Set to true to use the traditional tables from JPEG Annex K.
+		bool m_use_std_tables;
+	};
+
+	// Writes JPEG image to a file. 
+	// num_channels must be 1 (Y) or 3 (RGB), image pitch must be width*num_channels.
+	bool compress_image_to_jpeg_file(const char* pFilename, int width, int height, int num_channels, const uint8* pImage_data, const params& comp_params = params());
+
+	// Writes JPEG image to memory buffer. 
+	// On entry, buf_size is the size of the output buffer pointed at by pBuf, which should be at least ~1024 bytes. 
+	// If return value is true, buf_size will be set to the size of the compressed data.
+	bool compress_image_to_jpeg_file_in_memory(void* pBuf, int& buf_size, int width, int height, int num_channels, const uint8* pImage_data, const params& comp_params = params());
+
+	// Output stream abstract class - used by the jpeg_encoder class to write to the output stream. 
+	// put_buf() is generally called with len==JPGE_OUT_BUF_SIZE bytes, but for headers it'll be called with smaller amounts.
+	class output_stream
+	{
+	public:
+		virtual ~output_stream() { };
+		virtual bool put_buf(const void* Pbuf, int len) = 0;
+		template<class T> inline bool put_obj(const T& obj) { return put_buf(&obj, sizeof(T)); }
+	};
+
+	// Lower level jpeg_encoder class - useful if more control is needed than the above helper functions.
+	class jpeg_encoder
+	{
+	public:
+		jpeg_encoder();
+		~jpeg_encoder();
+
+		// Initializes the compressor.
+		// pStream: The stream object to use for writing compressed data.
+		// params - Compression parameters structure, defined above.
+		// width, height  - Image dimensions.
+		// channels - May be 1, or 3. 1 indicates grayscale, 3 indicates RGB source data.
+		// Returns false on out of memory or if a stream write fails.
+		bool init(output_stream* pStream, int width, int height, int src_channels, const params& comp_params = params());
+
+		const params& get_params() const { return m_params; }
+
+		// Deinitializes the compressor, freeing any allocated memory. May be called at any time.
+		void deinit();
+
+		uint get_total_passes() const { return m_params.m_two_pass_flag ? 2 : 1; }
+		inline uint get_cur_pass() { return m_pass_num; }
+
+		// Call this method with each source scanline.
+		// width * src_channels bytes per scanline is expected (RGB or Y format).
+		// You must call with NULL after all scanlines are processed to finish compression.
+		// Returns false on out of memory or if a stream write fails.
+		bool process_scanline(const void* pScanline);
+
+	private:
+		jpeg_encoder(const jpeg_encoder&);
+		jpeg_encoder& operator =(const jpeg_encoder&);
+
+		typedef int32 sample_array_t;
+
+		output_stream* m_pStream;
+		params m_params;
+		uint8 m_num_components;
+		uint8 m_comp_h_samp[3], m_comp_v_samp[3];
+		int m_image_x, m_image_y, m_image_bpp, m_image_bpl;
+		int m_image_x_mcu, m_image_y_mcu;
+		int m_image_bpl_xlt, m_image_bpl_mcu;
+		int m_mcus_per_row;
+		int m_mcu_x, m_mcu_y;
+		uint8* m_mcu_lines[16];
+		uint8 m_mcu_y_ofs;
+		sample_array_t m_sample_array[64];
+		int16 m_coefficient_array[64];
+		int32 m_quantization_tables[2][64];
+		uint m_huff_codes[4][256];
+		uint8 m_huff_code_sizes[4][256];
+		uint8 m_huff_bits[4][17];
+		uint8 m_huff_val[4][256];
+		uint32 m_huff_count[4][256];
+		int m_last_dc_val[3];
+		enum { JPGE_OUT_BUF_SIZE = 2048 };
+		uint8 m_out_buf[JPGE_OUT_BUF_SIZE];
+		uint8* m_pOut_buf;
+		uint m_out_buf_left;
+		uint32 m_bit_buffer;
+		uint m_bits_in;
+		uint8 m_pass_num;
+		bool m_all_stream_writes_succeeded;
+
+		void optimize_huffman_table(int table_num, int table_len);
+		void emit_byte(uint8 i);
+		void emit_word(uint i);
+		void emit_marker(int marker);
+		void emit_jfif_app0();
+		void emit_dqt();
+		void emit_sof();
+		void emit_dht(uint8* bits, uint8* val, int index, bool ac_flag);
+		void emit_dhts();
+		void emit_sos();
+		void emit_markers();
+		void compute_huffman_table(uint* codes, uint8* code_sizes, uint8* bits, uint8* val);
+		void compute_quant_table(int32* dst, int16* src);
+		void adjust_quant_table(int32* dst, int32* src);
+		void first_pass_init();
+		bool second_pass_init();
+		bool jpg_open(int p_x_res, int p_y_res, int src_channels);
+		void load_block_8_8_grey(int x);
+		void load_block_8_8(int x, int y, int c);
+		void load_block_16_8(int x, int c);
+		void load_block_16_8_8(int x, int c);
+		void load_quantized_coefficients(int component_num);
+		void flush_output_buffer();
+		void put_bits(uint bits, uint len);
+		void code_coefficients_pass_one(int component_num);
+		void code_coefficients_pass_two(int component_num);
+		void code_block(int component_num);
+		void process_mcu_row();
+		bool terminate_pass_one();
+		bool terminate_pass_two();
+		bool process_end_of_image();
+		void load_mcu(const void* src);
+		void clear();
+		void init();
+	};
+
+} // namespace jpge
+
+#endif // JPEG_ENCODER

src/libslic3r/CMakeLists.txt

@@ -109,6 +109,8 @@ add_library(libslic3r STATIC
     Format/CWS.cpp
     GCode/ThumbnailData.cpp
     GCode/ThumbnailData.hpp
+    GCode/Thumbnails.cpp
+    GCode/Thumbnails.hpp
     GCode/CoolingBuffer.cpp
     GCode/CoolingBuffer.hpp
     GCode/FanMover.cpp
@@ -371,6 +373,8 @@ target_link_libraries(libslic3r
     ${CMAKE_DL_LIBS}
     PNG::PNG
     ZLIB::ZLIB
+    qoi
+	jpeg-compressor
     )
 
 if (TARGET OpenVDB::openvdb)

src/libslic3r/GCode.cpp

@@ -7,6 +7,7 @@
 #include "Geometry/ConvexHull.hpp"
 #include "GCode/FanMover.hpp"
 #include "GCode/PrintExtents.hpp"
+#include "GCode/Thumbnails.hpp"
 #include "GCode/WipeTower.hpp"
 #include "ShortestPath.hpp"
 #include "PrintConfig.hpp"
@@ -58,8 +59,6 @@
 
 #include <Shiny/Shiny.h>
 
-#include "miniz_extension.hpp"
-
 using namespace std::literals::string_view_literals;
 
 #if 0
@@ -1098,56 +1097,6 @@ namespace DoExport {
 	    }
 	}
 
-	template<typename WriteToOutput, typename ThrowIfCanceledCallback>
-	static void export_thumbnails_to_file(ThumbnailsGeneratorCallback &thumbnail_cb, const std::vector<Vec2d> &sizes, bool thumbnails_with_bed, WriteToOutput output, ThrowIfCanceledCallback throw_if_canceled)
-	{
-	    // Write thumbnails using base64 encoding
-	    if (thumbnail_cb != nullptr)
-	    {
-            std::vector<Vec2d> good_sizes;
-            for (const Vec2d &size : sizes)
-                if (size.x() > 0 && size.y() > 0)
-                    good_sizes.push_back(size);
-            if (good_sizes.empty()) return;
-
-            //Create the thumbnails
-	        const size_t max_row_length = 78;
-            ThumbnailsList thumbnails = thumbnail_cb(ThumbnailsParams{ sizes, true, true, thumbnails_with_bed, true });
-	        for (const ThumbnailData& data : thumbnails)
-	        {
-	            if (data.is_valid())
-	            {
-	                size_t png_size = 0;
-	                void* png_data = tdefl_write_image_to_png_file_in_memory_ex((const void*)data.pixels.data(), data.width, data.height, 4, &png_size, MZ_DEFAULT_LEVEL, 1);
-	                if (png_data != nullptr)
-	                {
-	                    std::string encoded;
-	                    encoded.resize(boost::beast::detail::base64::encoded_size(png_size));
-	                    encoded.resize(boost::beast::detail::base64::encode((void*)&encoded[0], (const void*)png_data, png_size));
-
-	                    output((boost::format("\n;\n; thumbnail begin %dx%d %d\n") % data.width % data.height % encoded.size()).str().c_str());
-
-	                    unsigned int row_count = 0;
-	                    while (encoded.size() > max_row_length)
-	                    {
-	                        output((boost::format("; %s\n") % encoded.substr(0, max_row_length)).str().c_str());
-	                        encoded = encoded.substr(max_row_length);
-	                        ++row_count;
-	                    }
-
-	                    if (encoded.size() > 0)
-	                    	output((boost::format("; %s\n") % encoded).str().c_str());
-
-	                    output("; thumbnail end\n;\n");
-
-	                    mz_free(png_data);
-	                }
-	            }
-	            throw_if_canceled();
-	        }
-	    }
-	}
-
 	// Fill in print_statistics and return formatted string containing filament statistics to be inserted into G-code comment section.
 	static std::string update_print_stats_and_format_filament_stats(
 	    const bool                   has_wipe_tower,
@@ -1386,14 +1335,17 @@ void GCode::_do_export(Print& print, GCodeOutputStream &file, ThumbnailsGenerato
 
 
     //print thumbnails at the start unless requested at the end.
-    const ConfigOptionBool* thumbnails_with_bed = print.full_print_config().option<ConfigOptionBool>("thumbnails_with_bed");
     const ConfigOptionBool* thumbnails_end_file = print.full_print_config().option<ConfigOptionBool>("thumbnails_end_file");
-    if(!thumbnails_end_file || !thumbnails_end_file->value)
-        DoExport::export_thumbnails_to_file(thumbnail_cb, 
+    if(!thumbnails_end_file || !thumbnails_end_file->value) {
+        const ConfigOptionBool* thumbnails_with_bed = print.full_print_config().option<ConfigOptionBool>("thumbnails_with_bed");
+        const ConfigOptionEnum<GCodeThumbnailsFormat>* thumbnails_format = print.full_print_config().option<ConfigOptionEnum<GCodeThumbnailsFormat>>("thumbnails_format");
+        GCodeThumbnails::export_thumbnails_to_file(thumbnail_cb,
             print.full_print_config().option<ConfigOptionPoints>("thumbnails")->values,
-            thumbnails_with_bed==nullptr? false:thumbnails_with_bed->value,
-            [&file](const char* sz) { file.write(sz); }, 
+            thumbnails_with_bed == nullptr ? false : thumbnails_with_bed->value,
+            thumbnails_format ? thumbnails_format->value : GCodeThumbnailsFormat::PNG,
+            [&file](const char* sz) { file.write(sz); },
             [&print]() { print.throw_if_canceled(); });
+    }
 
     // Write notes (content of the Print Settings tab -> Notes)
     {
@@ -1986,12 +1938,16 @@ void GCode::_do_export(Print& print, GCodeOutputStream &file, ThumbnailsGenerato
     print.throw_if_canceled();
 
     //print thumbnails at the end instead of the start if requested
-    if (thumbnails_end_file && thumbnails_end_file->value)
-        DoExport::export_thumbnails_to_file(thumbnail_cb,
+    if (thumbnails_end_file && thumbnails_end_file->value) {
+        const ConfigOptionBool* thumbnails_with_bed = print.full_print_config().option<ConfigOptionBool>("thumbnails_with_bed");
+        const ConfigOptionEnum<GCodeThumbnailsFormat>* thumbnails_format = print.full_print_config().option<ConfigOptionEnum<GCodeThumbnailsFormat>>("thumbnails_format");
+        GCodeThumbnails::export_thumbnails_to_file(thumbnail_cb, 
             print.full_print_config().option<ConfigOptionPoints>("thumbnails")->values,
-            thumbnails_with_bed == nullptr ? false : thumbnails_with_bed->value,
+            thumbnails_with_bed==nullptr? false:thumbnails_with_bed->value,
+            thumbnails_format ? thumbnails_format->value : GCodeThumbnailsFormat::PNG,
             [&file](const char* sz) { file.write(sz); },
             [&print]() { print.throw_if_canceled(); });
+    }
     print.throw_if_canceled();
 }
 

src/libslic3r/GCode/Thumbnails.cpp

@@ -0,0 +1,97 @@
+#include "Thumbnails.hpp"
+#include "../miniz_extension.hpp"
+
+#include <qoi/qoi.h>
+#include <jpeg-compressor/jpge.h>
+
+namespace Slic3r::GCodeThumbnails {
+
+using namespace std::literals;
+
+struct CompressedPNG : CompressedImageBuffer 
+{
+    ~CompressedPNG() override { if (data) mz_free(data); }
+    std::string_view tag() const override { return "thumbnail"sv; }
+};
+
+struct CompressedJPG : CompressedImageBuffer
+{
+    ~CompressedJPG() override { free(data); }
+    std::string_view tag() const override { return "thumbnail_JPG"sv; }
+};
+
+struct CompressedQOI : CompressedImageBuffer 
+{
+    ~CompressedQOI() override { free(data); }
+    std::string_view tag() const override { return "thumbnail_QOI"sv; }
+};
+
+std::unique_ptr<CompressedImageBuffer> compress_thumbnail_png(const ThumbnailData &data)
+{
+    auto out = std::make_unique<CompressedPNG>();
+    out->data = tdefl_write_image_to_png_file_in_memory_ex((const void*)data.pixels.data(), data.width, data.height, 4, &out->size, MZ_DEFAULT_LEVEL, 1);
+    return out;
+}
+
+std::unique_ptr<CompressedImageBuffer> compress_thumbnail_jpg(const ThumbnailData& data)
+{
+    // Take vector of RGBA pixels and flip the image vertically
+    std::vector<uint8_t> rgba_pixels(data.pixels.size());
+    const size_t row_size = data.width * 4;
+    for (size_t y = 0; y < data.height; ++y)
+        ::memcpy(rgba_pixels.data() + (data.height - y - 1) * row_size, data.pixels.data() + y * row_size, row_size);
+
+    auto out = std::make_unique<CompressedJPG>();
+
+    std::vector<jpge::uint8> compressed_data(data.pixels.size());
+    jpge::params params;
+    params.m_quality = 85;
+    params.m_subsampling = jpge::H2V2;
+    params.m_no_chroma_discrim_flag = false;
+    params.m_two_pass_flag = false;
+    params.m_use_std_tables = false;
+
+    int compressed_data_size = int(compressed_data.size());
+    if (jpge::compress_image_to_jpeg_file_in_memory(compressed_data.data(), compressed_data_size, data.width, data.height, 4, rgba_pixels.data(), params)) {
+        out->data = malloc(compressed_data_size);
+        out->size = size_t(compressed_data_size);
+        ::memcpy(out->data, (const void*)compressed_data.data(), out->size);
+    }
+    return out;
+}
+
+std::unique_ptr<CompressedImageBuffer> compress_thumbnail_qoi(const ThumbnailData &data)
+{
+    qoi_desc desc;
+    desc.width      = data.width;
+    desc.height     = data.height;
+    desc.channels   = 4;
+    desc.colorspace = QOI_SRGB;
+
+    // Take vector of RGBA pixels and flip the image vertically
+    std::vector<uint8_t> rgba_pixels(data.pixels.size() * 4);
+    size_t row_size = data.width * 4;
+    for (size_t y = 0; y < data.height; ++ y)
+        memcpy(rgba_pixels.data() + (data.height - y - 1) * row_size, data.pixels.data() + y * row_size, row_size);
+    
+    auto out = std::make_unique<CompressedQOI>();
+    int  size;
+    out->data = qoi_encode((const void*)rgba_pixels.data(), &desc, &size);
+    out->size = size;
+    return out;
+}
+
+std::unique_ptr<CompressedImageBuffer> compress_thumbnail(const ThumbnailData &data, GCodeThumbnailsFormat format)
+{
+    switch (format) {
+        case GCodeThumbnailsFormat::PNG:
+        default:
+            return compress_thumbnail_png(data);
+        case GCodeThumbnailsFormat::JPG:
+            return compress_thumbnail_jpg(data);
+        case GCodeThumbnailsFormat::QOI:
+            return compress_thumbnail_qoi(data);
+    }
+}
+
+} // namespace Slic3r::GCodeThumbnails

src/libslic3r/GCode/Thumbnails.hpp

@@ -0,0 +1,67 @@
+#ifndef slic3r_GCodeThumbnails_hpp_
+#define slic3r_GCodeThumbnails_hpp_
+
+#include "../Point.hpp"
+#include "../PrintConfig.hpp"
+#include "ThumbnailData.hpp"
+
+#include <vector>
+#include <memory>
+#include <string_view>
+
+#include <boost/beast/core/detail/base64.hpp>
+
+namespace Slic3r::GCodeThumbnails {
+
+struct CompressedImageBuffer
+{
+    void       *data { nullptr };
+    size_t      size { 0 };
+    virtual ~CompressedImageBuffer() {}
+    virtual std::string_view tag() const = 0;
+};
+
+std::unique_ptr<CompressedImageBuffer> compress_thumbnail(const ThumbnailData &data, GCodeThumbnailsFormat format);
+
+template<typename WriteToOutput, typename ThrowIfCanceledCallback>
+inline void export_thumbnails_to_file(ThumbnailsGeneratorCallback &thumbnail_cb, const std::vector<Vec2d> &sizes, bool with_bed, GCodeThumbnailsFormat format, WriteToOutput output, ThrowIfCanceledCallback throw_if_canceled)
+{
+    // Write thumbnails using base64 encoding
+    if (thumbnail_cb != nullptr) {
+        std::vector<Vec2d> good_sizes;
+        for (const Vec2d& size : sizes)
+            if (size.x() > 0 && size.y() > 0)
+                good_sizes.push_back(size);
+        if (good_sizes.empty()) return;
+
+        //Create the thumbnails
+        static constexpr const size_t max_row_length = 78;
+        ThumbnailsList thumbnails = thumbnail_cb(ThumbnailsParams{ good_sizes, true, true, with_bed, true });
+        for (const ThumbnailData& data : thumbnails)
+            if (data.is_valid()) {
+                auto compressed = compress_thumbnail(data, format);
+                if (compressed->data && compressed->size) {
+                    std::string encoded;
+                    encoded.resize(boost::beast::detail::base64::encoded_size(compressed->size));
+                    encoded.resize(boost::beast::detail::base64::encode((void*)encoded.data(), (const void*)compressed->data, compressed->size));
+
+                    output((boost::format("\n;\n; %s begin %dx%d %d\n") % compressed->tag() % data.width % data.height % encoded.size()).str().c_str());
+
+                    while (encoded.size() > max_row_length) {
+                        output((boost::format("; %s\n") % encoded.substr(0, max_row_length)).str().c_str());
+                        encoded = encoded.substr(max_row_length);
+                    }
+
+                    if (encoded.size() > 0)
+                        output((boost::format("; %s\n") % encoded).str().c_str());
+
+                    output((boost::format("; %s end\n;\n") % compressed->tag()).str().c_str());
+                }
+                throw_if_canceled();
+            }
+    }
+}
+
+} // namespace Slic3r::GCodeThumbnails
+
+#endif // slic3r_GCodeThumbnails_hpp_