Re: JPEG Support For Libcairo

From f5c26f8c56b6cf6da96ece3c8527c7b1af8d7970 Mon Sep 17 00:00:00 2001
From: "Enrico Weigelt, metux IT consult" <[email protected]>
Date: Tue, 29 Dec 2015 02:59:36 +0100
Subject: [PATCH 3/3] jpeg: build rules for jpeg functions

---
 configure.ac         | 12 ++++++++++++
 src/Makefile.sources |  3 +++
 2 files changed, 15 insertions(+)

diff --git a/configure.ac b/configure.ac
index 2ce1959..a0cca2b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -344,6 +344,18 @@ CAIRO_ENABLE_FUNCTIONS(png, PNG, yes, [
 ])
 
 dnl ===========================================================================
+
+CAIRO_ENABLE_FUNCTIONS(jpeg, JPEG, yes, [
+  use_jpeg=no
+  PKG_CHECK_MODULES(jpeg, libjpeg, use_jpeg="yes", use_jpeg="no")
+
+  dnl try to find it the classical way
+  if test "$use_jpeg" = "no" ; then
+    AC_CHECK_LIB(jpeg,jpeg_start_compress,jpeg_LIBS="-ljpeg"; use_jpeg="yes",use_jpeg="no")
+  fi
+])
+
+dnl ===========================================================================
 CAIRO_ENABLE_SURFACE_BACKEND(gl, OpenGL, no, [
   gl_REQUIRES="gl"
   PKG_CHECK_MODULES(gl, $gl_REQUIRES,, [
diff --git a/src/Makefile.sources b/src/Makefile.sources
index fac24d7..f33000a 100644
--- a/src/Makefile.sources
+++ b/src/Makefile.sources
@@ -271,6 +271,9 @@ cairo_sources += $(_cairo_pdf_operators_sources)
 
 cairo_png_sources = cairo-png.c
 
+cairo_jpeg_sources = imagesource/cairo-jpeg.c
+cairo_jpeg_headers = imagesource/cairo-jpeg.h
+
 cairo_ps_headers = cairo-ps.h
 cairo_ps_private = cairo-ps-surface-private.h
 cairo_ps_sources = cairo-ps-surface.c
-- 
2.6.4.442.g545299f

From 0ca9321153f5132f60eb878e9dca07bb530e3643 Mon Sep 17 00:00:00 2001
From: "Enrico Weigelt, metux IT consult" <[email protected]>
Date: Tue, 29 Dec 2015 02:11:17 +0100
Subject: [PATCH 2/3] jpeg: public header for jpeg-related functions

---
 src/imagesource/cairo-jpeg.h | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 src/imagesource/cairo-jpeg.h

diff --git a/src/imagesource/cairo-jpeg.h b/src/imagesource/cairo-jpeg.h
new file mode 100644
index 0000000..7f9db36
--- /dev/null
+++ b/src/imagesource/cairo-jpeg.h
@@ -0,0 +1,40 @@
+#ifndef __CAIRO_JPEG_H_PUB
+#define __CAIRO_JPEG_H_PUB
+
+/**
+ * Public interface for Cairo's public JPEG API.
+ *
+ * Only available when Cairo was compiled w/ JPEG support
+ */
+
+#include <cairo.h>
+
+/**
+ * Create a new image surface from JPEG image file.
+ *
+ * @param	fn		name of the jpeg file.
+ *
+ * @return	pointer to cairo_surface_t structure.
+ *		may never be NULL, but the surface be in error state
+ */
+cairo_surface_t *cairo_image_surface_create_from_jpeg(const char *fn);
+
+/**
+ * Store image surface into JPEG file.
+ *
+ * @param	sfc	pointer to image surface structure
+ *			currently only supports the following pixel formats:
+ *			CAIRO_FORMAT_ARGB32 or CAIRO_FORMAT_RGB24
+ * @param	fn	JPEG target filename
+ * @param	quality	Compression quality, 0-100.
+ *
+ * @return	CAIRO_STATUS_SUCCESS (0)	if everything went fine
+ *		CAIRO_STATUS_FILE_NOT_FOUND	if file could not be opened
+ *						(errno is set accordingly)
+ *		CAIRO_STATUS_INVALID_FORMAT	if sfc has an invalid format
+ */
+cairo_status_t cairo_image_surface_write_to_jpeg(cairo_surface_t *sfc,
+						 const char *fn,
+						 int quality);
+
+#endif /* __CAIRO_JPEG_H_PUB */
-- 
2.6.4.442.g545299f

From a45124526f0a10e98e66b27c587e643cbcb3a4b3 Mon Sep 17 00:00:00 2001
From: "Bernhard R. Fischer, 2048R/5C5FFD47" <[email protected]>
Date: Tue, 29 Dec 2015 02:10:41 +0100
Subject: [PATCH 1/3] jpeg: added jpeg load/store sources

---
 src/imagesource/cairo-jpeg.c | 152 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 152 insertions(+)
 create mode 100644 src/imagesource/cairo-jpeg.c

diff --git a/src/imagesource/cairo-jpeg.c b/src/imagesource/cairo-jpeg.c
new file mode 100644
index 0000000..dc1303d
--- /dev/null
+++ b/src/imagesource/cairo-jpeg.c
@@ -0,0 +1,152 @@
+/*! This file contains two functions for reading and writing JPEG files from
+ * and to Cairo image surfaces. It uses the functions from the libjpeg.
+ * Most of the code is directly derived from the online example at
+ * http://libjpeg-turbo.virtualgl.org/Documentation/Documentation
+ *
+ * cairo_status_t cairo_image_surface_write_to_jpeg(cairo_surface_t *sfc, const char *filename, int quality)
+ * cairo_surface_t *cairo_image_surface_create_from_jpeg(const char *filename);
+ *
+ * The functions parameters and return values are described below directly at the functions.
+ *
+ * To compile the code you need to have installed the packages libcairo2-dev
+ * and libjpeg-dev.
+ * Compile with
+ * gcc -Wall -g `pkg-config cairo libjpeg --cflags --libs` cairo_jpg.c
+ *
+ * @author Bernhard R. Fischer, 2048R/5C5FFD47 [email protected]
+ * @version 2015/12/28
+ * @license This code is free software. Do whatever you like to do with it.
+ */
+
+#include <stdio.h>
+#include <cairo.h>
+#include <jpeglib.h>
+
+
+/*! This function creates a JPEG file from a Cairo image surface.
+ * @param sfc Pointer to a Cairo *image* surface. Its format must either be
+ * CAIRO_FORMAT_ARGB32 or CAIRO_FORMAT_RGB24. Other formats are not supported
+ * by this function, yet.
+ * @param filename Pointer to filename of the destination file.
+ * @param quality Compression quality, 0-100.
+ * @return On success, the function returns 0. If the file could not be opened,
+ * CAIRO_STATUS_FILE_NOT_FOUND is returned and errno is set according to fopen(3). If sfc has an invalid
+ *  format CAIRO_STATUS_INVALID_FORMAT is returned.
+ */
+cairo_status_t cairo_image_surface_write_to_jpeg(cairo_surface_t *sfc, const char *filename, int quality)
+{
+   struct jpeg_compress_struct cinfo;
+   struct jpeg_error_mgr jerr;
+   FILE *outfile;
+   JSAMPROW row_pointer[1];
+
+   // check valid input format
+   if (cairo_surface_get_type(sfc) != CAIRO_SURFACE_TYPE_IMAGE &&
+         cairo_image_surface_get_format(sfc) != CAIRO_FORMAT_ARGB32 &&
+         cairo_image_surface_get_format(sfc) != CAIRO_FORMAT_RGB24)
+      return CAIRO_STATUS_INVALID_FORMAT;
+
+   // finish queued drawing operations
+   cairo_surface_flush(sfc);
+
+   // init jpeg compression structures
+   cinfo.err = jpeg_std_error(&jerr);
+   jpeg_create_compress(&cinfo);
+
+   // open file
+   if ((outfile = fopen(filename, "wb")) == NULL)
+      return CAIRO_STATUS_FILE_NOT_FOUND;
+
+   // set compression parameters
+   jpeg_stdio_dest(&cinfo, outfile);
+   cinfo.image_width = cairo_image_surface_get_width(sfc);
+   cinfo.image_height = cairo_image_surface_get_height(sfc);
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+   cinfo.in_color_space = JCS_EXT_BGRX;
+#else
+   cinfo.in_color_space = JCS_EXT_XRGB;
+#endif
+   cinfo.input_components = 4;
+   jpeg_set_defaults(&cinfo);
+   jpeg_set_quality(&cinfo, quality, TRUE);
+
+   // start compressor
+   jpeg_start_compress(&cinfo, TRUE);
+
+   // loop over all lines and compress
+   while (cinfo.next_scanline < cinfo.image_height)
+   {
+      row_pointer[0] = cairo_image_surface_get_data(sfc) + (cinfo.next_scanline
+            * cairo_image_surface_get_stride(sfc));
+      (void) jpeg_write_scanlines(&cinfo, row_pointer, 1);
+   }
+
+   // finalize and close everything
+   jpeg_finish_compress(&cinfo);
+   fclose(outfile);
+   jpeg_destroy_compress(&cinfo);
+
+   return CAIRO_STATUS_SUCCESS;
+}
+
+
+/*! This function reads an JPEG image from a file an creates a Cairo image
+ * surface.
+ * @param filename Pointer to filename of JPEG file.
+ * @return Returns a pointer to a cairo_surface_t structure. It should be
+ * checked with cairo_surface_status() for errors.
+ */
+cairo_surface_t *cairo_image_surface_create_from_jpeg(const char *filename)
+{
+   struct jpeg_decompress_struct cinfo;
+   struct jpeg_error_mgr jerr;
+   FILE * infile;
+   JSAMPROW row_pointer[1];
+   cairo_surface_t *sfc;
+
+   // open input file
+   if ((infile = fopen(filename, "rb")) == NULL)
+      //return NULL;
+      return cairo_image_surface_create(CAIRO_FORMAT_INVALID, 0, 0);
+
+   // initialize jpeg decompression structures
+   cinfo.err = jpeg_std_error(&jerr);
+   jpeg_create_decompress(&cinfo);
+   jpeg_stdio_src(&cinfo, infile);
+   (void) jpeg_read_header(&cinfo, TRUE);
+
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+   cinfo.out_color_space = JCS_EXT_BGRA;
+#else
+   cinfo.out_color_space = JCS_EXT_ARGB;
+#endif
+
+   // start decompressor
+   (void) jpeg_start_decompress(&cinfo);
+
+   // create Cairo image surface
+   sfc = cairo_image_surface_create(CAIRO_FORMAT_RGB24, cinfo.output_width, cinfo.output_height);
+   if (cairo_surface_status(sfc) != CAIRO_STATUS_SUCCESS)
+   {
+      fclose(infile);
+      jpeg_destroy_decompress(&cinfo);
+      return sfc;
+   }
+
+
+   // loop over all scanlines and fill Cairo image surface
+   while (cinfo.output_scanline < cinfo.output_height)
+   {
+      row_pointer[0] = cairo_image_surface_get_data(sfc) +
+         (cinfo.output_scanline * cairo_image_surface_get_stride(sfc));
+      (void) jpeg_read_scanlines(&cinfo, row_pointer, 1);
+   }
+
+   // finish and close everything
+   cairo_surface_mark_dirty(sfc);
+   (void) jpeg_finish_decompress(&cinfo);
+   jpeg_destroy_decompress(&cinfo);
+   fclose(infile);
+
+   return sfc;
+}
-- 
2.6.4.442.g545299f