cairo-util: Add helper to load jpeg files

clients/cairo-util.c

@@ -28,6 +28,8 @@
 #include <cairo.h>
 #include "cairo-util.h"
 
+#include <jpeglib.h>
+
 #define ARRAY_LENGTH(a) (sizeof (a) / sizeof (a)[0])
 
 void
@@ -286,3 +288,55 @@ rounded_rect(cairo_t *cr, int x0, int y0, int x1, int y1, int radius)
 	cairo_arc(cr, x0 + radius, y1 - radius, radius, M_PI / 2, M_PI);
 	cairo_close_path(cr);
 }
+
+cairo_surface_t *
+load_jpeg(const char *filename)
+{
+	struct jpeg_decompress_struct cinfo;
+	struct jpeg_error_mgr jerr;
+	FILE *fp;
+	int stride, i;
+	JSAMPLE *data, *rows[4];
+
+	cinfo.err = jpeg_std_error(&jerr);
+	jpeg_create_decompress(&cinfo);
+
+	fp = fopen(filename, "rb");
+	if (fp == NULL) {
+		fprintf(stderr, "can't open %s\n", filename);
+		return NULL;
+	}
+	jpeg_stdio_src(&cinfo, fp);
+
+	jpeg_read_header(&cinfo, TRUE);
+
+	cinfo.out_color_space = JCS_EXT_BGRX;
+	jpeg_start_decompress(&cinfo);
+
+	stride = cairo_format_stride_for_width(CAIRO_FORMAT_RGB24,
+					       cinfo.output_width);
+	data = malloc(stride * cinfo.output_height);
+	if (data == NULL) {
+		fprintf(stderr, "couldn't allocate image data\n");
+		return NULL;
+	}
+
+	while (cinfo.output_scanline < cinfo.output_height) {
+		for (i = 0; i < ARRAY_LENGTH(rows); i++, p += stride)
+			rows[i] = data + (cinfo.output_scanline + i) * stride;
+
+		jpeg_read_scanlines(&cinfo, rows, ARRAY_LENGTH(rows));
+	}
+
+	jpeg_finish_decompress(&cinfo);
+
+	fclose(fp);
+
+	jpeg_destroy_decompress(&cinfo);
+
+	return cairo_image_surface_create_for_data (data,
+						    CAIRO_FORMAT_RGB24,
+						    cinfo.output_width,
+						    cinfo.output_height,
+						    stride);
+}

clients/cairo-util.h

@@ -40,4 +40,7 @@ tile_source(cairo_t *cr, cairo_surface_t *surface,
 void
 rounded_rect(cairo_t *cr, int x0, int y0, int x1, int y1, int radius);
 
+cairo_surface_t *
+load_jpeg(const char *filename);
+
 #endif

clients/desktop-shell.c

@@ -32,6 +32,7 @@
 #include <linux/input.h>
 
 #include "wayland-client.h"
+#include "cairo-util.h"
 #include "window.h"
 
 #include <desktop-shell-client-protocol.h>
@@ -241,7 +242,7 @@ background_draw(struct window *window, int width, int height, const char *path)
 	cairo_paint(cr);
 
 	if (path) {
-		image = cairo_image_surface_create_from_png(path);
+		image = load_jpeg(path);
 		pattern = cairo_pattern_create_for_surface(image);
 		sx = (double) cairo_image_surface_get_width(image) / width;
 		sy = (double) cairo_image_surface_get_height(image) / height;
@@ -250,6 +251,7 @@ background_draw(struct window *window, int width, int height, const char *path)
 		cairo_set_source(cr, pattern);
 		cairo_pattern_destroy (pattern);
 		cairo_paint(cr);
+		cairo_surface_destroy(image);
 	}
 
 	cairo_destroy(cr);

configure.ac

@@ -113,6 +113,14 @@ if test x$enable_clients == xyes; then
   AS_IF([test "x$have_cairo_egl" = "xyes"],
         [AC_DEFINE([HAVE_CAIRO_EGL], [1], [Have cairo-egl])],
         [AC_MSG_WARN([Cairo-EGL not found - clients will use cairo image])])
+
+  AC_CHECK_LIB([jpeg], [jpeg_CreateDecompress], have_jpeglib=yes)
+  if test x$have_jpeglib == xyes; then
+    CLIENT_LIBS="$CLIENT_LIBS -ljpeg"
+  else
+    AC_ERROR([libjpeg not found])
+  fi
+
 fi
 
 AM_CONDITIONAL(HAVE_POPPLER, test "x$have_poppler" = "xyes")