Image: JPEG: Decode to client bitmap format where possible.

1 files changed, 125 insertions, 51 deletions

diff --git a/content/handlers/image/jpeg.c b/content/handlers/image/jpeg.c
index 7d635f90c..e07fb47bb 100644
--- a/content/handlers/image/jpeg.c
+++ b/content/handlers/image/jpeg.c
@@ -161,6 +161,94 @@ static void nsjpeg_error_exit(j_common_ptr cinfo)
 }
 
 /**
+ * Convert scan lines from CMYK to core client bitmap layout.
+ */
+static inline void nsjpeg__decode_cmyk(
+		struct jpeg_decompress_struct *cinfo,
+		uint8_t * volatile pixels,
+		size_t rowstride)
+{
+	int width = cinfo->output_width * 4;
+
+	do {
+		JSAMPROW scanlines[1] = {
+			[0] = (JSAMPROW)
+				(pixels + rowstride * cinfo->output_scanline),
+		};
+		jpeg_read_scanlines(cinfo, scanlines, 1);
+
+		for (int i = width - 4; 0 <= i; i -= 4) {
+			/* Trivial inverse CMYK -> RGBA */
+			const int c = scanlines[0][i + 0];
+			const int m = scanlines[0][i + 1];
+			const int y = scanlines[0][i + 2];
+			const int k = scanlines[0][i + 3];
+
+			const int ck = c * k;
+			const int mk = m * k;
+			const int yk = y * k;
+
+#define DIV255(x) ((x) + 1 + ((x) >> 8)) >> 8
+			scanlines[0][i + bitmap_layout.r] = DIV255(ck);
+			scanlines[0][i + bitmap_layout.g] = DIV255(mk);
+			scanlines[0][i + bitmap_layout.b] = DIV255(yk);
+			scanlines[0][i + bitmap_layout.a] = 0xff;
+#undef DIV255
+		}
+	} while (cinfo->output_scanline != cinfo->output_height);
+}
+
+/**
+ * Convert scan lines from CMYK to core client bitmap layout.
+ */
+static inline void nsjpeg__decode_rgb(
+		struct jpeg_decompress_struct *cinfo,
+		uint8_t * volatile pixels,
+		size_t rowstride)
+{
+	int width = cinfo->output_width;
+
+	do {
+		JSAMPROW scanlines[1] = {
+			[0] = (JSAMPROW)
+				(pixels + rowstride * cinfo->output_scanline),
+		};
+		jpeg_read_scanlines(cinfo, scanlines, 1);
+
+#if RGB_RED != 0 || RGB_GREEN != 1 || RGB_BLUE != 2 || RGB_PIXELSIZE != 4
+		/* Missmatch between configured libjpeg pixel format and
+		 * NetSurf pixel format.  Convert to RGBA */
+		for (int i = width - 1; 0 <= i; i--) {
+			int r = scanlines[0][i * RGB_PIXELSIZE + RGB_RED];
+			int g = scanlines[0][i * RGB_PIXELSIZE + RGB_GREEN];
+			int b = scanlines[0][i * RGB_PIXELSIZE + RGB_BLUE];
+			scanlines[0][i * 4 + bitmap_layout.r] = r;
+			scanlines[0][i * 4 + bitmap_layout.g] = g;
+			scanlines[0][i * 4 + bitmap_layout.b] = b;
+			scanlines[0][i * 4 + bitmap_layout.a] = 0xff;
+		}
+#endif
+	} while (cinfo->output_scanline != cinfo->output_height);
+}
+
+/**
+ * Convert scan lines from CMYK to core client bitmap layout.
+ */
+static inline void nsjpeg__decode_client_fmt(
+		struct jpeg_decompress_struct *cinfo,
+		uint8_t * volatile pixels,
+		size_t rowstride)
+{
+	do {
+		JSAMPROW scanlines[1] = {
+			[0] = (JSAMPROW)
+				(pixels + rowstride * cinfo->output_scanline),
+		};
+		jpeg_read_scanlines(cinfo, scanlines, 1);
+	} while (cinfo->output_scanline != cinfo->output_height);
+}
+
+/**
  * create a bitmap from jpeg content.
  */
 static struct bitmap *
@@ -171,8 +259,6 @@ jpeg_cache_convert(struct content *c)
 	struct jpeg_decompress_struct cinfo;
 	struct jpeg_error_mgr jerr;
 	jmp_buf setjmp_buffer;
-	unsigned int height;
-	unsigned int width;
 	struct bitmap * volatile bitmap = NULL;
 	uint8_t * volatile pixels = NULL;
 	size_t rowstride;
@@ -217,21 +303,42 @@ jpeg_cache_convert(struct content *c)
 
 	/* set output processing parameters */
 	if (cinfo.jpeg_color_space == JCS_CMYK ||
-			cinfo.jpeg_color_space == JCS_YCCK) {
+	    cinfo.jpeg_color_space == JCS_YCCK) {
 		cinfo.out_color_space = JCS_CMYK;
 	} else {
+#ifdef JCS_ALPHA_EXTENSIONS
+		switch (bitmap_fmt.layout) {
+		case BITMAP_LAYOUT_R8G8B8A8:
+			cinfo.out_color_space = JCS_EXT_RGBA;
+			break;
+		case BITMAP_LAYOUT_B8G8R8A8:
+			cinfo.out_color_space = JCS_EXT_BGRA;
+			break;
+		case BITMAP_LAYOUT_A8R8G8B8:
+			cinfo.out_color_space = JCS_EXT_ARGB;
+			break;
+		case BITMAP_LAYOUT_A8B8G8R8:
+			cinfo.out_color_space = JCS_EXT_ABGR;
+			break;
+		default:
+			NSLOG(netsurf, ERROR, "Unexpected bitmap format: %u",
+					bitmap_fmt.layout);
+			jpeg_destroy_decompress(&cinfo);
+			return NULL;
+		}
+#else
 		cinfo.out_color_space = JCS_RGB;
+#endif
 	}
 	cinfo.dct_method = JDCT_ISLOW;
 
 	/* commence the decompression, output parameters now valid */
 	jpeg_start_decompress(&cinfo);
 
-	width = cinfo.output_width;
-	height = cinfo.output_height;
-
 	/* create opaque bitmap (jpegs cannot be transparent) */
-	bitmap = guit->bitmap->create(width, height, BITMAP_OPAQUE);
+	bitmap = guit->bitmap->create(
+			cinfo.output_width,
+			cinfo.output_height, BITMAP_OPAQUE);
 	if (bitmap == NULL) {
 		/* empty bitmap could not be created */
 		jpeg_destroy_decompress(&cinfo);
@@ -248,54 +355,21 @@ jpeg_cache_convert(struct content *c)
 
 	/* Convert scanlines from jpeg into bitmap */
 	rowstride = guit->bitmap->get_rowstride(bitmap);
-	do {
-		JSAMPROW scanlines[1];
-
-		scanlines[0] = (JSAMPROW) (pixels +
-					   rowstride * cinfo.output_scanline);
-		jpeg_read_scanlines(&cinfo, scanlines, 1);
 
-		if (cinfo.out_color_space == JCS_CMYK) {
-			int i;
-			for (i = width - 1; 0 <= i; i--) {
-				/* Trivial inverse CMYK -> RGBA */
-				const int c = scanlines[0][i * 4 + 0];
-				const int m = scanlines[0][i * 4 + 1];
-				const int y = scanlines[0][i * 4 + 2];
-				const int k = scanlines[0][i * 4 + 3];
+	switch (cinfo.out_color_space) {
+	case JCS_CMYK:
+		nsjpeg__decode_cmyk(&cinfo, pixels, rowstride);
+		break;
 
-				const int ck = c * k;
-				const int mk = m * k;
-				const int yk = y * k;
+	case JCS_RGB:
+		nsjpeg__decode_rgb(&cinfo, pixels, rowstride);
+		break;
 
-#define DIV255(x) ((x) + 1 + ((x) >> 8)) >> 8
-				scanlines[0][i * 4 + 0] = DIV255(ck);
-				scanlines[0][i * 4 + 1] = DIV255(mk);
-				scanlines[0][i * 4 + 2] = DIV255(yk);
-				scanlines[0][i * 4 + 3] = 0xff;
-#undef DIV255
-			}
-		} else {
-#if RGB_RED != 0 || RGB_GREEN != 1 || RGB_BLUE != 2 || RGB_PIXELSIZE != 4
-			/* Missmatch between configured libjpeg pixel format and
-			 * NetSurf pixel format.  Convert to RGBA */
-			int i;
-			for (i = width - 1; 0 <= i; i--) {
-				int r = scanlines[0][i * RGB_PIXELSIZE + RGB_RED];
-				int g = scanlines[0][i * RGB_PIXELSIZE + RGB_GREEN];
-				int b = scanlines[0][i * RGB_PIXELSIZE + RGB_BLUE];
-				scanlines[0][i * 4 + 0] = r;
-				scanlines[0][i * 4 + 1] = g;
-				scanlines[0][i * 4 + 2] = b;
-				scanlines[0][i * 4 + 3] = 0xff;
-			}
-#endif
-		}
-	} while (cinfo.output_scanline != cinfo.output_height);
+	default:
+		nsjpeg__decode_client_fmt(&cinfo, pixels, rowstride);
+		break;
+	}
 
-	bitmap_format_to_client(bitmap, &(bitmap_fmt_t) {
-		.layout = BITMAP_LAYOUT_R8G8B8A8,
-	});
 	guit->bitmap->modified(bitmap);
 
 	jpeg_finish_decompress(&cinfo);