Attachment 126243 Details for Bug 97612 – Patch fixing the bug

Patch fixing the bug

file_97612.txt (text/plain), 3.87 KB, created by Peter TB Brett on 2016-09-06 13:08:28 UTC

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Creator: Peter TB Brett

Created: 2016-09-06 13:08:28 UTC

Size: 3.87 KB

patch

obsolete

>Correctly decode Adobe CMYK JPEGs in PDF export
>
>From: Peter TB Brett <peter.brett@livecode.com>
>
>Adobe PhotoShop generates CMYK JPEG files with inverted CMYK.  When a
>JPEG file with this format is included in a PDF file, a `/Decode`
>array must be included to convert to "normal" CMYK.
>
>These JPEG files can be detected via the presence of the APP14 "Adobe"
>marker.  However, PDF viewers are not required to detect and handle
>this private marker, so it must be detected and handled (by adding a
>`/Decode`) by the PDF generator.
>
>Signed-Off-By: Peter TB Brett <peter.brett@livecode.com>
>
>---
> src/cairo-image-info-private.h |    1 +
> src/cairo-image-info.c         |   21 +++++++++++++++++++++
> src/cairo-pdf-surface.c        |    2 ++
> 3 files changed, 24 insertions(+)
>
>diff --git a/src/cairo-image-info-private.h b/src/cairo-image-info-private.h
>index e64928e..99cbbcc 100644
>--- a/src/cairo-image-info-private.h
>+++ b/src/cairo-image-info-private.h
>@@ -43,6 +43,7 @@ typedef struct _cairo_image_info {
>     int		 height;
>     int		 num_components;
>     int		 bits_per_component;
>+    int		 is_adobe_jpeg;
> } cairo_image_info_t;
> 
> cairo_private cairo_int_status_t
>diff --git a/src/cairo-image-info.c b/src/cairo-image-info.c
>index 26e7ae5..2ecce95 100644
>--- a/src/cairo-image-info.c
>+++ b/src/cairo-image-info.c
>@@ -67,6 +67,9 @@
> #define SOF14 0xce
> #define SOF15 0xcf
> 
>+/* Start of tag markers */
>+#define APP14 0xee	/* Adobe */
>+
> static const unsigned char *
> _jpeg_skip_segment (const unsigned char *p)
> {
>@@ -94,6 +97,8 @@ _cairo_image_info_get_jpeg_info (cairo_image_info_t	*info,
> {
>     const unsigned char *p = data;
> 
>+    info->is_adobe_jpeg = FALSE;
>+
>     while (p + 1 < data + length) {
> 	if (*p != 0xff)
> 	    return CAIRO_INT_STATUS_UNSUPPORTED;
>@@ -131,6 +136,18 @@ _cairo_image_info_get_jpeg_info (cairo_image_info_t	*info,
> 	    _jpeg_extract_info (info, p);
> 	    return CAIRO_STATUS_SUCCESS;
> 
>+	case APP14:
>+	    /* "Adobe" tags segment indicates inverted CMYK (in
>+	     * CMYK images). */
>+	    if (p + 12 > data + length)
>+		return CAIRO_INT_STATUS_UNSUPPORTED;
>+
>+	    info->is_adobe_jpeg =
>+		(0 == strncmp((const char *)(p + 3), "Adobe", 5));
>+
>+	    p = _jpeg_skip_segment(p);
>+	    break;
>+
> 	default:
> 	    if (*p >= RST_begin && *p <= RST_end) {
> 		p++;
>@@ -206,6 +223,7 @@ _jpx_extract_info (const unsigned char *p, cairo_image_info_t *info)
>     info->width = get_unaligned_be32 (p + 4);
>     info->num_components = (p[8] << 8) + p[9];
>     info->bits_per_component = p[10];
>+    info->is_adobe_jpeg = FALSE;
> }
> 
> cairo_int_status_t
>@@ -283,6 +301,8 @@ _cairo_image_info_get_png_info (cairo_image_info_t     *info,
>     p += 4;
>     info->height = get_unaligned_be32 (p);
> 
>+    info->is_adobe_jpeg = FALSE;
>+
>     return CAIRO_STATUS_SUCCESS;
> }
> 
>@@ -395,6 +415,7 @@ _jbig2_extract_info (cairo_image_info_t *info, const unsigned char *p)
>     info->height = get_unaligned_be32 (p + 4);
>     info->num_components = 1;
>     info->bits_per_component = 1;
>+    info->is_adobe_jpeg = FALSE;
> }
> 
> cairo_int_status_t
>diff --git a/src/cairo-pdf-surface.c b/src/cairo-pdf-surface.c
>index 09094ff..944e9d6 100644
>--- a/src/cairo-pdf-surface.c
>+++ b/src/cairo-pdf-surface.c
>@@ -2959,6 +2959,7 @@ _cairo_pdf_surface_emit_jpeg_image (cairo_pdf_surface_t              *surface,
> 						 "   /Height %d\n"
> 						 "   /ColorSpace %s\n"
> 						 "   /Interpolate %s\n"
>+						 "%s"
> 						 "   /BitsPerComponent %d\n"
> 						 "%s"
> 						 "   /Filter /DCTDecode\n",
>@@ -2966,6 +2967,7 @@ _cairo_pdf_surface_emit_jpeg_image (cairo_pdf_surface_t              *surface,
> 						 info.height,
> 						 colorspace,
> 						 surface_entry->interpolate ? "true" : "false",
>+						 info.is_adobe_jpeg && info.num_components == 4 ? "   /Decode [ 1 0 1 0 1 0 1 0 ]\n" : "",
> 						 info.bits_per_component,
> 						 smask_buf);
>     }

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