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libpng 1.6 is stricter in various ways, which trips up Cairo's PNG loader.
Upstream-Status: Submitted (first)/Backport (second)
Signed-off-by: Ross Burton <ross.burton@intel.com>
From 1535e4eeda7e0792fe5e7e5ab377c5253ee89ce7 Mon Sep 17 00:00:00 2001
From: Ingmar Runge <ingmar@irsoft.de>
Date: Tue, 16 Apr 2013 10:48:59 +0100
Subject: [PATCH 1/2] png: fix transform ordering
libpng 1.6 is stricter with the function ordering, emitting the warning "invalid
before the PNG header has been read" when calling png_set_read_user_transform_fn
whilst loading a PNG.
So, re-order the functions to the order that libpng is happy with.
Signed-off-by: Ross Burton <ross.burton@intel.com>
---
src/cairo-png.c | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
diff --git a/src/cairo-png.c b/src/cairo-png.c
index e74a4a8..3aec86a 100644
--- a/src/cairo-png.c
+++ b/src/cairo-png.c
@@ -497,6 +497,20 @@ convert_bytes_to_data (png_structp png, png_row_infop row_info, png_bytep data)
}
}
+/* branches into premultiply_data or convert_bytes_to_data depending on color type */
+static void read_user_transform_func (png_structp png, png_row_infop row_info, png_bytep data)
+{
+ switch ((cairo_format_t) png_get_user_transform_ptr (png)) {
+ case CAIRO_FORMAT_ARGB32:
+ premultiply_data (png, row_info, data);
+ break;
+
+ case CAIRO_FORMAT_RGB24:
+ convert_bytes_to_data (png, row_info, data);
+ break;
+ }
+}
+
static cairo_status_t
stdio_read_func (void *closure, unsigned char *data, unsigned int size)
{
@@ -623,6 +637,9 @@ read_png (struct png_read_closure_t *png_closure)
png_set_filler (png, 0xff, PNG_FILLER_AFTER);
+ /* this must be stored before calling png_read_update_info */
+ png_set_read_user_transform_fn (png, read_user_transform_func);
+
/* recheck header after setting EXPAND options */
png_read_update_info (png, info);
png_get_IHDR (png, info,
@@ -643,15 +660,15 @@ read_png (struct png_read_closure_t *png_closure)
case PNG_COLOR_TYPE_RGB_ALPHA:
format = CAIRO_FORMAT_ARGB32;
- png_set_read_user_transform_fn (png, premultiply_data);
break;
case PNG_COLOR_TYPE_RGB:
format = CAIRO_FORMAT_RGB24;
- png_set_read_user_transform_fn (png, convert_bytes_to_data);
break;
}
+ png_set_user_transform_info (png, (void*) format, 0, 0);
+
stride = cairo_format_stride_for_width (format, png_width);
if (stride < 0) {
surface = _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_INVALID_STRIDE));
--
1.7.10.4
From 2dd2c826a5b367d32cf2d48ed69754795990c5db Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 16 Apr 2013 10:58:56 +0100
Subject: [PATCH] png: Avoid marking the surface as in error after a png
warning
It turns out that libpng will continue to load an image after throwing a
warning, and that libpng16 now throws warnings for images that libpng15
and earlier loaded without error. As we were happily loading those
images into cairo surfaces before, we are therefore being overzealous
in throwing an error now - so just squelch the warning.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
src/cairo-png.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/src/cairo-png.c b/src/cairo-png.c
index e74a4a8..068617d 100644
--- a/src/cairo-png.c
+++ b/src/cairo-png.c
@@ -149,13 +149,13 @@ static void
png_simple_warning_callback (png_structp png,
png_const_charp error_msg)
{
- cairo_status_t *error = png_get_error_ptr (png);
-
- /* default to the most likely error */
- if (*error == CAIRO_STATUS_SUCCESS)
- *error = _cairo_error (CAIRO_STATUS_NO_MEMORY);
-
- /* png does not expect to abort and will try to tidy up after a warning */
+ /* png does not expect to abort and will try to tidy up and continue
+ * loading the image after a warning. So we also want to return the
+ * (incorrect?) surface.
+ *
+ * We use our own warning callback to squelch any attempts by libpng
+ * to write to stderr as we may not be in control of that output.
+ */
}
--
1.7.10.4
|
