gstate: Handle device scale on surface as source

When creating a transformed pattern we must apply the device
transform *before* the transform set on the pattern itself, otherwise
e.g. its translation will not be affected by the device scale.

We also fix up the device_transform related handling in
_cairo_default_context_pop_group().  With a device scale we can
no longer just use the device_transform_inverse to unset the
device offset for the extents, so we make that a simple translate
instead.

We also remove some weird code that tries to handle the device
transform but seems unnecessary (maybe a workaround for applying
the device transform in the wrong order?). With that code removed
things work fine, but with it things get translated wrongly when
there is a scale.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/cairo-pattern-private.h b/src/cairo-pattern-private.h
index dfd843fc1..bbcfadd85 100644
--- a/src/cairo-pattern-private.h
+++ b/src/cairo-pattern-private.h
@@ -237,6 +237,10 @@ cairo_private void
 _cairo_pattern_transform (cairo_pattern_t      *pattern,
 			  const cairo_matrix_t *ctm_inverse);
 
+cairo_private void
+_cairo_pattern_pretransform (cairo_pattern_t      *pattern,
+                             const cairo_matrix_t *ctm);
+
 cairo_private cairo_bool_t
 _cairo_pattern_is_opaque_solid (const cairo_pattern_t *pattern);