[PATCH libXrender] Fix documentation to explicitly mention premultiplied alpha
Lauri Kasanen
cand at gmx.com
Wed Mar 18 02:59:06 PDT 2015
Before this patch, it wasn't mentioned in this file at all, which
is a monumental oversight.
Signed-off-by: Lauri Kasanen <cand at gmx.com>
---
doc/libXrender.txt | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/doc/libXrender.txt b/doc/libXrender.txt
index 27cc75d..9455c2a 100644
--- a/doc/libXrender.txt
+++ b/doc/libXrender.txt
@@ -84,7 +84,7 @@ as a separate argument which marks the valid entries.
2.4 Colors
The core protocol XColor type doesn't include an alpha component, so Xrender
-has a separate type.
+has a separate type. Note that XRender expects premultiplied alpha.
typedef struct {
unsigned short red;
@@ -526,6 +526,8 @@ conceptually built.
7.1 Composite
XRenderComposite exposes the RenderComposite protocol request directly.
+If a format with alpha is used, make sure it is premultiplied into the
+color channels.
void
XRenderComposite (Display *dpy,
--
1.8.3.1
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