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-rw-r--r--doc/libXrender.txt5
1 files changed, 4 insertions, 1 deletions
diff --git a/doc/libXrender.txt b/doc/libXrender.txt
index 27cc75d..753ee98 100644
--- a/doc/libXrender.txt
+++ b/doc/libXrender.txt
@@ -84,7 +84,8 @@ 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 in all
+cases except with the gradient operations.
typedef struct {
unsigned short red;
@@ -526,6 +527,8 @@ 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,