From fdb5e2aa473a83cda9a3ecfab2fa47cdf40ffe65 Mon Sep 17 00:00:00 2001
From: Billy Biggs <vektor@dumbterm.net>
Date: Sun, 21 Aug 2005 21:04:52 +0000
Subject: [PATCH] Optimize away calls to cairo_paint_with_alpha() if the alpha
 value given is <= 0. Add a new macro CAIRO_ALPHA_IS_ZERO.

---
 ChangeLog      | 7 +++++++
 src/cairo.c    | 4 ++++
 src/cairoint.h | 1 +
 3 files changed, 12 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 795c2f954..9bb579af3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2005-08-21  Billy Biggs  <vektor@dumbterm.net>
+
+	* src/cairo.c: (cairo_paint_with_alpha): Optimize away calls to
+	cairo_paint_with_alpha() if the alpha value given is <= 0.
+
+	* src/cairoint.h: Add a new macro CAIRO_ALPHA_IS_ZERO.
+
 2005-08-21  Billy Biggs  <vektor@dumbterm.net>
 
 	Fix for bug #4172:
diff --git a/src/cairo.c b/src/cairo.c
index 6456ebad3..0aa2924fe 100644
--- a/src/cairo.c
+++ b/src/cairo.c
@@ -1302,6 +1302,10 @@ cairo_paint_with_alpha (cairo_t *cr,
 	return;
     }
 
+    if (CAIRO_ALPHA_IS_ZERO (alpha)) {
+	return;
+    }
+
     _cairo_color_init_rgba (&color, 1., 1., 1., alpha);
     _cairo_pattern_init_solid (&pattern.solid, &color);
 
diff --git a/src/cairoint.h b/src/cairoint.h
index c6196bbff..bf769c6bd 100644
--- a/src/cairoint.h
+++ b/src/cairoint.h
@@ -178,6 +178,7 @@ typedef cairo_fixed_16_16_t cairo_fixed_t;
 #define CAIRO_MINSHORT SHRT_MIN
 
 #define CAIRO_ALPHA_IS_OPAQUE(alpha) ((alpha) >= ((double)0xff00 / (double)0xffff))
+#define CAIRO_ALPHA_IS_ZERO(alpha) ((alpha) <= 0.0)
 
 #include "cairo-hash-private.h"