From 351cd4311bcf3992d762857d60920893dd53f703 Mon Sep 17 00:00:00 2001
From: "vladimir@pobox.com" <none@none>
Date: Tue, 22 May 2007 20:54:38 -0700
Subject: [PATCH] b=324698, disable bilinear filtering for upscaled images
 (upscaling causes misrendering), r=roc

---
 gfx/src/thebes/nsThebesImage.cpp | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/gfx/src/thebes/nsThebesImage.cpp b/gfx/src/thebes/nsThebesImage.cpp
index 2fa1001caa4..d384fccc31f 100644
--- a/gfx/src/thebes/nsThebesImage.cpp
+++ b/gfx/src/thebes/nsThebesImage.cpp
@@ -397,6 +397,21 @@ nsThebesImage::Draw(nsIRenderingContext &aContext,
     nsRefPtr<gfxPattern> pat = new gfxPattern(ThebesSurface());
     pat->SetMatrix(mat);
 
+    // XXX bug 324698
+#ifndef XP_MACOSX
+    if (xscale > 1.0 || yscale > 1.0) {
+        // See bug 324698.  This is a workaround.
+        //
+        // Set the filter to CAIRO_FILTER_FAST if we're scaling up -- otherwise,
+        // pixman's sampling will sample transparency for the outside edges and we'll
+        // get blurry edges.  CAIRO_EXTEND_PAD would also work here, but it's not
+        // implemented for image sources.
+        //
+        // This effectively disables smooth upscaling for images.
+        pat->SetFilter(0);
+    }
+#endif
+
     ctx->NewPath();
     ctx->SetPattern(pat);
     ctx->Rectangle(destRect);
@@ -504,6 +519,14 @@ nsThebesImage::ThebesDrawTile(gfxContext *thebesContext,
         pat->SetExtend(gfxPattern::EXTEND_REPEAT);
         pat->SetMatrix(patMat);
 
+#ifndef XP_MACOSX
+        if (scale > 1.0) {
+            // See bug 324698.  This is a workaround.  See comments
+            // by the earlier SetFilter call.
+            pat->SetFilter(0);
+        }
+#endif
+
         thebesContext->SetPattern(pat);
     }