Implement a persistent uniqueID-based cache for SkImageFilter.

src/gpu/SkGpuDevice.cpp

Index: src/gpu/SkGpuDevice.cpp
diff --git a/src/gpu/SkGpuDevice.cpp b/src/gpu/SkGpuDevice.cpp
index c35ff41219be49f68297780abb2303c1378be17e..8968a28c9e0b0d10537deb01b92f67707bb08edc 100644
--- a/src/gpu/SkGpuDevice.cpp
+++ b/src/gpu/SkGpuDevice.cpp
@@ -40,6 +40,8 @@
 #include "SkVertState.h"
 #include "SkErrorInternals.h"
 
+enum { kDefaultImageFilterCacheSize = 32 * 1024 * 1024 };
+
 #define CACHE_COMPATIBLE_DEVICE_TEXTURES 1
 
 #if 0
@@ -1424,8 +1426,7 @@ void SkGpuDevice::drawSprite(const SkDraw& draw, const SkBitmap& bitmap,
         SkMatrix matrix(*draw.fMatrix);
         matrix.postTranslate(SkIntToScalar(-left), SkIntToScalar(-top));
         SkIRect clipBounds = SkIRect::MakeWH(bitmap.width(), bitmap.height());
-        SkImageFilter::Cache* cache = SkImageFilter::Cache::Create();
-        SkAutoUnref aur(cache);
+        SkAutoTUnref<SkImageFilter::GenIDCache> cache(getImageFilterCache());

[bsalomon, 2014/07/25 14:11:58]

A comment here about tossing the textures after filtering is completed?

[Stephen White, 2014/07/25 17:34:17]

Done. Also done in SkGpuDevice::drawDevice(), which I realized was 
not properly unref'ing it (whoops).

Note that SkCanvas::internalDrawDevice() also does this in the GPU 
case, but not in the CPU case (which gets a ref on the singleton
instead).

         SkImageFilter::Context ctx(matrix, clipBounds, cache);
         if (filter_texture(this, fContext, texture, filter, w, h, ctx, &filteredBitmap,
                            &offset)) {
@@ -1534,9 +1535,7 @@ void SkGpuDevice::drawDevice(const SkDraw& draw, SkBaseDevice* device,
         SkMatrix matrix(*draw.fMatrix);
         matrix.postTranslate(SkIntToScalar(-x), SkIntToScalar(-y));
         SkIRect clipBounds = SkIRect::MakeWH(devTex->width(), devTex->height());
-        SkImageFilter::Cache* cache = SkImageFilter::Cache::Create();
-        SkAutoUnref aur(cache);
-        SkImageFilter::Context ctx(matrix, clipBounds, cache);
+        SkImageFilter::Context ctx(matrix, clipBounds, getImageFilterCache());
         if (filter_texture(this, fContext, devTex, filter, w, h, ctx, &filteredBitmap,
                            &offset)) {
             devTex = filteredBitmap.getTexture();
@@ -2058,3 +2057,9 @@ bool SkGpuDevice::EXPERIMENTAL_drawPicture(SkCanvas* canvas, const SkPicture* pi
 
     return true;
 }
+
+SkImageFilter::GenIDCache* SkGpuDevice::getImageFilterCache() {
+    // We always return a transient cache, so it is freed after each
+    // filter traversal.
+    return SkImageFilter::GenIDCache::Create(kDefaultImageFilterCacheSize);
+}