use special-image for imagefilters and save/restore layer

src/core/SkSpecialImage.cpp

Index: src/core/SkSpecialImage.cpp
diff --git a/src/core/SkSpecialImage.cpp b/src/core/SkSpecialImage.cpp
index 8875d2248ff6c1035c6ce940dfa3f5b2c1796583..0e23f5ee18df6caf0603f37ce8f006141a97b2b8 100644
--- a/src/core/SkSpecialImage.cpp
+++ b/src/core/SkSpecialImage.cpp
@@ -18,6 +18,10 @@
 #include "SkSpecialSurface.h"
 #include "SkSurfacePriv.h"
 

[robertphillips, 2016/07/20 12:20:05]

// The raster-specific image filters are written specifically for N32

?

+static bool valid_for_imagefilters(const SkImageInfo& info) {
+    return info.colorType() == kN32_SkColorType;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 class SkSpecialImage_Base : public SkSpecialImage {
 public:
@@ -315,7 +319,11 @@ sk_sp<SkSpecialImage> SkSpecialImage::MakeFromImage(const SkIRect& subset,
                                                     const SkSurfaceProps* props) {
     SkASSERT(rect_fits(subset, image->width(), image->height()));
 

[robertphillips, 2016/07/20 12:20:05]

GPU-backed SkImages should work fine 

-    return sk_make_sp<SkSpecialImage_Image>(subset, image, props);
+    if (valid_for_imagefilters(as_IB(image.get())->onImageInfo())) {
+        return sk_make_sp<SkSpecialImage_Image>(subset, image, props);
+    } else {
+        return nullptr;
+    }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -412,7 +420,16 @@ sk_sp<SkSpecialImage> SkSpecialImage::MakeFromRaster(const SkIRect& subset,
     SkASSERT(nullptr == bm.getTexture());
     SkASSERT(rect_fits(subset, bm.width(), bm.height()));
 
-    return sk_make_sp<SkSpecialImage_Raster>(subset, bm, props);
+    const SkBitmap* srcBM = &bm;
+    SkBitmap tmpStorage;

[robertphillips, 2016/07/20 12:20:05]

for -> force

[reed1, 2016/07/20 12:41:53]

Done.

+    // ImageFilters only handle N32 at the moment, so for our src to be that
+    if (!valid_for_imagefilters(bm.info())) {
+        if (!bm.copyTo(&tmpStorage, kN32_SkColorType)) {
+            return nullptr;
+        }
+        srcBM = &tmpStorage;
+    }
+    return sk_make_sp<SkSpecialImage_Raster>(subset, *srcBM, props);
 }
 
 #if SK_SUPPORT_GPU