Get OffsetImageFilter really working with SkSpecialImages

src/core/SkImageFilter.cpp

Index: src/core/SkImageFilter.cpp
diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index a38124b0e62b4db1894883e7654630cff0de9a1d..40dd05d7cd212c98cea3a5c0e0a93473343119a3 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -16,6 +16,8 @@
 #include "SkOncePtr.h"
 #include "SkReadBuffer.h"
 #include "SkRect.h"
+#include "SkSpecialImage.h"
+#include "SkSpecialSurface.h"
 #include "SkTDynamicHash.h"
 #include "SkTInternalLList.h"
 #include "SkValidationUtils.h"
@@ -231,6 +233,27 @@ void SkImageFilter::flatten(SkWriteBuffer& buffer) const {
     buffer.writeUInt(fCropRect.flags());
 }
 
+SkSpecialImage* SkImageFilter::filterImage(SkSpecialImage* src, const Context& context,
+                                           SkIPoint* offset) const {
+    SkASSERT(src && offset);
+
+    uint32_t srcGenID = fUsesSrcInput ? src->uniqueID() : 0;
+    Cache::Key key(fUniqueID, context.ctm(), context.clipBounds(), srcGenID);
+    if (context.cache()) {
+        SkSpecialImage* result = context.cache()->get(key, offset);
+        if (result) {
+            return SkRef(result);
+        }
+    }
+
+    SkSpecialImage* result = this->onFilterImage(src, context, offset);
+    if (result && context.cache()) {
+        context.cache()->set(key, result, *offset);
+    }
+
+    return result;
+}
+
 bool SkImageFilter::filterImageDeprecated(Proxy* proxy, const SkBitmap& src,
                                           const Context& context,
                                           SkBitmap* result, SkIPoint* offset) const {
@@ -436,6 +459,55 @@ bool SkImageFilter::applyCropRectDeprecated(const Context& ctx, Proxy* proxy, co
     }
 }
 
+// Return a larger (newWidth x newHeight) copy of 'src' with black padding
+// around it.
+static SkSpecialImage* pad_image(SkSpecialImage* src,
+                                 int newWidth, int newHeight, int offX, int offY) {
+
+    SkImageInfo info = SkImageInfo::MakeN32Premul(newWidth, newHeight);
+    SkAutoTUnref<SkSpecialSurface> surf(src->newSurface(info));
+    if (!surf) {
+        return nullptr;
+    }
+
+    SkCanvas* canvas = surf->getCanvas();
+    if (!canvas) {
+        return nullptr;
+    }
+
+    canvas->clear(0x0);
+
+    src->draw(canvas, offX, offY, nullptr);
+
+    return surf->newImageSnapshot();
+}
+
+SkSpecialImage* SkImageFilter::applyCropRect(const Context& ctx,
+                                             SkSpecialImage* src,
+                                             SkIPoint* srcOffset,
+                                             SkIRect* bounds) const {
+    SkIRect srcBounds;
+    srcBounds = SkIRect::MakeXYWH(srcOffset->fX, srcOffset->fY, src->width(), src->height());
+
+    SkIRect dstBounds;
+    this->onFilterNodeBounds(srcBounds, ctx.ctm(), &dstBounds, kForward_MapDirection);
+    fCropRect.applyTo(dstBounds, ctx.ctm(), bounds);
+    if (!bounds->intersect(ctx.clipBounds())) {
+        return nullptr;
+    }
+
+    if (srcBounds.contains(*bounds)) {
+        return SkRef(src);
+    } else {
+        SkSpecialImage* img = pad_image(src,
+                                        bounds->width(), bounds->height(),
+                                        srcOffset->x() - bounds->x(),
+                                        srcOffset->y() - bounds->y());
+        *srcOffset = SkIPoint::Make(bounds->x(), bounds->y());
+        return img;
+    }
+}
+
 bool SkImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,
                                    SkIRect* dst, MapDirection direction) const {
     if (fInputCount < 1) {
@@ -494,6 +566,36 @@ SkImageFilter* SkImageFilter::newWithLocalMatrix(const SkMatrix& matrix) const {
     return SkLocalMatrixImageFilter::Create(matrix, const_cast<SkImageFilter*>(this));
 }
 
+SkSpecialImage* SkImageFilter::filterInput(int index,
+                                           SkSpecialImage* src,
+                                           const Context& ctx,
+                                           SkIPoint* offset) const {
+    SkImageFilter* input = this->getInput(index);
+    if (!input) {
+        return SkRef(src);
+    }
+
+    if (input->supportsUnifiedFiltering()) {
+        // Ensure that calls in filterImage below will see an identity
+        // matrix with no clip and that the matrix and clip set before this function was
+        // called are restored before we return to the caller.
+        return input->filterImage(src, this->mapContext(ctx), offset);
+    } else {
+        SkBitmap tmpSrc, result;
+
+        if (!src->internal_getBM(&tmpSrc)) {

[Stephen White, 2016/02/18 17:56:17]

Would it work to put this chunk of code into the base class implementation of
SkImageFilter::filterImage() instead? Then we wouldn't need the
supportsUnifiedFiltering() virtual.

[robertphillips, 2016/02/19 19:37:59]

Done. It had to go in onFilterImage though. This does mean the caching code gets
hit twice, once in SkImageFilter::filterImage and (for those imagefilters that
don't implement their own onFilterImage) once in SkImageFilter::onFilterImage.

[Stephen White, 2016/02/19 19:53:55]

Sorry, that's actually what I meant!
That's probably bearable in the short term.

+            return nullptr;
+        }
+
+        if (!input->filterImageDeprecated(src->internal_getProxy(), tmpSrc,
+                                          this->mapContext(ctx), &result, offset)) {
+            return nullptr;
+        }
+
+        return SkSpecialImage::internal_fromBM(src->internal_getProxy(), result);
+    }
+}
+
 #if SK_SUPPORT_GPU
 
 bool SkImageFilter::filterInputGPUDeprecated(int index, SkImageFilter::Proxy* proxy,
@@ -531,9 +633,8 @@ namespace {
 
 class CacheImpl : public SkImageFilter::Cache {
 public:
-    CacheImpl(size_t maxBytes) : fMaxBytes(maxBytes), fCurrentBytes(0) {
-    }
-    virtual ~CacheImpl() {
+    CacheImpl(size_t maxBytes) : fMaxBytes(maxBytes), fCurrentBytes(0) { }
+    ~CacheImpl() override {
         SkTDynamicHash<Value, Key>::Iter iter(&fLookup);
 
         while (!iter.done()) {
@@ -545,8 +646,12 @@ public:
     struct Value {
         Value(const Key& key, const SkBitmap& bitmap, const SkIPoint& offset)
             : fKey(key), fBitmap(bitmap), fOffset(offset) {}
+        Value(const Key& key, SkSpecialImage* image, const SkIPoint& offset)
+            : fKey(key), fImage(SkRef(image)), fOffset(offset) {}
+
         Key fKey;
         SkBitmap fBitmap;
+        SkAutoTUnref<SkSpecialImage> fImage;
         SkIPoint fOffset;
         static const Key& GetKey(const Value& v) {
             return v.fKey;
@@ -556,6 +661,7 @@ public:
         }
         SK_DECLARE_INTERNAL_LLIST_INTERFACE(Value);
     };
+
     bool get(const Key& key, SkBitmap* result, SkIPoint* offset) const override {
         SkAutoMutexAcquire mutex(fMutex);
         if (Value* v = fLookup.find(key)) {
@@ -569,10 +675,24 @@ public:
         }
         return false;
     }
+
+    SkSpecialImage* get(const Key& key, SkIPoint* offset) const override {
+        SkAutoMutexAcquire mutex(fMutex);
+        if (Value* v = fLookup.find(key)) {
+            *offset = v->fOffset;
+            if (v != fLRU.head()) {
+                fLRU.remove(v);
+                fLRU.addToHead(v);
+            }
+            return v->fImage;
+        }
+        return nullptr;
+    }
+
     void set(const Key& key, const SkBitmap& result, const SkIPoint& offset) override {
         SkAutoMutexAcquire mutex(fMutex);
         if (Value* v = fLookup.find(key)) {
-            removeInternal(v);
+            this->removeInternal(v);
         }
         Value* v = new Value(key, result, offset);
         fLookup.add(v);
@@ -584,7 +704,26 @@ public:
             if (tail == v) {
                 break;
             }
-            removeInternal(tail);
+            this->removeInternal(tail);
+        }
+    }
+
+    void set(const Key& key, SkSpecialImage* image, const SkIPoint& offset) override {
+        SkAutoMutexAcquire mutex(fMutex);
+        if (Value* v = fLookup.find(key)) {
+            this->removeInternal(v);
+        }
+        Value* v = new Value(key, image, offset);
+        fLookup.add(v);
+        fLRU.addToHead(v);
+        fCurrentBytes += image->getSize();
+        while (fCurrentBytes > fMaxBytes) {
+            Value* tail = fLRU.tail();
+            SkASSERT(tail);
+            if (tail == v) {
+                break;
+            }
+            this->removeInternal(tail);
         }
     }