expose generalized imagecache key

src/core/SkBitmapCache.cpp

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkBitmapCache.h"
+#include "SkRect.h"
+
+/**
+ This function finds the bounds of the bitmap *within its pixelRef*.
+ If the bitmap lacks a pixelRef, it will return an empty rect, since
+ that doesn't make sense.  This may be a useful enough function that
+ it should be somewhere else (in SkBitmap?).
+ */
+static SkIRect get_bounds_from_bitmap(const SkBitmap& bm) {
+    if (!(bm.pixelRef())) {
+        return SkIRect::MakeEmpty();
+    }
+    SkIPoint origin = bm.pixelRefOrigin();
+    return SkIRect::MakeXYWH(origin.fX, origin.fY, bm.width(), bm.height());
+}
+
+struct BitmapKey : public SkScaledImageCache::Key {
+public:
+    BitmapKey(uint32_t genID, SkScalar scaleX, SkScalar scaleY, const SkIRect& bounds)
+    : fGenID(genID)
+    , fScaleX(scaleX)
+    , fScaleY(scaleY)
+    , fBounds(bounds)
+    {
+        this->init(sizeof(fGenID) + sizeof(fScaleX) + sizeof(fScaleY) + sizeof(fBounds));
+    }
+    
+    uint32_t    fGenID;
+    SkScalar    fScaleX;
+    SkScalar    fScaleY;
+    SkIRect     fBounds;
+};
+
+//////////////////////////////////////////////////////////////////////////////////////////
+
+SkScaledImageCache::ID* SkBitmapCache::FindAndLock(const SkBitmap& src,
+                                                   SkScalar invScaleX, SkScalar invScaleY,
+                                                   SkBitmap* result) {
+    if (0 == invScaleX || 0 == invScaleY) {
+        // degenerate, and the key we use for mipmaps
+        return NULL;
+    }
+    BitmapKey key(src.getGenerationID(), invScaleX, invScaleY, get_bounds_from_bitmap(src));
+    return SkScaledImageCache::FindAndLock(key, result);
+}
+
+SkScaledImageCache::ID* SkBitmapCache::AddAndLock(const SkBitmap& src,
+                                                  SkScalar invScaleX, SkScalar invScaleY,
+                                                  const SkBitmap& result) {
+    if (0 == invScaleX || 0 == invScaleY) {
+        // degenerate, and the key we use for mipmaps
+        return NULL;
+    }
+    BitmapKey key(src.getGenerationID(), invScaleX, invScaleY, get_bounds_from_bitmap(src));
+    return SkScaledImageCache::AddAndLock(key, result);
+}
+
+////
+
+SkScaledImageCache::ID* SkBitmapCache::FindAndLock(uint32_t genID, int width, int height,
+                                                   SkBitmap* result) {
+    BitmapKey key(genID, SK_Scalar1, SK_Scalar1, SkIRect::MakeWH(width, height));
+    return SkScaledImageCache::FindAndLock(key, result);
+}
+
+SkScaledImageCache::ID* SkBitmapCache::AddAndLock(uint32_t genID, int width, int height,
+                                                     const SkBitmap& result) {
+    BitmapKey key(genID, SK_Scalar1, SK_Scalar1, SkIRect::MakeWH(width, height));
+    return SkScaledImageCache::AddAndLock(key, result);
+}
+
+////
+
+SkScaledImageCache::ID* SkMipMapCache::FindAndLock(const SkBitmap& src, const SkMipMap** result) {
+    BitmapKey key(src.getGenerationID(), SK_Scalar1, SK_Scalar1, get_bounds_from_bitmap(src));
+    return SkScaledImageCache::FindAndLock(key, result);
+}
+
+SkScaledImageCache::ID* SkMipMapCache::AddAndLock(const SkBitmap& src, const SkMipMap* result) {
+    BitmapKey key(src.getGenerationID(), SK_Scalar1, SK_Scalar1, get_bounds_from_bitmap(src));
+    return SkScaledImageCache::AddAndLock(key, result);
+}
+