Avoid separate allocation of SkImageCacherator

src/image/SkImage_Generator.cpp

Index: src/image/SkImage_Generator.cpp
diff --git a/src/image/SkImage_Generator.cpp b/src/image/SkImage_Generator.cpp
index 412f573ba6dbe38d3a9da521fdc48889715db07d..8fa022de7bdc1a6f11fb21c73cf0504ec0963e0b 100644
--- a/src/image/SkImage_Generator.cpp
+++ b/src/image/SkImage_Generator.cpp
@@ -16,20 +16,20 @@
 
 class SkImage_Generator : public SkImage_Base {
 public:
-    SkImage_Generator(SkImageCacherator* cache)
-        : INHERITED(cache->info().width(), cache->info().height(), cache->uniqueID())
-        , fCache(cache) // take ownership
+    SkImage_Generator(SkImageCacherator::Validator* validator)
+        : INHERITED(validator->fInfo.width(), validator->fInfo.height(), validator->fUniqueID)
+        , fCache(validator)
     {}
 
     virtual SkImageInfo onImageInfo() const override {
-        return fCache->info();
+        return fCache.info();
     }
     SkAlphaType onAlphaType() const override {
-        return fCache->info().alphaType();
+        return fCache.info().alphaType();
     }
 
     bool onReadPixels(const SkImageInfo&, void*, size_t, int srcX, int srcY, CachingHint) const override;
-    SkImageCacherator* peekCacherator() const override { return fCache; }
+    SkImageCacherator* peekCacherator() const override { return &fCache; }
     SkData* onRefEncoded(GrContext*) const override;
     sk_sp<SkImage> onMakeSubset(const SkIRect&) const override;
     bool getROPixels(SkBitmap*, CachingHint) const override;
@@ -38,7 +38,7 @@ public:
     bool onIsLazyGenerated() const override { return true; }
 
 private:
-    SkAutoTDelete<SkImageCacherator> fCache;
+    mutable SkImageCacherator fCache;
 
     typedef SkImage_Base INHERITED;
 };
@@ -49,13 +49,13 @@ bool SkImage_Generator::onReadPixels(const SkImageInfo& dstInfo, void* dstPixels
                                      int srcX, int srcY, CachingHint chint) const {
     SkBitmap bm;
     if (kDisallow_CachingHint == chint) {
-        if (fCache->lockAsBitmapOnlyIfAlreadyCached(&bm)) {
+        if (fCache.lockAsBitmapOnlyIfAlreadyCached(&bm)) {
             return bm.readPixels(dstInfo, dstPixels, dstRB, srcX, srcY);
         } else {
             // Try passing the caller's buffer directly down to the generator. If this fails we
             // may still succeed in the general case, as the generator may prefer some other
             // config, which we could then convert via SkBitmap::readPixels.
-            if (fCache->directGeneratePixels(dstInfo, dstPixels, dstRB, srcX, srcY)) {
+            if (fCache.directGeneratePixels(dstInfo, dstPixels, dstRB, srcX, srcY)) {
                 return true;
             }
             // else fall through
@@ -69,16 +69,16 @@ bool SkImage_Generator::onReadPixels(const SkImageInfo& dstInfo, void* dstPixels
 }
 
 SkData* SkImage_Generator::onRefEncoded(GrContext* ctx) const {
-    return fCache->refEncoded(ctx);
+    return fCache.refEncoded(ctx);
 }
 
 bool SkImage_Generator::getROPixels(SkBitmap* bitmap, CachingHint chint) const {
-    return fCache->lockAsBitmap(bitmap, this, chint);
+    return fCache.lockAsBitmap(bitmap, this, chint);
 }
 
 GrTexture* SkImage_Generator::asTextureRef(GrContext* ctx, const GrTextureParams& params,
                                            SkSourceGammaTreatment gammaTreatment) const {
-    return fCache->lockAsTexture(ctx, params, gammaTreatment, this);
+    return fCache.lockAsTexture(ctx, params, gammaTreatment, this);
 }
 
 sk_sp<SkImage> SkImage_Generator::onMakeSubset(const SkIRect& subset) const {
@@ -98,12 +98,7 @@ sk_sp<SkImage> SkImage_Generator::onMakeSubset(const SkIRect& subset) const {
 }
 
 sk_sp<SkImage> SkImage::MakeFromGenerator(SkImageGenerator* generator, const SkIRect* subset) {
-    if (!generator) {
-        return nullptr;
-    }
-    SkImageCacherator* cache = SkImageCacherator::NewFromGenerator(generator, subset);
-    if (!cache) {
-        return nullptr;
-    }
-    return sk_make_sp<SkImage_Generator>(cache);
+    SkImageCacherator::Validator validator(generator, subset);
+
+    return validator ? sk_make_sp<SkImage_Generator>(&validator) : nullptr;

[reed1, 2016/10/27 13:45:19]

Can we force somebody to assert (Validator?) if we try to "use" one that isn't
valid? I'm trying to enforce the caller's responsibility to check the predicate
before using.

[f(malita), 2016/10/27 14:17:07]

The SkImageCacherator ctor (the only "user" of validator?) does assert that the
generator ptr is non-null, which is equivalent to checking the validator.  The
reason we can't just check the validator at that point is because we're
releasing the unique_ptr in the initializer list, so by the time we're reaching
the ctor body the validator is no longer "valid".

Does that sound sufficient, or do you have something else in mind?

 }