change API contract: disallow zero-sized images or surfaces

src/image/SkImage_Raster.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkImage_Base.h"
 #include "SkImagePriv.h"
 #include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkData.h"
 #include "SkDecodingImageGenerator.h"
 #include "SkSurface.h"
 
 class SkImage_Raster : public SkImage_Base {
 public:
     static bool ValidArgs(const Info& info, size_t rowBytes) {
         const int maxDimension = SK_MaxS32 >> 2;
         const size_t kMaxPixelByteSize = SK_MaxS32;
 
-        if (info.width() < 0 || info.height() < 0) {
+        if (info.width() <= 0 || info.height() <= 0) {
             return false;
         }
         if (info.width() > maxDimension || info.height() > maxDimension) {
             return false;
         }
         if ((unsigned)info.colorType() > (unsigned)kLastEnum_SkColorType) {
             return false;
         }
         if ((unsigned)info.alphaType() > (unsigned)kLastEnum_SkAlphaType) {
             return false;
         }
 
         if (kUnknown_SkColorType == info.colorType()) {
             return false;
         }
 
         // TODO: check colorspace
 
         if (rowBytes < SkImageMinRowBytes(info)) {
             return false;
         }
 
         int64_t size = (int64_t)info.height() * rowBytes;
         if (size > (int64_t)kMaxPixelByteSize) {
             return false;
         }
         return true;
     }
 
-    static SkImage* NewEmpty();
-
     SkImage_Raster(const SkImageInfo&, SkData*, size_t rb, const SkSurfaceProps*);
     virtual ~SkImage_Raster();
 
     void onDraw(SkCanvas*, SkScalar, SkScalar, const SkPaint*) const SK_OVERRIDE;
     void onDrawRect(SkCanvas*, const SkRect*, const SkRect&, const SkPaint*) const SK_OVERRIDE;
     SkSurface* onNewSurface(const SkImageInfo&, const SkSurfaceProps&) const SK_OVERRIDE;
     bool onReadPixels(const SkImageInfo&, void*, size_t, int srcX, int srcY) const SK_OVERRIDE;
     const void* onPeekPixels(SkImageInfo*, size_t* /*rowBytes*/) const SK_OVERRIDE;
     bool getROPixels(SkBitmap*) const SK_OVERRIDE;
 
@@ skipping 15 matching lines @@
 private:
     SkImage_Raster() : INHERITED(0, 0, NULL) {}
 
     SkBitmap    fBitmap;
 
     typedef SkImage_Base INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
-SkImage* SkImage_Raster::NewEmpty() {
-    // Returns lazily created singleton
-    static SkImage* gEmpty;
-    if (NULL == gEmpty) {
-        gEmpty = SkNEW(SkImage_Raster);
-    }
-    gEmpty->ref();
-    return gEmpty;
-}
-
 static void release_data(void* addr, void* context) {
     SkData* data = static_cast<SkData*>(context);
     data->unref();
 }
 
 SkImage_Raster::SkImage_Raster(const Info& info, SkData* data, size_t rowBytes,
                                const SkSurfaceProps* props)
     : INHERITED(info.width(), info.height(), props)
 {
     data->ref();
@@ skipping 53 matching lines @@
 }
 
 bool SkImage_Raster::getROPixels(SkBitmap* dst) const {
     *dst = fBitmap;
     return true;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 SkImage* SkImage::NewRasterCopy(const SkImageInfo& info, const void* pixels, size_t rowBytes) {
-    if (!SkImage_Raster::ValidArgs(info, rowBytes)) {
-        return NULL;
-    }
-    if (0 == info.width() && 0 == info.height()) {
-        return SkImage_Raster::NewEmpty();
-    }
-    // check this after empty-check
-    if (NULL == pixels) {
+    if (!SkImage_Raster::ValidArgs(info, rowBytes) || !pixels) {
         return NULL;
     }
 
     // Here we actually make a copy of the caller's pixel data
     SkAutoDataUnref data(SkData::NewWithCopy(pixels, info.height() * rowBytes));
     return SkNEW_ARGS(SkImage_Raster, (info, data, rowBytes, NULL));
 }
 
 
 SkImage* SkImage::NewRasterData(const SkImageInfo& info, SkData* data, size_t rowBytes) {
-    if (!SkImage_Raster::ValidArgs(info, rowBytes)) {
-        return NULL;
-    }
-    if (0 == info.width() && 0 == info.height()) {
-        return SkImage_Raster::NewEmpty();
-    }
-    // check this after empty-check
-    if (NULL == data) {
+    if (!SkImage_Raster::ValidArgs(info, rowBytes) || !data) {
         return NULL;
     }
 
     // did they give us enough data?
     size_t size = info.height() * rowBytes;
     if (data->size() < size) {
         return NULL;
     }
 
     return SkNEW_ARGS(SkImage_Raster, (info, data, rowBytes, NULL));
@@ skipping 12 matching lines @@
     return SkNEW_ARGS(SkImage_Raster, (info, pr, rowBytes, props));
 }
 
 const SkPixelRef* SkBitmapImageGetPixelRef(const SkImage* image) {
     return ((const SkImage_Raster*)image)->getPixelRef();
 }
 
 bool SkImage_Raster::isOpaque() const {
     return fBitmap.isOpaque();
 }