add SkPixmap and external locking to bitmaps

src/core/SkBitmapScaler.cpp

Index: src/core/SkBitmapScaler.cpp
diff --git a/src/core/SkBitmapScaler.cpp b/src/core/SkBitmapScaler.cpp
index 4bd3cc732db7949a8eb330297ed7b2d55a3ecac6..9ce4171879a1bdb39a268ab626f741bd47da2389 100644
--- a/src/core/SkBitmapScaler.cpp
+++ b/src/core/SkBitmapScaler.cpp
@@ -1,3 +1,10 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
 #include "SkBitmapScaler.h"
 #include "SkBitmapFilter.h"
 #include "SkRect.h"
@@ -241,74 +248,78 @@ static SkBitmapScaler::ResizeMethod ResizeMethodToAlgorithmMethod(
     }
 }
 
-// static
+static bool resize(const SkPixmap& pmap, SkBitmap* resultPtr, SkBitmapScaler::ResizeMethod method,
+                   float destWidth, float destHeight, SkBitmap::Allocator* allocator,
+                   const SkConvolutionProcs& convolveProcs) {
+    const SkRect destSubset = SkRect::MakeWH(destWidth, destHeight);
+    SkResizeFilter filter(method, pmap.width(), pmap.height(),
+                          destWidth, destHeight, destSubset, convolveProcs);
+
+    // Get a source bitmap encompassing this touched area. We construct the
+    // offsets and row strides such that it looks like a new bitmap, while
+    // referring to the old data.
+    const uint8_t* sourceSubset = reinterpret_cast<const uint8_t*>(pmap.addr());
+
+    // Convolve into the result.
+    SkBitmap result;
+    result.setInfo(SkImageInfo::MakeN32(SkScalarCeilToInt(destSubset.width()),
+                                        SkScalarCeilToInt(destSubset.height()),
+                                        pmap.alphaType()));
+    result.allocPixels(allocator, NULL);
+    if (!result.readyToDraw()) {
+        return false;
+    }
+
+    BGRAConvolve2D(sourceSubset, static_cast<int>(pmap.rowBytes()),
+                   !pmap.isOpaque(), filter.xFilter(), filter.yFilter(),
+                   static_cast<int>(result.rowBytes()),
+                   static_cast<unsigned char*>(result.getPixels()),
+                   convolveProcs, true);
+
+    *resultPtr = result;
+    resultPtr->lockPixels();
+    SkASSERT(resultPtr->getPixels());
+    return true;
+}
+
 bool SkBitmapScaler::Resize(SkBitmap* resultPtr,
                             const SkBitmap& source,
                             ResizeMethod method,
                             float destWidth, float destHeight,
                             SkBitmap::Allocator* allocator) {
+    if (source.colorType() != kN32_SkColorType) {
+        return false;
+    }
 
-  SkConvolutionProcs convolveProcs= { 0, NULL, NULL, NULL, NULL };
-  PlatformConvolutionProcs(&convolveProcs);
-
-  SkRect destSubset = { 0, 0, destWidth, destHeight };
+    SkConvolutionProcs convolveProcs= { 0, NULL, NULL, NULL, NULL };
+    PlatformConvolutionProcs(&convolveProcs);
 
-  // Ensure that the ResizeMethod enumeration is sound.
-  SkASSERT(((RESIZE_FIRST_QUALITY_METHOD <= method) &&
+    // Ensure that the ResizeMethod enumeration is sound.
+    SkASSERT(((RESIZE_FIRST_QUALITY_METHOD <= method) &&
       (method <= RESIZE_LAST_QUALITY_METHOD)) ||
       ((RESIZE_FIRST_ALGORITHM_METHOD <= method) &&
       (method <= RESIZE_LAST_ALGORITHM_METHOD)));
 
-  // If the size of source or destination is 0, i.e. 0x0, 0xN or Nx0, just
-  // return empty.
-  if (source.width() < 1 || source.height() < 1 ||
-      destWidth < 1 || destHeight < 1) {
-      // todo: seems like we could handle negative dstWidth/Height, since that
-      // is just a negative scale (flip)
-      return false;
-  }
+    // If the size of source or destination is 0, i.e. 0x0, 0xN or Nx0, just
+    // return empty.
+    if (source.width() < 1 || source.height() < 1 || destWidth < 1 || destHeight < 1) {
+        // todo: seems like we could handle negative dstWidth/Height, since that
+        // is just a negative scale (flip)
+        return false;
+    }
 
-  method = ResizeMethodToAlgorithmMethod(method);
+    method = ResizeMethodToAlgorithmMethod(method);
 
-  // Check that we deal with an "algorithm methods" from this point onward.
-  SkASSERT((SkBitmapScaler::RESIZE_FIRST_ALGORITHM_METHOD <= method) &&
+    // Check that we deal with an "algorithm methods" from this point onward.
+    SkASSERT((SkBitmapScaler::RESIZE_FIRST_ALGORITHM_METHOD <= method) &&
       (method <= SkBitmapScaler::RESIZE_LAST_ALGORITHM_METHOD));
 
-  SkAutoLockPixels locker(source);
-  if (!source.readyToDraw() ||
-      source.colorType() != kN32_SkColorType) {
-      return false;
-  }
-
-  SkResizeFilter filter(method, source.width(), source.height(),
-                        destWidth, destHeight, destSubset, convolveProcs);
-
-  // Get a source bitmap encompassing this touched area. We construct the
-  // offsets and row strides such that it looks like a new bitmap, while
-  // referring to the old data.
-  const unsigned char* sourceSubset =
-      reinterpret_cast<const unsigned char*>(source.getPixels());
-
-  // Convolve into the result.
-  SkBitmap result;
-  result.setInfo(SkImageInfo::MakeN32(SkScalarCeilToInt(destSubset.width()),
-                                      SkScalarCeilToInt(destSubset.height()),
-                                      source.alphaType()));
-  result.allocPixels(allocator, NULL);
-  if (!result.readyToDraw()) {
-      return false;
-  }
-
-  BGRAConvolve2D(sourceSubset, static_cast<int>(source.rowBytes()),
-      !source.isOpaque(), filter.xFilter(), filter.yFilter(),
-      static_cast<int>(result.rowBytes()),
-      static_cast<unsigned char*>(result.getPixels()),
-      convolveProcs, true);
-
-  *resultPtr = result;
-  resultPtr->lockPixels();
-  SkASSERT(resultPtr->getPixels());
-  return true;
+    SkAutoPixmapUnlock result;
+    if (!source.requestLock(&result)) {
+        return false;
+    }
+    return resize(result.pixmap(), resultPtr, method, destWidth, destHeight, allocator,
+                  convolveProcs);
 }
 
 // static -- simpler interface to the resizer; returns a default bitmap if scaling