Revert of Delete Mac & Cairo skia::BitmapPlatformDevice impls

skia/ext/bitmap_platform_device_mac.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "skia/ext/bitmap_platform_device_mac.h"
+
+#import <ApplicationServices/ApplicationServices.h>
+#include <stddef.h>
+#include <time.h>
+
+#include "base/mac/mac_util.h"
+#include "base/memory/ref_counted.h"
+#include "skia/ext/bitmap_platform_device.h"
+#include "skia/ext/platform_canvas.h"
+#include "skia/ext/skia_utils_mac.h"
+#include "third_party/skia/include/core/SkMatrix.h"
+#include "third_party/skia/include/core/SkPath.h"
+#include "third_party/skia/include/core/SkRect.h"
+#include "third_party/skia/include/core/SkTypes.h"
+
+namespace skia {
+
+namespace {
+
+// Returns true if it is unsafe to attempt to allocate an offscreen buffer
+// given these dimensions.
+bool RasterDeviceTooBigToAllocate(int width, int height) {
+
+#ifndef SKIA_EXT_RASTER_DEVICE_ALLOCATION_MAX
+#define SKIA_EXT_RASTER_DEVICE_ALLOCATION_MAX    (2 * 256 * 1024 * 1024)
+#endif
+
+    int bytesPerPixel = 4;
+    int64_t bytes = (int64_t)width * height * bytesPerPixel;
+    return bytes > SKIA_EXT_RASTER_DEVICE_ALLOCATION_MAX;
+}
+
+static CGContextRef CGContextForData(void* data, int width, int height) {
+#define HAS_ARGB_SHIFTS(a, r, g, b) \
+            (SK_A32_SHIFT == (a) && SK_R32_SHIFT == (r) \
+             && SK_G32_SHIFT == (g) && SK_B32_SHIFT == (b))
+#if defined(SK_CPU_LENDIAN) && HAS_ARGB_SHIFTS(24, 16, 8, 0)
+  // Allocate a bitmap context with 4 components per pixel (BGRA).  Apple
+  // recommends these flags for improved CG performance.
+
+  // CGBitmapContextCreate returns NULL if width/height are 0. However, our
+  // callers expect to get a canvas back (which they later resize/reallocate)
+  // so we pin the dimensions here.
+  width = SkMax32(1, width);
+  height = SkMax32(1, height);
+  CGContextRef context =
+      CGBitmapContextCreate(data, width, height, 8, width * 4,
+                            base::mac::GetSystemColorSpace(),
+                            kCGImageAlphaPremultipliedFirst |
+                                kCGBitmapByteOrder32Host);
+#else
+#error We require that Skia's and CoreGraphics's recommended \
+       image memory layout match.
+#endif
+#undef HAS_ARGB_SHIFTS
+
+  if (!context)
+    return NULL;
+
+  // Change the coordinate system to match WebCore's
+  CGContextTranslateCTM(context, 0, height);
+  CGContextScaleCTM(context, 1.0, -1.0);
+
+  return context;
+}
+
+}  // namespace
+
+void BitmapPlatformDevice::ReleaseBitmapContext() {
+  SkASSERT(bitmap_context_);
+  CGContextRelease(bitmap_context_);
+  bitmap_context_ = NULL;
+}
+
+// Loads the specified Skia transform into the device context
+static void LoadTransformToCGContext(CGContextRef context,
+                                     const SkMatrix& matrix) {
+  // CoreGraphics can concatenate transforms, but not reset the current one.
+  // So in order to get the required behavior here, we need to first make
+  // the current transformation matrix identity and only then load the new one.
+
+  // Reset matrix to identity.
+  CGAffineTransform orig_cg_matrix = CGContextGetCTM(context);
+  CGAffineTransform orig_cg_matrix_inv =
+      CGAffineTransformInvert(orig_cg_matrix);
+  CGContextConcatCTM(context, orig_cg_matrix_inv);
+
+  // assert that we have indeed returned to the identity Matrix.
+  SkASSERT(CGAffineTransformIsIdentity(CGContextGetCTM(context)));
+
+  // Convert xform to CG-land.
+  // Our coordinate system is flipped to match WebKit's so we need to modify
+  // the xform to match that.
+  SkMatrix transformed_matrix = matrix;
+  SkScalar sy = -matrix.getScaleY();
+  transformed_matrix.setScaleY(sy);
+  size_t height = CGBitmapContextGetHeight(context);
+  SkScalar ty = -matrix.getTranslateY();  // y axis is flipped.
+  transformed_matrix.setTranslateY(ty + (SkScalar)height);
+
+  CGAffineTransform cg_matrix =
+      skia::SkMatrixToCGAffineTransform(transformed_matrix);
+
+  // Load final transform into context.
+  CGContextConcatCTM(context, cg_matrix);
+}
+
+static void LoadClippingRegionToCGContext(CGContextRef context,
+                                          const SkIRect& clip_bounds,
+                                          const SkMatrix& transformation) {
+  // CoreGraphics applies the current transform to clip rects, which is
+  // unwanted. Inverse-transform the rect before sending it to CG. This only
+  // works for translations and scaling, but not for rotations (but the
+  // viewport is never rotated anyway).
+  SkMatrix t;
+  bool did_invert = transformation.invert(&t);
+  if (!did_invert)
+    t.reset();
+
+  SkRect rect = SkRect::Make(clip_bounds);
+  t.mapRect(&rect);
+  SkIRect irect;
+  rect.round(&irect);
+  CGContextClipToRect(context, skia::SkIRectToCGRect(irect));
+}
+
+void BitmapPlatformDevice::LoadConfig(const SkMatrix& transform,
+                                      const SkIRect& clip_bounds) {
+  if (!bitmap_context_)
+    return;  // Nothing to do.
+
+  // We must restore and then save the state of the graphics context since the
+  // calls to Load the clipping region to the context are strictly cummulative,
+  // i.e., you can't replace a clip rect, other than with a save/restore.
+  // But this implies that no other changes to the state are done elsewhere.
+  // If we ever get to need to change this, then we must replace the clip rect
+  // calls in LoadClippingRegionToCGContext() with an image mask instead.
+  CGContextRestoreGState(bitmap_context_);
+  CGContextSaveGState(bitmap_context_);
+  LoadTransformToCGContext(bitmap_context_, transform);
+  LoadClippingRegionToCGContext(bitmap_context_, clip_bounds, transform);
+}
+
+
+// We use this static factory function instead of the regular constructor so
+// that we can create the pixel data before calling the constructor. This is
+// required so that we can call the base class' constructor with the pixel
+// data.
+BitmapPlatformDevice* BitmapPlatformDevice::Create(CGContextRef context,
+                                                   int width,
+                                                   int height,
+                                                   bool is_opaque,
+                                                   bool do_clear) {
+  if (RasterDeviceTooBigToAllocate(width, height))
+    return NULL;
+
+  SkBitmap bitmap;
+  // TODO: verify that the CG Context's pixels will have tight rowbytes or pass in the correct
+  // rowbytes for the case when context != NULL.
+  bitmap.setInfo(SkImageInfo::MakeN32(width, height, is_opaque ? kOpaque_SkAlphaType : kPremul_SkAlphaType));
+
+  void* data;
+  if (context) {
+    data = CGBitmapContextGetData(context);
+    bitmap.setPixels(data);
+  } else {
+    if (!bitmap.tryAllocPixels())
+      return NULL;
+    data = bitmap.getPixels();
+  }
+  if (do_clear)
+    memset(data, 0, bitmap.getSafeSize());
+
+  // If we were given data, then don't clobber it!
+#ifndef NDEBUG
+  if (!context && is_opaque) {
+    // To aid in finding bugs, we set the background color to something
+    // obviously wrong so it will be noticable when it is not cleared
+    bitmap.eraseARGB(255, 0, 255, 128);  // bright bluish green
+  }
+#endif
+
+  if (!context) {
+    context = CGContextForData(data, width, height);
+    if (!context)
+      return NULL;
+  } else
+    CGContextRetain(context);
+
+  BitmapPlatformDevice* rv = new BitmapPlatformDevice(context, bitmap);
+
+  // The device object took ownership of the graphics context with its own
+  // CGContextRetain call.
+  CGContextRelease(context);
+
+  return rv;
+}
+
+BitmapPlatformDevice* BitmapPlatformDevice::CreateWithData(uint8_t* data,
+                                                           int width,
+                                                           int height,
+                                                           bool is_opaque) {
+  CGContextRef context = NULL;
+  if (data)
+    context = CGContextForData(data, width, height);
+
+  BitmapPlatformDevice* rv = Create(context, width, height, is_opaque, false);
+
+  // The device object took ownership of the graphics context with its own
+  // CGContextRetain call.
+  if (context)
+    CGContextRelease(context);
+
+  return rv;
+}
+
+// The device will own the bitmap, which corresponds to also owning the pixel
+// data. Therefore, we do not transfer ownership to the SkBitmapDevice's bitmap.
+BitmapPlatformDevice::BitmapPlatformDevice(
+    CGContextRef context, const SkBitmap& bitmap)
+    : SkBitmapDevice(bitmap),
+      bitmap_context_(context) {
+  SetPlatformDevice(this, this);
+  SkASSERT(bitmap_context_);
+  // Initialize the clip region to the entire bitmap.
+
+  SkIRect rect;
+  rect.set(0, 0,
+           CGBitmapContextGetWidth(bitmap_context_),
+           CGBitmapContextGetHeight(bitmap_context_));
+  CGContextRetain(bitmap_context_);
+  // We must save the state once so that we can use the restore/save trick
+  // in LoadConfig().
+  CGContextSaveGState(bitmap_context_);
+}
+
+BitmapPlatformDevice::~BitmapPlatformDevice() {
+  if (bitmap_context_)
+    CGContextRelease(bitmap_context_);
+}
+
+NativeDrawingContext BitmapPlatformDevice::BeginPlatformPaint(
+    const SkMatrix& transform,
+    const SkIRect& clip_bounds) {
+  LoadConfig(transform, clip_bounds);
+  return bitmap_context_;
+}
+
+SkBaseDevice* BitmapPlatformDevice::onCreateDevice(const CreateInfo& cinfo,
+                                                   const SkPaint*) {
+  const SkImageInfo& info = cinfo.fInfo;
+  const bool do_clear = !info.isOpaque();
+  SkASSERT(info.colorType() == kN32_SkColorType);
+  return Create(NULL, info.width(), info.height(), info.isOpaque(), do_clear);
+}
+
+// PlatformCanvas impl
+
+std::unique_ptr<SkCanvas> CreatePlatformCanvasWithPixels(
+    int width,
+    int height,
+    bool is_opaque,
+    uint8_t* data,
+    OnFailureType failureType) {
+  sk_sp<SkBaseDevice> dev(
+      BitmapPlatformDevice::CreateWithData(data, width, height, is_opaque));
+  return CreateCanvas(dev, failureType);
+}
+
+}  // namespace skia