Reverting 20516 by re-landing this previous patch.

Keep the cairo clipping region in sync with the Skia one.

The PlatformCanvas now tracks this, so we don't need to have the similar code
in gfx::Canvas. I moved most references of cairo_surface_t to cairo_t since the
cairo_t has a transform and clip but the surface does not.

Review URL: http://codereview.chromium.org/149409
Review URL: http://codereview.chromium.org/155700

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@20992 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 109 insertions, 10 deletions

diff --git a/skia/ext/bitmap_platform_device_linux.cc b/skia/ext/bitmap_platform_device_linux.cc
index 1b061b0..a74ec83 100644
--- a/skia/ext/bitmap_platform_device_linux.cc
+++ b/skia/ext/bitmap_platform_device_linux.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2009 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.
 
@@ -8,6 +8,33 @@
 
 namespace skia {
 
+namespace {
+
+void LoadMatrixToContext(cairo_t* context, const SkMatrix& matrix) {
+  cairo_matrix_t cairo_matrix;
+  cairo_matrix_init(&cairo_matrix,
+                    SkScalarToFloat(matrix.getScaleX()),
+                    SkScalarToFloat(matrix.getSkewY()),
+                    SkScalarToFloat(matrix.getSkewX()),
+                    SkScalarToFloat(matrix.getScaleY()),
+                    SkScalarToFloat(matrix.getTranslateX()),
+                    SkScalarToFloat(matrix.getTranslateY()));
+  cairo_set_matrix(context, &cairo_matrix);
+}
+
+void LoadClipToContext(cairo_t* context, const SkRegion& clip) {
+  cairo_reset_clip(context);
+
+  // TODO(brettw) support non-rect clips.
+  SkIRect bounding = clip.getBounds();
+  cairo_rectangle(context, bounding.fLeft, bounding.fTop,
+                  bounding.fRight - bounding.fLeft,
+                  bounding.fBottom - bounding.fTop);
+  cairo_clip(context);
+}
+
+}  // namespace
+
 // -----------------------------------------------------------------------------
 // These objects are reference counted and own a Cairo surface. The surface is
 // the backing store for a Skia bitmap and we reference count it so that we can
@@ -17,18 +44,39 @@ namespace skia {
 class BitmapPlatformDevice::BitmapPlatformDeviceData
     : public base::RefCounted<BitmapPlatformDeviceData> {
  public:
-  explicit BitmapPlatformDeviceData(cairo_surface_t* surface)
-      : surface_(surface) { }
+  explicit BitmapPlatformDeviceData(cairo_surface_t* surface);
 
-  cairo_surface_t* surface() const { return surface_; }
+  cairo_t* GetContext();
+  cairo_surface_t* GetSurface();
+
+  // Sets the transform and clip operations. This will not update the Cairo
+  // surface, but will mark the config as dirty. The next call of LoadConfig
+  // will pick up these changes.
+  void SetMatrixClip(const SkMatrix& transform, const SkRegion& region);
 
  protected:
+  friend class base::RefCounted<BitmapPlatformDeviceData>;
+
+  ~BitmapPlatformDeviceData();
+
+  void LoadConfig();
+
+  // The Cairo surface inside this DC.
+  cairo_t* context_;
   cairo_surface_t *const surface_;
 
-  friend class base::RefCounted<BitmapPlatformDeviceData>;
-  ~BitmapPlatformDeviceData() {
-    cairo_surface_destroy(surface_);
-  }
+  // True when there is a transform or clip that has not been set to the
+  // surface.  The surface is retrieved for every text operation, and the
+  // transform and clip do not change as much. We can save time by not loading
+  // the clip and transform for every one.
+  bool config_dirty_;
+
+  // Translation assigned to the DC: we need to keep track of this separately
+  // so it can be updated even if the DC isn't created yet.
+  SkMatrix transform_;
+
+  // The current clipping
+  SkRegion clip_region_;
 
   // Disallow copy & assign.
   BitmapPlatformDeviceData(const BitmapPlatformDeviceData&);
@@ -36,6 +84,52 @@ class BitmapPlatformDevice::BitmapPlatformDeviceData
       const BitmapPlatformDeviceData&);
 };
 
+BitmapPlatformDevice::BitmapPlatformDeviceData::BitmapPlatformDeviceData(
+    cairo_surface_t* surface)
+    : surface_(surface),
+      config_dirty_(true) {  // Want to load the config next time.
+  context_ = cairo_create(surface);
+}
+
+BitmapPlatformDevice::BitmapPlatformDeviceData::~BitmapPlatformDeviceData() {
+  cairo_destroy(context_);
+  cairo_surface_destroy(surface_);
+}
+
+cairo_t* BitmapPlatformDevice::BitmapPlatformDeviceData::GetContext() {
+  LoadConfig();
+  return context_;
+}
+
+void BitmapPlatformDevice::BitmapPlatformDeviceData::SetMatrixClip(
+    const SkMatrix& transform,
+    const SkRegion& region) {
+  transform_ = transform;
+  clip_region_ = region;
+  config_dirty_ = true;
+}
+
+cairo_surface_t*
+BitmapPlatformDevice::BitmapPlatformDeviceData::GetSurface() {
+  // TODO(brettw) this function should be removed.
+  LoadConfig();
+  return surface_;
+}
+
+void BitmapPlatformDevice::BitmapPlatformDeviceData::LoadConfig() {
+  if (!config_dirty_ || !context_)
+    return;  // Nothing to do.
+  config_dirty_ = false;
+
+  // Load the identity matrix since this is what our clip is relative to.
+  cairo_matrix_t cairo_matrix;
+  cairo_matrix_init_identity(&cairo_matrix);
+  cairo_set_matrix(context_, &cairo_matrix);
+
+  LoadClipToContext(context_, clip_region_);
+  LoadMatrixToContext(context_, 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
@@ -98,8 +192,13 @@ BitmapPlatformDevice::BitmapPlatformDevice(
 BitmapPlatformDevice::~BitmapPlatformDevice() {
 }
 
-cairo_surface_t* BitmapPlatformDevice::surface() const {
-  return data_->surface();
+cairo_t* BitmapPlatformDevice::beginPlatformPaint() {
+  return data_->GetContext();
+}
+
+void BitmapPlatformDevice::setMatrixClip(const SkMatrix& transform,
+                                         const SkRegion& region) {
+  data_->SetMatrixClip(transform, region);
 }
 
 BitmapPlatformDevice& BitmapPlatformDevice::operator=(