Refactor the PlatformContext layer to have only one class.

skia/ext/platform_canvas_win.h

-// 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.
 
-#ifndef SKIA_EXT_PLATFORM_CANVAS_WIN_H_
-#define SKIA_EXT_PLATFORM_CANVAS_WIN_H_
 
-#include <windows.h>
+// TODO(brettw) erase this file. This file is necessary because
+// FontChromiumWin.cpp in WebKit includes it, and I want to avoid having to
+// synchronize the checkins to Chromium and WebKit.
 
-#include "skia/ext/platform_device_win.h"
-
-#include "third_party/skia/include/core/SkCanvas.h"
-
-namespace skia {
-
-// This class is a specialization of the regular SkCanvas that is designed to
-// work with a PlatformDevice to manage platform-specific drawing. It allows
-// using both Skia operations and platform-specific operations.
-class PlatformCanvasWin : public SkCanvas {
- public:
-  // Set is_opaque if you are going to erase the bitmap and not use
-  // transparency: this will enable some optimizations.  The shared_section
-  // parameter is passed to gfx::PlatformDevice::create.  See it for details.
-  //
-  // If you use the version with no arguments, you MUST call initialize()
-  PlatformCanvasWin();
-  PlatformCanvasWin(int width, int height, bool is_opaque);
-  PlatformCanvasWin(int width, int height, bool is_opaque,
-                    HANDLE shared_section);
-  virtual ~PlatformCanvasWin();
-
-  // For two-part init, call if you use the no-argument constructor above. Note
-  // that we want this to optionally match the Linux initialize if you only
-  // pass 3 arguments, hence the evil default argument.
-  bool initialize(int width, int height, bool is_opaque,
-                  HANDLE shared_section = NULL);
-
-  // These calls should surround calls to platform drawing routines, the DC
-  // returned by beginPlatformPaint is the DC that can be used to draw into.
-  // Call endPlatformPaint when you are done and want to use Skia operations
-  // again; this will synchronize the bitmap to Windows.
-  virtual HDC beginPlatformPaint();
-  virtual void endPlatformPaint();
-
-  // Returns the platform device pointer of the topmost rect with a non-empty
-  // clip. In practice, this is usually either the top layer or nothing, since
-  // we usually set the clip to new layers when we make them.
-  //
-  // If there is no layer that is not all clipped out, this will return a
-  // dummy device so callers do not have to check. If you are concerned about
-  // performance, check the clip before doing any painting.
-  //
-  // This is different than SkCanvas' getDevice, because that returns the
-  // bottommost device.
-  //
-  // Danger: the resulting device should not be saved. It will be invalidated
-  // by the next call to save() or restore().
-  PlatformDeviceWin& getTopPlatformDevice() const;
-
-  static size_t StrideForWidth(unsigned width);
-
- protected:
-  // Creates a device store for use by the canvas. We override this so that
-  // the device is always our own so we know that we can use GDI operations
-  // on it. Simply calls into createPlatformDevice().
-  virtual SkDevice* createDevice(SkBitmap::Config, int width, int height,
-                                 bool is_opaque, bool isForLayer);
-
-  // Creates a device store for use by the canvas. By default, it creates a
-  // BitmapPlatformDeviceWin. Can be overridden to change the object type.
-  virtual SkDevice* createPlatformDevice(int width, int height, bool is_opaque,
-                                         HANDLE shared_section);
-
- private:
-  // Unimplemented.
-  virtual SkDevice* setBitmapDevice(const SkBitmap& bitmap);
-
-  // Disallow copy and assign.
-  PlatformCanvasWin(const PlatformCanvasWin&);
-  PlatformCanvasWin& operator=(const PlatformCanvasWin&);
-};
-
-// A class designed to help with WM_PAINT operations on Windows. It will
-// do BeginPaint/EndPaint on init/destruction, and will create the bitmap and
-// canvas with the correct size and transform for the dirty rect. The bitmap
-// will be automatically painted to the screen on destruction.
-//
-// You MUST call isEmpty before painting to determine if anything needs
-// painting. Sometimes the dirty rect can actually be empty, and this makes
-// the bitmap functions we call unhappy. The caller should not paint in this
-// case.
-//
-// Therefore, all you need to do is:
-//   case WM_PAINT: {
-//     gfx::PlatformCanvasWinPaint canvas(hwnd);
-//     if (!canvas.isEmpty()) {
-//       ... paint to the canvas ...
-//     }
-//     return 0;
-//   }
-template <class T>
-class CanvasPaintT : public T {
- public:
-  explicit CanvasPaintT(HWND hwnd) : hwnd_(hwnd), paint_dc_(NULL),
-    for_paint_(true) {
-    memset(&ps_, 0, sizeof(ps_));
-    initPaint(true);
-  }
-
-  CanvasPaintT(HWND hwnd, bool opaque) : hwnd_(hwnd), paint_dc_(NULL),
-      for_paint_(true) {
-    memset(&ps_, 0, sizeof(ps_));
-    initPaint(opaque);
-  }
-
-  // Creates a CanvasPaintT for the specified region that paints to the
-  // specified dc. This does NOT do BeginPaint/EndPaint.
-  CanvasPaintT(HDC dc, bool opaque, int x, int y, int w, int h)
-      : hwnd_(NULL),
-        paint_dc_(dc),
-        for_paint_(false) {
-    memset(&ps_, 0, sizeof(ps_));
-    ps_.rcPaint.left = x;
-    ps_.rcPaint.right = x + w;
-    ps_.rcPaint.top = y;
-    ps_.rcPaint.bottom = y + h;
-    init(opaque);
-  }
-
-
-  virtual ~CanvasPaintT() {
-    if (!isEmpty()) {
-      restoreToCount(1);
-      // Commit the drawing to the screen
-      getTopPlatformDevice().drawToHDC(paint_dc_,
-                                       ps_.rcPaint.left, ps_.rcPaint.top,
-                                       NULL);
-    }
-    if (for_paint_)
-      EndPaint(hwnd_, &ps_);
-  }
-
-  // Returns true if the invalid region is empty. The caller should call this
-  // function to determine if anything needs painting.
-  bool isEmpty() const {
-    return ps_.rcPaint.right - ps_.rcPaint.left == 0 ||
-           ps_.rcPaint.bottom - ps_.rcPaint.top == 0;
-  }
-
-  // Use to access the Windows painting parameters, especially useful for
-  // getting the bounding rect for painting: paintstruct().rcPaint
-  const PAINTSTRUCT& paintStruct() const {
-    return ps_;
-  }
-
-  // Returns the DC that will be painted to
-  HDC paintDC() const {
-    return paint_dc_;
-  }
-
- protected:
-  HWND hwnd_;
-  HDC paint_dc_;
-  PAINTSTRUCT ps_;
-
- private:
-  void initPaint(bool opaque) {
-    paint_dc_ = BeginPaint(hwnd_, &ps_);
-
-    init(opaque);
-  }
-
-  void init(bool opaque) {
-    // FIXME(brettw) for ClearType, we probably want to expand the bounds of
-    // painting by one pixel so that the boundaries will be correct (ClearType
-    // text can depend on the adjacent pixel). Then we would paint just the
-    // inset pixels to the screen.
-    const int width = ps_.rcPaint.right - ps_.rcPaint.left;
-    const int height = ps_.rcPaint.bottom - ps_.rcPaint.top;
-    if (!initialize(width, height, opaque, NULL)) {
-      // Cause a deliberate crash;
-      *(char*) 0 = 0;
-    }
-
-    // This will bring the canvas into the screen coordinate system for the
-    // dirty rect
-    translate(SkIntToScalar(-ps_.rcPaint.left),
-              SkIntToScalar(-ps_.rcPaint.top));
-  }
-
-  // If true, this canvas was created for a BeginPaint.
-  const bool for_paint_;
-
-  // Disallow copy and assign.
-  CanvasPaintT(const CanvasPaintT&);
-  CanvasPaintT& operator=(const CanvasPaintT&);
-};
-
-typedef CanvasPaintT<PlatformCanvasWin> PlatformCanvasWinPaint;
-
-}  // namespace skia
-
-#endif  // SKIA_EXT_PLATFORM_CANVAS_WIN_H_
+#include "skia/ext/platform_canvas.h"