| // 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_CANVAS_PAINT_WIN_H_ |
| #define SKIA_EXT_CANVAS_PAINT_WIN_H_ |
| |
| #include "skia/ext/platform_canvas.h" |
| |
| namespace skia { |
| |
| // 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::PlatformCanvasPaint canvas(hwnd); |
| // if (!canvas.isEmpty()) { |
| // ... paint to the canvas ... |
| // } |
| // return 0; |
| // } |
| template <class T> |
| class CanvasPaintT : public T { |
| public: |
| // This constructor assumes the canvas is opaque. |
| 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<PlatformCanvas> PlatformCanvasPaint; |
| |
| } // namespace skia |
| |
| #endif // SKIA_EXT_CANVAS_PAINT_WIN_H_ |