gecko-dev/gfx/thebes/gfxQuartzNativeDrawing.h

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef _GFXQUARTZNATIVEDRAWING_H_
#define _GFXQUARTZNATIVEDRAWING_H_

#include "mozilla/Attributes.h"

#include "mozilla/gfx/2D.h"
#include "mozilla/gfx/BorrowedContext.h"
#include "mozilla/RefPtr.h"

class gfxQuartzNativeDrawing {
  typedef mozilla::gfx::DrawTarget DrawTarget;
  typedef mozilla::gfx::Rect Rect;

 public:
  /* Create native Quartz drawing for a rectangle bounded by
   * nativeRect.
   *
   * Typical usage looks like:
   *
   *   gfxQuartzNativeDrawing nativeDraw(ctx, nativeRect);
   *   CGContextRef cgContext = nativeDraw.BeginNativeDrawing();
   *   if (!cgContext)
   *     return NS_ERROR_FAILURE;
   *
   *     ... call Quartz operations on CGContextRef to draw to nativeRect ...
   *
   *   nativeDraw.EndNativeDrawing();
   *
   * aNativeRect is the size of the surface (in Quartz/Cocoa points) that
   * will be created _if_ the gfxQuartzNativeDrawing decides to create a new
   * surface and CGContext for its drawing operations, which it then
   * composites into the target DrawTarget.
   *
   * (Note that aNativeRect will be ignored if the gfxQuartzNativeDrawing
   * uses the target DrawTarget directly.)
   *
   * The optional aBackingScale parameter is a scaling factor that will be
   * applied when creating and rendering into such a temporary surface.
   */
  gfxQuartzNativeDrawing(DrawTarget& aDrawTarget, const Rect& aNativeRect);

  /* Returns a CGContextRef which may be used for native drawing.  This
   * CGContextRef is valid until EndNativeDrawing is called; if it is used
   * for drawing after that time, the result is undefined. */
  CGContextRef BeginNativeDrawing();

  /* Marks the end of native drawing */
  void EndNativeDrawing();

 private:
  // don't allow copying via construction or assignment
  gfxQuartzNativeDrawing(const gfxQuartzNativeDrawing&) = delete;
  const gfxQuartzNativeDrawing& operator=(const gfxQuartzNativeDrawing&) =
      delete;

  // Final destination context
  RefPtr<DrawTarget> mDrawTarget;
  RefPtr<DrawTarget> mTempDrawTarget;
  mozilla::gfx::BorrowedCGContext mBorrowedContext;
  mozilla::gfx::Rect mNativeRect;

  // saved state
  CGContextRef mCGContext;
};

#endif