gecko-dev/gfx/thebes/gfxWindowsNativeDrawing.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 _GFXWINDOWSNATIVEDRAWING_H_
#define _GFXWINDOWSNATIVEDRAWING_H_

#include <windows.h>

#include "gfxContext.h"
#include "gfxWindowsSurface.h"

class gfxWindowsNativeDrawing {
 public:
  /* Flags for notifying this class what kind of operations the native
   * drawing supports
   */

  enum {
    /* Whether the native drawing can draw to a surface of content COLOR_ALPHA
     */
    CAN_DRAW_TO_COLOR_ALPHA = 1 << 0,
    CANNOT_DRAW_TO_COLOR_ALPHA = 0 << 0,

    /* Whether the native drawing can be scaled using SetWorldTransform */
    CAN_AXIS_ALIGNED_SCALE = 1 << 1,
    CANNOT_AXIS_ALIGNED_SCALE = 0 << 1,

    /* Whether the native drawing can be both scaled and rotated arbitrarily
       using SetWorldTransform */
    CAN_COMPLEX_TRANSFORM = 1 << 2,
    CANNOT_COMPLEX_TRANSFORM = 0 << 2,
  };

  /* Create native win32 drawing for a rectangle bounded by
   * nativeRect.
   *
   * Typical usage looks like:
   *
   *   gfxWindowsNativeDrawing nativeDraw(ctx, destGfxRect, capabilities);
   *   do {
   *     HDC dc = nativeDraw.BeginNativeDrawing();
   *     if (!dc)
   *       return NS_ERROR_FAILURE;
   *
   *     RECT winRect;
   *     nativeDraw.TransformToNativeRect(rect, winRect);
   *
   *       ... call win32 operations on HDC to draw to winRect ...
   *
   *     nativeDraw.EndNativeDrawing();
   *   } while (nativeDraw.ShouldRenderAgain());
   *   nativeDraw.PaintToContext();
   */
  gfxWindowsNativeDrawing(
      gfxContext* ctx, const gfxRect& nativeRect,
      uint32_t nativeDrawFlags = CANNOT_DRAW_TO_COLOR_ALPHA |
                                 CANNOT_AXIS_ALIGNED_SCALE |
                                 CANNOT_COMPLEX_TRANSFORM);

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

  /* Transform the native rect into something valid for rendering
   * to the HDC.  This may or may not change RECT, depending on
   * whether SetWorldTransform is used or not. */
  void TransformToNativeRect(const gfxRect& r, RECT& rout);

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

  /* Returns true if the native drawing should be executed again */
  bool ShouldRenderAgain();

  /* Places the result to the context, if necessary */
  void PaintToContext();

 private:
  RefPtr<gfxContext> mContext;
  gfxRect mNativeRect;
  uint32_t mNativeDrawFlags;

  // what state the rendering is in
  uint8_t mRenderState;

  mozilla::gfx::Point mDeviceOffset;
  RefPtr<gfxPattern> mBlackPattern, mWhitePattern;

  enum TransformType { TRANSLATION_ONLY, AXIS_ALIGNED_SCALE, COMPLEX };

  TransformType mTransformType;
  gfxPoint mTranslation;
  gfxSize mScale;
  XFORM mWorldTransform;

  // saved state
  RefPtr<gfxWindowsSurface> mWinSurface, mBlackSurface, mWhiteSurface;
  HDC mDC;
  XFORM mOldWorldTransform;
  POINT mOrigViewportOrigin;
  mozilla::gfx::IntSize mTempSurfaceSize;
};

#endif