gecko-dev/gfx/layers/basic/BasicImplData.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 GFX_BASICIMPLDATA_H
#define GFX_BASICIMPLDATA_H

#include "mozilla/AlreadyAddRefed.h"  // for already_AddRefed
#include "mozilla/gfx/Point.h"        // for Point
#include "mozilla/gfx/Types.h"  // for CompositionOp, CompositionOp::OP_OVER, CompositionOp::OP_SOURCE
#include "mozilla/layers/LayerManager.h"  // for LayerManager, LayerManager::DrawPaintedLayerCallback
#include "nsDebug.h"      // for NS_ASSERTION
#include "nsISupports.h"  // for MOZ_COUNTED_DTOR_VIRTUAL, MOZ_COUNT_CTOR

class gfxContext;

namespace mozilla {
namespace gfx {
class DrawTarget;
class SourceSurface;
}  // namespace gfx

namespace layers {

class Layer;
class ReadbackProcessor;

/**
 * This is the ImplData for all Basic layers. It also exposes methods
 * private to the Basic implementation that are common to all Basic layer types.
 * In particular, there is an internal Paint() method that we can use
 * to paint the contents of non-PaintedLayers.
 *
 * The class hierarchy for Basic layers is like this:
 *                                 BasicImplData
 * Layer                            |   |   |
 *  |                               |   |   |
 *  +-> ContainerLayer              |   |   |
 *  |    |                          |   |   |
 *  |    +-> BasicContainerLayer <--+   |   |
 *  |                                   |   |
 *  +-> PaintedLayer                     |   |
 *  |    |                              |   |
 *  |    +-> BasicPaintedLayer <---------+   |
 *  |                                       |
 *  +-> ImageLayer                          |
 *       |                                  |
 *       +-> BasicImageLayer <--------------+
 */
class BasicImplData {
 public:
  BasicImplData()
      : mHidden(false),
        mClipToVisibleRegion(false),
        mDrawAtomically(false),
        mOperator(gfx::CompositionOp::OP_OVER) {
    MOZ_COUNT_CTOR(BasicImplData);
  }
  MOZ_COUNTED_DTOR_VIRTUAL(BasicImplData)

  /**
   * Layers that paint themselves, such as ImageLayers, should paint
   * in response to this method call. aContext will already have been
   * set up to account for all the properties of the layer (transform,
   * opacity, etc).
   */
  virtual void Paint(gfx::DrawTarget* aDT, const gfx::Point& aDeviceOffset,
                     Layer* aMaskLayer) {}

  /**
   * Like Paint() but called for PaintedLayers with the additional parameters
   * they need.
   * If mClipToVisibleRegion is set, then the layer must clip to its
   * effective visible region (snapped or unsnapped, it doesn't matter).
   */
  virtual void PaintThebes(gfxContext* aContext, Layer* aMasklayer,
                           LayerManager::DrawPaintedLayerCallback aCallback,
                           void* aCallbackData) {}

  virtual void Validate(LayerManager::DrawPaintedLayerCallback aCallback,
                        void* aCallbackData, ReadbackProcessor* aReadback) {}

  /**
   * Layers will get this call when their layer manager is destroyed, this
   * indicates they should clear resources they don't really need after their
   * LayerManager ceases to exist.
   */
  virtual void ClearCachedResources() {}

  /**
   * This variable is set by MarkLayersHidden() before painting. It indicates
   * that the layer should not be composited during this transaction.
   */
  void SetHidden(bool aCovered) { mHidden = aCovered; }
  bool IsHidden() const { return false; }
  /**
   * This variable is set by MarkLayersHidden() before painting. This is
   * the operator to be used when compositing the layer in this transaction. It
   * must be OVER or SOURCE.
   */
  void SetOperator(gfx::CompositionOp aOperator) {
    NS_ASSERTION(aOperator == gfx::CompositionOp::OP_OVER ||
                     aOperator == gfx::CompositionOp::OP_SOURCE,
                 "Bad composition operator");
    mOperator = aOperator;
  }

  gfx::CompositionOp GetOperator() const { return mOperator; }

  /**
   * Return a surface for this layer. Will use an existing surface, if
   * possible, or may create a temporary surface.  Implement this
   * method for any layers that might be used as a mask.  Should only
   * return false if a surface cannot be created.  If true is
   * returned, only one of |aSurface| or |aDescriptor| is valid.
   */
  virtual already_AddRefed<gfx::SourceSurface> GetAsSourceSurface() {
    return nullptr;
  }

  bool GetClipToVisibleRegion() { return mClipToVisibleRegion; }
  void SetClipToVisibleRegion(bool aClip) { mClipToVisibleRegion = aClip; }

  void SetDrawAtomically(bool aDrawAtomically) {
    mDrawAtomically = aDrawAtomically;
  }

 protected:
  bool mHidden;
  bool mClipToVisibleRegion;
  bool mDrawAtomically;
  gfx::CompositionOp mOperator;
};

}  // namespace layers
}  // namespace mozilla

#endif