Source/WebCore/platform/graphics/android/ScrollableLayerAndroid.h

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef ScrollableLayerAndroid_h
#define ScrollableLayerAndroid_h

#if USE(ACCELERATED_COMPOSITING)

#include "LayerAndroid.h"

namespace WebCore {

class ScrollableLayerAndroid : public LayerAndroid {

public:
    ScrollableLayerAndroid(RenderLayer* owner)
        : LayerAndroid(owner) {}
    ScrollableLayerAndroid(const ScrollableLayerAndroid& layer)
        : LayerAndroid(layer)
        , m_scrollLimits(layer.m_scrollLimits) {}
    ScrollableLayerAndroid(const LayerAndroid& layer)
        : LayerAndroid(layer)
    {
        m_scrollLimits.setEmpty();
    }
    virtual ~ScrollableLayerAndroid() {};

    virtual bool contentIsScrollable() const { return true; }

    virtual LayerAndroid* copy() const { return new ScrollableLayerAndroid(*this); }

    virtual bool updateWithLayer(LayerAndroid*) { return true; }

    // Scrolls to the given position in the layer.
    // Returns whether or not any scrolling was required.
    bool scrollTo(int x, int y);

    // Fills the rect with the current scroll offset and the maximum scroll offset.
    // fLeft   = scrollX
    // fTop    = scrollY
    // fRight  = maxScrollX
    // fBottom = maxScrollY
    void getScrollRect(SkIRect*) const;

    void setScrollLimits(float x, float y, float width, float height)
    {
        m_scrollLimits.set(x, y, x + width, y + height);
    }

    // Given a rect in the layer, scrolls to bring the rect into view. Uses a
    // lazy approach, whereby we scroll as little as possible to bring the
    // entire rect into view. If the size of the rect exceeds that of the
    // visible area of the layer, we favor the top and left of the rect.
    // Returns whether or not any scrolling was required.
    bool scrollRectIntoView(const SkIRect&);

    friend void android::serializeLayer(LayerAndroid* layer, SkWStream* stream);
    friend LayerAndroid* android::deserializeLayer(SkStream* stream);

private:
    // The position of the visible area of the layer, relative to the parent
    // layer. This is fixed during scrolling. We acheive scrolling by modifying
    // the position of the layer.
    SkRect m_scrollLimits;
};

}

#endif // USE(ACCELERATED_COMPOSITING)

#endif // LayerAndroid_h