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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef ScrollableLayerAndroid_h
     18 #define ScrollableLayerAndroid_h
     19 
     20 #if USE(ACCELERATED_COMPOSITING)
     21 
     22 #include "LayerAndroid.h"
     23 
     24 namespace WebCore {
     25 
     26 class ScrollableLayerAndroid : public LayerAndroid {
     27 
     28 public:
     29     ScrollableLayerAndroid(RenderLayer* owner)
     30         : LayerAndroid(owner) {}
     31     ScrollableLayerAndroid(const ScrollableLayerAndroid& layer)
     32         : LayerAndroid(layer)
     33         , m_scrollLimits(layer.m_scrollLimits) {}
     34     ScrollableLayerAndroid(const LayerAndroid& layer)
     35         : LayerAndroid(layer)
     36     {
     37         m_scrollLimits.setEmpty();
     38     }
     39     virtual ~ScrollableLayerAndroid() {};
     40 
     41     virtual bool contentIsScrollable() const { return true; }
     42 
     43     virtual LayerAndroid* copy() const { return new ScrollableLayerAndroid(*this); }
     44 
     45     virtual bool updateWithLayer(LayerAndroid*) { return true; }
     46 
     47     // Scrolls to the given position in the layer.
     48     // Returns whether or not any scrolling was required.
     49     bool scrollTo(int x, int y);
     50 
     51     // Fills the rect with the current scroll offset and the maximum scroll offset.
     52     // fLeft   = scrollX
     53     // fTop    = scrollY
     54     // fRight  = maxScrollX
     55     // fBottom = maxScrollY
     56     void getScrollRect(SkIRect*) const;
     57 
     58     void setScrollLimits(float x, float y, float width, float height)
     59     {
     60         m_scrollLimits.set(x, y, x + width, y + height);
     61     }
     62 
     63     // Given a rect in the layer, scrolls to bring the rect into view. Uses a
     64     // lazy approach, whereby we scroll as little as possible to bring the
     65     // entire rect into view. If the size of the rect exceeds that of the
     66     // visible area of the layer, we favor the top and left of the rect.
     67     // Returns whether or not any scrolling was required.
     68     bool scrollRectIntoView(const SkIRect&);
     69 
     70     friend void android::serializeLayer(LayerAndroid* layer, SkWStream* stream);
     71     friend LayerAndroid* android::deserializeLayer(SkStream* stream);
     72 
     73 private:
     74     // The position of the visible area of the layer, relative to the parent
     75     // layer. This is fixed during scrolling. We acheive scrolling by modifying
     76     // the position of the layer.
     77     SkRect m_scrollLimits;
     78 };
     79 
     80 }
     81 
     82 #endif // USE(ACCELERATED_COMPOSITING)
     83 
     84 #endif // LayerAndroid_h
     85