core/java/android/view/HardwareCanvas.java

/*
 * 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.
 */

package android.view;

import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;

/**
 * Hardware accelerated canvas. 
 */
abstract class HardwareCanvas extends Canvas {
    @Override
    public boolean isHardwareAccelerated() {
        return true;
    }

    @Override
    public void setBitmap(Bitmap bitmap) {
        throw new UnsupportedOperationException();
    }
    
    /**
     * Invoked before any drawing operation is performed in this canvas.
     */
    abstract void onPreDraw();

    /**
     * Invoked after all drawing operation have been performed.
     */
    abstract void onPostDraw();
    
    /**
     * Draws the specified display list onto this canvas.
     * 
     * @param displayList The display list to replay.
     */
    abstract void drawDisplayList(DisplayList displayList);

    /**
     * Draws the specified layer onto this canvas.
     *
     * @param left The left coordinate of the layer
     * @param top The top coordinate of the layer
     * @param right The right coordinate of the layer
     * @param bottom The bottom coordinate of the layer
     * @param layer The layer to composite on this canvas
     * @param paint The paint used to draw the layer
     */
    abstract void drawHardwareLayer(float left, float top, float right, float bottom,
            HardwareLayer layer, Paint paint); 
}