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Android example source code file (BaseSurfaceHolder.java)

This example Android source code file (BaseSurfaceHolder.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

android, basesurfaceholder, canvas, debug, drawing, exception, graphics, interruptedexception, paint, rect, reentrantlock, returned, string, surface, surface_type_gpu, surface_type_normal, surface_type_push_buffers, tag, ui, view

The BaseSurfaceHolder.java Android example source code

/*
 * Copyright (C) 2009 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 com.android.internal.view;

import android.graphics.Canvas;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.os.SystemClock;
import android.util.Log;
import android.view.Surface;
import android.view.SurfaceHolder;

import java.util.ArrayList;
import java.util.concurrent.locks.ReentrantLock;

public abstract class BaseSurfaceHolder implements SurfaceHolder {
    private static final String TAG = "BaseSurfaceHolder";
    static final boolean DEBUG = false;

    public final ArrayList<SurfaceHolder.Callback> mCallbacks
            = new ArrayList<SurfaceHolder.Callback>();

    public final ReentrantLock mSurfaceLock = new ReentrantLock();
    public final Surface mSurface = new Surface();

    int mRequestedWidth = -1;
    int mRequestedHeight = -1;
    int mRequestedFormat = PixelFormat.OPAQUE;
    int mRequestedType = -1;

    long mLastLockTime = 0;
    
    int mType = -1;
    final Rect mSurfaceFrame = new Rect();
    
    public abstract void onUpdateSurface();
    public abstract void onRelayoutContainer();
    public abstract boolean onAllowLockCanvas();
    
    public int getRequestedWidth() {
        return mRequestedWidth;
    }
    
    public int getRequestedHeight() {
        return mRequestedHeight;
    }
    
    public int getRequestedFormat() {
        return mRequestedFormat;
    }
    
    public int getRequestedType() {
        return mRequestedType;
    }
    
    public void addCallback(Callback callback) {
        synchronized (mCallbacks) {
            // This is a linear search, but in practice we'll 
            // have only a couple callbacks, so it doesn't matter.
            if (mCallbacks.contains(callback) == false) {      
                mCallbacks.add(callback);
            }
        }
    }

    public void removeCallback(Callback callback) {
        synchronized (mCallbacks) {
            mCallbacks.remove(callback);
        }
    }
    
    public void setFixedSize(int width, int height) {
        if (mRequestedWidth != width || mRequestedHeight != height) {
            mRequestedWidth = width;
            mRequestedHeight = height;
            onRelayoutContainer();
        }
    }

    public void setSizeFromLayout() {
        if (mRequestedWidth != -1 || mRequestedHeight != -1) {
            mRequestedWidth = mRequestedHeight = -1;
            onRelayoutContainer();
        }
    }

    public void setFormat(int format) {
        if (mRequestedFormat != format) {
            mRequestedFormat = format;
            onUpdateSurface();
        }
    }

    public void setType(int type) {
        switch (type) {
        case SURFACE_TYPE_HARDWARE:
        case SURFACE_TYPE_GPU:
            // these are deprecated, treat as "NORMAL"
            type = SURFACE_TYPE_NORMAL;
            break;
        }
        switch (type) {
        case SURFACE_TYPE_NORMAL:
        case SURFACE_TYPE_PUSH_BUFFERS:
            if (mRequestedType != type) {
                mRequestedType = type;
                onUpdateSurface();
            }
            break;
        }
    }

    public Canvas lockCanvas() {
        return internalLockCanvas(null);
    }

    public Canvas lockCanvas(Rect dirty) {
        return internalLockCanvas(dirty);
    }

    private final Canvas internalLockCanvas(Rect dirty) {
        if (mType == SURFACE_TYPE_PUSH_BUFFERS) {
            throw new BadSurfaceTypeException(
                    "Surface type is SURFACE_TYPE_PUSH_BUFFERS");
        }
        mSurfaceLock.lock();

        if (DEBUG) Log.i(TAG, "Locking canvas..,");

        Canvas c = null;
        if (onAllowLockCanvas()) {
            Rect frame = dirty != null ? dirty : mSurfaceFrame;
            try {
                c = mSurface.lockCanvas(frame);
            } catch (Exception e) {
                Log.e(TAG, "Exception locking surface", e);
            }
        }

        if (DEBUG) Log.i(TAG, "Returned canvas: " + c);
        if (c != null) {
            mLastLockTime = SystemClock.uptimeMillis();
            return c;
        }
        
        // If the Surface is not ready to be drawn, then return null,
        // but throttle calls to this function so it isn't called more
        // than every 100ms.
        long now = SystemClock.uptimeMillis();
        long nextTime = mLastLockTime + 100;
        if (nextTime > now) {
            try {
                Thread.sleep(nextTime-now);
            } catch (InterruptedException e) {
            }
            now = SystemClock.uptimeMillis();
        }
        mLastLockTime = now;
        mSurfaceLock.unlock();
        
        return null;
    }

    public void unlockCanvasAndPost(Canvas canvas) {
        mSurface.unlockCanvasAndPost(canvas);
        mSurfaceLock.unlock();
    }

    public Surface getSurface() {
        return mSurface;
    }

    public Rect getSurfaceFrame() {
        return mSurfaceFrame;
    }
};

Other Android examples (source code examples)

Here is a short list of links related to this Android BaseSurfaceHolder.java source code file:

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