我已经创建了 SurfaceView 类，用于通过 onTouch 方法在视图上绘图...我已经阅读并学习了一些关于 SurfaceView 和绘图活动的示例代码，并创建了以下类：
public class DrawingSurface extends SurfaceView implements
SurfaceHolder.Callback{
private DrawingThread drawingthread;
public Paint mPaint;
private Bitmap mBitmap;
private Canvas mCanvas;
private Path mPath;
private Paint mBitmapPaint;
private float cx = 0, cy = 0;
private boolean easer = false;
private boolean touch = false;
private Paint mEarserPaint;
int count = 0;
public DrawingSurface(Context context, AttributeSet attrs) {
super(context, attrs);
getHolder().addCallback(this);
}
public DrawingSurface(Context context) {
super(context);
getHolder().addCallback(this);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
System.out.println("onSizeChange");
mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
System.out.println("onSurfaceChange");
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
System.out.println("onSurfaceCreated");
// For drawing that is called in the onDraw method
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(0xF0000000);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(12);
mEarserPaint = new Paint();
mEarserPaint.setAntiAlias(true);
mEarserPaint.setDither(true);
mEarserPaint.setColor(0xF0000000);
mEarserPaint.setStyle(Paint.Style.STROKE);
mEarserPaint.setStrokeJoin(Paint.Join.ROUND);
mEarserPaint.setStrokeCap(Paint.Cap.ROUND);
mEarserPaint.setStrokeWidth(12);
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
drawingthread = new DrawingThread(getHolder(), this);
drawingthread.setRunning(true);
drawingthread.start();
setFocusable(true);
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
System.out.println("OnDestroy");
boolean retry = true;
drawingthread.setRunning(false);
while (retry) {
try {
drawingthread.join();
retry = false;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
@Override
public void onDraw(Canvas canvas) {
// on earser mode draw circal on touch
if (easer && touch) {
canvas.drawColor(0xFFAAAAAA);
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
canvas.drawCircle(cx, cy, 50, mEarserPaint);
} else {
canvas.drawColor(0xFFAAAAAA);
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
canvas.drawPath(mPath, mPaint);
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
// get the touch postion for drawing the circal
cx = event.getX();
cy = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
touch_start(x, y);
touch = true;
invalidate();
break;
case MotionEvent.ACTION_MOVE:
touch_move(x, y);
invalidate();
touch = true;
break;
case MotionEvent.ACTION_UP:
touch_up();
invalidate();
touch = false;
break;
}
return true;
}
private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;
private void touch_start(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
}
private void touch_move(float x, float y) {
float dx = Math.abs(x - mX);
float dy = Math.abs(y - mY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
mX = x;
mY = y;
}
if (easer)
mCanvas.drawPath(mPath, mPaint);
}
private void touch_up() {
mPath.lineTo(mX, mY);
mCanvas.drawPath(mPath, mPaint);
mPath.reset();
}
public void onAttributeChange(Paint paint, boolean e) {
mPaint = paint;
easer = e;
}
public Bitmap getDrawingSurface() {
return mBitmap;
}
}
这是 SurfaceView 的线程类：
public class DrawingThread extends Thread {
private SurfaceHolder drawingHolder;
private DrawingSurface drawingSurface;
private boolean run = false;
public DrawingThread(SurfaceHolder surfaceholder, DrawingSurface surfaceview) {
drawingHolder = surfaceholder;
drawingSurface = surfaceview;
}
public void setRunning(boolean running) {
run = running;
}
@Override
public void run() {
Canvas c;
while (run) {
c = null;
try {
c = drawingHolder.lockCanvas(null);
if (c != null) {
synchronized (drawingHolder) {
drawingSurface.onDraw(c);
}
}
}finally {
if (c != null)
drawingHolder.unlockCanvasAndPost(c);
}
}
}
}
这从一开始就可以正常工作，但是当我继续绘制时（在 5 秒到 3 分钟之间）它会停止在视图上随机绘制（不崩溃）.. 我认为 onDraw 方法停止处理并且我不知道为什么，日志中没有异常，并且当 onDraw 停止响应我的触摸时不会调用 onDestory 方法。
希望你能帮我解决这个问题。