大家好，我有一个应用程序，可以在位图上放置一个圆圈，并使用滑动条更改圆圈内像素的 RGB 值。我想使用 asynctask 来加速更改像素的过程。我不知道从哪里开始。我在活动文件底部注释掉了一些代码，因为这是我第一次尝试:)。谁能指出我如何实现这一点的正确方向。该活动调用自定义视图（touchview），据我所知，异步任务必须在 UI 线程上实例化。我正在考虑在 onPreExecute() 中初始化滑块等，但不确定如何将所有工作人员的内容放入 doInBackground() 中。任何帮助将不胜感激，谢谢马特。
public class Jjilapp extends Activity {
private Button b1;
private static final String TAG = "*********jjil";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.e(TAG, "***********inside oncreate about to set contentview = ");
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.touchview);
final TouchView touchView = (TouchView)findViewById(R.id.touchview);
final HorizontalSlider slider = (HorizontalSlider)findViewById(R.id.slider);
touchView.initSlider(slider);
b1 = (Button)findViewById(R.id.button1);
b1.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Log.e(TAG, "onClickButton1");
}
});
}//end of oncreate
/* private class UpdateCirclePixels extends AsyncTask<Integer,Integer,Integer>{
@Override
protected void onPreExecute(){
final TouchView touchView = (TouchView)findViewById(R.id.touchview);
final HorizontalSlider slider = (HorizontalSlider)findViewById(R.id.slider);
touchView.initSlider(slider);
}
@Override
protected Integer doInBackground(Integer... arg0) {
// TODO Auto-generated method stub
publishProgress(progress);
return null;
}
@Override
protected void onProgressUpdate(Integer... progress){
}
}//end of AsyncTask */
}//end of jjilapp
.
public class TouchView extends View{
private File tempFile;
private byte[] imageArray;
private Bitmap bgr;
private Bitmap bm;
private Paint pTouch;
private int centreX = 1;
private int centreY = 1;
private int radius = 50;
private int Progress;
private static final String TAG = "*********TouchView";
public TouchView(Context context) {
super(context);
// TouchView(context, null);
}
public TouchView(Context context, AttributeSet attr) {
super(context,attr);
tempFile = new File(Environment.getExternalStorageDirectory().
getAbsolutePath() + "/"+"image.jpg");
imageArray = new byte[(int)tempFile.length()];
try{
InputStream is = new FileInputStream(tempFile);
BufferedInputStream bis = new BufferedInputStream(is);
DataInputStream dis = new DataInputStream(bis);
int i = 0;
while (dis.available() > 0) {
imageArray[i] = dis.readByte();
i++;
}
dis.close();
} catch (Exception e) {
e.printStackTrace();
}
BitmapFactory.Options bfo = new BitmapFactory.Options();
bfo.inSampleSize = 1;
bm = BitmapFactory.decodeByteArray(imageArray, 0, imageArray.length, bfo);
bgr = Bitmap.createBitmap(bm.getWidth(), bm.getHeight(), bm.getConfig());
bgr = bm.copy(bm.getConfig(), true);
pTouch = new Paint(Paint.ANTI_ALIAS_FLAG);
pTouch.setXfermode(new PorterDuffXfermode(Mode.SRC_OUT));
pTouch.setColor(Color.TRANSPARENT);
pTouch.setStyle(Paint.Style.STROKE);
//pTouch.setMaskFilter(new BlurMaskFilter(15, Blur.NORMAL));
}// end of touchView constructor
public void findCirclePixels(){
for (int i=centreX-50; i < centreX+50; ++i) {
for (int y=centreY-50; y <centreY+50 ; ++y) {
if( Math.sqrt( Math.pow(i - centreX, 2) + ( Math.pow(y - centreY, 2) ) ) <= radius ){
bgr.setPixel(i,y,Color.rgb(Progress+50,Progress,Progress+100));
}
}
}
}// end of changePixel()
@Override
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN: {
centreX = (int) ev.getX();
centreY = (int) ev.getY();
findCirclePixels();
invalidate();
break;
}
case MotionEvent.ACTION_MOVE: {
centreX = (int) ev.getX();
centreY = (int) ev.getY();
findCirclePixels();
invalidate();
break;
}
case MotionEvent.ACTION_UP:
break;
}
return true;
}//end of onTouchEvent
public void initSlider(final HorizontalSlider slider)
{
Log.e(TAG, "******setting up slider*********** ");
slider.setOnProgressChangeListener(changeListener);
}
private OnProgressChangeListener changeListener = new OnProgressChangeListener() {
@Override
public void onProgressChanged(View v, int progress) {
// TODO Auto-generated method stub
setProgress(progress);
Log.e(TAG, "***********progress = "+Progress);
}
};
@Override
public void onDraw(Canvas canvas){
super.onDraw(canvas);
canvas.drawBitmap(bgr, 0, 0, null);
canvas.drawCircle(centreX, centreY, radius,pTouch);
}//end of onDraw
protected void setProgress(int progress2) {
this.Progress = progress2;
findCirclePixels();
invalidate();
}
}
