我在触摸事件的基础上在画布上绘制多行。当我点击我需要通过Last in first out方式删除行时，我在活动中有一个清除按钮。我在arrayobject中存储触摸坐标，我在ondraw（）方法中使用它。我在按钮单击时清除矢量。但它在onDraw（）方法中没有效果。请帮助我。
public class ImageViewTest extends SurfaceView implements ClearData,SurfaceHolder.Callback {
int xpoint, ypoint, xendpoint, yendpoint;
Vector v, v1;
Canvas canvas;
private ViewThread mThread;
boolean motionevent = false ,clear =false;
ArrayList<Vector> objects = new ArrayList<Vector>();
ArrayList<Vector> objects1 = new ArrayList<Vector>();
Vector vobj = new Vector();
public ImageViewTest(Context context) {
super(context);
getHolder().addCallback(this);
mThread = new ViewThread(this);
// TODO Auto-generated constructor stub
}
public ImageViewTest(Context context, AttributeSet attr) {
super(context, attr);
getHolder().addCallback(this);
mThread = new ViewThread(this);
// TODO Auto-generated constructor stub
}
public void cleardata() {
System.out.println(" cleardata");
this.objects.clear();
this.objects1.clear();
// v = null;
//
//
// System.out.println(" v value "+v);
// onDraw(canvas);
invalidate();
}
public void doDraw(Canvas canvas) {
// TODO Auto-generated method stub
//super.onDraw(canvas);
Paint p = new Paint();
System.out.println("ondraw " + objects.size() + " // "
+ objects1.size()+ "CANVAS "+canvas);
DisplayMetrics metrics = getResources().getDisplayMetrics();
Bitmap mapImg = BitmapFactory.decodeResource(getResources(),
R.drawable.film2);
Rect dest = new Rect(0, 0, getWidth(), getHeight());
p.setFilterBitmap(true);
canvas.drawColor(Color.BLACK);
canvas.drawBitmap(mapImg, null, dest, p);
if(motionevent)
{
p.setColor(Color.RED);
p.setStrokeWidth(2);
canvas.drawLine(xpoint, ypoint, xendpoint, yendpoint, p);
}else{
canvas.drawBitmap(mapImg, null, dest, p);
// System.out.println("Objects size "+objects.size()+" // "+objects1.size());
//
for (int index = 0; index < objects.size(); index++) {
p.setColor(Color.RED);
p.setStrokeWidth(2);
Vector vv = objects.get(index);
Vector vv1 = new Vector();
xpoint = (int) Float.parseFloat(vv.elementAt(0).toString());
ypoint = (int) Float.parseFloat(vv.elementAt(1).toString());
if (objects1.size() > index) {
vv1 = objects1.get(index);
// System.out.println("VV SIZE " + vv.size() + " // " + vv1.size());
if (vv1.size() == 2) {
xendpoint = (int) Float.parseFloat(vv1.elementAt(0)
.toString());
yendpoint = (int) Float.parseFloat(vv1.elementAt(1)
.toString());
}
}
canvas.drawLine(xpoint, ypoint, xendpoint, yendpoint, p);
}
}
// canvas.drawLine(xpoint, ypoint, xendpoint, yendpoint, p);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
//System.out.println("getAction " + event.getAction());
//System.out.println("X CORdinates " + event.getX() + " Y coornaf "
// + event.getY() + " V " + objects.size());
v = new Vector();
v1 = new Vector();
switch (event.getAction()) {
case 0: // down
xpoint = (int) event.getX();
ypoint = (int) event.getY();
v.add(event.getX());
v.add(event.getY());
objects.add(v);
break;
case 1: // up
motionevent = false;
v1.add(event.getX());
v1.add(event.getY());
objects1.add(v1);
break;
case 2: // move
motionevent = true;
xendpoint = (int) event.getX();
yendpoint = (int) event.getY();
break;
}
// if(v.isEmpty())
// {
// v.add(event.getX());
// v.add(event.getY());
// System.out.println("hi ");
// xpoint =(int)Float.parseFloat(v.get(0).toString());
// ypoint = (int)Float.parseFloat(v.get(1).toString());
//
//
// }
// xendpoint = (int)event.getX();
// yendpoint = (int)event.getY();
// DisplayMetrics metrics = getResources().getDisplayMetrics();
invalidate();
return true;
}
@Override
public void clearData() {
// TODO Auto-generated method stub
System.err.println(" hi m");
this.objects.clear();
this.objects1.clear();
System.out.println("OBJECTS VALUE "+objects.size()+ " // "+objects1.size() );
clear =true;
System.err.println(clear+" CLEAR");
// postInvalidate();
// onDraw(canvas);
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
System.err.println("Srface changed");
// TODO Auto-generated method stub
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
System.out.println("Surface created");
if (!mThread.isAlive()) {
mThread = new ViewThread(this);
mThread.setRunning(true);
mThread.start();
}
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
}
class ViewThread extends Thread {
private ImageViewTest mPanel;
private SurfaceHolder mHolder;
private boolean mRun = false;
public ViewThread(ImageViewTest panel) {
System.out.println("ViewThREd constructor");
mPanel = panel;
mHolder = mPanel.getHolder();
}
public void setRunning(boolean run) {
mRun = run;
}
@Override
public void run() {
Canvas canvas = null;
while (mRun) {
System.out.println("Inside Run "+mPanel.clear);
canvas = mHolder.lockCanvas();
if (canvas != null) {
if(clear)
{
System.out.println("clear call back");
mHolder.removeCallback(mPanel);
}
mPanel.doDraw(canvas);
mHolder.unlockCanvasAndPost(canvas);
}
}
}
}
}