我正在从事绘画工作。画线时画得很完美。当我画一条新线时，以前画的线会从视图中删除，我不知道为什么会发生这种情况。任何人都知道请帮助我。
public class DrawView extends View implements OnTouchListener {// custom view
private Canvas mCanvas;
private Path mPath;
private ArrayList<Pair<Path, Paint>> paths = new ArrayList<Pair<Path, Paint>>();
private ArrayList<Pair<Path, Paint>> undonePaths = new ArrayList<Pair<Path, Paint>>();
public DrawView(Context context) {
super(context);
setFocusable(true);
setFocusableInTouchMode(true);
this.setOnTouchListener(this);
mCanvas = new Canvas();
mPath = new Path();
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh); //do as user want
}
@Override
protected void onDraw(Canvas canvas) { //onDraw method
//DRAWING LINE................................
linearray[0]=stupx;
linearray[1]=stupy;
linearray[2]=upx;
linearray[3]=upy;
canvas.drawLines(linearray, mPaint);
Log.d("METHOD", "ONDRAW LINE FIRED "+stupx+" "+stupy+""+upx+" "+upy);
}
private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;
private void touch_start(float x, float y) {
undonePaths.clear();
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;
}
}
private void touchline() {
// TODO Auto-generated method stub
Log.d("METHOD", "TOUCHLINE FIRED ");
mPath.lineTo(mX, mY);
// commit the path to our offscreen
mCanvas.drawPath(mPath, mPaint);
// kill this so we don't double draw
newShapePaint = new Paint(mPaint); // Clones the mPaint object
paths.add(new Pair<Path, Paint>(mPath, newShapePaint));
Log.d("TOUCH UP", "METHOD FIRED WITHOUT COLOR CHANGE"+_color);
mPath = new Path();
}
}
// onTouch 事件
@Override
public boolean onTouch(View arg0, MotionEvent event) {
x = event.getX();
y = event.getY();
upx=0f;
upy=0f;
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
stupx=event.getX();
stupy=event.getY();
touch_start(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
touch_move(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
Log.d("method", "touch up fired");
upx=event.getX();
upy=event.getY();
touchline(); //call after remove finger
invalidate();
break;
}
return true;
}
}