package com.vision.myapplicationtest;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
public class MyPath extends View {
public MyPath(Context context) {
super(context);
}
public MyPath(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public MyPath(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private Path path;
private Paint paint;
private void init() {
path = new Path();
paint = new Paint();
paint.setColor(Color.RED);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(2);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
path.moveTo(event.getX(), event.getY());
return true;
case MotionEvent.ACTION_MOVE:
path.lineTo(event.getX(), event.getY());
invalidate();
break;
}
return super.onTouchEvent(event);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawPath(path, paint);
}
public void reset(){
path.reset();
invalidate();
}
}
1.其中 case MotionEvent.ACTION_DOWN 時 return true 表示當前控件已經消費了按下動作,之後的ACTION_MOVE、ACTION_UP動作也會繼續傳遞到當前控件中,如果 return false 那麼之後的動作就不會再傳到這個控件來了。
2.pastInvalidate()和invalidate()。invalidate必須在主線程中,postInvalidate可以在任意線程