android - 用润色结束 Canvas

Question

我用 Canvas 画线并触摸但我的问题是，当我们再次触摸屏幕时，前面的行被删除了我想再次触摸画新线，但最后一行没有删除发件人 protected void onDraw(Canvas canvas) { super.onDraw( Canvas ); //onDraw时在 Canvas 上用mPaint绘制mPath canvas.drawLine(sX, sY, eX, eY, mPaint);

// when ACTION_DOWN start touch according to the x,y values
private void startTouch(float x, float y) {
    sX = x;
    sY = y;
}

// when ACTION_MOVE move touch according to the x,y values
private void moveTouch(float x, float y) {
        eX = x;
        eY = y;
}
private void upTouch(float x, float y) {
    eX = x;
    eY = y;
}

public void clearCanvas() {
    invalidate();
}



@Override
public boolean onTouchEvent(MotionEvent event) {
    float x = event.getX();
    float y = event.getY();

    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:
        startTouch(x, y);
        invalidate();
        break;
    case MotionEvent.ACTION_MOVE:
        moveTouch(x, y);
        invalidate();
        break;
    case MotionEvent.ACTION_UP:
        upTouch(x,y);
        invalidate();
        break;
    }
    return true;
}

Answer 1

Here is Canvas 和绘图的一个很好的例子