[移动开发]android 自定义view实现手签

public class SignView extends View {

    int painColor = Color.BLACK; //画笔颜色
    float paintSize = 8;//画笔宽度
    Path path;//路径
    Paint paint;//画笔
    float start_x, start_y, click_x, click_y;//坐标点
    public SignView(Context context) {//代码new用的
        this(context, null);
    }
    public SignView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }
    public SignView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initPaint();  //实例化paint
    }
    private void initPaint() {
        path = new Path();
        paint = new Paint();
        paint.setStrokeWidth(paintSize);
        paint.setColor(painColor);
        paint.setAntiAlias(true);//抗锯齿
        paint.setStyle(Paint.Style.STROKE);//样式
    }
    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawPath(path, paint);//画路线
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        start_x = event.getX();//记录当前的坐标
        start_y = event.getY();
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                return downEvent();
            case MotionEvent.ACTION_MOVE:
                moveEvent();
            default:
                break;
        }
        return super.onTouchEvent(event);
    }
    private void moveEvent() {
        click_x = start_x;
        click_y = start_y;
        path.quadTo(click_x, click_y, (start_x + click_x) / 2, (start_y + click_y) / 2);
        invalidate();
    }
    private boolean downEvent() {
        click_x = start_x;//保存起点坐标
        click_y = start_y;
        path.moveTo(start_x, start_y);//移动画笔
        return true;
    }
    public void clear(){
        if (path!=null){
            path.reset();
        }
        invalidate();
    }
}