Android自定义View--手写签名

 

1.要实现自定义view，要处理一下几个问题

  1）View的绘制，onDraw方法。

  2）事件处理，复写onTouchEvent方法。

2.自定义SignView

  1)初始化

 private void init(Context context) {
        this.context = context;
        this.paint = new Paint();
        paint.setAntiAlias(true);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(10);
        paint.setColor(Color.BLACK);
        path = new Path();
    }

  2）

 @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        width = getMeasuredWidth();
        height = getMeasuredHeight();
    }

3）手写签名，主要是利用了Path的moveTo和drawLine方法。

 @Override
    protected void onDraw(Canvas canvas) {
        if (path == null) {
            return;
        }
        canvas.drawPath(path, paint);
    }

4）事件处理

    Down的时候调用 moveTo方法，MOVE时调用lineTo，这样屏幕上就能显示手指划过的痕迹

 @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                float downX = event.getX();
                float downY = event.getY();

                path.moveTo(downX, downY);
                invalidate();
                break;
            case MotionEvent.ACTION_MOVE:
                float x = event.getX();
                float y = event.getY();
                path.lineTo(x, y);
                invalidate();
                break;
            case MotionEvent.ACTION_UP:
                break;
        }
        return true;
    }

5）将手写签名保存为Bitmap。通过View.draw方法

     int width = signView.getMeasuredWidth();
     int height = signView.getMeasuredHeight();
     Bitmap bitmap = Bitmap.createBitmap(width,height, Bitmap.Config.ARGB_8888);
     Canvas canvas = new Canvas(bitmap);
     signView.draw(canvas);

Demo下载：

https://download.csdn.net/download/niuyongzhi/86541558