ScannerOverlay.java 文件源码

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    // draw transparent rect
    int cornerRadius = 0;
    Paint eraser = new Paint();
    eraser.setAntiAlias(true);
    eraser.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));


    RectF rect = new RectF(left, top, dpToPx(rectWidth) + left, dpToPx(rectHeight) + top);
    canvas.drawRoundRect(rect, (float) cornerRadius, (float) cornerRadius, eraser);

    // draw horizontal line
    Paint line = new Paint();
    line.setColor(lineColor);
    line.setStrokeWidth(Float.valueOf(lineWidth));

    // draw the line to product animation
    if (endY >= top + dpToPx(rectHeight) + frames) {
        revAnimation = true;
    } else if (endY == top + frames) {
        revAnimation = false;
    }

    // check if the line has reached to bottom
    if (revAnimation) {
        endY -= frames;
    } else {
        endY += frames;
    }
    canvas.drawLine(left, endY, left + dpToPx(rectWidth), endY, line);
    invalidate();
}