Android TextView 划线

要求：1.TextView 自定义划线功能，要求划线颜色为红字（可自定义）

2.TextView 部分内容划线，按照开始位置与结束位置划线

效果如下

public class RedTextView extends TextView {
    public RedTextView(Context context) {
        super(context);
    }

    public RedTextView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public RedTextView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        if (show) {
            Rect satrtRect = new Rect();

            int start = getLayout().getLineForOffset(startPosition);
            getLayout().getLineBounds(start, satrtRect);

            float xAxisLeft = getLayout().getPrimaryHorizontal(startPosition);///字符左边x坐标
            float xAxisRight = getLayout().getSecondaryHorizontal(endPosition);//字符右边x坐标
            canvas.drawLine(xAxisLeft, satrtRect.centerY(), xAxisRight, satrtRect.centerY(), linePaint);
        }
    }


    Paint linePaint;
    int startPosition;
    int endPosition;
    boolean show = false;

    public void setShowText(String text, int startPosition, int endPosition) {
        this.setText(text);

        this.show = true;
        this.startPosition = startPosition;
        this.endPosition = endPosition;

        if (linePaint == null) {
            linePaint = new Paint();
            linePaint.setAntiAlias(true);
            linePaint.setColor(Color.RED);
        }
        invalidate();
    }

    public void setNoText(String text) {
        this.show = false;
        this.setText(text);

    }
}