Android自定义消息提示控件

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开发中经常会用到消息提示这个功能，就像

这样的效果，这里先简单做一个Demo看看效果，之后会在我的工具库中做更多的兼容和优化，然后发布！

首先老规矩

private int measureWidth;
private int measureHieght;
private float textSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 10, getResources().getDisplayMetrics());
private TextPaint mTextPaint;
private String testContent = "99+";
private Paint mBackground;
private Rect mRect;
private int textWidht;
private int textHeight;
private String content = "";

public class CustomTextVew extends AppCompatTextView {

    public CustomTextVew(Context context) {
        this(context, null);
    }

    public CustomTextVew(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public CustomTextVew(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        //初始化画笔
        initPaint();
        //初始化尺寸(文字)
        initSize();
    }
}

重写onMeasure(测量控件尺寸)

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        measureWidth = MeasureSpec.getSize(widthMeasureSpec);
        measureHieght = MeasureSpec.getSize(heightMeasureSpec);
    }

初始化画笔

    private void initPaint() {
        //文字画笔
        mTextPaint = new TextPaint();
        mTextPaint.setAntiAlias(true);
        mTextPaint.setTextSize(textSize);
        //文字居中
        mTextPaint.setTextAlign(Paint.Align.CENTER);
        mTextPaint.setColor(Color.WHITE);
        //背景画笔
        mBackground = new Paint();
        mBackground.setColor(Color.RED);
        mBackground.setAntiAlias(true);
        //绘制实心
        mBackground.setStyle(Paint.Style.FILL);
    }

初始化文字尺寸

        //这里默认使用"99+"字符的尺寸
        mRect = new Rect();
        mTextPaint.getTextBounds(testContent, 0, testContent.length(), mRect);
        //文字最大的宽
        textWidht = mRect.width();
        //文字的高
        textHeight = mRect.height();

重要的绘制

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (!TextUtils.isEmpty(content)) {
            //需要绘制背景的尺寸(默认在最大尺寸的基础了左右在加2dp的空间)
            float size = textWidht + TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 4, getResources().getDisplayMetrics());
            //绘制背景
            canvas.drawCircle(measureWidth - size / 2, size / 2, size / 2, mBackground);
            //绘制文字
            canvas.drawText(content, measureWidth - size / 2, size / 2 + textHeight / 2, mTextPaint);
        }
    }

最后暴露一个方法，方便设置值

    /**
     * 设置提示数字
     *
     * @param hint
     */
    public void setHintText(String hint) {
        this.content = hint;
        //重绘
        invalidate();
    }

效果

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