android群英传笔记--第三章--自定义控件三简单形状View

onMeasure OnDraw 最简单的使用教程

 @Override
    protected void onMeasure(int widthMeasureSpec,
                             int heightMeasureSpec) {
        mMeasureWidth = MeasureSpec.getSize(widthMeasureSpec);
        mMeasureHeigth = MeasureSpec.getSize(heightMeasureSpec);
        setMeasuredDimension(mMeasureWidth, mMeasureHeigth);
        initView();
    }

 @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        // 绘制圆
        canvas.drawCircle(mCircleXY, mCircleXY, mRadius, mCirclePaint);
        // 绘制弧线
        canvas.drawArc(mArcRectF, 270, mSweepAngle, false, mArcPaint);
        // 绘制文字
        canvas.drawText(mShowText, 0, mShowText.length(),
                mCircleXY, mCircleXY + (mShowTextSize / 4), mTextPaint);
    }

关键逻辑方法：

private void initView() {
        float length = 0;
        if (mMeasureHeigth >= mMeasureWidth) {
            length = mMeasureWidth;
        } else {
            length = mMeasureHeigth;
        }

        mCircleXY = length / 2;
        mRadius = (float) (length * 0.5 / 2);
        mCirclePaint = new Paint();
        mCirclePaint.setAntiAlias(true);
        mCirclePaint.setColor(getResources().getColor(
                android.R.color.holo_blue_bright));

        mArcRectF = new RectF(
                (float) (length * 0.1),
                (float) (length * 0.1),
                (float) (length * 0.9),
                (float) (length * 0.9));
        mSweepAngle = (mSweepValue / 100f) * 360f;
        mArcPaint = new Paint();
        mArcPaint.setAntiAlias(true);
        mArcPaint.setColor(getResources().getColor(
                android.R.color.darker_gray));
        mArcPaint.setStrokeWidth((float) (length * 0.1));
        mArcPaint.setStyle(Style.STROKE);

        mShowText = setShowText();
        mShowTextSize = setShowTextSize();
        mTextPaint = new Paint();
        mTextPaint.setTextSize(mShowTextSize);
        mTextPaint.setTextAlign(Paint.Align.CENTER);
    }