自定义View（一）

public class Circle extends View {    Paint mPaint;    Paint mWordPaint;    Paint mPoint;    float width;    float height;    String textContent = "ABC";    public Circle(Context context) {        this(context, null);    }    public Circle(Context context, @Nullable AttributeSet attrs) {        this(context, attrs, 0);    }    public Circle(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        mPaint = new Paint();        mWordPaint = new Paint();        mPoint = new Paint();    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        super.onMeasure(widthMeasureSpec, heightMeasureSpec);        /**         * 获取在加载该View时给的宽高，（以下具体的宽高是200dp,200dp）            <com.b.widget.Circle                android:layout_width="200dp"                android:layout_height="200dp"                android:background="#f00"/>         */        width = getMeasuredWidth();        height = getMeasuredHeight();    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        mPaint.setColor(Color.GRAY);        mWordPaint.setColor(Color.RED);        mPoint.setColor(Color.BLACK);        mWordPaint.setTextSize(60);        //半径        float radius = width > height ? height / 2 : width / 2;        //画圆参数含义（圆心横坐标，圆心纵坐标，半径，画笔对象）        canvas.drawCircle(width / 2, height / 2, radius, mPaint);        Rect rect = new Rect();        //getTextBounds 参数的含义（字符串内容，开始计数位置，结束计数位置，返回的rect对象）        //得到的rect就可以获取文字的宽高        mWordPaint.getTextBounds(textContent, 0, textContent.length(), rect);        //画文字,参数含义（文字内容，文字左下端的横坐标，文字左下端的纵坐标，画笔对象）        //在具体的操作过程中要考虑到文字的本身的宽高，才能将文字画在中心位置        canvas.drawText(textContent, width / 2 - rect.width() / 2, height / 2 + rect.height() / 2, mWordPaint);        canvas.drawCircle(width / 2, height / 2, 10, mPoint);    }}