自定义View圆的点击事件实现

import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Rect;import android.graphics.RectF;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.DisplayMetrics;import android.view.MotionEvent;import android.view.View;import android.webkit.WebView;import android.widget.Toast;public class MainActivity extends AppCompatActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        DisplayMetrics metrics = new DisplayMetrics();        this.getWindowManager().getDefaultDisplay().getMetrics(metrics);        // 屏幕的分辨率        int width = metrics.widthPixels;        int height = metrics.heightPixels;        setContentView(new MyCircle(this, width, height));    }    class MyCircle extends View {        private Context context;        /**         * 屏幕的宽         */        private int width;        /**         * 屏幕的高         */        private int height;        /**         *  颜色区分区域         */        private int[] colors = new int[] { Color.BLACK, Color.BLUE, Color.CYAN,                Color.GREEN, Color.GRAY, Color.MAGENTA, Color.RED, Color.LTGRAY};        private String[] colorStrs = new String[] {                "黑色", "蓝色", "青绿色", "绿色", "灰色", "洋红色", "红色", "浅灰色"};        /**         * 大园半径         */        private float bigR;        /**         * 小圆半径         */        private float litterR;        /**         * 屏幕中间点的X坐标         */        private float centerX;        /**         * 屏幕中间点的Y坐标         */        private float centerY;        public MyCircle(Context context, int width, int height) {            super(context);            this.context = context;            this.width = width;            this.height = height;            setFocusable(true);            System.out.println("width="+width+"<---->height="+height);            // 设置两个圆的半径            bigR = (width - 20)/2;            litterR = bigR/2;            centerX = width/2;            centerY = height/2;        }        @Override        protected void onDraw(Canvas canvas) {            // 画背景颜色            Paint bg = new Paint();            bg.setColor(Color.WHITE);            Rect bgR = new Rect(0, 0, width, height);            canvas.drawRect(bgR, bg);            float start = 0F;            Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);            for(int i = 0; i < 4; i ++) {                //注意一定要先画大圆，再画小圆，不然看不到效果，小圆在下面会被大圆覆盖                // 画大圆                RectF bigOval = new RectF(centerX - bigR, centerY - bigR,                        centerX + bigR, centerY + bigR);                paint.setColor(colors[i]);                canvas.drawArc(bigOval, start, 90, true, paint);                // 画小圆                RectF litterOval = new RectF(centerX - litterR, centerY - litterR,                        centerX + litterR, centerY + litterR);                paint.setColor(colors[i+2]);                canvas.drawArc(litterOval, start, 90, true, paint);                start += 90F;            }            super.onDraw(canvas);        }        @Override        public boolean onTouchEvent(MotionEvent event) {            // 获取点击屏幕时的点的坐标            float x = event.getX();            float y = event.getY();            whichCircle(x, y);            return super.onTouchEvent(event);        }        /**         * 确定点击的点在哪个圆内         * @param x         * @param y         */        private void whichCircle(float x, float y) {            // 将屏幕中的点转换成以屏幕中心为原点的坐标点            float mx = x - centerX;            float my = y - centerY;            float result = mx * mx + my * my;            StringBuilder tip = new StringBuilder();            tip.append("您点击了");            // 高中的解析几何            if(result <= litterR*litterR) {// 点击的点在小圆内                tip.append("小圆的");                tip.append(colorStrs[whichZone(mx, my)+2]);                tip.append("区域");            } else if(result <= bigR * bigR) {// 点击的点在大圆内                tip.append("大圆的");                tip.append(colorStrs[whichZone(mx, my)]);                tip.append("区域");            } else {// 点不在作作区域                tip.append("作用区域以外的区域");            }            Toast.makeText(context, tip, Toast.LENGTH_SHORT).show();        }        /**         * 判断点击了圆的哪个区域         * @param x         * @param y         * @return         */        private int whichZone(float x, float y) {            // 简单的象限点处理            // 第一象限在右下角，第二象限在左下角，代数里面的是逆时针，这里是顺时针            if(x > 0 && y > 0) {                return 0;            } else if(x > 0 && y < 0) {                return 3;            } else if(x < 0 && y < 0) {                return 2;            } else if(x < 0 && y > 0) {                return 1;            }            return -1;        }    }}