package com.avenwu.radialdemo;import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;/*** @author chaobin* @date 1/10/14.*/
public class CircleView extends View {private float mCenterX;private float mCenterY;private float mRadius;private Paint mPaint;public CircleView(Context context) {this(context, null);}public CircleView(Context context, AttributeSet attrs) {this(context, attrs, 0);}public CircleView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);init();}private void init() {mRadius = getContext().getResources().getDisplayMetrics().density * 100;mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);mPaint.setColor(Color.RED);mPaint.setStrokeWidth(getContext().getResources().getDisplayMetrics().density * 5);}@Overrideprotected void onDraw(Canvas canvas) {canvas.drawCircle(mCenterX, mCenterY, mRadius, mPaint);}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {super.onMeasure(widthMeasureSpec, heightMeasureSpec);int width = MeasureSpec.getSize(widthMeasureSpec) / 2;int height = MeasureSpec.getSize(heightMeasureSpec) / 2;Log.d("CircleView", "onMeasure, height=" + height + ", width=" + width);updateCenter(width, height);}@Overrideprotected void onSizeChanged(int w, int h, int oldw, int oldh) {super.onSizeChanged(w, h, oldw, oldh);Log.d("CircleView", "onSizeChanged: w=" + w + ", h=" + h);updateCenter(w, h);}void updateCenter(int x, int y) {mCenterX = x / 2;mCenterY = y / 2;}boolean isInside(float x, float y) {return Math.pow(x - mCenterX, 2) + Math.pow(y - mCenterY, 2)<= Math.pow(mCenterX - getPaddingLeft(), 2);}@Overridepublic boolean onTouchEvent(MotionEvent event) {switch (event.getAction()) {case MotionEvent.ACTION_DOWN:if (isInside(event.getX(), event.getY())) {mPaint.setColor(Color.MAGENTA);}break;case MotionEvent.ACTION_UP:mPaint.setColor(Color.RED);break;case MotionEvent.ACTION_MOVE:if (!isInside(event.getX(), event.getY())) {mPaint.setColor(Color.RED);}Log.d("CircleView", "position, x=" + event.getX() + ", y=" + event.getY());break;}invalidate();return true;}}