Android自定义View绘制彩色圆弧

package com.example.yan;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.SweepGradient;
import android.util.AttributeSet;
import android.view.View;

/**
 * Created by xiaoyanzi on 2016/3/18.
 * 渐变圆弧
 */
public class GradualView extends View {

 private Context context;
 private Paint paint;//画笔
 private Paint paintFull;//实心圆画笔
 private Paint textPaint;//标识字画笔
 private Paint valuePaint;//移动小球画笔
 private int[] mColors;//渐变色数组

 private int centerX;//中心X
 private int centerY;//中心Y
 private int srcH;//控件高度
 private float startAngle = 110;//圆弧起始角度
 private float sweepAngle = 320;//圆弧所占度数
 private float airValue = 66;

 /**
 * 直接在代码中调用时，使用该函数
 *
 * @param context
 */
 public GradualView(Context context) {
 super(context);
 initData(context);
 }

 /**
 * 在xml中使用自定义view时，使用这个函数
 *
 * @param context
 * @param attrs
 */
 public GradualView(Context context, AttributeSet attrs) {
 super(context, attrs);
 initData(context);
 }

 /**
 * 可以由上一个函数中手动调用
 *
 * @param context
 * @param atrrs
 * @param defStyle 自定义函数中的attrs表示view的属性集，defStyle表示默认的属性资源集的id
 */
 public GradualView(Context context, AttributeSet atrrs, int defStyle) {
 super(context, atrrs, defStyle);
 }

 /**
 * 初始化
 * @param context
 */
 private void initData(Context context) {
 this.context = context;
 paint = new Paint(Paint.ANTI_ALIAS_FLAG);
 paint.setStyle(Paint.Style.STROKE);
 mColors = new int[]{
  0xFF660099,//紫色
  0xFF330033,//褐色
  0xFF99FF00,//草绿色
  0xFFFFFF00,//黄色
  0xFFFF6600,//橘色
  0xFFFF0000,//红色
  0xFF660099,//紫色

 };
 Shader s = new SweepGradient(0, 0, mColors, null);
 paint.setAntiAlias(true);//设置画笔为无锯齿
 paint.setStrokeWidth(dip2px(context, 14));//线宽
 paint.setShader(s);
 paintFull = new Paint(Paint.ANTI_ALIAS_FLAG);
 paintFull.setStyle(Paint.Style.FILL_AND_STROKE);
 paintFull.setAntiAlias(true);//设置画笔为无锯齿
 paintFull.setShader(s);
 textPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
 textPaint.setTextSize(dip2px(context, 22));//设置字体大小
 textPaint.setColor(0xFFFFFFFF);
 valuePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
 valuePaint.setAntiAlias(true);//设置画笔为无锯齿
 }

 public void setAirValue(float airValue) {
 this.airValue = airValue;
 }

 @Override
 protected void onSizeChanged(int w, int h, int oldw, int oldh) {
 super.onSizeChanged(w, h, oldw, oldh);
 srcH = h;
 centerX = w / 2;
 centerY = h / 2;
 }

 @Override
 protected void onDraw(Canvas canvas) {
 super.onDraw(canvas);
 float r = srcH / 2 - paint.getStrokeWidth() * 0.5f - dip2px(context, 200);
 //移动中心
 canvas.translate(centerX, centerY);
 RectF oval = new RectF();
 oval.left = -r;//左边
 oval.top = -r;//上边
 oval.right = r;//右边
 oval.bottom = r;//下边
 canvas.drawArc(oval, startAngle, sweepAngle, false, paint); //绘制圆弧
 //绘制圆弧两头的小圆
 float mr = dip2px(context, 7);
 float x1 = (float) (-r * Math.sin((360 - sweepAngle) / 2 * Math.PI / 180));
 float y1 = (float) (r * Math.cos((360 - sweepAngle) / 2 * Math.PI / 180));
 canvas.drawCircle(x1, y1, mr, paintFull);
 float x2 = (float) (r * Math.sin((360 - sweepAngle) / 2 * Math.PI / 180));
 float y2 = (float) (r * Math.cos((360 - sweepAngle) / 2 * Math.PI / 180));
 canvas.drawCircle(x2, y2, mr, paintFull);
 //小圆离球的距离
 float range = r + dip2px(context, 30);
 float ar = 12f;
 //画周围小球和数字
 float ax1 = (float) (-range * Math.sin(45 * Math.PI / 180));
 float ay1 = (float) (range * Math.cos(45 * Math.PI / 180));
 canvas.drawCircle(ax1, ay1, ar, paintFull);
 canvas.drawText("0", ax1 - getTextW() * 3, ay1 + getTextH() / 2, textPaint);
 float ax2 = -range;
 float ay2 = 0;
 canvas.drawCircle(ax2, ay2, ar, paintFull);
 canvas.drawText("50", ax2 - getTextW() * 5, ay2 + getTextH() / 2, textPaint);
 float ax3 = (float) (-range * Math.sin(45 * Math.PI / 180));
 float ay3 = (float) (-range * Math.cos(45 * Math.PI / 180));
 canvas.drawCircle(ax3, ay3, ar, paintFull);
 canvas.drawText("100", ax3 - getTextW() * 7, ay3 + getTextH() / 2, textPaint);
 float ax4 = 0;
 float ay4 = -range;
 canvas.drawCircle(ax4, ay4, ar, paintFull);
 canvas.drawText("150", ax4 - getTextW() * 3, ay4 - getTextH(), textPaint);
 float ax5 = (float) (range * Math.sin(45 * Math.PI / 180));
 float ay5 = (float) (-range * Math.cos(45 * Math.PI / 180));
 canvas.drawCircle(ax5, ay5, ar, paintFull);
 canvas.drawText("200", ax5 + getTextW(), ay5 + getTextH() / 2, textPaint);
 float ax6 = range;
 float ay6 = 0;
 canvas.drawCircle(ax6, ay6, ar, paintFull);
 canvas.drawText("300", ax6 + getTextW(), ay6 + getTextH() / 2, textPaint);
 float ax7 = (float) (range * Math.sin(45 * Math.PI / 180));
 float ay7 = (float) (range * Math.cos(45 * Math.PI / 180));
 canvas.drawCircle(ax7, ay7, ar, paintFull);
 canvas.drawText("500", ax7 + getTextW(), ay7 + getTextH() / 2, textPaint);
 //画标识小球
 valuePaint.setColor(0xFFFFFFFF);
 float cx;
 float cy;
 if (airValue >= 0 && airValue <= 50) {
  cx = (float) (-r * Math.cos((45 - airValue * 0.9) * Math.PI / 180));
  cy = (float) (r * Math.sin((45 - airValue * 0.9) * Math.PI / 180));
 } else if (airValue > 50 && airValue <= 150) {
  cx = (float) (-r * Math.cos((airValue * 0.9 - 45) * Math.PI / 180));
  cy = (float) (-r * Math.sin((airValue * 0.9 - 45) * Math.PI / 180));
 } else if (airValue > 150 && airValue <= 200) {
  cx = (float) (-r * Math.cos((airValue * 0.9 - 45) * Math.PI / 180));
  cy = (float) (-r * Math.sin((airValue * 0.9 - 45) * Math.PI / 180));
 } else if (airValue > 200 && airValue <= 300) {
  cx = (float) (-r * Math.cos((airValue * 0.45 + 45) * Math.PI / 180));
  cy = (float) (-r * Math.sin((airValue * 0.45 + 45) * Math.PI / 180));
 } else if (airValue > 300 && airValue <= 500) {//此处有问题
  cx = (float) (r * Math.cos(((airValue - 300) * 0.225) * Math.PI / 180));
  cy = (float) (r * Math.sin(((airValue - 300) * 0.225) * Math.PI / 180));
 } else {
  cx = (float) (-r * Math.cos(45 * Math.PI / 180));
  cy = (float) (r * Math.sin(45 * Math.PI / 180));
 }
 canvas.drawCircle(cx, cy, dip2px(context, 11), valuePaint);
 canvas.drawCircle(cx, cy, dip2px(context, 4), paintFull);
 }

 /**
 * dip转px
 * @param context
 * @param dpValue
 * @return
 */
 private int dip2px(Context context, float dpValue) {
 final float scale = context.getResources().getDisplayMetrics().density;
 return (int) (dpValue * scale + 0.5f);
 }

 /**
 * 获取"正"的高度
 *
 * @return
 */
 private float getTextH() {
 Paint pFont = new Paint();
 Rect rect = new Rect();
 //返回包围整个字符串的最小的一个Rect区域
 pFont.getTextBounds("正", 0, 1, rect);
 return rect.height();
 }

 /**
 * 获取"正"的宽度
 *
 * @return
 */
 private float getTextW() {
 Paint pFont = new Paint();
 Rect rect = new Rect();
 //返回包围整个字符串的最小的一个Rect区域
 pFont.getTextBounds("正", 0, 1, rect);
 return rect.width();
 }
}