自定义View饼状图的绘制

package com.loaderman.customviewdemo;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.View;

import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by MQ on 2016/12/15.
 */

public class CakeView extends View {
    //装载的饼状圆数据
    private List<CakeBean> beanList;
    //画圆的矩形
    private RectF          mRectF;
    //右边的小矩形
    private RectF          iRectF;
    private Paint          mPaint;
    private int            mRWidth, mRHeight;
    private float rotateDegree;//每个圆弧的起始角度
    private float sumValue = 0;//所有值的和
    private float diameter;//圆的直径
    private float textY;//绘制文字的Y坐标

    private float mRectHeight = 40;//矩形高度
    private float mRectWidth = 80;//矩形宽度
    private float mMargin = 40;//矩形和圆的距离
    private Context mContext;

    public CakeView(Context context) {
        //CakeView cakeView=new CakeView(context);
        // 在代码中new CakeView()会调用这个构造函数
        this(context, null);
    }

    public CakeView(Context context, AttributeSet attrs) {
        //InflateLayoutManager时会调用这个构造函数
        this(context, attrs, 0);
    }

    public CakeView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        mContext = context;
        init();
    }

    private void init() {
        beanList = new ArrayList<>();
        mRectF = new RectF();
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setDither(true);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        //MeasureSpec封装了父View传递给子View的布局要求
        int wMode = MeasureSpec.getMode(widthMeasureSpec);
        int wSize = MeasureSpec.getSize(widthMeasureSpec);
        int hMode = MeasureSpec.getMode(heightMeasureSpec);
        int hSize = MeasureSpec.getSize(heightMeasureSpec);
        switch (wMode) {
            case MeasureSpec.EXACTLY:
                //相当于match_parent或者一个具体值
                mRWidth = wSize;
                break;
            case MeasureSpec.AT_MOST:
                // 相当于wrap_content 默认会充满父View
                // 可以根据子View的大小来计算父View大小，这里先写死大小
                mRWidth = (int) DpUtil.dp2px(mContext, 400f);
                break;
            case MeasureSpec.UNSPECIFIED:
                //很少会用到
                break;
            default:
                break;
        }
        switch (hMode) {
            case MeasureSpec.EXACTLY:
                //相当于match_parent或者一个具体值
                mRHeight = hSize;
                break;
            case MeasureSpec.AT_MOST:
                // 相当于wrap_content 默认会充满父View
                // 可以根据子View的大小来计算父View大小，这里先写死大小
                mRHeight = (int) DpUtil.dp2px(mContext, 200f);
                break;
            case MeasureSpec.UNSPECIFIED:
                //很少会用到
                break;
            default:
                break;
        }
        //存储测量好的宽和高
        setMeasuredDimension(wSize, hSize);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        diameter = Math.min(mRWidth, mRHeight);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        textY = 0f;
        //设置圆形绘制的范围
        mRectF.set(0, 0, diameter, diameter);
        //画布中心X坐标向右移动（控件宽度-圆直径）之差的八分之一的距离
        //画布中心Y坐标向下移动（控件宽度-圆直径）之差的二分之一的距离
        canvas.translate((mRWidth - diameter) / 8, (mRHeight - diameter) / 2);
        if (beanList.size() > 0 && Float.compare(sumValue, 0.0f) != 0) {
            for (int i = 0; i < beanList.size(); i++) {
                CakeBean bean = beanList.get(i);
                //画圆弧
                mPaint.setColor(bean.mColor);
                canvas.drawArc(mRectF, rotateDegree, bean.degree, true, mPaint);
                rotateDegree += bean.degree;
                //画矩形和文字
                drawRectAndText(canvas, bean);
            }
        }
    }

    private void drawRectAndText(Canvas canvas, CakeBean bean) {
        iRectF = new RectF();
        //设置画矩形的范围
        float left = diameter + mMargin;
        float right = diameter + mMargin + mRectWidth;
        float bottom = textY + mRectHeight;
        iRectF.set(left, textY, right, bottom);
        canvas.drawRect(iRectF, mPaint);
        //设置颜色
        mPaint.setColor(Color.BLACK);
        //设置文字大小
        mPaint.setTextSize(30);
        //画文字
        canvas.drawText(bean.name + "(" + new DecimalFormat(".00").format(bean.value / sumValue * 100) + "%)", right + 10, textY + 30, mPaint);
        textY += mRectHeight;
    }

    /**
     * 饼状图添加数据
     *
     * @param beans CakeBean数据
     */
    public void setData(List<CakeBean> beans) {
        if (beans == null || beans.size() <= 0) return;
        for (int i = 0; i < beans.size(); i++) {
            CakeBean bean = beans.get(i);
            sumValue += bean.value;
        }
        for (int i = 0; i < beans.size(); i++) {
            CakeBean bean = beans.get(i);
            bean.degree = bean.value / sumValue * 360;
            beanList.add(bean);
        }
        invalidate();
    }

    /**
     * @param startDegree 设置起始角度
     */
    public void setStartDegree(float startDegree) {
        this.rotateDegree = startDegree;
        invalidate();
    }
}

package com.loaderman.customviewdemo;

import java.io.Serializable;

public class CakeBean implements Serializable {
    public String name;//名字
    public float value;//值
    public float degree;//旋转过的角度
    public int mColor;//圆弧颜色
}

package com.loaderman.customviewdemo;

import android.app.Activity;
import android.content.Context;
import android.util.DisplayMetrics;

/**
 * Created by MQ on 2016/12/16.
 */

public class DpUtil {
    /**
     * dp转换成px
     *
     * @param context Context
     * @param dp      dp
     * @return px值
     */
    public static float dp2px(Context context, float dp) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return dp * scale + 0.5f;
    }

    /**
     * sp转换成px
     *
     * @param context Context
     * @param sp      sp
     * @return px值
     */
    public static float sp2px(Context context, float sp) {
        final float scale = context.getResources().getDisplayMetrics().scaledDensity;
        return sp * scale;
    }

    /**
     * 获得屏幕宽度
     *
     * @param context Context
     * @return 屏幕宽度（像素）
     */
    public static int getScreenSizeWidth(Context context) {
        DisplayMetrics metric = new DisplayMetrics();
        ((Activity) context).getWindowManager().getDefaultDisplay().getMetrics(metric);
        return metric.widthPixels;
    }
}

package com.loaderman.customviewdemo;

import android.graphics.Color;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private List<CakeBean> beans;
    private String[] names = {"php", "object-c", "c", "c++", "java", "android", "linux"};
    private float[] values = {2f, 2f, 3f, 4f, 5f, 6f, 7f};
    private int[] colArrs = {Color.RED, Color.parseColor("#4ebcd3"), Color.MAGENTA, Color.YELLOW, Color.GREEN, Color.parseColor("#f68b2b"), Color.parseColor("#6fb30d")};//圆弧颜色
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        CakeView cake_view = (CakeView) findViewById(R.id.cake_view);
        initData();
        cake_view.setData(beans);

    }

    private void initData() {
        beans = new ArrayList<>();
        for (int i = 0; i < 7; i++) {
            CakeBean bean = new CakeBean();
            bean.name = names[i];
            bean.value = values[i];
            bean.mColor = colArrs[i];
            beans.add(bean);
        }
    }

}

效果图：