效果图
效果图
效果图
</div>
实现原理分析
- 每段弧线的绘制：根据每个数据所占总数的百分比得出该弧线的度数（一共360度），然后使用canvas.drawArc绘制即可。至于弧线的颜色，我们可以随机生成。
- 弧线中数据的绘制：只要能获取到每段弧线的中心点在view中的坐标，我们就能在弧线中心坐标处绘制数据。那么如何获取呢？答案是三角函数（没学好的，百度去百度链接）。每段弧线的中心点与Y轴的夹角我们是知道的（根据上一步可以算出），然后斜边是圆弧的半径，已知夹角和斜边，使用cos和sin，每段弧线的中心点与圆心的距离就能算出来，那么弧线中心点在整个view的坐标就得到了，绘制数据就是轻轻松松的了。
代码中有详细的注释，具体代码下面贴出。
项目地址
完整的代码和项目大家可以到我的github中查看，里面有相关的使用方法，同时这个项目上传到了maven仓库，可以通过gradle直接使用
compile 'com.zhijieeeeee:pieviewlibrary:2.0.0'
github地址：https://github.com/zhijieeeeee/PieView
实现代码
public class PieView2 extends View {
/**
* 使用wrap_content时默认的尺寸
*/
private static final int DEFAULT_WIDTH = 800;
private static final int DEFAULT_HEIGHT = 800;
/**
* 中心坐标
*/
private int centerX;
private int centerY;
/**
* 半径
*/
private float radius;
/**
* 弧形外接矩形
*/
private RectF rectF;
/**
* 中间文本的大小
*/
private Rect centerTextBound = new Rect();
/**
* 数据文本的大小
*/
private Rect dataTextBound = new Rect();
/**
* 扇形画笔
*/
private Paint mArcPaint;
/**
* 中心文本画笔
*/
private Paint centerTextPaint;
/**
* 数据画笔
*/
private Paint dataPaint;
/**
* 数据源数字数组
*/
private int[] numbers;
/**
* 数据源名称数组
*/
private String[] names;
/**
* 数据源总和
*/
private int sum;
/**
* 颜色数组
*/
private int[] colors;
private Random random = new Random();
//自定义属性 Start
/**
* 中间字体大小
*/
private float centerTextSize = 80;
/**
* 数据字体大小
*/
private float dataTextSize = 30;
/**
* 中间字体颜色
*/
private int centerTextColor = Color.BLACK;
/**
* 数据字体颜色
*/
private int dataTextColor = Color.BLACK;
/**
* 圆圈的宽度
*/
private float circleWidth = 100;
//自定义属性 End
public PieView2(Context context) {
super(context);
init();
}
public PieView2(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public PieView2(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.PieView);
centerTextSize = typedArray.getDimension(R.styleable.PieView_centerTextSize, centerTextSize);
dataTextSize = typedArray.getDimension(R.styleable.PieView_dataTextSize, dataTextSize);
circleWidth = typedArray.getDimension(R.styleable.PieView_circleWidth, circleWidth);
centerTextColor = typedArray.getColor(R.styleable.PieView_centerTextColor, centerTextColor);
dataTextColor = typedArray.getColor(R.styleable.PieView_dataTextColor, dataTextColor);
typedArray.recycle();
init();
}
/**
* 初始化
*/
private void init() {
mArcPaint = new Paint();
mArcPaint.setStrokeWidth(circleWidth);
mArcPaint.setAntiAlias(true);
mArcPaint.setStyle(Paint.Style.STROKE);
centerTextPaint = new Paint();
centerTextPaint.setTextSize(centerTextSize);
centerTextPaint.setAntiAlias(true);
centerTextPaint.setColor(centerTextColor);
dataPaint = new Paint();
dataPaint.setStrokeWidth(2);
dataPaint.setTextSize(dataTextSize);
dataPaint.setAntiAlias(true);
dataPaint.setColor(dataTextColor);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int measureWidthSize = MeasureSpec.getSize(widthMeasureSpec);
int measureHeightSize = MeasureSpec.getSize(heightMeasureSpec);
int measureWidthMode = MeasureSpec.getMode(widthMeasureSpec);
int measureHeightMode = MeasureSpec.getMode(heightMeasureSpec);
if (measureWidthMode == MeasureSpec.AT_MOST
&& measureHeightMode == MeasureSpec.AT_MOST) {
setMeasuredDimension(DEFAULT_WIDTH, DEFAULT_HEIGHT);
} else if (measureWidthMode == MeasureSpec.AT_MOST) {
setMeasuredDimension(DEFAULT_WIDTH, measureHeightSize);
} else if (measureHeightMode == MeasureSpec.AT_MOST) {
setMeasuredDimension(measureWidthSize, DEFAULT_HEIGHT);
}
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
centerX = getMeasuredWidth() / 2;
centerY = getMeasuredHeight() / 2;
//设置半径为宽高最小值的1/4
radius = Math.min(getMeasuredWidth(), getMeasuredHeight()) / 4;
//设置扇形外接矩形
rectF = new RectF(centerX - radius,
centerY - radius,
centerX + radius,
centerY + radius);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
calculateAndDraw(canvas);
}
/**
* 计算比例并且绘制扇形和数据
*/
private void calculateAndDraw(Canvas canvas) {
if (numbers == null || numbers.length == 0) {
return;
}
//扇形开始度数
int startAngle = 0;
//所占百分比
float percent;
//所占度数
float angle;
for (int i = 0; i < numbers.length; i++) {
percent = numbers[i] / (float) sum;
//获取百分比在360中所占度数
if (i == numbers.length - 1) {//保证所有度数加起来等于360
angle = 360 - startAngle;
} else {
angle = (float) Math.ceil(percent * 360);
}
//绘制第i段扇形
drawArc(canvas, startAngle, angle, colors[i]);
startAngle += angle;
//绘制数据
if (numbers[i] <= 0) {
continue;
}
//当前弧线中心点相对于纵轴的夹角度数,由于扇形的绘制是从三点钟方向开始，所以加90
float arcCenterDegree = 90 + startAngle - angle / 2;
drawData(canvas, arcCenterDegree, i, percent);
}
//绘制中心数字总和
canvas.drawText(sum + "", centerX - centerTextBound.width() / 2, centerY + centerTextBound.height() / 2, centerTextPaint);
}
/**
* 计算每段弧度的中心坐标
*
* @param degree 当前扇形中心度数
*/
private float[] calculatePosition(float degree) {
//由于Math.sin(double a)中参数a不是度数而是弧度，所以需要将度数转化为弧度
//而Math.toRadians(degree)的作用就是将度数转化为弧度
//sin 一二正，三四负 sin（180-a）=sin(a)
//扇形弧线中心点距离圆心的x坐标
float x = (float) (Math.sin(Math.toRadians(degree)) * radius);
//cos 一四正，二三负
//扇形弧线中心点距离圆心的y坐标
float y = (float) (Math.cos(Math.toRadians(degree)) * radius);
//每段弧度的中心坐标(扇形弧线中心点相对于view的坐标)
float startX = centerX + x;
float startY = centerY - y;
float[] position = new float[2];
position[0] = startX;
position[1] = startY;
return position;
}
/**
* 绘制数据
*
* @param canvas 画布
* @param degree 第i段弧线中心点相对于纵轴的夹角度数
* @param i 第i段弧线
* @param percent 数据百分比
*/
private void drawData(Canvas canvas, float degree, int i, float percent) {
//弧度中心坐标
float startX = calculatePosition(degree)[0];
float startY = calculatePosition(degree)[1];
//获取名称文本大小
dataPaint.getTextBounds(names[i], 0, names[i].length(), dataTextBound);
//绘制名称数据，20为纵坐标偏移量
canvas.drawText(names[i],
startX - dataTextBound.width() / 2,
startY + dataTextBound.height() / 2 - 20,
dataPaint);
//拼接百分比并获取文本大小
DecimalFormat df = new DecimalFormat("0.0");
String percentString = df.format(percent * 100) + "%";
dataPaint.getTextBounds(percentString, 0, percentString.length(), dataTextBound);
//绘制百分比数据，20为纵坐标偏移量
canvas.drawText(percentString,
startX - dataTextBound.width() / 2,
startY + dataTextBound.height() * 2 - 20,
dataPaint);
}
/**
* 绘制扇形
*
* @param canvas 画布
* @param startAngle 开始度数
* @param angle 扇形的度数
* @param color 颜色
*/
private void drawArc(Canvas canvas, float startAngle, float angle, int color) {
mArcPaint.setColor(color);
//-0.5和+0.5是为了让每个扇形之间没有间隙
canvas.drawArc(rectF, startAngle - 0.5f, angle + 0.5f, false, mArcPaint);
}
/**
* 生成随机颜色
*/
private int randomColor() {
int red = random.nextInt(256);
int green = random.nextInt(256);
int blue = random.nextInt(256);
return Color.rgb(red, green, blue);
}
/**
* 设置数据
*
* @param numbers 数字数组
* @param names 名称数组
*/
public void setData(int[] numbers, String[] names) {
if (numbers == null || numbers.length == 0 || names == null || names.length == 0) {
return;
}
if (numbers.length != names.length) {
//名称个数与数字个数不相等
return;
}
this.numbers = numbers;
this.names = names;
colors = new int[numbers.length];
for (int i = 0; i < this.numbers.length; i++) {
//计算总和
sum += numbers[i];
//随机颜色
colors[i] = randomColor();
}
//计算总和数字的宽高
centerTextPaint.getTextBounds(sum + "", 0, (sum + "").length(), centerTextBound);
invalidate();
}
}
自定义属性
<declare-styleable name="PieView">
<attr name="centerTextSize" format="dimension" />
<attr name="dataTextSize" format="dimension" />
<attr name="centerTextColor" format="color" />
<attr name="dataTextColor" format="color" />
<attr name="circleWidth" format="dimension" />
</declare-styleable>