你可能看见过这个图。
2. 实现思路
- 继承View，复写onDraw。
- 确定N边形和每个边对应的角度；
- 确定多边形外接圆的半径以及圆心（也就是中心点）
- 确定每条半径上的所有点的坐标。
- 确定每条数据在图形上的坐标；
- 确定文字在图形上的位置；
- 采用合适的绘制方式绘制；
3. 实现
3.1 定义自定义属性
主要定义这几个属性，可以根据需要继续扩展。
<declare-styleable name="CustomRadarChart">
<!-- 蜘蛛网线条宽度 -->
<attr name="radarLineWidth" format="dimension"/>
<!-- 蜘蛛网颜色 -->
<attr name="radarLineColor" format="color"/>
<!-- 半径分成N段-->
<attr name="radarLineSegments" format="integer"/>
<!-- 文字颜色 -->
<attr name="radarTextColor" format="color"/>
<!-- 文字字体大小-->
<attr name="radarTextSize" format="integer"/>
<!-- 数据展示覆盖区域颜色 -->
<attr name="radarCoverColor" format="color"/>
</declare-styleable>3.2 自定义View代码
注释代码中都有写出来，主要是看下实现的方式。没有过多的修饰和精简。
public class CustomRadarChart extends View {
/**
* N 边形，默认为6边形
*/
private final int DEFAULT_PIECE_NUMBER = 7;
/**
* 线条宽度，默认为10px
*/
private final int DEFAULT_LINE_WIDTH = 4;
/**
* 线条颜色,默认为灰色
*/
private final int DEFAULT_LINE_COLOR = 0xffd0d6dc;
/**
* 半径分成N段,默认为4段，圆心算一段
*/
private final int DEFAULT_LINE_SEGMENTS = 4;
/**
* 外接圆半径，默认为50px
*/
private final int DEFAULT_RADIUS = 50;
/**
* 文本颜色和文本字体, 默认为黑色，10px
*/
private final int DEFAULT_TEXT_COLOR = 0xff647d91;
private final int DEFAULT_TEXT_SIZE = 10;
/**
* 覆盖面绘制颜色
*/
private final int DEFAULT_COVER_COLOR = 0x55ced6dc;
private int mPieceNumber = DEFAULT_PIECE_NUMBER;
private int mRadius = DEFAULT_RADIUS;
private int mLineWidth = DEFAULT_LINE_WIDTH;
private int mLineColor = DEFAULT_LINE_COLOR;
private int mLineSegments = DEFAULT_LINE_SEGMENTS;
private int mTextColor = DEFAULT_TEXT_COLOR;
private int mTextSize = DEFAULT_TEXT_SIZE;
private int mCoverColor = DEFAULT_COVER_COLOR;
private double mAverageAngle = 0;
private Paint mRadarPaint;
private TextPaint mTextPaint;
private Paint mCoverPaint;
private Path mCoverPath;
List<RadarPoints> mRadarPointses = new ArrayList<>();
List<RadarEntry> mRadarEntries = new ArrayList<>();
List<PointF> mCoverPoints = new ArrayList<>();
List<PointF> mTextPoints = new ArrayList<>();
/**
* 外接圆中心位置
*/
private int mPositionX = 0;
private int mPositionY = 0;
public CustomRadarChart(Context context) {
this(context, null);
}
public CustomRadarChart(Context context,
@Nullable AttributeSet attrs) {
this(context, attrs, 0);
}
public CustomRadarChart(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
TypedArray attributes = getContext().obtainStyledAttributes(attrs, R.styleable.CustomRadarChart);
mLineWidth = (int) attributes.getDimension(R.styleable.CustomRadarChart_radarLineWidth, DEFAULT_LINE_WIDTH);
mLineColor = attributes.getColor(R.styleable.CustomRadarChart_radarLineColor, DEFAULT_LINE_COLOR);
mLineSegments = attributes.getInteger(R.styleable.CustomRadarChart_radarLineSegments, DEFAULT_LINE_SEGMENTS);
mTextColor = attributes.getColor(R.styleable.CustomRadarChart_radarTextColor, DEFAULT_TEXT_COLOR);
mTextSize = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,
attributes.getInteger(R.styleable.CustomRadarChart_radarTextSize, DEFAULT_TEXT_SIZE), getResources().getDisplayMetrics());
mCoverColor = (int) attributes.getColor(R.styleable.CustomRadarChart_radarCoverColor, DEFAULT_COVER_COLOR);
init();
}
private void init() {
/**
* 蜘蛛网Paint初始化
*/
mRadarPaint = new Paint();
mRadarPaint.setColor(mLineColor);
mRadarPaint.setStrokeWidth(mLineWidth);
mRadarPaint.setAntiAlias(true);
mRadarPaint.setStyle(Paint.Style.STROKE);
/**
* 文字绘制Paint初始化
*/
mTextPaint = new TextPaint();
mTextPaint.setColor(mTextColor);
mTextPaint.setTextSize(mTextSize);
mTextPaint.setAntiAlias(true);
mTextPaint.setStyle(Paint.Style.STROKE);
/**
*覆盖面绘制Paint初始化
*/
mCoverPaint = new Paint();
mCoverPaint.setColor(mCoverColor);
mCoverPaint.setAntiAlias(true);
mCoverPaint.setStyle(Paint.Style.FILL);
mCoverPath = new Path();
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mPositionX = w / 2;
mPositionY = h / 2;
mAverageAngle = 360.0 / mPieceNumber;
int max = 0;
for(RadarEntry entry : mRadarEntries) {
Rect textBound = new Rect();
mTextPaint.getTextBounds(entry.title, 0, entry.title.length(),
textBound);
max = Math.max(textBound.width(), max);
}
mRadius = Math.min(w / 2 - max, h / 2);
if (mRadarEntries==null || mRadarEntries.size()==0) {
throw new NullPointerException("请先设置数据集");
}
/**
* 计算每一条轴线上的所有点
*/
for (int i = 0; i < mPieceNumber; i++) {
List<PointF> pointFs = new ArrayList<>();
for (int j = 0; j < mLineSegments; j++) {
PointF point = new PointF();
double percent = j * 1.0 / (mLineSegments - 1);
point.set(getPloygonX(mAverageAngle * i, percent),
getPloygonY(mAverageAngle * i, percent));
pointFs.add(point);
}
RadarPoints radarPoints = new RadarPoints(i, pointFs);
mRadarPointses.add(radarPoints);
}
/**
* 根据数据集计算覆盖多变形的点
*/
for (int m = 0; m < mPieceNumber; m++) {
PointF pointF = new PointF();
double percent = mRadarEntries.get(m).level / 100.0;
pointF.set(getPloygonX(mAverageAngle * m, percent),
getPloygonY(mAverageAngle * m, percent));
mCoverPoints.add(pointF);
}
/**
* 设置文字显示位置
*/
for (int m = 0; m < mPieceNumber; m++) {
PointF pointF = new PointF();
String title = mRadarEntries.get(m).title;
Rect textBound = new Rect();
mTextPaint.getTextBounds(title, 0, title.length(),
textBound);
float boundx = mRadarPointses.get(m).getPointFs().get(mLineSegments -1).x;
float boundy = mRadarPointses.get(m).getPointFs().get(mLineSegments -1).y;
if( boundx > mRadius && boundy <= mRadius) {
pointF.set(getPloygonX(mAverageAngle * m, 1),
getPloygonY(mAverageAngle * m, 1) - textBound.height()*2) ;
} else if ( boundx <= mRadius && boundy <= mRadius){
pointF.set(getPloygonX(mAverageAngle * m, 1) - textBound.width(),
getPloygonY(mAverageAngle * m, 1) - textBound.height()*2);
} else if( boundx <= mRadius && boundy > mRadius) {
pointF.set(getPloygonX(mAverageAngle * m, 1) - textBound.width(),
getPloygonY(mAverageAngle * m, 1) );
} else {
pointF.set(getPloygonX(mAverageAngle * m, 1),
getPloygonY(mAverageAngle * m, 1));
}
mTextPoints.add(pointF);
}
}
/**
* 设置数据集，数据集的index决定位置，顺时针方向，起始角度为0度
*/
public void setRadatEntries(List<RadarEntry> entries) {
this.mRadarEntries = entries;
mPieceNumber = entries.size();
postInvalidate();
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
/**
* 绘制中心点
*/
canvas.drawPoint(mPositionX, mPositionY, mRadarPaint);
/**
* 绘制蜘蛛网
*/
for (int i = 0; i < mLineSegments; i++) {
for (int j = 0; j < mPieceNumber - 1; j++) {
canvas.drawLine(mRadarPointses.get(j).getPointFs().get(i).x, mRadarPointses.get(
j).getPointFs().get(i).y,
mRadarPointses.get(j + 1).getPointFs().get(i).x, mRadarPointses.get(
j + 1).getPointFs().get(i).y, mRadarPaint);
}
canvas.drawLine(mRadarPointses.get(mPieceNumber - 2).getPointFs().get(i).x,
mRadarPointses.get(mPieceNumber - 2).getPointFs().get(i).y,
mRadarPointses.get(mPieceNumber - 1).getPointFs().get(i).x, mRadarPointses.get(
mPieceNumber - 1).getPointFs().get(i).y, mRadarPaint);
canvas.drawLine(mRadarPointses.get(mPieceNumber - 1).getPointFs().get(i).x,
mRadarPointses.get(mPieceNumber - 1).getPointFs().get(i).y,
mRadarPointses.get(0).getPointFs().get(i).x, mRadarPointses.get(
0).getPointFs().get(i).y, mRadarPaint);
}
/**
* 绘制轴线
*/
for (int k = 0; k < mPieceNumber; k++) {
canvas.drawLine(mRadarPointses.get(k).getPointFs().get(0).x,
mRadarPointses.get(k).getPointFs().get(0).y,
mRadarPointses.get(k).getPointFs().get(mLineSegments - 1).x, mRadarPointses.get(
k).getPointFs().get(mLineSegments - 1).y, mRadarPaint);
}
/**
* 绘制数据
*/
if (mCoverPoints != null && mCoverPoints.size() == mPieceNumber) {
mCoverPath.reset();
mCoverPath.moveTo(mCoverPoints.get(0).x, mCoverPoints.get(0).y);
for (int i = 1; i < mPieceNumber; i++) {
mCoverPath.lineTo(mCoverPoints.get(i).x, mCoverPoints.get(i).y);
}
mCoverPath.close();
canvas.drawPath(mCoverPath, mCoverPaint);
} else {
throw new NullPointerException("请先设置数据集");
}
/**
* 绘制文字,使用StaticLayout进行换行文字的绘制
*/
for (int i = 0; i < mPieceNumber; i++) {
canvas.save();
String str= mRadarEntries.get(i).title + "\r\n" + Math.floor(mRadarEntries.get(i).level*10)/10;
StaticLayout layout = new StaticLayout(str, mTextPaint, 300,
Layout.Alignment.ALIGN_NORMAL, 1.0F, 0.0F, true);
canvas.translate(mTextPoints.get(i).x,mTextPoints.get(i).y);
layout.draw(canvas);
canvas.restore();
}
}
public float getPloygonX(double angle, double percent) {
return Float.parseFloat(
String.valueOf(
mPositionX + Math.cos(angle / 360.0 * 2 * Math.PI) * mRadius * percent));
}
public float getPloygonY(double angle, double percent) {
return Float.parseFloat(String.valueOf(
mPositionY + Math.sin(angle / 360.0 * 2 * Math.PI) * mRadius * percent));
}
/**
* 雷达图数据载体
*/
public static class RadarEntry {
private String title;
private Float level;
public RadarEntry(String title, float level) {
this.title = title;
this.level = level;
}
}
/**
* 每一条线上的所有点集合
*/
public class RadarPoints {
int index;
List<PointF> mPointFs;
public RadarPoints(int index, List<PointF> pointFs) {
this.index = index;
mPointFs = pointFs;
}
public int getIndex() {
return index;
}
public void setIndex(int index) {
this.index = index;
}
public List<PointF> getPointFs() {
return mPointFs;
}
public void setPointFs(List<PointF> pointFs) {
mPointFs = pointFs;
}
}
} 可能画图过程中的实现方式优点粗糙，大家可以根据自己的方式，改写即可。
个人是先将每条半径上的端点全部计算出来进行保存，然后一次连接，然后把每个半径首尾端点连接，然后绘制覆盖区域，覆盖区域也是采用先计算点位置，然后连接的方式实现，最后确定文本的显示位置和文字的绘制。由于这里涉及到绘制换行文字，使用到来StaticLayout。使用方法请查阅对应API。
