一、首先看下支付寶上芝麻信用分的效果圖:

二、思路
1、確定雷達圖中心點坐標
2、繪制多邊形及連接線
3、根據維度值繪制覆蓋區域
4、繪制分數
5、繪制每個維度的標題文字和圖標
三、實現
獲取布局的中心坐標
在onSizeChanged(int w, int h, int oldw, int oldh)方法里面,根據View的長寬,計算出雷達圖的半徑(這里取布局寬高最小值的四分之一,可以自定義),獲取整個布局的中心坐標。
public class CreditScoreView extends View { //數據個數 private int dataCount = 5; //每個角的弧度 private float radian = (float) (Math.PI * 2 / dataCount); //雷達圖半徑 private float radius; //中心X坐標 private int centerX; //中心Y坐標 private int centerY; //各維度標題 private String[] titles = {"履約能力", "信用歷史", "人脈關系", "行為偏好", "身份特質"}; //各維度圖標 private int[] icons = {R.mipmap.ic_performance, R.mipmap.ic_history, R.mipmap.ic_contacts, R.mipmap.ic_predilection, R.mipmap.ic_identity}; //各維度分值 private float[] data = {170, 180, 160, 170, 180}; //數據最大值 private float maxValue = 190; //雷達圖與標題的間距 private int radarMargin = DensityUtils.dp2px(getContext(), 15); //雷達區畫筆 private Paint mainPaint; //數據區畫筆 private Paint valuePaint; //分數畫筆 private Paint scorePaint; //標題畫筆 private Paint titlePaint; //圖標畫筆 private Paint iconPaint; //分數大小 private int scoreSize = DensityUtils.dp2px(getContext(), 28); //標題文字大小 private int titleSize = DensityUtils.dp2px(getContext(), 13); ... @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { //雷達圖半徑 radius = Math.min(h, w) / 2 * 0.5f; //中心坐標 centerX = w / 2; centerY = h / 2; postInvalidate(); super.onSizeChanged(w, h, oldw, oldh); } ...}繪制多邊形和連接線
主要看下getPoint方法,此方法封裝了獲取雷達圖上各個點坐標的計算邏輯。
/** * 繪制多邊形 * * @param canvas 畫布 */private void drawPolygon(Canvas canvas) { Path path = new Path(); for (int i = 0; i < dataCount; i++) { if (i == 0) { path.moveTo(getPoint(i).x, getPoint(i).y); } else { path.lineTo(getPoint(i).x, getPoint(i).y); } } //閉合路徑 path.close(); canvas.drawPath(path, mainPaint);}/** * 繪制連接線 * * @param canvas 畫布 */private void drawLines(Canvas canvas) { Path path = new Path(); for (int i = 0; i < dataCount; i++) { path.reset(); path.moveTo(centerX, centerY); path.lineTo(getPoint(i).x, getPoint(i).y); canvas.drawPath(path, mainPaint); }}getPoint方法,參數radarMargin與percent在此步驟賦予默認值。
/** * 獲取雷達圖上各個點的坐標 * * @param position 坐標位置(右上角為0,順時針遞增) * @return 坐標 */private Point getPoint(int position) { return getPoint(position, 0, 1);}/** * 獲取雷達圖上各個點的坐標(包括維度標題與圖標的坐標) * * @param position 坐標位置 * @param radarMargin 雷達圖與維度標題的間距 * @param percent 覆蓋區的的百分比 * @return 坐標 */private Point getPoint(int position, int radarMargin, float percent) { int x = 0; int y = 0; if (position == 0) { x = (int) (centerX + (radius + radarMargin) * Math.sin(radian) * percent); y = (int) (centerY - (radius + radarMargin) * Math.cos(radian) * percent); } else if (position == 1) { x = (int) (centerX + (radius + radarMargin) * Math.sin(radian / 2) * percent); y = (int) (centerY + (radius + radarMargin) * Math.cos(radian / 2) * percent); } else if (position == 2) { x = (int) (centerX - (radius + radarMargin) * Math.sin(radian / 2) * percent); y = (int) (centerY + (radius + radarMargin) * Math.cos(radian / 2) * percent); } else if (position == 3) { x = (int) (centerX - (radius + radarMargin) * Math.sin(radian) * percent); y = (int) (centerY - (radius + radarMargin) * Math.cos(radian) * percent); } else if (position == 4) { x = centerX; y = (int) (centerY - (radius + radarMargin) * percent); } return new Point(x, y);}
多邊形和連接線
繪制覆蓋區域
/** * 繪制覆蓋區域 * * @param canvas 畫布 */private void drawRegion(Canvas canvas) { Path path = new Path(); for (int i = 0; i < dataCount; i++) { //計算百分比 float percent = data[i] / maxValue; int x = getPoint(i, 0, percent).x; int y = getPoint(i, 0, percent).y; if (i == 0) { path.moveTo(x, y); } else { path.lineTo(x, y); } } //繪制填充區域的邊界 path.close(); valuePaint.setStyle(Paint.Style.STROKE); canvas.drawPath(path, valuePaint); //繪制填充區域 valuePaint.setStyle(Paint.Style.FILL_AND_STROKE); canvas.drawPath(path, valuePaint);}
覆蓋區域
繪制分數
/** * 繪制分數 * * @param canvas 畫布 */private void drawScore(Canvas canvas) { int score = 0; //計算總分 for (int i = 0; i < dataCount; i++) { score += data[i]; } canvas.drawText(score + "", centerX, centerY + scoreSize / 2, scorePaint);}
分數
繪制標題
/** * 繪制標題 * * @param canvas 畫布 */private void drawTitle(Canvas canvas) { for (int i = 0; i < dataCount; i++) { int x = getPoint(i, radarMargin, 1).x; int y = getPoint(i, radarMargin, 1).y; Bitmap bitmap = BitmapFactory.decodeResource(getResources(), icons[i]); int iconHeight = bitmap.getHeight(); float titleWidth = titlePaint.measureText(titles[i]); //底下兩個角的坐標需要向下移動半個圖片的位置(1、2) if (i == 1) { y += (iconHeight / 2); } else if (i == 2) { x -= titleWidth; y += (iconHeight / 2); } else if (i == 3) { x -= titleWidth; } else if (i == 4) { x -= titleWidth / 2; } canvas.drawText(titles[i], x, y, titlePaint); }}
標題
繪制圖標
/** * 繪制圖標 * * @param canvas 畫布 */private void drawIcon(Canvas canvas) { for (int i = 0; i < dataCount; i++) { int x = getPoint(i, radarMargin, 1).x; int y = getPoint(i, radarMargin, 1).y; Bitmap bitmap = BitmapFactory.decodeResource(getResources(), icons[i]); int iconWidth = bitmap.getWidth(); int iconHeight = bitmap.getHeight(); float titleWidth = titlePaint.measureText(titles[i]); //上面獲取到的x、y坐標是標題左下角的坐標 //需要將圖標移動到標題上方居中位置 if (i == 0) { x += (titleWidth - iconWidth) / 2; y -= (iconHeight + getTextHeight(titlePaint)); } else if (i == 1) { x += (titleWidth - iconWidth) / 2; y -= (iconHeight / 2 + getTextHeight(titlePaint)); } else if (i == 2) { x -= (iconWidth + (titleWidth - iconWidth) / 2); y -= (iconHeight / 2 + getTextHeight(titlePaint)); } else if (i == 3) { x -= (iconWidth + (titleWidth - iconWidth) / 2); y -= (iconHeight + getTextHeight(titlePaint)); } else if (i == 4) { x -= iconWidth / 2; y -= (iconHeight + getTextHeight(titlePaint)); } canvas.drawBitmap(bitmap, x, y, titlePaint); }}/** * 獲取文本的高度 * * @param paint 文本繪制的畫筆 * @return 文本高度 */private int getTextHeight(Paint paint) { Paint.FontMetrics fontMetrics = paint.getFontMetrics(); return (int) (fontMetrics.descent - fontMetrics.ascent);}
圖標
總結
好了,到這里主要的繪制工作就完成了,有些圖標實在找不到,就用相似的代替了。希望這篇文章的內容對各位Android開發者們能有所幫助,如果有疑問大家可以留言交流。
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