在做Android平台开发的时候，经常会遇到安卓原生控件无法满足需求的情况，安卓允许开发者去继承已经存在的控件或者实现你自己的控件。
先来看一下效果图
采用直接集成View类，重写onDrow方法绘制。
下面附上主要代码。
1 新建一个类CircleView 继承自View
1 package com.lennon.view; 2 3 import android.content.Context; 4 import android.graphics.Canvas; 5 import android.graphics.Color; 6 import android.graphics.Paint; 7 import android.graphics.Path; 8 import android.graphics.RectF; 9 import android.util.AttributeSet; 10 import android.view.MotionEvent; 11 import android.view.View; 12 /** 13 * 自定义圆形的方向布局 14 * 15 * @author 樊列龙 16 * @since 2014-06-07 17 */ 18 public class CircleView extends View { 19 20 private int circleWidth = 100; // 圆环直径 21 private int circleColor = Color.argb(150, 255, 0, 0); 22 private int innerCircleColor = Color.rgb(0, 150, 0); 23 private int backgroundColor = Color.rgb(255, 255, 255); 24 private Paint paint = new Paint(); 25 int center = 0; 26 int innerRadius = 0; 27 private float innerCircleRadius = 0; 28 private float smallCircle = 10; 29 public Dir dir = Dir.UP; 30 31 public CircleView(Context context, AttributeSet attrs) { 32 super(context, attrs); 33 } 34 35 public CircleView(Context context) { 36 super(context); 37 38 // paint = new Paint(); 39 } 40 41 public CircleView(Context context, AttributeSet attrs, int defStyle) { 42 super(context, attrs, defStyle); 43 44 } 45 46 @Override 47 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 48 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 49 50 int measuredHeight = measureHeight(heightMeasureSpec); 51 int measuredWidth = measureWidth(widthMeasureSpec); 52 53 setMeasuredDimension(measuredWidth, measuredHeight); 54 55 center = getWidth() / 2; 56 innerRadius = (center - circleWidth / 2 - 10);// 圆环 57 innerCircleRadius = center / 3; 58 this.setOnTouchListener(onTouchListener); 59 } 60 61 /** 62 * 测量宽度 63 * 64 * @param measureSpec 65 * @return 66 */ 67 private int measureWidth(int measureSpec) { 68 int specMode = MeasureSpec.getMode(measureSpec); 69 int specSize = MeasureSpec.getSize(measureSpec); 70 71 int result = 0; 72 73 if (specMode == MeasureSpec.AT_MOST) { 74 result = getWidth(); 75 } else if (specMode == MeasureSpec.EXACTLY) { 76 result = specSize; 77 } 78 return result; 79 } 80 81 /** 82 * 测量高度 83 * 84 * @param measureSpec 85 * @return 86 */ 87 private int measureHeight(int measureSpec) { 88 89 int specMode = MeasureSpec.getMode(measureSpec); 90 int specSize = MeasureSpec.getSize(measureSpec); 91 92 int result = 0; 93 94 if (specMode == MeasureSpec.AT_MOST) { 95 96 result = specSize; 97 } else if (specMode == MeasureSpec.EXACTLY) { 98 result = specSize; 99 } 100 return result; 101 } 102 103 /** 104 * 开始绘制 105 */ 106 @Override 107 protected void onDraw(Canvas canvas) { 108 super.onDraw(canvas); 109 110 initBackGround(canvas); 111 drawDirTriangle(canvas, dir); 112 113 } 114 115 /** 116 * 绘制方向小箭头 117 * 118 * @param canvas 119 */ 120 private void drawDirTriangle(Canvas canvas, Dir dir) { 121 paint.setColor(innerCircleColor); 122 paint.setStrokeWidth(1); 123 paint.setStyle(Paint.Style.FILL); 124 125 switch (dir) { 126 case UP: 127 drawUpTriangle(canvas); 128 break; 129 case DOWN: 130 drawDownTriangle(canvas); 131 break; 132 case LEFT: 133 drawLeftTriangle(canvas); 134 break; 135 case RIGHT: 136 drawRightTriangle(canvas); 137 break; 138 case CENTER: 139 invalidate(); 140 break; 141 default: 142 break; 143 } 144 145 paint.setColor(backgroundColor); 146 147 canvas.drawCircle(center, center, smallCircle, paint); 148 // canvas.drawText(text, center, center+40, paint); 149 150 } 151 152 /** 153 * 绘制向右的小箭头 154 * 155 * @param canvas 156 */ 157 private void drawRightTriangle(Canvas canvas) { 158 Path path = new Path(); 159 path.moveTo(center, center); 160 double sqrt2 = innerCircleRadius / Math.sqrt(2); 161 double pow05 = innerCircleRadius * Math.sqrt(2); 162 path.lineTo((float) (center + sqrt2), (float) (center - sqrt2)); 163 path.lineTo((float) (center + pow05), center); 164 path.lineTo((float) (center + sqrt2), (float) (center + sqrt2)); 165 canvas.drawPath(path, paint); 166 paint.setColor(backgroundColor); 167 canvas.drawLine(center, center, center + innerCircleRadius, center, paint); 168 169 drawOnclikColor(canvas, Dir.RIGHT); 170 } 171 172 /** 173 * 绘制想左的小箭头 174 * 175 * @param canvas 176 */ 177 private void drawLeftTriangle(Canvas canvas) { 178 Path path = new Path(); 179 path.moveTo(center, center); 180 double sqrt2 = innerCircleRadius / Math.sqrt(2); 181 double pow05 = innerCircleRadius * Math.sqrt(2); 182 path.lineTo((float) (center - sqrt2), (float) (center - sqrt2)); 183 path.lineTo((float) (center - pow05), center); 184 path.lineTo((float) (center - sqrt2), (float) (center + sqrt2)); 185 canvas.drawPath(path, paint); 186 187 paint.setColor(backgroundColor); 188 canvas.drawLine(center, center, center - innerCircleRadius, center, paint); 189 190 drawOnclikColor(canvas, Dir.LEFT); 191 192 } 193 194 /** 195 * 绘制向下的小箭头 196 * 197 * @param canvas 198 */ 199 private void drawDownTriangle(Canvas canvas) { 200 Path path = new Path(); 201 path.moveTo(center, center); 202 double sqrt2 = innerCircleRadius / Math.sqrt(2); 203 double pow05 = innerCircleRadius * Math.sqrt(2); 204 path.lineTo((float) (center - sqrt2), (float) (center + sqrt2)); 205 path.lineTo(center, (float) (center + pow05)); 206 path.lineTo((float) (center + sqrt2), (float) (center + sqrt2)); 207 canvas.drawPath(path, paint); 208 209 paint.setColor(backgroundColor); 210 canvas.drawLine(center, center, center, center + innerCircleRadius, paint); 211 212 drawOnclikColor(canvas, Dir.DOWN); 213 } 214 215 /** 216 * 点击的时候绘制黑色的扇形 217 * 218 * @param canvas 219 * @param dir 220 */ 221 private void drawOnclikColor(Canvas canvas, Dir dir) { 222 paint.setColor(Color.BLACK); 223 paint.setStyle(Paint.Style.STROKE); 224 paint.setStrokeWidth(100); 225 switch (dir) { 226 case UP: 227 canvas.drawArc(new RectF(center - innerRadius, center - innerRadius, center + innerRadius, center 228 + innerRadius), 225, 90, false, paint); 229 break; 230 case DOWN: 231 canvas.drawArc(new RectF(center - innerRadius, center - innerRadius, center + innerRadius, center 232 + innerRadius), 45, 90, false, paint); 233 break; 234 case LEFT: 235 canvas.drawArc(new RectF(center - innerRadius, center - innerRadius, center + innerRadius, center 236 + innerRadius), 135, 90, false, paint); 237 break; 238 case RIGHT: 239 canvas.drawArc(new RectF(center - innerRadius, center - innerRadius, center + innerRadius, center 240 + innerRadius), -45, 90, false, paint); 241 break; 242 243 default: 244 break; 245 } 246 247 paint.setStyle(Paint.Style.FILL); 248 } 249 250 /** 251 * 绘制像向上的箭头 252 * 253 * @param canvas 254 */ 255 private void drawUpTriangle(Canvas canvas) { 256 Path path = new Path(); 257 path.moveTo(center, center); 258 double sqrt2 = innerCircleRadius / Math.sqrt(2); 259 double pow05 = innerCircleRadius * Math.sqrt(2); 260 261 path.lineTo((float) (center - sqrt2), (float) (center - sqrt2)); 262 path.lineTo(center, (float) (center - pow05)); 263 path.lineTo((float) (center + sqrt2), (float) (center - sqrt2)); 264 canvas.drawPath(path, paint); 265 266 paint.setColor(backgroundColor); 267 canvas.drawLine(center, center, center, center - innerCircleRadius, paint); 268 269 drawOnclikColor(canvas, Dir.UP); 270 } 271 272 /** 273 * 绘制基本的背景， 这包括了三个步骤：1.清空画布 2.绘制外圈的圆 3.绘制内圈的圆 274 * 275 * @param canvas 276 */ 277 private void initBackGround(Canvas canvas) { 278 clearCanvas(canvas); 279 drawBackCircle(canvas); 280 drawInnerCircle(canvas); 281 282 } 283 284 /** 285 * 绘制中心白色小圆 286 * 287 * @param canvas 288 */ 289 private void drawInnerCircle(Canvas canvas) { 290 paint.setColor(innerCircleColor); 291 paint.setStyle(Paint.Style.FILL); 292 paint.setStrokeWidth(1); 293 canvas.drawCircle(center, center, innerCircleRadius, paint); 294 } 295 296 /** 297 * 绘制背景的圆圈和隔线 298 * 299 * @param canvas 300 */ 301 private void drawBackCircle(Canvas canvas) { 302 paint.setColor(circleColor); 303 paint.setStrokeWidth(circleWidth); 304 paint.setAntiAlias(true); 305 paint.setStyle(Paint.Style.STROKE); 306 canvas.drawCircle(center, center, innerRadius, paint); // 绘制圆圈 307 308 paint.setColor(backgroundColor); 309 paint.setStyle(Paint.Style.FILL); 310 paint.setStrokeWidth(4); 311 canvas.drawLine(center, center, 0, 0, paint); 312 canvas.drawLine(center, center, center * 2, 0, paint); 313 canvas.drawLine(center, center, 0, center * 2, paint); 314 canvas.drawLine(center, center, center * 2, center * 2, paint); 315 316 } 317 318 /** 319 * 清空画布 320 * 321 * @param canvas 322 */ 323 private void clearCanvas(Canvas canvas) { 324 canvas.drawColor(backgroundColor); 325 } 326 327 OnTouchListener onTouchListener = new OnTouchListener() { 328 329 @Override 330 public boolean onTouch(View view, MotionEvent event) { 331 Dir tmp = Dir.UNDEFINE; 332 if ((tmp = checkDir(event.getX(), event.getY())) != Dir.UNDEFINE) { 333 dir = tmp; 334 invalidate(); 335 } 336 return true; 337 } 338 339 /** 340 * 检测方向 341 * 342 * @param x 343 * @param y 344 * @return 345 */ 346 private Dir checkDir(float x, float y) { 347 Dir dir = Dir.UNDEFINE; 348 349 if (Math.sqrt(Math.pow(y - center, 2) + Math.pow(x - center, 2)) < innerCircleRadius) {// 判断在中心圆圈内 350 dir = Dir.CENTER; 351 System.out.println("----中央"); 352 } else if (y < x && y + x < 2 * center) { 353 dir = Dir.UP; 354 System.out.println("----向上"); 355 } else if (y < x && y + x > 2 * center) { 356 dir = Dir.RIGHT; 357 System.out.println("----向右"); 358 } else if (y > x && y + x < 2 * center) { 359 dir = Dir.LEFT; 360 System.out.println("----向左"); 361 } else if (y > x && y + x > 2 * center) { 362 dir = Dir.DOWN; 363 System.out.println("----向下"); 364 } 365 366 return dir; 367 } 368 369 }; 370 371 /** 372 * 关于方向的枚举 373 * 374 * @author Administrator 375 * 376 */ 377 public enum Dir { 378 UP, DOWN, LEFT, RIGHT, CENTER, UNDEFINE 379 } 380 381 }