一、概述
在上一篇博文中，我们给大家介绍了Android自定义控件系列的基础篇。链接：
这一篇博文中，我们将在基础篇的基础上，再通过重写ondraw（）方法和自定义属性实现圆形进度条，效果如图所示：
二、实现步骤
1、 编写自定义组件MyCircleProgress扩展View
public class MyCircleProgress extends View {…}
2、 在MyCircleProgress类中，定制属性
* 自定义控件属性，可灵活的设置圆形进度条的大小、颜色、类型等mR;bgColor;fgColor;drawStyle; strokeWidth;max;* 设置进度，此为线程安全控件，由于考虑多线的问题，需要同步setProgress(int progress) {if(progress<0){progress=0;}else if(progress>max){progress=max;}else{this.progress = progress;}}public int getMax() {return max; }
3、 为定制的属性编写attrs.xml资源，，该资源文件放在res/values目录下，内容如下：
4、 在MyCircleProgress类中定义构造函数，初始化属性
private void initProperty(AttributeSet attrs){TypedArray tArray = context.obtainStyledAttributes(attrs, R.styleable.CircleProgressBar);mR=tArray.getInteger(R.styleable.CircleProgressBar_r,10);bgColor=tArray.getColor(R.styleable.CircleProgressBar_bgColor, Color.GRAY);fgColor=tArray.getColor(R.styleable.CircleProgressBar_fgColor, Color.RED);drawStyle=tArray.getInt(R.styleable.CircleProgressBar_drawStyle, 0);strokeWidth=tArray.getInteger(R.styleable.CircleProgressBar_strokeWidth, 10);max=tArray.getInteger(R.styleable.CircleProgressBar_max, 100);}public MyCircleProgress(Context context, AttributeSet attrs) {super(context, attrs);this.context = context;this.paint = new Paint();.paint.setStyle(Style.STROKE); // 绘制空心圆或 空心矩形initProperty(attrs);}
5、 在MainActivity中布局文件中添加MyCircleProgress组件，如下所示
xmlns:tools=""xmlns:app=""android:layout_width="match_parent"android:layout_height="match_parent"android:paddingBottom="@dimen/activity_vertical_margin"android:paddingLeft="@dimen/activity_horizontal_margin"android:paddingRight="@dimen/activity_horizontal_margin"android:paddingTop="@dimen/activity_vertical_margin"tools:contextcom.jereh.views.MyCircleProgressandroid:id="@+id/MyCircleProgress"android:layout_width="wrap_content"android:layout_height="wrap_content"app:r="45"app:strokeWidth="10"app:bgColor="#cccccc"app:fgColor="#ff0000"app:drawStyle="FILL"app:max
6、 自定义组件MyCircleProgress中重写onDraw方法：
protected void onDraw(Canvas canvas) {super.onDraw(canvas);.paint.setColor(bgColor);this.paint.setStrokeWidth(strokeWidth);canvas.drawCircle(center, center, mR, this.paint);.paint.setColor(fgColor);if(drawStyle==0){this.paint.setStyle(Style.STROKE);opt=false;}else{this.paint.setStyle(Style.FILL);opt=true;}int top = (center – mR);int bottom = (center + mR);RectF oval = new RectF(top, top, bottom, bottom);canvas.drawArc(oval, 270, 360*progress/max, opt, paint);}
7、编写MainActivity
public class MainActivity extends Activity {private MyCircleProgress progressView;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);progressView = (MyCircleProgress) findViewById(R.id.MyCircleProgress);new ProgressAnimation().execute();}class ProgressAnimation extends AsyncTask<Void, Integer, Void> {@Overrideprotected Void doInBackground(Void… params) {(int i = 0; i < progressView.getMax(); i++) {try {publishProgress(i);Thread.sleep(100);} catch (InterruptedException e) {e.printStackTrace();}}return null;}@Overrideprotected void onProgressUpdate(Integer… values) {//更新进度值progressView.setProgress(values[0]);progressView.invalidate();super.onProgressUpdate(values);}}}
见所未见，闻所未闻。
