android自定义控件

Android为开发者提供了大量的控件，这些控件只能满足一般性的需求，有时候需要开发者重新定制控件。控件的定制有三种形式：对原有控件的重写；对原有控件进行组合；自定义新的控件。Android中所有控件类都是View的子类。

本例主要是讲一个自定义时钟控件，该控件直接继承View类。

1.控件类

首先需要编写控件类，该类继承View类，并实现接口Runnable。时钟控件主要包含的参数：clockimageresourceid，scale，handcenterwidthscale，handcenterheightscale，minutehandsize，hourhandsize。

 1 public class HandClock extends View implements Runnable {

 2 

 3     private int clockImageResourceId;//图像资源id

 4     private Bitmap bitmap;//图像资源

 5     private float scale;//图像显示的比例

 6     private float handCenterWidthScale;//横坐标显示比例

 7     private float handCenterHeightScale;//纵坐标显示比例

 8     private int minuteHandSize;//分钟长度

 9     private int hourHandSize;//时针长度

10     private Handler hanlder=new Handler();

11     public HandClock(Context context, AttributeSet attrs) {

12         super(context, attrs);

13         // TODO Auto-generated constructor stub

14         //读取属性值

15         clockImageResourceId=attrs.getAttributeResourceValue(null, "clockImageSrc", 0);

16         if(clockImageResourceId>0)

17         {

18             bitmap=BitmapFactory.decodeResource(getResources(), clockImageResourceId);

19         }

20         scale=attrs.getAttributeFloatValue(null, "scale", 1);

21         handCenterWidthScale=attrs.getAttributeFloatValue(null, "handCenterWidthScale", bitmap.getWidth()/2);

22         handCenterHeightScale=attrs.getAttributeFloatValue(null, "handCenterHeightScale", bitmap.getHeight()/2);

23         minuteHandSize=(int)(attrs.getAttributeIntValue(null, "minuteHandSize",0)*scale);

24         hourHandSize=(int)(attrs.getAttributeIntValue(null, "hourHandSize", 0)*scale);

25         int curentSecond=Calendar.getInstance().get(Calendar.SECOND);

26         hanlder.postDelayed(this, (60-curentSecond)*1000);

27     }

28 

29     protected void onDetachedFromWindow()

30     {

31         super.onDetachedFromWindow();

32         hanlder.removeCallbacks(this);

33     }

34     @Override

35     public void run() {

36         // TODO Auto-generated method stub

37         invalidate();

38         hanlder.postDelayed(this,60*1000);

39     }

40     protected void onMeasure(int widthMeasurespc,int heightMeasurespe)

41     {

42         super.onMeasure(widthMeasurespc, heightMeasurespe);

43         setMeasuredDimension((int)(bitmap.getWidth()*scale),(int)(bitmap.getHeight()*scale));

44         

45     }

46     protected void onDraw(Canvas canvas)

47     {

48         super.onDraw(canvas);

49         Paint paint=new Paint();

50         Rect src=new Rect();

51         Rect target=new Rect();

52         src.left=0;

53         src.top=0;

54         src.right=bitmap.getWidth();

55         src.bottom=bitmap.getHeight();

56         target.left=0;

57         target.top=0;

58         target.bottom=(int)(src.bottom*scale);

59         target.right=(int)(src.right*scale);

60         //画表盘图像

61         canvas.drawBitmap(bitmap, src, target,paint);

62         //计算表盘中心点的横坐标

63         float centerX=bitmap.getWidth()*scale*handCenterWidthScale;

64         //计算表盘中心店的纵坐标

65         float centerY=bitmap.getHeight()*scale*handCenterHeightScale;

66         

67         canvas.drawCircle(centerX, centerY, 5, paint);

68         paint.setStrokeWidth(3);

69         Calendar calendar=Calendar.getInstance();

70         int currentMin=calendar.get(Calendar.MINUTE);

71         int currentHour=calendar.get(Calendar.HOUR);

72         //计算时针和分针角度

73         double minuteRadian=Math.toRadians((360-((currentMin*6)-90))%360);

74         double hourRadian=Math.toRadians((360-((currentHour*30)-90))%360-(30*currentMin/60));

75         //画分针

76         canvas.drawLine(centerX, centerY,(int)(centerX+minuteHandSize*Math.cos(minuteRadian)),(int)(centerY-minuteHandSize*Math.sin(minuteRadian)),paint);

77         paint.setStrokeWidth(4);

78         //画时针

79         canvas.drawLine(centerX, centerY,(int)(centerX+hourHandSize*Math.cos(hourRadian)),(int)(centerY-hourHandSize*Math.sin(hourRadian)),paint);

80     }

81 

82 }

HandClock

这里面有很多重点，比如说时针与分针角度的计算，重绘的时间等。Runnable接口是软定时器类，这里定义一分钟重绘一次。

2.handclok.xml

在一个xml页面引用刚刚自定义的控件。

 1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

 2     android:layout_width="match_parent"

 3     android:layout_height="match_parent"

 4     android:orientation="vertical" >

 5     

 6 <com.example.myandroiddemp.HandClock

 7     android:layout_width="wrap_content"

 8     android:layout_height="wrap_content"

 9     clockImageSrc="@drawable/clock1" 

10     scale="0.7"

11     handCenterWidthScale="0.5"

12     handCenterHeightScale="0.5"

13     minuteHandSize="54"

14     hourHandSize="40"/>

15 

16 </LinearLayout>

handclock.xml