Small example of Android app-the ball that follows your finger

 

implementation:

Implementation method:

Inherit the view class and redraw a circle yourself, and then add this custom inherited view class to the current activity and adds a Ontouchlitener event for this custom view control

Custom components inherit from the view class:

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2. Package Com.jiahui.draw;
4.   
6. import android.content.Context;
8. import Android.graphics.Canvas;
10. import android.graphics.Color;
12. import android.graphics.Paint;
14. import android.view.View;
16.   
18. public class drawview extends View {
20.   
22. public float currentx=;
24. public float currenty=;
26.       
28. //Must override a constructor method
30. Public Drawview (context context) {
32. Super(context);
34. //TODO auto-generated constructor stub
36.     }  
38. //Rewrite the OnDraw method through canvas painting
40. @Override
42. protected void onDraw (canvas canvas) {
44. Super. OnDraw (canvas);
46. //Create brushes
48. Paint paint=new paint ();
50. Paint.setcolor (color.red);
52. //Draw a small circle
54. canvas.drawcircle (CurrentX, CurrentY, +, paint);
56.   
58.     }  
60.       
62. }  

Add a custom component to the current activity

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2. Package Com.jiahui.draw;
4.   
6. import android.app.Activity;
8. import Android.os.Bundle;
10. import android.view.MotionEvent;
12. import Android.view.View;
14. import android.widget.LinearLayout;
16.   
18. Public class Customeviewactivity extends Activity {
20. Public void OnCreate (Bundle savedinstancestate) {
22. super.oncreate (savedinstancestate);
24. Setcontentview (R.layout.main);
26.           
28. linearlayout root= (linearlayout) Findviewbyid (r.id.root);
30.           
32. //Create an object that you inherit from the view
34. final Drawview drawview=new Drawview (this);
36. //Set the maximum width and height of the custom component
38. Drawview.setminimumwidth (300);
40. Drawview.setminimumheight (500);
42.     
44. Drawview.setontouchlistener (New View.ontouchlistener () {
46. Public Boolean OnTouch (View V, motionevent event) {
48. drawview.currentx=event. GetX ();
50. drawview.currenty=event. GetY ();
52. // Redraw
54. drawview.invalidate ();
56. //Returns True to indicate that the method has handled the event
58. return true;
60.             }  
62.         });
64. Root.addview (Drawview);
66.     }  
68. }  

Main.xml:

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2. <? XML version="1.0" encoding="Utf-8" ?>
4. < linearlayout xmlns:android="http://schemas.android.com /apk/res/android "
6. android:layout_width="fill_parent"
8. android:layout_height="fill_parent"
10. android:orientation="vertical"
12. android:background="#99FFCC"
14. android:id="@+id/root">
16. </linearlayout >

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Source code Download: http://download.csdn.net/detail/jiahui524/3786788

Small example of Android app-the ball that follows your finger