拖动 view
转载
Android中自带的view种类很多，但是有时候不能满足我们的需求，下面介绍一种自定义view的方法，实现了拖动矩形到屏幕任意位置的需求。
代码片段(5)
[图片] 程序截图
[代码] Activity.java
01 | package com.zhuozhuo; |
03 | import android.app.Activity; |
04 | import android.os.Bundle; |
06 | public class CSDNActivity extends Activity { |
07 | /** Called when the activity is first created. */ |
09 | public void onCreate(Bundle savedInstanceState) { |
10 | super.onCreate(savedInstanceState); |
11 | setContentView(R.layout.main); |
[代码] CustomView.java
01 | package com.zhuozhuo; |
03 | import android.content.Context; |
04 | import android.graphics.Canvas; |
05 | import android.graphics.Color; |
06 | import android.graphics.Paint; |
07 | import android.graphics.Rect; |
08 | import android.util.AttributeSet; |
09 | import android.view.MotionEvent; |
10 | import android.view.View; |
13 | * 自定义的view，需要覆盖onDraw()方法绘制控件，覆盖onTouchEvent()接收触摸消息 |
15 | public class CustomView extends View { |
17 | private static final int WIDTH = 40; |
19 | private Rect rect = new Rect(0, 0, WIDTH, WIDTH); |
20 | private int deltaX,deltaY; |
21 | private static Paint paint = new Paint(); |
23 | public CustomView(Context context, AttributeSet attrs) { |
24 | super(context, attrs); |
25 | paint = new Paint(); |
26 | paint.setColor(Color.RED); |
30 | protected void onDraw(Canvas canvas) { |
31 | canvas.drawRect(rect, paint); |
36 | public boolean onTouchEvent (MotionEvent event) { |
37 | int x = (int) event.getX(); |
38 | int y = (int) event.getY(); |
39 | switch(event.getAction()) { |
40 | case MotionEvent.ACTION_DOWN: |
41 | if(!rect.contains(x, y)) { |
42 | return false; |
44 | deltaX = x - rect.left; |
45 | deltaY = y - rect.top; |
47 | case MotionEvent.ACTION_MOVE: |
48 | case MotionEvent.ACTION_UP: |
49 | Rect old = new Rect(rect); |
51 | rect.left = x - deltaX; |
52 | rect.top = y - deltaY; |
53 | rect.right = rect.left + WIDTH; |
54 | rect.bottom = rect.top + WIDTH; |
55 | old.union(rect); |
56 | invalidate(old); |
59 | return true; |
[代码] main.xml 布局文件
1 | <?xml version="1.0" encoding="utf-8"?> |
2 | <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" |
3 | android:orientation="vertical" |
4 | android:layout_width="fill_parent" |
5 | android:layout_height="fill_parent" |
7 | <com.zhuozhuo.CustomView android:layout_width="fill_parent" |
8 | android:layout_height="fill_parent"/> |
9 | </LinearLayout> |
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