拖动 view
16lz
2021-01-26
引用：http://www.oschina.net/code/snippet_54100_6262
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。 标签： Android SDK代码片段(5)
[图片]程序截图
[代码]Activity.java
01 | packagecom.zhuozhuo; |
02 |
03 | importandroid.app.Activity; |
04 | importandroid.os.Bundle; |
05 |
06 | publicclassCSDNActivityextendsActivity { |
07 | /** Called when the activity is first created. */ |
08 | @Override |
09 | publicvoidonCreate(Bundle savedInstanceState) { |
10 | super.onCreate(savedInstanceState); |
11 | setContentView(R.layout.main); |
12 | } |
13 | |
14 | |
15 | } |
[代码]CustomView.java
01 | packagecom.zhuozhuo; |
02 |
03 | importandroid.content.Context; |
04 | importandroid.graphics.Canvas; |
05 | importandroid.graphics.Color; |
06 | importandroid.graphics.Paint; |
07 | importandroid.graphics.Rect; |
08 | importandroid.util.AttributeSet; |
09 | importandroid.view.MotionEvent; |
10 | importandroid.view.View; |
11 |
12 | /** |
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 |
14 | */ |
15 | publicclassCustomViewextendsView { |
16 |
17 | privatestaticfinalintWIDTH =40; |
18 | |
19 | privateRect rect =newRect(0,0, WIDTH, WIDTH);//绘制矩形的区域 |
20 | privateintdeltaX,deltaY;//点击位置和图形边界的偏移量 |
21 | privatestaticPaint paint =newPaint();//画笔 |
22 | |
23 | publicCustomView(Context context, AttributeSet attrs) { |
24 | super(context, attrs); |
25 | paint =newPaint(); |
26 | paint.setColor(Color.RED);//填充红色 |
27 | } |
28 | |
29 | @Override |
30 | protectedvoidonDraw(Canvas canvas) { |
31 | canvas.drawRect(rect, paint);//画矩形 |
32 |
33 | } |
34 | |
35 | @Override |
36 | publicbooleanonTouchEvent (MotionEvent event) { |
37 | intx = (int) event.getX(); |
38 | inty = (int) event.getY(); |
39 | switch(event.getAction()) { |
40 | caseMotionEvent.ACTION_DOWN: |
41 | if(!rect.contains(x, y)) { |
42 | returnfalse;//没有在矩形上点击，不处理触摸消息 |
43 | } |
44 | deltaX = x - rect.left; |
45 | deltaY = y - rect.top; |
46 | break; |
47 | caseMotionEvent.ACTION_MOVE: |
48 | caseMotionEvent.ACTION_UP: |
49 | Rect old =newRect(rect); |
50 | //更新矩形的位置 |
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);//要刷新的区域，求新矩形区域与旧矩形区域的并集 |
56 | invalidate(old);//出于效率考虑，设定脏区域，只进行局部刷新，不是刷新整个view |
57 | break; |
58 | } |
59 | returntrue;//处理了触摸消息，消息不再传递 |
60 | } |
61 |
62 | } |
[代码]main.xml 布局文件
1 | <?xmlversion="1.0"encoding="utf-8"?> |
2 | <LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android" |
3 | android:orientation="vertical" |
4 | android:layout_width="fill_parent" |
5 | android:layout_height="fill_parent" |
6 | > |
7 | <com.zhuozhuo.CustomViewandroid:layout_width="fill_parent" |
8 | android:layout_height="fill_parent"/> |
9 | </LinearLayout> |
[文件]工程打包下载 ~39KB下载(6)
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