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
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package com.zhuozhuo; |
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import android.app.Activity; |
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import android.os.Bundle; |
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public class CSDNActivity extends Activity { |
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/** Called when the activity is first created. */ |
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@Override |
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public void onCreate(Bundle savedInstanceState) { |
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super.onCreate(savedInstanceState); |
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setContentView(R.layout.main); |
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} |
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|
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|
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} |
[代码] CustomView.java
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package com.zhuozhuo; |
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import android.content.Context; |
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import android.graphics.Canvas; |
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import android.graphics.Color; |
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import android.graphics.Paint; |
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import android.graphics.Rect; |
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import android.util.AttributeSet; |
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import android.view.MotionEvent; |
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import android.view.View; |
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/** |
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* 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 |
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*/ |
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public class CustomView extends View { |
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private static final int WIDTH = 40; |
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|
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private Rect rect = new Rect(0, 0, WIDTH, WIDTH);//绘制矩形的区域 |
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private int deltaX,deltaY;//点击位置和图形边界的偏移量 |
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private static Paint paint = new Paint();//画笔 |
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|
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public CustomView(Context context, AttributeSet attrs) { |
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super(context, attrs); |
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paint = new Paint(); |
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paint.setColor(Color.RED);//填充红色 |
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} |
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|
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@Override |
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protected void onDraw(Canvas canvas) { |
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canvas.drawRect(rect, paint);//画矩形 |
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} |
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|
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@Override |
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public boolean onTouchEvent (MotionEvent event) { |
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int x = (int) event.getX(); |
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int y = (int) event.getY(); |
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switch(event.getAction()) { |
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case MotionEvent.ACTION_DOWN: |
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if(!rect.contains(x, y)) { |
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return false;//没有在矩形上点击，不处理触摸消息 |
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} |
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deltaX = x - rect.left; |
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deltaY = y - rect.top; |
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break; |
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case MotionEvent.ACTION_MOVE: |
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case MotionEvent.ACTION_UP: |
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Rect old = new Rect(rect); |
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//更新矩形的位置 |
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rect.left = x - deltaX; |
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rect.top = y - deltaY; |
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rect.right = rect.left + WIDTH; |
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rect.bottom = rect.top + WIDTH; |
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old.union(rect);//要刷新的区域，求新矩形区域与旧矩形区域的并集 |
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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 |
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break; |
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} |
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return true;//处理了触摸消息，消息不再传递 |
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} |
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} |
[代码] main.xml 布局文件
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<?xml version="1.0" encoding="utf-8"?> |
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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" |
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android:orientation="vertical" |
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android:layout_width="fill_parent" |
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android:layout_height="fill_parent" |
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> |
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<com.zhuozhuo.CustomView android:layout_width="fill_parent" |
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android:layout_height="fill_parent"/> |
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</LinearLayout> |
