Android 可在全屏幕自由拖动的view

Android初学，转载的一些知识点，共同学习

[1].[图片] 程序截图 

[2].[代码] Activity.java

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

package com.zhuozhuo;   import android.app.Activity; import android.os.Bundle;   public class 优快云Activity extends Activity {      /** Called when the activity is first created. */      @Override      public void onCreate(Bundle savedInstanceState) {          super .onCreate(savedInstanceState);          setContentView(R.layout.main);      }             }

[3].[代码] CustomView.java

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62

package com.zhuozhuo;   import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Rect; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View;   /**   * 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   */ public class CustomView extends View {        private static final int WIDTH = 40 ;            private Rect rect = new Rect( 0 , 0 , WIDTH, WIDTH); //绘制矩形的区域      private int deltaX,deltaY; //点击位置和图形边界的偏移量      private static Paint paint = new Paint(); //画笔            public CustomView(Context context, AttributeSet attrs) {          super (context, attrs);          paint = new Paint();          paint.setColor(Color.RED); //填充红色      }            @Override      protected void onDraw(Canvas canvas) {          canvas.drawRect(rect, paint); //画矩形        }            @Override      public boolean onTouchEvent (MotionEvent event) {          int x = ( int ) event.getX();          int y = ( int ) event.getY();          switch (event.getAction()) {          case MotionEvent.ACTION_DOWN:              if (!rect.contains(x, y)) {                  return false ; //没有在矩形上点击，不处理触摸消息              }              deltaX = x - rect.left;              deltaY = y - rect.top;              break ;          case MotionEvent.ACTION_MOVE:          case MotionEvent.ACTION_UP:              Rect old = new Rect(rect);              //更新矩形的位置              rect.left = x - deltaX;              rect.top = y - deltaY;              rect.right = rect.left + WIDTH;              rect.bottom = rect.top + WIDTH;              old.union(rect); //要刷新的区域，求新矩形区域与旧矩形区域的并集              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              break ;          }          return true ; //处理了触摸消息，消息不再传递      }   }

[4].[代码] main.xml 布局文件

?

1 2 3 4 5 6 7 8 9

<? xml version = "1.0" encoding = "utf-8" ?> < LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android"      android:orientation = "vertical"      android:layout_width = "fill_parent"      android:layout_height = "fill_parent"      > < com.zhuozhuo.CustomView android:layout_width = "fill_parent"      android:layout_height = "fill_parent" /> </ LinearLayout >