可在全屏幕自由拖动的view,全屏幕拖动view
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可在全屏幕自由拖动的view,全屏幕拖动view
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。1.[图片] 程序截图
2.Activity.java
package com.zhuozhuo; import android.app.Activity; import android.os.Bundle; public class CSDNActivity extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } }
3.CustomView.java
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.main.xml 布局文件
<?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>
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