标签：Popupwindow 拖动 update int import Android View android view
关于View的拖动你们应该比较了解了，好比对一个控件IamgeView拖动，或者一个视图View拖动，实现方式也很容易，继承OnTouchListener接口，而后重写onTouch方法，在触屏事件进行处理便可。可是Popupwindow如何实现拖动呢，咱们都知道它和普通的View不同，由于它不是继承于View类的，可是它的实现倒是和View密切相关的，由于咱们都知道Android视图的显示都是由View来处理的，因此必定离不开它。从Popupwindow的实现就能够看出来，ide
import com.android.internal.R; import android.content.Context; import android.content.res.Resources; import android.content.res.TypedArray; import android.graphics.PixelFormat; import android.graphics.Rect; import android.graphics.drawable.Drawable; import android.graphics.drawable.StateListDrawable; import android.os.Build; import android.os.IBinder; import android.util.AttributeSet; import android.view.Gravity; import android.view.KeyEvent; import android.view.MotionEvent; import android.view.View; import android.view.View.OnTouchListener; import android.view.ViewGroup; import android.view.ViewTreeObserver; import android.view.ViewTreeObserver.OnScrollChangedListener; import android.view.WindowManager; import java.lang.ref.WeakReference;上面是它的导包状况，基本上不是和View相关，就是和绘图相关。所以关于Popupwindow的拖动这一块，也和View有联系。首先看一下它的API，看一看有没有和View移动、变化相关的方法，果真在最后有几个update()方法，以下：
update()方法用来更新Popupwindow的位置和大小的，那么问题就好解决了。看代码：布局
package com.example.drag_and_drop_movablepopupwindow;
import android.support.v7.app.ActionBarActivity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.PopupWindow;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity {
private Button btnOpenPopup;
private int mCurrentX;
private int mCurrentY;
private PopupWindow mPopup;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnOpenPopup = (Button) findViewById(R.id.openpopup);
btnOpenPopup.setOnClickListener(new Button.OnClickListener() {
@Override
public void onClick(View arg0) {
creatPopubWindow_1();
}
});
}
/**
* 1
*/
private void creatPopubWindow_1() {
LayoutInflater layoutInflater = (LayoutInflater) getBaseContext()
.getSystemService(LAYOUT_INFLATER_SERVICE);
View popupView = layoutInflater.inflate(R.layout.popup, null);
final PopupWindow popupWindow = new PopupWindow(popupView,
200, 200);
Button btnDismiss = (Button) popupView.findViewById(R.id.dismiss);
btnDismiss.setOnClickListener(new Button.OnClickListener() {
@Override
public void onClick(View v) {
popupWindow.dismiss();
}
});
popupWindow.showAsDropDown(btnOpenPopup, 50, 50);
popupView.setOnTouchListener(new OnTouchListener() {
int orgX, orgY;
int offsetX, offsetY;
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
orgX = (int) event.getX();
orgY = (int) event.getY();
break;
case MotionEvent.ACTION_MOVE:
offsetX = (int) event.getRawX() - orgX;
offsetY = (int) event.getRawY() - orgY;
popupWindow.update(offsetX, offsetY, -1, -1, true);
break;
}
return true;
}
});
}
}
效果如图：ui
首先对Popupwindow设置触摸事件，而后在回调方法中进行计算，若是手指拖动了Popupwindow，那么就调用update()方法来更新它的位置。有些同窗可能不太理解参数-1是什么意思，在上面的API中，写明的是宽和高，这里怎么变成-1了呢，看一下Popupwindow源代码就明白了。this
/**
* <p>Updates the position and the dimension of the popup window. Width and
* height can be set to -1 to update location only. Calling this function
* also updates the window with the current popup state as
* described for {@link #update()}.</p>
*
* @param x the new x location
* @param y the new y location
* @param width the new width, can be -1 to ignore
* @param height the new height, can be -1 to ignore
* @param force reposition the window even if the specified position
* already seems to correspond to the LayoutParams
*/
public void update(int x, int y, int width, int height, boolean force) {
if (width != -1) {
mLastWidth = width;
setWidth(width);
}
if (height != -1) {
mLastHeight = height;
setHeight(height);
}
if (!isShowing() || mContentView == null) {
return;
}
WindowManager.LayoutParams p = (WindowManager.LayoutParams) mPopupView.getLayoutParams();
boolean update = force;
final int finalWidth = mWidthMode < 0 ? mWidthMode : mLastWidth;
if (width != -1 && p.width != finalWidth) {
p.width = mLastWidth = finalWidth;
update = true;
}
final int finalHeight = mHeightMode < 0 ? mHeightMode : mLastHeight;
if (height != -1 && p.height != finalHeight) {
p.height = mLastHeight = finalHeight;
update = true;
}
if (p.x != x) {
p.x = x;
update = true;
}
if (p.y != y) {
p.y = y;
update = true;
}
final int newAnim = computeAnimationResource();
if (newAnim != p.windowAnimations) {
p.windowAnimations = newAnim;
update = true;
}
final int newFlags = computeFlags(p.flags);
if (newFlags != p.flags) {
p.flags = newFlags;
update = true;
}
if (update) {
setLayoutDirectionFromAnchor();
mWindowManager.updateViewLayout(mPopupView, p);
}
}
前两个if判断已经说得很清楚了，若是参数是-1的话，就不改变Popupwindow的大小了，由于咱们只是移动位置，因此才这样写。那关于Popupwindow的移动最后是怎么实现的呢，能够看出就是调用WindowManager的updateViewLayout()方法，这个方法在WindowManager中并无实现，它是ViewManager接口里面的方法，WindowManager继承了ViewManager。说到ViewManager，它里面定义的方法都很经常使用，看代码：
/** Interface to let you add and remove child views to an Activity. To get an instance
* of this class, call {@link android.content.Context#getSystemService(java.lang.String) Context.getSystemService()}.
*/
public interface ViewManager
{
/**
* Assign the passed LayoutParams to the passed View and add the view to the window.
* <p>Throws {@link android.view.WindowManager.BadTokenException} for certain programming
* errors, such as adding a second view to a window without removing the first view.
* <p>Throws {@link android.view.WindowManager.InvalidDisplayException} if the window is on a
* secondary {@link Display} and the specified display can't be found
* (see {@link android.app.Presentation}).
* @param view The view to be added to this window.
* @param params The LayoutParams to assign to view.
*/
public void addView(View view, ViewGroup.LayoutParams params);
public void updateViewLayout(View view, ViewGroup.LayoutParams params);
public void removeView(View view);
}
这下你们应该明了，咱们常常用的addView、removeView方法就是在这里面定义的，那么谁去实现呢？就是Layout控件，好比LinearLayout、RelativeLayout等，因此咱们刚才用的updateViewLayout()方法也是在xml布局文件中的layout定义好的。
标签：Popupwindow,拖动,update,int,import,Android,View,android,view 来源： https://www.cnblogs.com/xgjblog/p/16356675.html
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