popupwindow 的使用

popupwindow 常用api

1. 构造PopupWindow()对象

//方法一：
public PopupWindow (Context context)
//方法二：
public PopupWindow(View contentView)
//方法三：
public PopupWindow(View contentView, int width, int height)
//方法四：
public PopupWindow(View contentView, int width, int height, boolean focusable)

2. 展示PopupWindow()

//相对某个控件的位置（正左下方），无偏移
showAsDropDown(View anchor)：
//相对某个控件的位置，有偏移;xoff表示x轴的偏移，正值表示向左，负值表示向右；yoff表示相对y轴的偏移，正值是向下，负值是向上；
showAsDropDown(View anchor, int xoff, int yoff)：
//相对于父控件的位置（例如正中央Gravity.CENTER，下方Gravity.BOTTOM等），可以设置偏移或无偏移
showAtLocation(View parent, int gravity, int x, int y)：

3. 其它Api

public void dismiss()
public void setFocusable(boolean focusable)
public void setTouchable(boolean touchable)
public void setOutsideTouchable(boolean touchable)
public void setBackgroundDrawable(Drawable background)

源码

从showAsDropDown(View anchor)说起

PopupWindow
|
|-showAsDropDown(View anchor, int xoff, int yoff, int gravity)
    |
    |- final WindowManager.LayoutParams p =createPopupLayoutParams(anchor.getApplicationWindowToken());
    |1. 创建WindowManager.LayoutParams
    |
    |
    |-preparePopup(p);
    |2. 准备Popup，包括创建mBackgroundView，mDecorView
    |
    |
    |-invokePopup(p);
    |3. 将decorView 通过mWindowManager.addView(decorView, p);添加window上
    

#1.createPopupLayoutParams
PopupWindow
|
|-createPopupLayoutParams(IBinder token)
    |
    |-final WindowManager.LayoutParams p = new WindowManager.LayoutParams();
    |创建 WindowManager.LayoutParams 实例
    |
    |
    |-p.gravity = computeGravity();
    |-p.flags = computeFlags(p.flags);
    |-p.type = mWindowLayoutType = WindowManager.LayoutParams.TYPE_APPLICATION_PANEL;
    |-p.height = mLastHeight = mHeight;
    |- p.width = mLastWidth = mWidth;
    |这部分内容主要是设置WindowManager.LayoutParams 的属性，宽高，flgas，type等
    

#2.preparePopup
PopupWindow
|
|-preparePopup(p)
    |
    |-if (mBackground != null) mBackgroundView = createBackgroundView(mContentView);
    |-mBackgroundView.setBackground(mBackground);
    |-else mBackgroundView = mContentView;
    |如果mBackground !=null 会创建一个PopupBackgroundView赋值给mBackgroundView
    |否则，直接将mContentView赋值给mBackgroundView
    |
    |
    |-mDecorView = createDecorView(mBackgroundView);
    |创建PopupDecorView，PopupDecorView extends FrameLayout
    |重写dispatchKeyEvent(KeyEvent event)，在按返回键的时候，会dismiss方法
    |重写了 onTouchEvent(MotionEvent event) 方法
    |在点击popup 外面的时候，会执行dismiss方法 if(event.getAction() == MotionEvent.ACTION_OUTSIDE)   dismiss();
    |
    |


#3.invokePopup
PopupWindow
|
|-invokePopup(p)
    |
    |
    |-mWindowManager.addView(decorView, p);
    |通过WindowManager将PopupDecorView 添加到Window上