可拖动、可靠边的 popupWindow 实现

0 背景

开发要实现一个可以拖动的圆角小窗，要求松手时，哪边近些靠哪边。并且还规定了拖动范围。样式如下：
在这里插入图片描述

1 实现

首先把 PopupWindow 的布局文件 pop.xml 实现

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"android:layout_width="88dp"android:layout_height="132dp"android:background="@drawable/radius_12"android:id="@+id/mini_popup"android:visibility="visible"><com.google.android.material.imageview.ShapeableImageViewandroid:id="@+id/iv_live_cover"android:layout_width="88dp"android:scaleType="fitXY"android:layout_height="132dp"android:background="@color/purple_200"app:shapeAppearanceOverlay="@style/MiniDialogRoundedImageStyle" /><ImageViewandroid:id="@+id/iv_close"android:layout_width="16dp"android:layout_height="16dp"android:layout_alignParentRight="true"android:layout_marginTop="4dp"android:layout_marginRight="4dp"android:src="@color/teal_200" />
</RelativeLayout>

布局中圆角和 PopupWindow 的动画 style.xml

    <!-- 圆角图片 --><style name="MiniDialogRoundedImageStyle"><item name="cornerFamily">rounded</item><item name="cornerSize">12dp</item></style><!-- PopupWindow 的动画效果 --><style name="PopupWindowAnimation"><item name="android:windowEnterAnimation">@anim/live_popup_window_in_anim</item></style>

radius_12.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"><corners android:radius="12dp"/><solid android:color="@color/white"/>
</shape>

MyPopupWindow.java

package com.example.myapplication.popupwindow;import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.content.res.Resources;
import android.text.TextUtils;
import android.util.DisplayMetrics;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import android.widget.PopupWindow;import com.bumptech.glide.Glide;
import com.example.myapplication.R;public class MyPopupWindow extends PopupWindow {private Context mContext;private View mRootView;// 背景private ImageView mBackground;// 关闭弹窗private ImageView mIvClose;// 弹窗的移动范围private int mMinX;private int mMinY;private int mMaxX;private int mMaxY;// 屏幕宽高private int mScreenWidth;public MyPopupWindow(Context context) {super(context);mContext = context;mRootView = View.inflate(mContext, R.layout.pop, null);mScreenWidth = getScreenWidth(mContext);mMinX = dp2px(12);mMaxX = mScreenWidth - dp2px(12) - dp2px(88);mMinY = dp2px(12);mMaxY = dp2px(500);// 为了保证整体是圆角形状mRootView.findViewById(R.id.mini_popup).setClipToOutline(true);initView();}private void initView() {setContentView(mRootView);mBackground = mRootView.findViewById(R.id.iv_live_cover);mIvClose = mRootView.findViewById(R.id.iv_close);mIvClose.setOnClickListener(view -> this.dismiss());// 小窗的宽高setHeight(dp2px(132));setWidth(dp2px(88));this.setTouchInterceptor(new View.OnTouchListener() {int orgX, orgY;int offsetX, offsetY;@Overridepublic boolean onTouch(View view, MotionEvent motionEvent) {switch (motionEvent.getAction()) {case MotionEvent.ACTION_DOWN:orgX = (int) motionEvent.getX();orgY = (int) motionEvent.getY();break;case MotionEvent.ACTION_MOVE:offsetX = (int) motionEvent.getRawX() - orgX;offsetY = (int) motionEvent.getRawY() - orgY;// 限制 x 坐标offsetX = Math.max(offsetX, mMinX);offsetX = Math.min(offsetX, mMaxX);// 限制 y 坐标offsetY = Math.max(offsetY, mMinY);offsetY = Math.min(offsetY, mMaxY);update(offsetX, offsetY, -1, -1, true);break;case MotionEvent.ACTION_UP:// 小窗靠边if (offsetX < mScreenWidth / 2) {offsetX = mMinX;} else {offsetX = mMaxX;}update(offsetX, offsetY, -1, -1, true);break;}// 避免 view 中的其他点击事件被吞掉return false;}});// 设置小窗背景this.setBackgroundDrawable(mContext.getResources().getDrawable(R.drawable.abc_vector_test));// 出现的动画this.setAnimationStyle(R.style.PopupWindowAnimation);}public void show(View anchor) {this.showAtLocation(anchor, Gravity.NO_GRAVITY, mMaxX, mMaxY);}@SuppressLint("CheckResult")public void setBackground(String url) {if (url != null && !TextUtils.isEmpty(url))Glide.with(mContext).load(url).into(mBackground);}public int dp2px(float dpValue) {return (int) (0.5f + dpValue * Resources.getSystem().getDisplayMetrics().density);}public int getScreenWidth(Context context) {DisplayMetrics localDisplayMetrics = new DisplayMetrics();((Activity) context).getWindowManager().getDefaultDisplay().getMetrics(localDisplayMetrics);return localDisplayMetrics.widthPixels;}
}

最后在 MainActivity 中使用

mTextView = findViewById(R.id.myView);
if (mMyPopupWindow == null) {mMyPopupWindow = new MyPopupWindow(MainActivity.this);
}
mTextView.post(() -> {mMyPopupWindow.show(mTextView);
});