最近重构项目，想把之前的一些控件替换成BottomSheetDialog。最后选用的是更加方便的BottomSheetDialogFragment。也遇到了很多坑，写出来分享一下。
1.BottomSheetDialogFragment背景圆角设置
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<solid android:color="@color/white" />
<corners
android:topLeftRadius="20dp"
android:topRightRadius="20dp" />
</shape>
Screenshot_2018-05-24-11-20-50
解决方法：
BottomSheetDialog dialog = (BottomSheetDialog) super.onCreateDialog(savedInstanceState);
View view = View.inflate(getContext(), R.layout.layout_room_more_setting, null);
dialog.setContentView(view);
((View) view.getParent()).setBackgroundColor(getResources().getColor(android.R.color.transparent));
设置BottomSheetDialog的背景为透明色。
2.弹出BottomSheetDialog背景变暗
默认情况下直接弹出BottomSheetDialogFragment背景会变暗，需求是不能变暗。可以通过设置style解决问题。
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setStyle(BottomSheetDialogFragment.STYLE_NORMAL, R.style.TransBottomSheetDialogStyle);
}
<style name="TransBottomSheetDialogStyle" parent="Theme.Design.Light.BottomSheetDialog">
<item name="android:windowFrame">@null</item>
<item name="android:windowIsFloating">true</item>
<item name="android:windowIsTranslucent">true</item>
<item name="android:background">@android:color/transparent</item>
<item name="android:backgroundDimEnabled">false</item>
</style>
这样弹出Dialog时背景就不会变暗。
3.弹出的BottomSheetDialog占满屏幕
如果BottomSheetDialog中内容很多的话弹出的Dialog首先会到达一个peekHeight，然后如果滑动内容，整个Dialog就会向上滑动，直到铺满屏幕。很多时候我们是不希望整个Dialog向上滑动到整个屏幕的，比如在需要实时预览设置效果的画面：
image.png
如果再向上滑动就会一直占满整个屏幕，无法实时看到预览的画面。这时我们就需要控制BottomSheetDialog的peekHeight和最大高度。
在BottomSheetBehavior中有一个
setPeekHeight()方法可以控制首次弹出的高度，BottomSheetDialog没有将这个方法开放给我们。查看setContentView()源码：
@Override
public void setContentView(@LayoutRes int layoutResId) {
super.setContentView(wrapInBottomSheet(layoutResId, null, null));
}
再打开wrapInBottomSheet(layoutResId, null, null):
private View wrapInBottomSheet(int layoutResId, View view, ViewGroup.LayoutParams params) {
final FrameLayout container = (FrameLayout) View.inflate(getContext(),
R.layout.design_bottom_sheet_dialog, null);
final CoordinatorLayout coordinator =
(CoordinatorLayout) container.findViewById(R.id.coordinator);
if (layoutResId != 0 && view == null) {
view = getLayoutInflater().inflate(layoutResId, coordinator, false);
}
FrameLayout bottomSheet = (FrameLayout) coordinator.findViewById(R.id.design_bottom_sheet);
mBehavior = BottomSheetBehavior.from(bottomSheet);
mBehavior.setBottomSheetCallback(mBottomSheetCallback);
mBehavior.setHideable(mCancelable);
if (params == null) {
bottomSheet.addView(view);
} else {
bottomSheet.addView(view, params);
}
// We treat the CoordinatorLayout as outside the dialog though it is technically inside
coordinator.findViewById(R.id.touch_outside).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (mCancelable && isShowing() && shouldWindowCloseOnTouchOutside()) {
cancel();
}
}
});
// Handle accessibility events
ViewCompat.setAccessibilityDelegate(bottomSheet, new AccessibilityDelegateCompat() {
@Override
public void onInitializeAccessibilityNodeInfo(View host,
AccessibilityNodeInfoCompat info) {
super.onInitializeAccessibilityNodeInfo(host, info);
if (mCancelable) {
info.addAction(AccessibilityNodeInfoCompat.ACTION_DISMISS);
info.setDismissable(true);
} else {
info.setDismissable(false);
}
}
@Override
public boolean performAccessibilityAction(View host, int action, Bundle args) {
if (action == AccessibilityNodeInfoCompat.ACTION_DISMISS && mCancelable) {
cancel();
return true;
}
return super.performAccessibilityAction(host, action, args);
}
});
bottomSheet.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View view, MotionEvent event) {
// Consume the event and prevent it from falling through
return true;
}
});
return container;
}
在第十行可以看到BottomSheetBehavior，这个BottomSheetBehavior是从R.id.design_bottom_sheet这个View获取的。那么我们同样可以通过这个方法获取BottomSheetBehavior，然后设置peekHeight。
View view = bottomSheetDialog.getWindow().findViewById(android.support.design.R.id.design_bottom_sheet);
BottomSheetBehavior.from(view).setPeekHeight(1600);
由于我们的代码没有在Support包下面，所以不能直接写R.id.design_bottom_sheet，而是要写成android.support.design.R.id.design_bottom_sheet。
这时我们已经完成了设置首次弹出高度。接下来我们需要设置Dialog的最大高度。
查看BottomSheetDialog的源码可以再onCreate()方法中发现如下代码：
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Window window = getWindow();
if (window != null) {
if (Build.VERSION.SDK_INT >= 21) {
window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
}
window.setLayout(ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT);
}
}
这里面window.setLayout()方法就是设置整个Dialog占满屏幕，这样如果内容过长就会一直向上滑动，直到占满屏幕。那么我们只需要改变这个属性即可。
mWindow.setLayout(ViewGroup.LayoutParams.MATCH_PARENT, mMaxHeight);
现在我们发现Dialog的高度是我们想要的高度了，但是Dialog没有像预期一样固定在屏幕底部。这时需要简单设置下dialog的gravity即可：
bottomSheetDialog.getWindow().setGravity(Gravity.BOTTOM);
需要注意的是需要在onCreate() 中对宽高进行设置，或者 show() 之后进行设置，否则高度设置不生效。
综合上述的过程，可以对这个可以自定peekHeight和maxHeight的BottomSheetDialog做一个简单的封装，方便使用：
package com.zouludaifeng.daifeng.widget;
import android.content.Context;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomSheetBehavior;
import android.support.design.widget.BottomSheetDialog;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
/**
* @author sun on 2018/5/25.
*/
public class CustomHeightBottomSheetDialog extends BottomSheetDialog {
private int mPeekHeight;
private int mMaxHeight;
private boolean mCreated;
private Window mWindow;
private BottomSheetBehavior mBottomSheetBehavior;
public CustomHeightBottomSheetDialog(@NonNull Context context,int peekHeight,int maxHeight) {
super(context);
init(peekHeight, maxHeight);
}
public CustomHeightBottomSheetDialog(@NonNull Context context, int theme,int peekHeight,int maxHeight) {
super(context, theme);
init(peekHeight, maxHeight);
}
public CustomHeightBottomSheetDialog(@NonNull Context context, boolean cancelable, OnCancelListener cancelListener,int peekHeight,int maxHeight) {
super(context, cancelable, cancelListener);
init(peekHeight, maxHeight);
}
private void init(int peekHeight, int maxHeight) {
mWindow = getWindow();
mPeekHeight = peekHeight;
mMaxHeight = maxHeight;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mCreated = true;
setPeekHeight();
setMaxHeight();
setBottomSheetCallback();
}
public void setPeekHeight(int peekHeight) {
mPeekHeight = peekHeight;
if (mCreated) {
setPeekHeight();
}
}
public void setMaxHeight(int height) {
mMaxHeight = height;
if (mCreated) {
setMaxHeight();
}
}
public void setBatterSwipeDismiss(boolean enabled) {
if (enabled) {
}
}
private void setPeekHeight() {
if (mPeekHeight <= 0) {
return;
}
if (getBottomSheetBehavior() != null) {
mBottomSheetBehavior.setPeekHeight(mPeekHeight);
}
}
private void setMaxHeight() {
if (mMaxHeight <= 0) {
return;
}
mWindow.setLayout(ViewGroup.LayoutParams.MATCH_PARENT, mMaxHeight);
mWindow.setGravity(Gravity.BOTTOM);
}
private BottomSheetBehavior getBottomSheetBehavior() {
if (mBottomSheetBehavior != null) {
return mBottomSheetBehavior;
}
View view = mWindow.findViewById(android.support.design.R.id.design_bottom_sheet);
// setContentView() 没有调用
if (view == null) {
return null;
}
mBottomSheetBehavior = BottomSheetBehavior.from(view);
return mBottomSheetBehavior;
}
private void setBottomSheetCallback() {
if (getBottomSheetBehavior() != null) {
mBottomSheetBehavior.setBottomSheetCallback(mBottomSheetCallback);
}
}
private final BottomSheetBehavior.BottomSheetCallback mBottomSheetCallback
= new BottomSheetBehavior.BottomSheetCallback() {
@Override
public void onStateChanged(@NonNull View bottomSheet,
@BottomSheetBehavior.State int newState) {
if (newState == BottomSheetBehavior.STATE_HIDDEN) {
dismiss();
BottomSheetBehavior.from(bottomSheet).setState(
BottomSheetBehavior.STATE_COLLAPSED);
}
}
@Override
public void onSlide(@NonNull View bottomSheet, float slideOffset) {
}
};
}
4.java.lang.IllegalStateException: Fragment does not have a view
在BottomSheetDialog中使用ViewPager会报这个错误。错误的原因没有深究，提供一个简单的解决方案就是不要再onCreateDialog()中创建Dialog，转到onCreateView中创建View，就不会报这个异常。
但是这么干又会带来第一个问题里面提到的，背景变成了白色。如果直接在onCreateView()或者onViewCreated()里面调用
((View) view.getParent()).setBackgroundColor(getResources().getColor(android.R.color.transparent));
会报空指针异常，这时需要在onActivityCreated（）中调用这个方法，就可以避免这个问题。汗，一趟走过来，问题还真是不少。
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