Import ExpandableViewLayout from rview

Source: https://github.com/jruesga/rview

Original commits:
    commit c7c72aca0fd3ac74133328efe00d48c5396bf49f
    Author: Jorge Ruesga <jorge@ruesga.com>
    Date:   Fri Aug 24 23:34:15 2018 +0200

        Migrate to androidx

        Signed-off-by: Jorge Ruesga <jorge@ruesga.com>

    commit 2eb2171983afadc25850ed39fcee92c1c160758b
    Author: Jorge Ruesga <jorge@ruesga.com>
    Date:   Sat Jun 10 01:42:42 2017 +0200

        Add support for Android O

        Signed-off-by: Jorge Ruesga <jorge@ruesga.com>

    commit 19906b658f65f7c44ab27bc286a727f17b087b78
    Author: Jorge Ruesga <jorge@ruesga.com>
    Date:   Sat Nov 5 17:35:44 2016 +0100

        Initial collapse commit message if its text rebased 240dp

        Signed-off-by: Jorge Ruesga <jorge@ruesga.com>

Change-Id: I512ab20daf58a884b65e7ef9ba60eecb022de17d

vector/src/main/assets/open_source_licenses.html

@@ -442,6 +442,11 @@ THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
         <br/>
         Copyright 2018, Nick / materialdesignicons.com
     </li>
+    <li>
+        <b>ExpandableViewLayout</b>
+        <br/>
+        Copyright (C) 2016 Jorge Ruesga
+    </li>
     <li>
         <b>Calling ringtone</b>
         <br/>

vector/src/main/java/com/ruesga/rview/widget/ExpandableViewLayout.java

@@ -0,0 +1,164 @@
+/*
+ * Copyright (C) 2016 Jorge Ruesga
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.ruesga.rview.widget;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.content.res.TypedArray;
+import android.os.Parcel;
+import android.os.Parcelable;
+import android.util.AttributeSet;
+import android.view.View;
+import android.widget.FrameLayout;
+
+import androidx.annotation.NonNull;
+import androidx.customview.view.AbsSavedState;
+
+import im.vector.app.R;
+
+public class ExpandableViewLayout extends FrameLayout {
+
+    private int mMaxHeight;
+    private boolean mExpanded;
+    private View mExpandableControl;
+    private int mChildViewHeight;
+
+    public ExpandableViewLayout(Context context) {
+        this(context, null);
+    }
+
+    public ExpandableViewLayout(Context context, AttributeSet attrs) {
+        this(context, attrs, 0);
+    }
+
+    public ExpandableViewLayout(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+
+        Resources.Theme theme = context.getTheme();
+        TypedArray a = theme.obtainStyledAttributes(
+                attrs, R.styleable.ExpandableViewLayout, defStyleAttr, 0);
+        int n = a.getIndexCount();
+        for (int i = 0; i < n; i++) {
+            int attr = a.getIndex(i);
+            if (attr == R.styleable.ExpandableViewLayout_maxHeight) {
+                mMaxHeight = a.getDimensionPixelSize(attr, mMaxHeight);
+            } else if (attr == R.styleable.ExpandableViewLayout_expanded) {
+                mExpanded = a.getBoolean(attr, false);
+            }
+        }
+        a.recycle();
+    }
+
+    @Override
+    protected void onFinishInflate() {
+        super.onFinishInflate();
+
+        if (getChildCount() != 2) {
+            throw new IllegalStateException(
+                    "ExpandableViewLayout needs 2 views (main view and expandable control view)");
+        }
+
+        // Obtain the expandable control
+        mExpandableControl = getChildAt(1);
+        mExpandableControl.setOnClickListener(view -> {
+            mExpanded = !mExpanded;
+            setExpandableControlVisibility();
+            requestLayout();
+        });
+    }
+
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        // Obtain the main view height
+        View view = getChildAt(0);
+        view.measure(MeasureSpec.makeMeasureSpec(widthMeasureSpec, MeasureSpec.AT_MOST),
+                MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
+        mChildViewHeight = view.getMeasuredHeight();
+        setExpandableControlVisibility();
+
+        // Measure this view according
+        if (!mExpanded && mMaxHeight > 0) {
+            heightMeasureSpec = MeasureSpec.makeMeasureSpec(mMaxHeight, MeasureSpec.AT_MOST);
+        }
+        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
+    }
+
+    private void setExpandableControlVisibility() {
+        final boolean expanded = mExpanded || mMaxHeight == 0 || mMaxHeight > mChildViewHeight;
+        mExpandableControl.setVisibility(expanded ? View.GONE : View.VISIBLE);
+    }
+
+    @Override
+    protected Parcelable onSaveInstanceState() {
+        SavedState savedState = new SavedState(super.onSaveInstanceState());
+        savedState.mExpanded = mExpanded;
+        return savedState;
+    }
+
+    @Override
+    protected void onRestoreInstanceState(Parcelable state) {
+        //begin boilerplate code so parent classes can restore state
+        if(!(state instanceof SavedState)) {
+            super.onRestoreInstanceState(state);
+            return;
+        }
+
+        SavedState savedState = (SavedState) state;
+        super.onRestoreInstanceState(savedState.getSuperState());
+
+        mExpanded = savedState.mExpanded;
+        setExpandableControlVisibility();
+        requestLayout();
+    }
+
+    @SuppressWarnings("WeakerAccess")
+    public static class SavedState extends AbsSavedState {
+        public boolean mExpanded;
+
+        public SavedState(Parcel in, ClassLoader loader) {
+            super(in, loader);
+            mExpanded = in.readInt() == 1;
+        }
+
+        public SavedState(Parcelable superState) {
+            super(superState);
+        }
+
+        @Override
+        public void writeToParcel(@NonNull Parcel dest, int flags) {
+            super.writeToParcel(dest, flags);
+            dest.writeInt(mExpanded ? 1 : 0);
+        }
+
+        public static final Parcelable.ClassLoaderCreator<SavedState> CREATOR
+                = new Parcelable.ClassLoaderCreator<SavedState>() {
+            @Override
+            public SavedState createFromParcel(Parcel source) {
+                return createFromParcel(source, null);
+            }
+
+            @Override
+            public SavedState createFromParcel(Parcel source, ClassLoader loader) {
+                return new SavedState(source, loader);
+            }
+
+            @Override
+            public SavedState[] newArray(int size) {
+                return new SavedState[size];
+            }
+        };
+    }
+}

vector/src/main/res/drawable/bg_expandable_edge_shadow.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+     Copyright (C) 2016 Jorge Ruesga
+
+     Licensed under the Apache License, ServerVersion 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+ -->
+<shape xmlns:android="http://schemas.android.com/apk/res/android">
+    <gradient android:angle="90" android:startColor="#FFFFFFFF" android:endColor="#99FFFFFF" />
+</shape>

vector/src/main/res/values/expandable_view_layout_attrs.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+     Copyright (C) 2016 Jorge Ruesga
+
+     Licensed under the Apache License, ServerVersion 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+ -->
+<resources>
+    <declare-styleable name="ExpandableViewLayout">
+        <attr name="maxHeight" format="dimension"/>
+        <attr name="expanded" format="boolean"/>
+    </declare-styleable>
+</resources>