searchfilters: make default dialog not stretch vertically

Originally stretching vertically over the whole screen was used
to avoid resizing the UI each time the selected content filter
selects another set of sort filters.

As it turns out fullscreen vertically dialogs can be ugly and my
other attempt to use View.INVISIBLE instead of (View.GONE) in order
to have some sort of placeholder, didn't work well with the Spinner
Views either. So we go back and let Android resize the UI.

Another resizing annoyance is now avoided. The Material's Chip with the
Filter style was also resized each time a Chip was selected.

To avoid resizing for the Chip views the checkmark icon is removed
by using a custom chip style: "@style/ChipSearchFilter". The
custom chip style also improves the contrast when a chip is selected

To save some space a ChipGroup that holds more than
CHIP_GROUP_ELEMENTS_THRESHOLD elements will be spanned
over all cells of a row in the GridLayout.

app/src/main/java/org/schabi/newpipe/fragments/list/search/filter/SearchFilterDialogGenerator.java

@@ -4,6 +4,7 @@ package org.schabi.newpipe.fragments.list.search.filter;
 
 import android.content.Context;
 import android.view.Gravity;
+import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.AdapterView;
@@ -23,9 +24,11 @@ import org.schabi.newpipe.util.ServiceHelper;
 import java.util.List;
 
 import androidx.annotation.NonNull;
-import androidx.appcompat.view.ContextThemeWrapper;
+import androidx.annotation.Nullable;
 
 public class SearchFilterDialogGenerator extends BaseSearchFilterUiDialogGenerator {
+    private static final int CHIP_GROUP_ELEMENTS_THRESHOLD = 2;
+    private static final int CHIP_MIN_TOUCH_TARGET_SIZE_DP = 40;
     private final GridLayout globalLayout;
 
     public SearchFilterDialogGenerator(
@@ -62,8 +65,9 @@ public class SearchFilterDialogGenerator extends BaseSearchFilterUiDialogGenerat
         final UiItemWrapperViews viewsWrapper = new UiItemWrapperViews(
                 filterGroup.getIdentifier());
 
+        final TextView filterLabel;
         if (filterGroup.getNameId() != null) {
-            final TextView filterLabel = new TextView(context);
+            filterLabel = new TextView(context);
 
             filterLabel.setId(filterGroup.getIdentifier());
             filterLabel.setText(
@@ -73,13 +77,16 @@ public class SearchFilterDialogGenerator extends BaseSearchFilterUiDialogGenerat
             setZeroPadding(filterLabel);
 
             filterLabel.setLayoutParams(layoutParams);
-            globalLayout.addView(filterLabel);
             viewsWrapper.add(filterLabel);
         } else {
+            filterLabel = null;
             doSpanDataOverMultipleCells = true;
         }
 
         if (filterGroup.isOnlyOneCheckable()) {
+            if (filterLabel != null) {
+                globalLayout.addView(filterLabel);
+            }
 
             final Spinner filterDataSpinner = new Spinner(context, Spinner.MODE_DROPDOWN);
 
@@ -97,6 +104,9 @@ public class SearchFilterDialogGenerator extends BaseSearchFilterUiDialogGenerat
 
         } else { // multiple items in FilterGroup selectable
             final ChipGroup chipGroup = new ChipGroup(context);
+            doSpanDataOverMultipleCells = chooseParentViewForFilterLabelAndAdd(
+                    filterGroup, doSpanDataOverMultipleCells, filterLabel, chipGroup);
+
             viewsWrapper.add(chipGroup);
             globalLayout.addView(chipGroup);
             chipGroup.setLayoutParams(
@@ -110,6 +120,28 @@ public class SearchFilterDialogGenerator extends BaseSearchFilterUiDialogGenerat
         wrapperDelegate.put(filterGroup.getIdentifier(), viewsWrapper);
     }
 
+    private boolean chooseParentViewForFilterLabelAndAdd(
+            @NonNull final FilterGroup filterGroup,
+            final boolean doSpanDataOverMultipleCells,
+            @Nullable final TextView filterLabel,
+            @NonNull final ChipGroup possibleParentView) {
+
+        boolean spanOverMultipleCells = doSpanDataOverMultipleCells;
+        if (filterLabel != null) {
+            // If we have more than CHIP_GROUP_ELEMENTS_THRESHOLD elements to be
+            // displayed as Chips add its filterLabel as first element to ChipGroup.
+            // Now the ChipGroup can be spanned over all the cells to use
+            // the space better.
+            if (filterGroup.getFilterItems().size() > CHIP_GROUP_ELEMENTS_THRESHOLD) {
+                possibleParentView.addView(filterLabel);
+                spanOverMultipleCells = true;
+            } else {
+                globalLayout.addView(filterLabel);
+            }
+        }
+        return spanOverMultipleCells;
+    }
+
     private void createUiElementsForSingleSelectableItemsFilterGroup(
             @NonNull final FilterGroup filterGroup,
             @NonNull final UiWrapperMapDelegate wrapperDelegate,
@@ -143,8 +175,10 @@ public class SearchFilterDialogGenerator extends BaseSearchFilterUiDialogGenerat
             @NonNull final UiSelectorDelegate selectorDelegate,
             @NonNull final ChipGroup chipGroup) {
         for (final FilterItem item : filterGroup.getFilterItems()) {
-            final Chip chip = new Chip(new ContextThemeWrapper(
-                    context, R.style.Theme_MaterialComponents_Light));
+            final Chip chip = (Chip) LayoutInflater.from(context).inflate(
+                    R.layout.chip_search_filter, chipGroup, false);
+            chip.ensureAccessibleTouchTarget(
+                    DeviceUtils.dpToPx(CHIP_MIN_TOUCH_TARGET_SIZE_DP, context));
             chip.setText(ServiceHelper.getTranslatedFilterString(item.getNameId(), context));
             chip.setId(item.getIdentifier());
             chip.setCheckable(true);
@@ -205,7 +239,7 @@ public class SearchFilterDialogGenerator extends BaseSearchFilterUiDialogGenerat
     @NonNull
     private GridLayout.LayoutParams getLayoutParamsViews() {
         final GridLayout.LayoutParams layoutParams = new GridLayout.LayoutParams();
-        layoutParams.setGravity(Gravity.TOP);
+        layoutParams.setGravity(Gravity.CENTER_VERTICAL);
         setDefaultMargin(layoutParams);
         return layoutParams;
     }
@@ -247,7 +281,6 @@ public class SearchFilterDialogGenerator extends BaseSearchFilterUiDialogGenerat
 
         @Override
         public void setChecked(final boolean checked) {
-            view.setSelected(checked);
             ((Chip) view).setChecked(checked);
 
             if (checked) {

app/src/main/res/color/mtrl_search_filter_chip_background_color.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+  <!-- adding more contrast than @color/mtrl_chip_background_color if a Chip is selected -->
+  <item android:alpha="0.30" android:color="?attr/colorOnSurface" android:state_enabled="true" android:state_selected="true"/>
+  <item android:alpha="0.18" android:color="?attr/colorOnSurface" android:state_enabled="true" android:state_checked="true"/>
+  <!-- 12% of 87% opacity -->
+  <item android:alpha="0.10" android:color="?attr/colorOnSurface" android:state_enabled="true"/>
+  <item android:alpha="0.12" android:color="?attr/colorOnSurface"/>
+</selector>

app/src/main/res/layout/chip_search_filter.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- This is used to inflate a chip with a Material theme, otherwise it would crash -->
+<!-- Theme.MaterialComponents.DayNight is used to guarantee auto day/night switching -->
+<com.google.android.material.chip.Chip xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    style="@style/ChipSearchFilter"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    android:theme="@style/Theme.MaterialComponents.DayNight" />

app/src/main/res/layout/search_filter_dialog_fragment.xml

@@ -1,7 +1,7 @@
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
-    android:layout_height="match_parent" >
+    android:layout_height="wrap_content" >
 
     <include
         android:id="@+id/toolbar_layout"
@@ -9,8 +9,8 @@
 
     <ScrollView
         android:layout_width="match_parent"
-        android:layout_height="match_parent"
-        android:layout_below="@+id/toolbar_layout">
+        android:layout_height="wrap_content"
+        android:layout_below="@id/toolbar_layout">
 
         <LinearLayout
             android:id="@+id/vertical_scroll"

app/src/main/res/values/styles.xml

@@ -155,4 +155,12 @@
 
     <style name="RouterActivityThemeDark" parent="Base.RouterActivityThemeDark" />
 
+    <!-- custom Chip style for SearchFilterDialogFragment -->
+    <style name="ChipSearchFilter" parent="Widget.MaterialComponents.Chip.Filter">
+        <item name="checkedIconEnabled">false</item>
+        <item name="checkedIcon">@null</item>
+        <item name="chipBackgroundColor">@color/mtrl_search_filter_chip_background_color</item>
+        <item name="chipStrokeWidth">0.1dp</item>
+    </style>
+
 </resources>