Provide a preference to scale all UI text (#3248)

Font scaling is applied in addition to any scaling set in Android system preferences. So if the user set the Android font size to largest (a 1.3x increase) and then sets the preference to 120%, the total change is 1.56x.

Create SliderPreference to adjust the preference.

- Use Slider, which supports float values and step sizes > 1
- Display the selected value in the preference's summary
- Provide buttons to increment / decrement the value

Restart the activity if the preference changes so that the user sees the impact of the change immediately. Fix a bug in PreferencesActivity where the "EXTRA_RESTART_ON_BACK" intent was never processed. Fix this to ensure that other activities are restarted so the new font scale takes effect.

Implement the scaling in BaseActivity by overriding onAttachBaseContext, and providing a wrapped context with the font scaling applied.

Fixes https://github.com/tuskyapp/Tusky/issues/2982, https://github.com/tuskyapp/Tusky/issues/2461

app/src/main/java/com/keylesspalace/tusky/BaseActivity.java

@@ -16,9 +16,11 @@
 package com.keylesspalace.tusky;
 
 import android.app.ActivityManager;
+import android.content.Context;
 import android.content.Intent;
 import android.content.SharedPreferences;
 import android.content.pm.PackageManager;
+import android.content.res.Configuration;
 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.graphics.Color;
@@ -45,6 +47,7 @@ import com.keylesspalace.tusky.db.AccountManager;
 import com.keylesspalace.tusky.di.Injectable;
 import com.keylesspalace.tusky.interfaces.AccountSelectionListener;
 import com.keylesspalace.tusky.interfaces.PermissionRequester;
+import com.keylesspalace.tusky.settings.PrefKeys;
 import com.keylesspalace.tusky.util.ThemeUtils;
 
 import java.util.ArrayList;
@@ -54,6 +57,7 @@ import java.util.List;
 import javax.inject.Inject;
 
 public abstract class BaseActivity extends AppCompatActivity implements Injectable {
+    private static final String TAG = "BaseActivity";
 
     @Inject
     public AccountManager accountManager;
@@ -93,6 +97,44 @@ public abstract class BaseActivity extends AppCompatActivity implements Injectab
         requesters = new HashMap<>();
     }
 
+    @Override
+    protected void attachBaseContext(Context newBase) {
+        SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(newBase);
+
+        // Scale text in the UI from PrefKeys.UI_TEXT_SCALE_RATIO
+        float uiScaleRatio = preferences.getFloat(PrefKeys.UI_TEXT_SCALE_RATIO, 100F);
+
+        Configuration configuration = newBase.getResources().getConfiguration();
+
+        // Adjust `fontScale` in the configuration.
+        //
+        // You can't repeatedly adjust the `fontScale` in `newBase` because that will contain the
+        // result of previous adjustments. E.g., going from 100% to 80% to 100% does not return
+        // you to the original 100%, it leaves it at 80%.
+        //
+        // Instead, calculate the new scale from the application context. This is unaffected by
+        // changes to the base context. It does contain contain any changes to the font scale from
+        // "Settings > Display > Font size" in the device settings, so scaling performed here
+        // is in addition to any scaling in the device settings.
+        Configuration appConfiguration = newBase.getApplicationContext().getResources().getConfiguration();
+
+        // This only adjusts the fonts, anything measured in `dp` is unaffected by this.
+        // You can try to adjust `densityDpi` as shown in the commented out code below. This
+        // works, to a point. However, dialogs do not react well to this. Beyond a certain
+        // scale (~ 120%) the right hand edge of the dialog will clip off the right of the
+        // screen.
+        //
+        // So for now, just adjust the font scale
+        //
+        // val displayMetrics = appContext.resources.displayMetrics
+        // configuration.densityDpi = ((displayMetrics.densityDpi * uiScaleRatio).toInt())
+        configuration.fontScale = appConfiguration.fontScale * uiScaleRatio / 100F;
+
+        Context fontScaleContext = newBase.createConfigurationContext(configuration);
+
+        super.attachBaseContext(fontScaleContext);
+    }
+
     protected boolean requiresLogin() {
         return true;
     }

app/src/main/java/com/keylesspalace/tusky/components/preference/PreferencesActivity.kt

@@ -95,7 +95,9 @@ class PreferencesActivity :
         }
 
         onBackPressedDispatcher.addCallback(this, restartActivitiesOnBackPressedCallback)
-        restartActivitiesOnBackPressedCallback.isEnabled = savedInstanceState?.getBoolean(EXTRA_RESTART_ON_BACK, false) ?: false
+        restartActivitiesOnBackPressedCallback.isEnabled = intent.extras?.getBoolean(
+            EXTRA_RESTART_ON_BACK
+        ) ?: savedInstanceState?.getBoolean(EXTRA_RESTART_ON_BACK, false) ?: false
     }
 
     override fun onPreferenceStartFragment(
@@ -151,6 +153,10 @@ class PreferencesActivity :
                 restartActivitiesOnBackPressedCallback.isEnabled = true
                 this.restartCurrentActivity()
             }
+            PrefKeys.UI_TEXT_SCALE_RATIO -> {
+                restartActivitiesOnBackPressedCallback.isEnabled = true
+                this.restartCurrentActivity()
+            }
             "statusTextSize", "absoluteTimeView", "showBotOverlay", "animateGifAvatars", "useBlurhash",
             "showSelfUsername", "showCardsInTimelines", "confirmReblogs", "confirmFavourites",
             "enableSwipeForTabs", "mainNavPosition", PrefKeys.HIDE_TOP_TOOLBAR, PrefKeys.SHOW_STATS_INLINE -> {
@@ -175,7 +181,8 @@ class PreferencesActivity :
     override fun androidInjector() = androidInjector
 
     companion object {
-
+        @Suppress("unused")
+        private const val TAG = "PreferencesActivity"
         const val GENERAL_PREFERENCES = 0
         const val ACCOUNT_PREFERENCES = 1
         const val NOTIFICATION_PREFERENCES = 2

app/src/main/java/com/keylesspalace/tusky/components/preference/PreferencesFragment.kt

@@ -29,6 +29,7 @@ import com.keylesspalace.tusky.settings.listPreference
 import com.keylesspalace.tusky.settings.makePreferenceScreen
 import com.keylesspalace.tusky.settings.preference
 import com.keylesspalace.tusky.settings.preferenceCategory
+import com.keylesspalace.tusky.settings.sliderPreference
 import com.keylesspalace.tusky.settings.switchPreference
 import com.keylesspalace.tusky.util.LocaleManager
 import com.keylesspalace.tusky.util.deserialize
@@ -99,6 +100,19 @@ class PreferencesFragment : PreferenceFragmentCompat(), Injectable {
                     preferenceDataStore = localeManager
                 }
 
+                sliderPreference {
+                    key = PrefKeys.UI_TEXT_SCALE_RATIO
+                    setDefaultValue(100F)
+                    valueTo = 150F
+                    valueFrom = 50F
+                    stepSize = 5F
+                    setTitle(R.string.pref_ui_text_size)
+                    format = "%.0f%%"
+                    decrementIcon = makeIcon(GoogleMaterial.Icon.gmd_zoom_out)
+                    incrementIcon = makeIcon(GoogleMaterial.Icon.gmd_zoom_in)
+                    icon = makeIcon(GoogleMaterial.Icon.gmd_format_size)
+                }
+
                 listPreference {
                     setDefaultValue("medium")
                     setEntries(R.array.post_text_size_names)

app/src/main/java/com/keylesspalace/tusky/settings/SettingsConstants.kt

@@ -101,4 +101,7 @@ object PrefKeys {
 
     const val TAB_FILTER_HOME_REPLIES = "tabFilterHomeReplies_v2" // This was changed once to reset an unintentionally set default.
     const val TAB_FILTER_HOME_BOOSTS = "tabFilterHomeBoosts"
+
+    /** UI text scaling factor, stored as float, 100 = 100% = no scaling */
+    const val UI_TEXT_SCALE_RATIO = "uiTextScaleRatio"
 }

app/src/main/java/com/keylesspalace/tusky/settings/SettingsDSL.kt

@@ -14,6 +14,7 @@ import androidx.preference.PreferenceCategory
 import androidx.preference.PreferenceFragmentCompat
 import androidx.preference.PreferenceScreen
 import androidx.preference.SwitchPreference
+import com.keylesspalace.tusky.view.SliderPreference
 import de.c1710.filemojicompat_ui.views.picker.preference.EmojiPickerPreference
 
 class PreferenceParent(
@@ -43,6 +44,15 @@ inline fun <A> PreferenceParent.emojiPreference(activity: A, builder: EmojiPicke
     return pref
 }
 
+inline fun PreferenceParent.sliderPreference(
+    builder: SliderPreference.() -> Unit
+): SliderPreference {
+    val pref = SliderPreference(context)
+    builder(pref)
+    addPref(pref)
+    return pref
+}
+
 inline fun PreferenceParent.switchPreference(
     builder: SwitchPreference.() -> Unit
 ): SwitchPreference {

app/src/main/java/com/keylesspalace/tusky/view/SliderPreference.kt

@@ -0,0 +1,185 @@
+package com.keylesspalace.tusky.view
+
+import android.content.Context
+import android.content.res.TypedArray
+import android.graphics.drawable.Drawable
+import android.util.AttributeSet
+import android.view.View.VISIBLE
+import androidx.appcompat.content.res.AppCompatResources
+import androidx.preference.Preference
+import androidx.preference.PreferenceViewHolder
+import com.google.android.material.slider.LabelFormatter.LABEL_GONE
+import com.google.android.material.slider.Slider
+import com.keylesspalace.tusky.R
+import com.keylesspalace.tusky.databinding.PrefSliderBinding
+import java.lang.Float.max
+import java.lang.Float.min
+
+/**
+ * Slider preference
+ *
+ * Similar to [androidx.preference.SeekBarPreference], but better because:
+ *
+ * - Uses a [Slider] instead of a [android.widget.SeekBar]. Slider supports float values, and step sizes
+ *   other than 1.
+ * - Displays the currently selected value in the Preference's summary, for consistency
+ *   with platform norms.
+ * - Icon buttons can be displayed at the start/end of the slider. Pressing them will
+ *   increment/decrement the slider by `stepSize`.
+ * - User can supply a custom formatter to format the summary value
+ */
+class SliderPreference @JvmOverloads constructor(
+    context: Context,
+    attrs: AttributeSet? = null,
+    defStyleAttr: Int = androidx.preference.R.attr.preferenceStyle,
+    defStyleRes: Int = 0
+) : Preference(context, attrs, defStyleAttr, defStyleRes),
+    Slider.OnChangeListener,
+    Slider.OnSliderTouchListener {
+
+    /** Backing property for `value` */
+    private var _value = 0F
+
+    /**
+     * @see Slider.getValue
+     * @see Slider.setValue
+     */
+    var value: Float = defaultValue
+        get() = _value
+        set(v) {
+            val clamped = max(max(v, valueFrom), min(v, valueTo))
+            if (clamped == field) return
+            _value = clamped
+            persistFloat(v)
+            notifyChanged()
+        }
+
+    /** @see Slider.setValueFrom */
+    var valueFrom: Float
+
+    /** @see Slider.setValueTo */
+    var valueTo: Float
+
+    /** @see Slider.setStepSize */
+    var stepSize: Float
+
+    /**
+     * Format string to be applied to values before setting the summary. For more control set
+     * [SliderPreference.formatter]
+     */
+    var format: String = defaultFormat
+
+    /**
+     * Function that will be used to format the summary. The default formatter formats using the
+     * value of the [SliderPreference.format] property.
+     */
+    var formatter: (Float) -> String = { format.format(it) }
+
+    /**
+     * Optional icon to show in a button at the start of the slide. If non-null the button is
+     * shown. Clicking the button decrements the value by one step.
+     */
+    var decrementIcon: Drawable? = null
+
+    /**
+     * Optional icon to show in a button at the end of the slider. If non-null the button is
+     * shown. Clicking the button increments the value by one step.
+     */
+    var incrementIcon: Drawable? = null
+
+    /** View binding */
+    private lateinit var binding: PrefSliderBinding
+
+    init {
+        // Using `widgetLayoutResource` here would be incorrect, as that tries to put the entire
+        // preference layout to the right of the title and summary.
+        layoutResource = R.layout.pref_slider
+
+        val a = context.obtainStyledAttributes(attrs, R.styleable.SliderPreference, defStyleAttr, defStyleRes)
+
+        value = a.getFloat(R.styleable.SliderPreference_android_value, defaultValue)
+        valueFrom = a.getFloat(R.styleable.SliderPreference_android_valueFrom, defaultValueFrom)
+        valueTo = a.getFloat(R.styleable.SliderPreference_android_valueTo, defaultValueTo)
+        stepSize = a.getFloat(R.styleable.SliderPreference_android_stepSize, defaultStepSize)
+        format = a.getString(R.styleable.SliderPreference_format) ?: defaultFormat
+
+        val decrementIconResource = a.getResourceId(R.styleable.SliderPreference_iconStart, -1)
+        if (decrementIconResource != -1) {
+            decrementIcon = AppCompatResources.getDrawable(context, decrementIconResource)
+        }
+
+        val incrementIconResource = a.getResourceId(R.styleable.SliderPreference_iconEnd, -1)
+        if (incrementIconResource != -1) {
+            incrementIcon = AppCompatResources.getDrawable(context, incrementIconResource)
+        }
+
+        a.recycle()
+    }
+
+    override fun onGetDefaultValue(a: TypedArray, i: Int): Any {
+        return a.getFloat(i, defaultValue)
+    }
+
+    override fun onSetInitialValue(defaultValue: Any?) {
+        value = getPersistedFloat((defaultValue ?: Companion.defaultValue) as Float)
+    }
+
+    override fun onBindViewHolder(holder: PreferenceViewHolder) {
+        super.onBindViewHolder(holder)
+        binding = PrefSliderBinding.bind(holder.itemView)
+
+        binding.root.isClickable = false
+
+        binding.slider.addOnChangeListener(this)
+        binding.slider.addOnSliderTouchListener(this)
+        binding.slider.value = value // sliderValue
+        binding.slider.valueTo = valueTo
+        binding.slider.valueFrom = valueFrom
+        binding.slider.stepSize = stepSize
+
+        // Disable the label, the value is shown in the preference summary
+        binding.slider.labelBehavior = LABEL_GONE
+        binding.slider.isEnabled = isEnabled
+
+        binding.summary.visibility = VISIBLE
+        binding.summary.text = formatter(value)
+
+        decrementIcon?.let { icon ->
+            binding.decrement.icon = icon
+            binding.decrement.visibility = VISIBLE
+            binding.decrement.setOnClickListener {
+                value -= stepSize
+            }
+        }
+
+        incrementIcon?.let { icon ->
+            binding.increment.icon = icon
+            binding.increment.visibility = VISIBLE
+            binding.increment.setOnClickListener {
+                value += stepSize
+            }
+        }
+    }
+
+    override fun onValueChange(slider: Slider, value: Float, fromUser: Boolean) {
+        if (!fromUser) return
+        binding.summary.text = formatter(value)
+    }
+
+    override fun onStartTrackingTouch(slider: Slider) {
+        // Deliberately empty
+    }
+
+    override fun onStopTrackingTouch(slider: Slider) {
+        value = slider.value
+    }
+
+    companion object {
+        private const val TAG = "SliderPreference"
+        private const val defaultValueFrom = 0F
+        private const val defaultValueTo = 1F
+        private const val defaultValue = 0.5F
+        private const val defaultStepSize = 0.1F
+        private const val defaultFormat = "%3.1f"
+    }
+}

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

@@ -0,0 +1,124 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2018 The Android Open Source Project
+  ~
+  ~ 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.
+  -->
+
+<!-- Layout used by SeekBarPreference for the seekbar widget style. Minimally adapted for use
+     with Slider instead of SeekBar. -->
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:minHeight="?android:attr/listPreferredItemHeightSmall"
+    android:gravity="center_vertical"
+    android:paddingStart="?android:attr/listPreferredItemPaddingStart"
+    android:paddingEnd="?android:attr/listPreferredItemPaddingEnd"
+    android:clipChildren="false"
+    android:clipToPadding="false"
+    android:baselineAligned="false">
+
+    <include layout="@layout/image_frame"/>
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="vertical"
+        android:layout_marginTop="8dp"
+        android:layout_marginBottom="8dp"
+        android:clipChildren="false"
+        android:clipToPadding="false">
+
+        <RelativeLayout
+            android:layout_width="wrap_content"
+            android:layout_height="0dp"
+            android:layout_weight="1">
+
+            <TextView
+                android:id="@android:id/title"
+                android:labelFor="@id/slider"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:singleLine="true"
+                android:textAppearance="?android:attr/textAppearanceListItem"
+                android:ellipsize="marquee"
+                tools:ignore="LabelFor,SelectableText" />
+
+            <TextView
+                android:id="@android:id/summary"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_below="@android:id/title"
+                android:layout_alignStart="@android:id/title"
+                android:layout_gravity="start"
+                android:textAlignment="viewStart"
+                android:textColor="?android:attr/textColorSecondary"
+                android:maxLines="4"
+                style="@style/PreferenceSummaryTextStyle"
+                tools:ignore="SelectableText" />
+
+        </RelativeLayout>
+
+        <!-- Using UnPressableLinearLayout as a workaround to disable the pressed state propagation
+        to the children of this container layout. Otherwise, the animated pressed state will also
+        play for the thumb in the AbsSeekBar in addition to the preference's ripple background.
+        The background of the SeekBar is also set to null to disable the ripple background -->
+        <androidx.preference.UnPressableLinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:gravity="center_vertical"
+            android:paddingLeft="0dp"
+            android:paddingStart="0dp"
+            android:paddingRight="0dp"
+            android:paddingEnd="0dp"
+            android:clipChildren="false"
+            android:clipToPadding="false">
+
+            <com.google.android.material.button.MaterialButton
+                android:id="@+id/decrement"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:visibility="gone"
+                style="@style/Widget.Material3.Button.IconButton" />
+
+            <!-- The total height of the Seekbar widget's area should be 48dp - this allows for an
+            increased touch area so you do not need to exactly tap the thumb to move it. However,
+            setting the Seekbar height directly causes the thumb and seekbar to be misaligned on
+            API 22 and 23 - so instead we just set 15dp padding above and below, to account for the
+            18dp default height of the Seekbar thumb for a total of 48dp.
+            Note: we set 0dp padding at the start and end of this seekbar to allow it to properly
+            fit into the layout, but this means that there's no leeway on either side for touch
+            input - this might be something we should reconsider down the line. -->
+            <com.google.android.material.slider.Slider
+                android:id="@+id/slider"
+                android:layout_width="0dp"
+                android:layout_weight="1"
+                android:layout_height="wrap_content"
+                android:paddingLeft="@dimen/preference_seekbar_padding_horizontal"
+                android:paddingStart="@dimen/preference_seekbar_padding_horizontal"
+                android:paddingRight="@dimen/preference_seekbar_padding_horizontal"
+                android:paddingEnd="@dimen/preference_seekbar_padding_horizontal"
+                android:paddingTop="@dimen/preference_seekbar_padding_vertical"
+                android:paddingBottom="@dimen/preference_seekbar_padding_vertical"
+                android:background="@null"/>
+
+            <com.google.android.material.button.MaterialButton
+                android:id="@+id/increment"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:visibility="gone"
+                style="@style/Widget.Material3.Button.IconButton" />
+        </androidx.preference.UnPressableLinearLayout>
+    </LinearLayout>
+</LinearLayout>

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

@@ -22,6 +22,16 @@
         <attr name="proportionalTrending" format="boolean" />
     </declare-styleable>
 
+    <declare-styleable name="SliderPreference">
+        <attr name="android:value" format="string|reference" />
+        <attr name="android:valueFrom" format="string|reference" />
+        <attr name="android:valueTo" format="string|reference" />
+        <attr name="android:stepSize" format="string|reference" />
+        <attr name="format" format="string|reference" />
+        <attr name="iconStart" format="reference" />
+        <attr name="iconEnd" format="reference" />
+    </declare-styleable>
+
     <!--Themed Attributes-->
     <attr name="colorBackgroundAccent" format="reference|color" />
     <attr name="colorBackgroundHighlight" format="reference|color" />

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

@@ -338,6 +338,7 @@
     <string name="post_privacy_unlisted">Unlisted</string>
     <string name="post_privacy_followers_only">Followers-only</string>
 
+    <string name="pref_ui_text_size">UI text size</string>
     <string name="pref_post_text_size">Post text size</string>
 
     <string name="post_text_size_smallest">Smallest</string>