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/* -*- Mode: Java; c-basic-offset: 4; tab-width: 4; indent-tabs-mode: nil; -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
package org.mozilla.geckoview;
import android.annotation.SuppressLint;
import android.content.ContentResolver;
import android.content.Context;
import android.database.ContentObserver;
import android.net.Uri;
import android.provider.Settings;
import android.util.Log;
import androidx.annotation.UiThread;
import org.mozilla.gecko.util.ThreadUtils;
/**
* A class that automatically adjusts font size settings for web content in Gecko in accordance with
* the device's OS font scale setting.
*
* @see android.provider.Settings.System#FONT_SCALE
*/
/* package */ final class GeckoFontScaleListener extends ContentObserver {
private static final String LOGTAG = "GeckoFontScaleListener";
private static final float DEFAULT_FONT_SCALE = 1.0f;
// We're referencing the *application* context, so this is in fact okay.
@SuppressLint("StaticFieldLeak")
private static final GeckoFontScaleListener sInstance = new GeckoFontScaleListener();
private Context mApplicationContext;
private GeckoRuntimeSettings mSettings;
private boolean mAttached;
private boolean mEnabled;
private boolean mRunning;
private float mPrevGeckoFontScale;
public static GeckoFontScaleListener getInstance() {
return sInstance;
}
private GeckoFontScaleListener() {
// Ensure the ContentObserver callback runs on the UI thread.
super(ThreadUtils.getUiHandler());
}
/**
* Prepare the GeckoFontScaleListener for usage. If it has been previously enabled, it will now
* start actively working.
*/
public void attachToContext(final Context context, final GeckoRuntimeSettings settings) {
ThreadUtils.assertOnUiThread();
if (mAttached) {
Log.w(LOGTAG, "Already attached!");
return;
}
mAttached = true;
mSettings = settings;
mApplicationContext = context.getApplicationContext();
onEnabledChange();
}
/**
* Detaches the context and also stops the GeckoFontScaleListener if it was previously enabled.
* This will also restore the previously used font size settings.
*/
public void detachFromContext() {
ThreadUtils.assertOnUiThread();
if (!mAttached) {
Log.w(LOGTAG, "Already detached!");
return;
}
stop();
mApplicationContext = null;
mSettings = null;
mAttached = false;
}
/**
* Controls whether the GeckoFontScaleListener should automatically adjust font sizes for web
* content in Gecko. When disabling, this will restore the previously used font size settings.
*
* <p>This method can be called at any time, but the GeckoFontScaleListener won't start actively
* adjusting font sizes until it has been attached to a context.
*
* @param enabled True if automatic font size setting should be enabled.
*/
public void setEnabled(final boolean enabled) {
ThreadUtils.assertOnUiThread();
mEnabled = enabled;
onEnabledChange();
}
/**
* Get whether the GeckoFontScaleListener is currently enabled.
*
* @return True if the GeckoFontScaleListener is currently enabled.
*/
public boolean getEnabled() {
return mEnabled;
}
private void onEnabledChange() {
if (!mAttached) {
return;
}
if (mEnabled) {
start();
} else {
stop();
}
}
private void start() {
if (mRunning) {
return;
}
mPrevGeckoFontScale = mSettings.getFontSizeFactor();
final ContentResolver contentResolver = mApplicationContext.getContentResolver();
final Uri fontSizeSetting = Settings.System.getUriFor(Settings.System.FONT_SCALE);
contentResolver.registerContentObserver(fontSizeSetting, false, this);
onSystemFontScaleChange(contentResolver, false);
mRunning = true;
}
private void stop() {
if (!mRunning) {
return;
}
final ContentResolver contentResolver = mApplicationContext.getContentResolver();
contentResolver.unregisterContentObserver(this);
onSystemFontScaleChange(contentResolver, /*stopping*/ true);
mRunning = false;
}
private void onSystemFontScaleChange(
final ContentResolver contentResolver, final boolean stopping) {
float fontScale;
if (!stopping) { // Either we were enabled, or else the system font scale changed.
fontScale =
Settings.System.getFloat(contentResolver, Settings.System.FONT_SCALE, DEFAULT_FONT_SCALE);
if (fontScale < 0) {
fontScale = DEFAULT_FONT_SCALE;
}
} else { // We were turned off.
fontScale = mPrevGeckoFontScale;
}
mSettings.setFontSizeFactorInternal(fontScale);
}
@UiThread // See constructor.
@Override
public void onChange(final boolean selfChange) {
onSystemFontScaleChange(mApplicationContext.getContentResolver(), false);
}
}