// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package org.chromium.components.browser_ui.accessibility;
import android.annotation.SuppressLint;
import androidx.annotation.VisibleForTesting;
import org.jni_zero.CalledByNative;
import org.jni_zero.JNINamespace;
import org.jni_zero.NativeMethods;
import org.chromium.base.ContextUtils;
import org.chromium.base.MathUtils;
import org.chromium.base.ObserverList;
import org.chromium.base.ResettersForTesting;
import org.chromium.base.StrictModeContext;
import org.chromium.base.ThreadUtils;
import org.chromium.base.metrics.RecordHistogram;
import org.chromium.content_public.browser.BrowserContextHandle;
/**
* Singleton class for accessing these font size-related preferences:
* - User Font Scale Factor: the font scale value that the user sees and can set. This is a value
* between 50% and 200% (i.e. 0.5 and 2).
* - Font Scale Factor: the font scale factor applied to webpage text during font boosting. This
* equals the user font scale factor times the Android system font scale factor, which
* reflects the font size indicated in Android settings > Display > Font size.
* - Force Enable Zoom: whether force enable zoom is on or off
* - User Set Force Enable Zoom: whether the user has manually set the force enable zoom button
*/
@JNINamespace("browser_ui")
public class FontSizePrefs {
/**
* The font scale threshold beyond which force enable zoom is automatically turned on. It
* is chosen such that force enable zoom will be activated when the accessibility large text
* setting is on (i.e. this value should be the same as or lesser than the font size scale used
* by accessibility large text).
*/
public static final float FORCE_ENABLE_ZOOM_THRESHOLD_MULTIPLIER = 1.3f;
@VisibleForTesting
public static final String FONT_SIZE_CHANGE_HISTOGRAM =
"Accessibility.Android.UserFontSizePref.Change";
private static final String FONT_SIZE_STARTUP_HISTOGRAM =
"Accessibility.Android.UserFontSizePref.OnStartup";
private static final float EPSILON = 0.001f;
@SuppressLint("StaticFieldLeak")
private static FontSizePrefs sFontSizePrefs;
private final long mFontSizePrefsAndroidPtr;
private final ObserverList<FontSizePrefsObserver> mObserverList;
private Float mSystemFontScaleForTests;
/** Interface for observing changes in font size-related preferences. */
public interface FontSizePrefsObserver {
void onFontScaleFactorChanged(float fontScaleFactor, float userFontScaleFactor);
void onForceEnableZoomChanged(boolean enabled);
}
private FontSizePrefs(BrowserContextHandle browserContextHandle) {
mFontSizePrefsAndroidPtr =
FontSizePrefsJni.get().init(FontSizePrefs.this, browserContextHandle);
mObserverList = new ObserverList<FontSizePrefsObserver>();
}
/** Returns the singleton FontSizePrefs, constructing it if it doesn't already exist. */
public static FontSizePrefs getInstance(BrowserContextHandle browserContextHandle) {
ThreadUtils.assertOnUiThread();
if (sFontSizePrefs == null) {
sFontSizePrefs = new FontSizePrefs(browserContextHandle);
}
return sFontSizePrefs;
}
/** Destroys the instance of FontSizePrefs if there is one. */
public static void destroyInstance() {
if (sFontSizePrefs == null) {
return;
}
FontSizePrefsJni.get().destroy(sFontSizePrefs.mFontSizePrefsAndroidPtr);
sFontSizePrefs = null;
}
/** Adds an observer to listen for changes to font scale-related preferences. */
public void addObserver(FontSizePrefsObserver observer) {
mObserverList.addObserver(observer);
}
/**
* Removes an observer so it will no longer receive updates for changes to font scale-related
* preferences.
*/
public void removeObserver(FontSizePrefsObserver observer) {
mObserverList.removeObserver(observer);
}
/**
* Updates the fontScaleFactor based on the userFontScaleFactor and the system-wide font scale.
*
* This should be called during application start-up and whenever the system font size changes.
*/
public void onSystemFontScaleChanged() {
float userFontScaleFactor = getUserFontScaleFactor();
if (userFontScaleFactor != 0f) {
setFontScaleFactor(userFontScaleFactor * getSystemFontScale());
}
}
/** Sets the userFontScaleFactor. This should be a value between .5 and 2. */
public void setUserFontScaleFactor(float userFontScaleFactor) {
ContextUtils.getAppSharedPreferences()
.edit()
.putFloat(AccessibilityConstants.FONT_USER_FONT_SCALE_FACTOR, userFontScaleFactor)
.apply();
setFontScaleFactor(userFontScaleFactor * getSystemFontScale());
}
/** Returns the userFontScaleFactor. This is the value that should be displayed to the user. */
public float getUserFontScaleFactor() {
float userFontScaleFactor;
try (StrictModeContext ignored = StrictModeContext.allowDiskReads()) {
userFontScaleFactor =
ContextUtils.getAppSharedPreferences()
.getFloat(AccessibilityConstants.FONT_USER_FONT_SCALE_FACTOR, 0f);
}
if (userFontScaleFactor == 0f) {
float fontScaleFactor = getFontScaleFactor();
if (Math.abs(fontScaleFactor - 1f) <= EPSILON) {
// If the font scale factor is 1, assume that the user hasn't customized their font
// scale and/or wants the default value
userFontScaleFactor = 1f;
} else {
// Initialize userFontScaleFactor based on fontScaleFactor, since
// userFontScaleFactor was added long after fontScaleFactor.
userFontScaleFactor =
MathUtils.clamp(fontScaleFactor / getSystemFontScale(), 0.5f, 2f);
}
ContextUtils.getAppSharedPreferences()
.edit()
.putFloat(
AccessibilityConstants.FONT_USER_FONT_SCALE_FACTOR, userFontScaleFactor)
.apply();
}
return userFontScaleFactor;
}
/**
* Returns the fontScaleFactor. This is the product of the userFontScaleFactor and the system
* font scale, and is the amount by which webpage text will be scaled during font boosting.
*/
public float getFontScaleFactor() {
return FontSizePrefsJni.get()
.getFontScaleFactor(mFontSizePrefsAndroidPtr, FontSizePrefs.this);
}
/**
* Sets forceEnableZoom due to a user request (e.g. checking a checkbox). This implicitly sets
* userSetForceEnableZoom.
*/
public void setForceEnableZoomFromUser(boolean enabled) {
setForceEnableZoom(enabled, true);
}
/** Returns whether forceEnableZoom is enabled. */
public boolean getForceEnableZoom() {
return FontSizePrefsJni.get()
.getForceEnableZoom(mFontSizePrefsAndroidPtr, FontSizePrefs.this);
}
/** Record the user font setting. Intended to be logged on activity startup. */
public void recordUserFontPrefOnStartup() {
recordUserFontPrefHistogram(FONT_SIZE_STARTUP_HISTOGRAM);
}
/** Record the user font setting when the setting is changed by the user. */
public void recordUserFontPrefChange() {
recordUserFontPrefHistogram(FONT_SIZE_CHANGE_HISTOGRAM);
}
private void recordUserFontPrefHistogram(String histogramName) {
// User font size prefs range from 0.5 to 2.0 (50% to 200%) and can be updated in increments
// of 5% (see org.chromium.chrome.browser.accessibility.settings.TextScalePreference).
int sample = (int) (getUserFontScaleFactor() * 100);
assert sample >= 50 && sample <= 200 : "Unexpected font size pref";
RecordHistogram.recordSparseHistogram(histogramName, sample);
}
/** Sets a mock value for the system-wide font scale. Use only in tests. */
public void setSystemFontScaleForTest(float fontScale) {
mSystemFontScaleForTests = fontScale;
ResettersForTesting.register(() -> mSystemFontScaleForTests = null);
}
private float getSystemFontScale() {
if (mSystemFontScaleForTests != null) return mSystemFontScaleForTests;
return ContextUtils.getApplicationContext().getResources().getConfiguration().fontScale;
}
private void setForceEnableZoom(boolean enabled, boolean fromUser) {
ContextUtils.getAppSharedPreferences()
.edit()
.putBoolean(AccessibilityConstants.FONT_USER_SET_FORCE_ENABLE_ZOOM, fromUser)
.apply();
FontSizePrefsJni.get()
.setForceEnableZoom(mFontSizePrefsAndroidPtr, FontSizePrefs.this, enabled);
}
private boolean getUserSetForceEnableZoom() {
try (StrictModeContext ignored = StrictModeContext.allowDiskReads()) {
return ContextUtils.getAppSharedPreferences()
.getBoolean(AccessibilityConstants.FONT_USER_SET_FORCE_ENABLE_ZOOM, false);
}
}
private void setFontScaleFactor(float fontScaleFactor) {
float previousFontScaleFactor = getFontScaleFactor();
FontSizePrefsJni.get()
.setFontScaleFactor(mFontSizePrefsAndroidPtr, FontSizePrefs.this, fontScaleFactor);
if (previousFontScaleFactor < FORCE_ENABLE_ZOOM_THRESHOLD_MULTIPLIER
&& fontScaleFactor >= FORCE_ENABLE_ZOOM_THRESHOLD_MULTIPLIER
&& !getForceEnableZoom()) {
// If the font scale factor just crossed above the threshold, set force enable zoom even
// if the user has previously unset it.
setForceEnableZoom(true, false);
} else if (previousFontScaleFactor >= FORCE_ENABLE_ZOOM_THRESHOLD_MULTIPLIER
&& fontScaleFactor < FORCE_ENABLE_ZOOM_THRESHOLD_MULTIPLIER
&& !getUserSetForceEnableZoom()) {
// If the font scale factor just crossed below the threshold and the user didn't set
// force enable zoom manually, then unset force enable zoom.
setForceEnableZoom(false, false);
}
}
@CalledByNative
private void onFontScaleFactorChanged(float fontScaleFactor) {
float userFontScaleFactor = getUserFontScaleFactor();
for (FontSizePrefsObserver observer : mObserverList) {
observer.onFontScaleFactorChanged(fontScaleFactor, userFontScaleFactor);
}
}
@CalledByNative
private void onForceEnableZoomChanged(boolean enabled) {
for (FontSizePrefsObserver observer : mObserverList) {
observer.onForceEnableZoomChanged(enabled);
}
}
@NativeMethods
interface Natives {
long init(FontSizePrefs caller, BrowserContextHandle browserContextHandle);
void destroy(long nativeFontSizePrefsAndroid);
void setFontScaleFactor(
long nativeFontSizePrefsAndroid, FontSizePrefs caller, float fontScaleFactor);
float getFontScaleFactor(long nativeFontSizePrefsAndroid, FontSizePrefs caller);
boolean getForceEnableZoom(long nativeFontSizePrefsAndroid, FontSizePrefs caller);
void setForceEnableZoom(
long nativeFontSizePrefsAndroid, FontSizePrefs caller, boolean enabled);
}
}
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