Upstream accessibility font size preferences.

chrome/android/java/src/org/chromium/chrome/browser/accessibility/FontSizePrefs.java

Index: chrome/android/java/src/org/chromium/chrome/browser/accessibility/FontSizePrefs.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/accessibility/FontSizePrefs.java b/chrome/android/java/src/org/chromium/chrome/browser/accessibility/FontSizePrefs.java
new file mode 100644
index 0000000000000000000000000000000000000000..daefb8971bb7c73bbb74a698005f74338eb1e9b5
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/accessibility/FontSizePrefs.java
@@ -0,0 +1,180 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.accessibility;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.preference.PreferenceManager;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.NativeCall;
+import org.chromium.base.ThreadUtils;
+import org.chromium.chrome.browser.profiles.Profile;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Interface for Font Scale Factor, Force Enable Zoom, and User Set Force
+ * Enable Zoom preferences.
+ */
+public class FontSizePrefs {
+
+    public static final String PREF_FORCE_ENABLE_ZOOM = "force_enable_zoom";
+    public static final String PREF_TEXT_SCALE = "text_scale";
+    public static final String PREF_USER_SET_FORCE_ENABLE_ZOOM = "user_set_force_enable_zoom";
+
+    public static final float FORCE_ENABLE_ZOOM_THRESHOLD_MULTIPLIER = 1.3f;

[robliao, 2014/07/25 16:49:19]

How was this number determined? Discuss that in a comment above the value.

[sunangel, 2014/07/25 19:22:56]

Done...comment was used from old AccessibilityPreferences comment.
On 2014/07/25 16:49:19, robliao wrote:

+
+    private long mFontSizePrefsAndroidPtr;
+    private SharedPreferences mSharedPreferences;

[robliao, 2014/07/25 16:49:19]

Make the constructor initialized variables final.

[sunangel, 2014/07/25 19:22:56]

Done.

+    private Map<Observer, FontSizePrefsObserverWrapper> mObserverMap;
+    private static HashMap<Profile, FontSizePrefs> sFontSizeMap =
+            new HashMap<Profile, FontSizePrefs>();
+
+    /*
+     * Observer interface for observing changes in FontScaleFactor and ForceEnableZoom.
+     * Note that this observer does not observe changes in UserSetForceEnableZoom/=.
+     */
+    public interface Observer {
+        void onChangeFontSize(float newFontSize);
+        void onChangeForceEnableZoom(boolean enabled);
+    }
+
+    /*
+     * Wrapper for FontSizePrefsObserverAndroid.
+     */
+    public class FontSizePrefsObserverWrapper {
+        private final Observer mFontSizePrefsObserver;
+        private final long mNativeFontSizePrefsObserverWrapperPtr;
+
+        public FontSizePrefsObserverWrapper(Observer observer) {
+            mNativeFontSizePrefsObserverWrapperPtr = nativeInitObserverAndroid();
+            mFontSizePrefsObserver = observer;
+        }
+
+        public long getNativePtr() {
+            return mNativeFontSizePrefsObserverWrapperPtr;
+        }
+
+        public void destroy() {
+            nativeDestroyObserverAndroid(mNativeFontSizePrefsObserverWrapperPtr);
+        }
+
+        @CalledByNative("FontSizePrefsObserverWrapper")
+        public void onChangeFontSize(float newFontSize) {
+            mFontSizePrefsObserver.onChangeFontSize(newFontSize);
+        }
+
+        @CalledByNative("FontSizePrefsObserverWrapper")
+        public void onChangeForceEnableZoom(boolean enabled) {
+            mFontSizePrefsObserver.onChangeForceEnableZoom(enabled);
+        }
+
+        @NativeCall("FontSizePrefsObserverWrapper")
+        private native long nativeInitObserverAndroid();
+
+        @NativeCall("FontSizePrefsObserverWrapper")
+        private native void nativeDestroyObserverAndroid(long nativeFontSizePrefsObserverAndroid);
+    }
+
+    public FontSizePrefs(Profile profile, Context context) {
+        mSharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
+        mFontSizePrefsAndroidPtr = nativeInit(profile);
+        mObserverMap = new HashMap<Observer, FontSizePrefsObserverWrapper>();
+    }
+
+    public static FontSizePrefs getForProfile(Profile profile, Context context) {
+        ThreadUtils.assertOnUiThread();
+        FontSizePrefs fontSizePrefs = sFontSizeMap.get(profile);
+        if (fontSizePrefs == null) {
+            fontSizePrefs = new FontSizePrefs(profile, context);
+            sFontSizeMap.put(profile, fontSizePrefs);
+        }
+        return fontSizePrefs;
+    }
+
+    public void addObserver(Observer obs) {
+        FontSizePrefsObserverWrapper wrappedObserver = new
+                FontSizePrefsObserverWrapper(obs);
+        nativeAddObserver(mFontSizePrefsAndroidPtr, wrappedObserver.getNativePtr());
+        mObserverMap.put(obs, wrappedObserver);
+    }
+
+    public void removeObserver(Observer obs) {
+        FontSizePrefsObserverWrapper wrappedObserver = mObserverMap.remove(obs);
+        if (wrappedObserver != null) {

[robliao, 2014/07/25 16:49:19]

When are you expecting this to be null? This sounds like a good assert in
addObserver.

[sunangel, 2014/07/25 19:22:56]

If someone called for example, removeObserver(new Observer())
On 2014/07/25 16:49:19, robliao wrote:

+            nativeRemoveObserver(mFontSizePrefsAndroidPtr, wrappedObserver.getNativePtr());
+            wrappedObserver.destroy();
+        }
+    }
+
+    public boolean getPrefUserSetForceEnableZoom() {
+        return mSharedPreferences.getBoolean(PREF_USER_SET_FORCE_ENABLE_ZOOM,
+                false);
+    }
+
+    public void setFontScaleFactor(float font) {
+        float oldTextScale = getFontScaleFactor();
+        nativeSetFontScaleFactor(mFontSizePrefsAndroidPtr, font);

[robliao, 2014/07/25 16:49:19]

Consider having a corresponding java side setFontScaleFactor to improve
readability.

[sunangel, 2014/07/25 19:22:56]

Done.

+        float newTextScale = getFontScaleFactor();
+        float threshold = FORCE_ENABLE_ZOOM_THRESHOLD_MULTIPLIER;
+        if (oldTextScale < threshold
+                && newTextScale >= threshold
+                && !getForceEnableZoom()) {
+            // If the slider is moved from below the threshold to above the threshold, we check
+            // force enable zoom even if the user has previously set it.
+            setForceEnableZoom(true);
+            onUserSetForceEnableZoomChanged(false);
+       } else if (oldTextScale >= threshold
+                && newTextScale < threshold
+                && !getPrefUserSetForceEnableZoom()) {
+            // If the slider is moved from above the threshold to below it, we only
+            // uncheck force enable zoom if it was not set manually.
+          setForceEnableZoom(false);
+        }
+    }
+
+    public void onUserSetForceEnableZoomChanged(boolean enabled) {
+      SharedPreferences.Editor sharedPreferencesEditor = mSharedPreferences.edit();
+      sharedPreferencesEditor.putBoolean(PREF_USER_SET_FORCE_ENABLE_ZOOM, enabled);
+      sharedPreferencesEditor.apply();
+    }
+
+    public void onDestroy() {
+      nativeDestroy(mFontSizePrefsAndroidPtr);
+    }
+
+    public void setForceEnableZoom(boolean enabled) {
+        nativeSetForceEnableZoom(mFontSizePrefsAndroidPtr, enabled);
+    }
+
+    public float getFontScaleFactor() {
+        return nativeGetFontScaleFactor(mFontSizePrefsAndroidPtr);
+    }
+
+    public boolean getForceEnableZoom() {
+        return nativeGetForceEnableZoom(mFontSizePrefsAndroidPtr);
+    }
+
+    private native void nativeAddObserver(long nativeFontSizePrefsAndroid,
+            long nativeObserverPtr);
+
+    private native void nativeRemoveObserver(long nativeFontSizePrefsAndroid,
+            long nativeObserverPtr);
+
+    private native long nativeInit(Profile profile);
+
+    private native void nativeSetFontScaleFactor(long nativeFontSizePrefsAndroid, float font);
+
+    private native float nativeGetFontScaleFactor(long nativeFontSizePrefsAndroid);
+
+    private native boolean nativeGetForceEnableZoom(long nativeFontSizePrefsAndroid);
+
+    private native void nativeSetForceEnableZoom(long nativeFontSizePrefsAndroid, boolean enabled);
+
+    private native void nativeDestroy(long nativeFontSizePrefsAndroid);
+
+}