// Copyright 2015 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.content.browser.accessibility.captioning;
import android.graphics.Color;
import android.graphics.Typeface;
import android.view.accessibility.CaptioningManager.CaptionStyle;
import androidx.annotation.VisibleForTesting;
import org.chromium.content.browser.accessibility.captioning.SystemCaptioningBridge.SystemCaptioningBridgeListener;
import java.lang.ref.WeakReference;
import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.util.HashSet;
import java.util.Locale;
/**
* API level agnostic delegate for getting updates about caption styles.
*
* This class is based on CaptioningManager.CaptioningChangeListener except it uses internal
* classes instead of the API level dependent versions. Here is the documentation for that class:
*
* @link https://developer.android.com/reference/android/view/accessibility/CaptioningManager.CaptioningChangeListener.html
*/
public class CaptioningChangeDelegate {
private static final String FONT_STYLE_ITALIC = "italic";
@VisibleForTesting public static final String DEFAULT_CAPTIONING_PREF_VALUE = "";
private boolean mTextTracksEnabled;
private String mTextTrackBackgroundColor;
private String mTextTrackFontFamily;
private String mTextTrackFontStyle;
private String mTextTrackFontVariant;
private String mTextTrackTextColor;
private String mTextTrackTextShadow;
private String mTextTrackTextSize;
// Using weak references to avoid preventing listeners from getting GC'ed.
private final HashSet<WeakReference<SystemCaptioningBridgeListener>> mListeners =
new HashSet<>();
/**
* @see android.view.accessibility.CaptioningManager.CaptioningChangeListener#onEnabledChanged
*/
public void onEnabledChanged(boolean enabled) {
mTextTracksEnabled = enabled;
notifySettingsChanged();
}
/**
* @see android.view.accessibility.CaptioningManager.CaptioningChangeListener#onFontScaleChanged
*/
public void onFontScaleChanged(float fontScale) {
mTextTrackTextSize = androidFontScaleToPercentage(fontScale);
notifySettingsChanged();
}
/**
* @see android.view.accessibility.CaptioningManager.CaptioningChangeListener#onLocaleChanged
*/
public void onLocaleChanged(Locale locale) {}
/**
* @see android.view.accessibility.CaptioningManager.CaptioningChangeListener#onUserStyleChanged
*/
public void onUserStyleChanged(CaptioningStyle userStyle) {
mTextTrackTextColor = androidColorToCssColor(userStyle.getForegroundColor());
mTextTrackBackgroundColor = androidColorToCssColor(userStyle.getBackgroundColor());
mTextTrackTextShadow =
getShadowFromColorAndSystemEdge(
androidColorToCssColor(userStyle.getEdgeColor()), userStyle.getEdgeType());
final Typeface typeFace = userStyle.getTypeface();
mTextTrackFontFamily = getFontFromSystemFont(typeFace);
if (typeFace != null && typeFace.isItalic()) {
mTextTrackFontStyle = FONT_STYLE_ITALIC;
} else {
mTextTrackFontStyle = DEFAULT_CAPTIONING_PREF_VALUE;
}
mTextTrackFontVariant = DEFAULT_CAPTIONING_PREF_VALUE;
notifySettingsChanged();
}
/** Construct a new CaptioningChangeDelegate object. */
public CaptioningChangeDelegate() {}
/**
* Get the formatted Text Shadow CSS property from the edge and color attribute.
*
* @return the CSS-friendly String representation of the
* edge attribute.
*/
public static String getShadowFromColorAndSystemEdge(String color, Integer type) {
String edgeShadow = "";
if (type != null) {
switch (type) {
case CaptionStyle.EDGE_TYPE_OUTLINE:
edgeShadow =
"%2$s %2$s 0 %1$s, -%2$s -%2$s 0 %1$s, %2$s -%2$s 0 %1$s, -%2$s %2$s 0"
+ " %1$s";
break;
case CaptionStyle.EDGE_TYPE_DROP_SHADOW:
edgeShadow = "%1$s %2$s %2$s 0.1em";
break;
case CaptionStyle.EDGE_TYPE_RAISED:
edgeShadow = "-%2$s -%2$s 0 %1$s";
break;
case CaptionStyle.EDGE_TYPE_DEPRESSED:
edgeShadow = "%2$s %2$s 0 %1$s";
break;
default:
// CaptionStyle.EDGE_TYPE_NONE
// CaptionStyle.EDGE_TYPE_UNSPECIFIED
break;
}
}
String edgeColor = color;
if (edgeColor == null || edgeColor.isEmpty()) edgeColor = "silver";
return String.format(edgeShadow, edgeColor, "0.05em");
}
/**
* Create a font family name based on provided Typeface.
*
* @param typeFace a Typeface object.
* @return a string representation of the font family name.
*/
public static String getFontFromSystemFont(Typeface typeFace) {
if (typeFace == null) return "";
// The list of fonts are obtained from apps/Settings/res/values/arrays.xml
// in Android settings app.
String fonts[] = { // Fonts in Lollipop and above
"", "sans-serif", "sans-serif-condensed", "sans-serif-monospace", "serif",
"serif-monospace", "casual", "cursive", "sans-serif-smallcaps", "monospace"
};
for (String font : fonts) {
if (Typeface.create(font, typeFace.getStyle()).equals(typeFace)) return font;
}
// This includes Typeface.DEFAULT_BOLD since font-weight
// is not yet supported as a WebKit setting for a VTTCue.
return "";
}
/**
* Convert an Integer color to a "rgba" CSS style string
*
* @param color The Integer color to convert
* @return a "rgba" CSS style string
*/
public static String androidColorToCssColor(Integer color) {
if (color == null) {
return DEFAULT_CAPTIONING_PREF_VALUE;
}
// CSS uses values between 0 and 1 for the alpha level
final String alpha =
new DecimalFormat("#.##", new DecimalFormatSymbols(Locale.US))
.format(Color.alpha(color) / 255.0);
// Return a CSS string in the form rgba(r,g,b,a)
return String.format(
"rgba(%s, %s, %s, %s)",
Color.red(color), Color.green(color), Color.blue(color), alpha);
}
/**
* Convert a font scale to a percentage String
*
* @param fontScale the font scale value to convert
* @return a percentage value as a String (eg 50%)
*/
public static String androidFontScaleToPercentage(float fontScale) {
return new DecimalFormat("#%", new DecimalFormatSymbols(Locale.US)).format(fontScale);
}
private void notifySettingsChanged() {
for (WeakReference<SystemCaptioningBridgeListener> weakRef : mListeners) {
SystemCaptioningBridgeListener listener = weakRef.get();
if (listener != null) {
notifyListener(listener);
}
}
}
/**
* Notify a listener about the current text track settings.
*
* @param listener the listener to notify.
*/
public void notifyListener(SystemCaptioningBridgeListener listener) {
if (mTextTracksEnabled) {
final TextTrackSettings settings =
new TextTrackSettings(
mTextTracksEnabled,
mTextTrackBackgroundColor,
mTextTrackFontFamily,
mTextTrackFontStyle,
mTextTrackFontVariant,
mTextTrackTextColor,
mTextTrackTextShadow,
mTextTrackTextSize);
listener.onSystemCaptioningChanged(settings);
} else {
listener.onSystemCaptioningChanged(new TextTrackSettings());
}
}
/**
* Add a listener for changes with the system CaptioningManager.
*
* @param listener The SystemCaptioningBridgeListener object to add.
*/
public void addListener(SystemCaptioningBridgeListener listener) {
mListeners.add(new WeakReference<>(listener));
}
/**
* Remove a listener from system CaptionManager.
*
* @param listener The SystemCaptioningBridgeListener object to remove.
*/
public void removeListener(SystemCaptioningBridgeListener listener) {
// Use an iterator to safely remove weak references to listeners.
mListeners.removeIf(
weakRef -> {
SystemCaptioningBridgeListener target = weakRef.get();
return target == null || target == listener;
});
}
/**
* Return whether there are listeners associated with this class.
*
* @return true if there are at least one listener, or false otherwise.
*/
public boolean hasActiveListener() {
return !mListeners.isEmpty();
}
}
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