系统默认的字体缩放
2019-10-16 本文已影响0人
Guuuj
系统默认的字体缩放大小
// Configuration.java
public float fontScale;
public Configuration() {
setToDefaults();
}
public void setToDefaults() {
fontScale = 1; // 默认为1
...
}
系统提供字体缩放的设置项Settings.System.FONT_SCALE,可以通过修改这个设置项,使系统字体改变,默认不配置此值。
// Settings.java
public static final class System extends NameValueTable {
private static final float DEFAULT_FONT_SCALE = 1.0f;
...
public static final String FONT_SCALE = "font_scale";
}
设置应用的无障碍功能中,可以通过"放大或缩小文字"修改此设置项,并定义了一组数值,作为参考选项
<string-array name="entryvalues_font_size" translatable="false">
<item>0.85</item>
<item>1.0</item>
<item>1.15</item>
<item>1.30</item>
</string-array>
ActivityManagerService中监测这个设置项的改变,这个值的改变会更新系统配置
private final class FontScaleSettingObserver extends ContentObserver {
private final Uri mFontScaleUri = Settings.System.getUriFor(FONT_SCALE);
public FontScaleSettingObserver() {
super(mHandler);
ContentResolver resolver = mContext.getContentResolver();
resolver.registerContentObserver(mFontScaleUri, false, this, UserHandle.USER_ALL);
}
@Override
public void onChange(boolean selfChange, Uri uri, @UserIdInt int userId) {
if (mFontScaleUri.equals(uri)) {
updateFontScaleIfNeeded(userId);
}
}
}
private void updateFontScaleIfNeeded(@UserIdInt int userId) {
final float scaleFactor = Settings.System.getFloatForUser(mContext.getContentResolver(),
FONT_SCALE, 1.0f, userId);
if (mConfiguration.fontScale != scaleFactor) {
final Configuration configuration = mWindowManager.computeNewConfiguration();
configuration.fontScale = scaleFactor;
synchronized (this) {
updatePersistentConfigurationLocked(configuration, userId);
}
}
}
private void updatePersistentConfigurationLocked(Configuration values, @UserIdInt int userId) {
final long origId = Binder.clearCallingIdentity();
try {
// 更新到当前配置mConfiguration中
updateConfigurationLocked(values, null, false, true, userId, false /* deferResume */);
} finally {
Binder.restoreCallingIdentity(origId);
}
}
使用adb测试系统屏幕字体大小的变化
adb shell settings put system font_scale 1.30
adb获取font_scale的值
adb shell settings get system font_scale