修改android系統默認字體大小

原文：http://blog.chinaunix.net/uid-29535415-id-4150770.html

android系統字體大小在“設置” 中“顯示”中“字體大小”設置，一共提四種等級設置：小 、普通 、 大、 超大

四種等級選擇相應配置代碼位置

packages/apps/setttings/res/values/arrays.xml

    <string-array name="entries_font_size">
            <item msgid="6490061470416867723">Small</item>
            <item msgid="3579015730662088893">Normal</item>
            <item msgid="1678068858001018666">Large</item>
            <item msgid="490158884605093126">Huge</item>
        </string-array>

        <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>

以上配置是通過如下代碼加載後供給終端用戶選擇
packages/app/settings/DisplaySettings.java

    public void readFontSizePreference(ListPreference pref) {
            try {
                mCurConfig.updateFrom(ActivityManagerNative.getDefault().getConfiguration()); 
            } catch (RemoteException e) {
                Log.w(TAG, "Unable to retrieve font size");
            }

            // mark the appropriate item in the preferences list
            int index = floatToIndex(mCurConfig.fontScale);
            pref.setValueIndex(index);

            // report the current size in the summary text
            final Resources res = getResources();
            String[] fontSizeNames = res.getStringArray(R.array.entries_font_size);
            pref.setSummary(String.format(res.getString(R.string.summary_font_size),
                    fontSizeNames[index]));
        }

在frameworks層會對系統的字體大小設置一個默認值，字體放縮比例爲1，也就是對應顯示設置中的“普通”字體

frameworks/base/core/java/android/content/res/Configuration.java

    /**
         * Set this object to the system defaults.
         */
        public void setToDefaults() {
            fontScale = 1; //此處賦值爲默認字體的放縮比例
            mcc = mnc = 0;
            locale = null;
            userSetLocale = false;
            touchscreen = TOUCHSCREEN_UNDEFINED;
            keyboard = KEYBOARD_UNDEFINED;
            keyboardHidden = KEYBOARDHIDDEN_UNDEFINED;
            hardKeyboardHidden = HARDKEYBOARDHIDDEN_UNDEFINED;
            navigation = NAVIGATION_UNDEFINED;
            navigationHidden = NAVIGATIONHIDDEN_UNDEFINED;
            orientation = ORIENTATION_UNDEFINED;
            screenLayout = SCREENLAYOUT_UNDEFINED;
            uiMode = UI_MODE_TYPE_UNDEFINED;
            screenWidthDp = compatScreenWidthDp = SCREEN_WIDTH_DP_UNDEFINED;
            screenHeightDp = compatScreenHeightDp = SCREEN_HEIGHT_DP_UNDEFINED;
            smallestScreenWidthDp = compatSmallestScreenWidthDp = SMALLEST_SCREEN_WIDTH_DP_UNDEFINED;
            densityDpi = DENSITY_DPI_UNDEFINED;
            seq = 0;
        }