ReactFontManager.java

/**
 * Copyright (c) 2015-present, Facebook, Inc. All rights reserved.
 * <p/>
 * This source code is licensed under the BSD-style license found in the LICENSE file in the root
 * directory of this source tree. An additional grant of patent rights can be found in the PATENTS
 * file in the same directory.
 */

package com.facebook.react.views.text;

import javax.annotation.Nullable;

import java.util.HashMap;
import java.util.Map;

import android.content.res.AssetManager;
import android.graphics.Typeface;
import android.util.SparseArray;

/**
 * Class responsible to load and cache Typeface objects. It will first try to load typefaces inside
 * the assets/fonts folder and if it doesn't find the right Typeface in that folder will fall back
 * on the best matching system Typeface The supported custom fonts extensions are .ttf and .otf. For
 * each font family the bold, italic and bold_italic variants are supported. Given a "family" font
 * family the files in the assets/fonts folder need to be family.ttf(.otf) family_bold.ttf(.otf)
 * family_italic.ttf(.otf) and family_bold_italic.ttf(.otf)
 */
public class ReactFontManager {

  private static final String[] EXTENSIONS = {
      "",
      "_bold",
      "_italic",
      "_bold_italic"};
  private static final String[] FILE_EXTENSIONS = {".ttf", ".otf"};
  private static final String FONTS_ASSET_PATH = "fonts/";

  private static ReactFontManager sReactFontManagerInstance;

  private Map<String, FontFamily> mFontCache;

  private ReactFontManager() {
    mFontCache = new HashMap<>();
  }

  public static ReactFontManager getInstance() {
    if (sReactFontManagerInstance == null) {
      sReactFontManagerInstance = new ReactFontManager();
    }
    return sReactFontManagerInstance;
  }

  public
  @Nullable Typeface getTypeface(
      String fontFamilyName,
      int style,
      AssetManager assetManager) {
    FontFamily fontFamily = mFontCache.get(fontFamilyName);
    if (fontFamily == null) {
      fontFamily = new FontFamily();
      mFontCache.put(fontFamilyName, fontFamily);
    }

    Typeface typeface = fontFamily.getTypeface(style);
    if (typeface == null) {
      typeface = createTypeface(fontFamilyName, style, assetManager);
      if (typeface != null) {
        fontFamily.setTypeface(style, typeface);
      }
    }

    return typeface;
  }

  /**
   * Add additional font family, or replace the exist one in the font memory cache.
   * @param style
   * @see {@link Typeface#DEFAULT}
   * @see {@link Typeface#BOLD}
   * @see {@link Typeface#ITALIC}
   * @see {@link Typeface#BOLD_ITALIC}
   */
  public void setTypeface(String fontFamilyName, int style, Typeface typeface) {
    if (typeface != null) {
      FontFamily fontFamily = mFontCache.get(fontFamilyName);
      if (fontFamily == null) {
        fontFamily = new FontFamily();
        mFontCache.put(fontFamilyName, fontFamily);
      }
      fontFamily.setTypeface(style, typeface);
    }
  }

  private static
  @Nullable Typeface createTypeface(
      String fontFamilyName,
      int style,
      AssetManager assetManager) {
    String extension = EXTENSIONS[style];
    for (String fileExtension : FILE_EXTENSIONS) {
      String fileName = new StringBuilder()
          .append(FONTS_ASSET_PATH)
          .append(fontFamilyName)
          .append(extension)
          .append(fileExtension)
          .toString();
      try {
        return Typeface.createFromAsset(assetManager, fileName);
      } catch (RuntimeException e) {
        // unfortunately Typeface.createFromAsset throws an exception instead of returning null
        // if the typeface doesn't exist
      }
    }

    return Typeface.create(fontFamilyName, style);
  }

  private static class FontFamily {

    private SparseArray<Typeface> mTypefaceSparseArray;

    private FontFamily() {
      mTypefaceSparseArray = new SparseArray<>(4);
    }

    public Typeface getTypeface(int style) {
      return mTypefaceSparseArray.get(style);
    }

    public void setTypeface(int style, Typeface typeface) {
      mTypefaceSparseArray.put(style, typeface);
    }

  }
}