Add fallback support to local ideograph font families

platform/android/CHANGELOG.md

@@ -4,6 +4,9 @@ Mapbox welcomes participation and contributions from everyone.  If you'd like to
 
 ## master
 
+### Features
+ - Add fallback support to local ideograph font families [#15255](https://github.com/mapbox/mapbox-gl-native/pull/15255)
+
 ### Bug fixes
 
 - Fixed an issue where it was possible to set the map’s content insets then tilt the map enough to see the horizon, causing performance issues [#15195](https://github.com/mapbox/mapbox-gl-native/pull/15195)

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/constants/MapboxConstants.java

@@ -43,6 +43,11 @@ public class MapboxConstants {
 
   public static final boolean DEFAULT_MANAGE_SKU_TOKEN = true;
 
+  /**
+   * Default value for font fallback for local ideograph fonts
+   */
+  public static final String DEFAULT_FONT = "sans-serif";
+
   /**
    * Unmeasured state
    */

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/MapboxMapOptions.java

@@ -19,6 +19,7 @@
 import com.mapbox.mapboxsdk.camera.CameraPosition;
 import com.mapbox.mapboxsdk.constants.MapboxConstants;
 import com.mapbox.mapboxsdk.utils.BitmapUtils;
+import com.mapbox.mapboxsdk.utils.FontUtils;
 
 import java.util.Arrays;
 
@@ -70,7 +71,6 @@ public class MapboxMapOptions implements Parcelable {
   private boolean prefetchesTiles = true;
   private boolean zMediaOverlay = false;
   private String localIdeographFontFamily;
-
   private String apiBaseUri;
 
   private boolean textureMode;
@@ -250,7 +250,7 @@ public static MapboxMapOptions createFromAttributes(@NonNull Context context, @N
       String localIdeographFontFamily =
         typedArray.getString(R.styleable.mapbox_MapView_mapbox_localIdeographFontFamily);
       if (localIdeographFontFamily == null) {
-        localIdeographFontFamily = "sans-serif";
+        localIdeographFontFamily = MapboxConstants.DEFAULT_FONT;
       }
       mapboxMapOptions.localIdeographFontFamily(localIdeographFontFamily);
 
@@ -637,14 +637,33 @@ public MapboxMapOptions crossSourceCollisions(boolean crossSourceCollisions) {
    * <p>
    * The font family argument is passed to {@link android.graphics.Typeface#create(String, int)}.
    * Default system fonts are defined in &#x27;/system/etc/fonts.xml&#x27;
-   * Default font for local ideograph font family is "sans-serif".
+   * Default font for local ideograph font family is {@link MapboxConstants#DEFAULT_FONT}.
    *
    * @param fontFamily font family for local ideograph generation.
    * @return This
    */
   @NonNull
   public MapboxMapOptions localIdeographFontFamily(String fontFamily) {
-    this.localIdeographFontFamily = fontFamily;
+    this.localIdeographFontFamily = FontUtils.extractValidFont(fontFamily);
+    return this;
+  }
+
+  /**
+   * Set a font family from range of font families for generating glyphs locally for ideographs in the
+   * &#x27;CJK Unified Ideographs&#x27; and &#x27;Hangul Syllables&#x27; ranges. The first matching font
+   * will be selected. If no valid font found, it defaults to {@link MapboxConstants#DEFAULT_FONT}.
+   * <p>
+   * The font families are checked against the default system fonts defined in
+   * &#x27;/system/etc/fonts.xml&#x27; Default font for local ideograph font family is
+   * {@link MapboxConstants#DEFAULT_FONT}.
+   * </p>
+   *
+   * @param fontFamilies an array of font families for local ideograph generation.
+   * @return This
+   */
+  @NonNull
+  public MapboxMapOptions localIdeographFontFamily(String... fontFamilies) {
+    this.localIdeographFontFamily = FontUtils.extractValidFont(fontFamilies);
     return this;
   }
 
@@ -942,7 +961,7 @@ public int getForegroundLoadColor() {
   /**
    * Returns the font-family for locally overriding generation of glyphs in the
    * &#x27;CJK Unified Ideographs&#x27; and &#x27;Hangul Syllables&#x27; ranges.
-   * Default font for local ideograph font family is "sans-serif".
+   * Default font for local ideograph font family is {@link MapboxConstants#DEFAULT_FONT}.
    *
    * @return Local ideograph font family name.
    */

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/snapshotter/MapSnapshotter.java

@@ -18,17 +18,20 @@
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.TextView;
+
 import com.mapbox.mapboxsdk.Mapbox;
 import com.mapbox.mapboxsdk.R;
 import com.mapbox.mapboxsdk.attribution.AttributionLayout;
 import com.mapbox.mapboxsdk.attribution.AttributionMeasure;
 import com.mapbox.mapboxsdk.attribution.AttributionParser;
 import com.mapbox.mapboxsdk.camera.CameraPosition;
+import com.mapbox.mapboxsdk.constants.MapboxConstants;
 import com.mapbox.mapboxsdk.geometry.LatLngBounds;
 import com.mapbox.mapboxsdk.log.Logger;
 import com.mapbox.mapboxsdk.maps.Style;
 import com.mapbox.mapboxsdk.maps.TelemetryDefinition;
 import com.mapbox.mapboxsdk.storage.FileSource;
+import com.mapbox.mapboxsdk.utils.FontUtils;
 import com.mapbox.mapboxsdk.utils.ThreadUtils;
 
 /**
@@ -98,7 +101,7 @@ public static class Options {
     private LatLngBounds region;
     private CameraPosition cameraPosition;
     private boolean showLogo = true;
-    private String localIdeographFontFamily = "sans-serif";
+    private String localIdeographFontFamily = MapboxConstants.DEFAULT_FONT;
     private String apiBaseUrl;
 
     /**
@@ -182,14 +185,31 @@ public Options withLogo(boolean showLogo) {
      * <p>
      * The font family argument is passed to {@link android.graphics.Typeface#create(String, int)}.
      * Default system fonts are defined in &#x27;/system/etc/fonts.xml&#x27;
-     * Default font for local ideograph font family is "sans-serif".
-     *
+     * Default font for local ideograph font family is {@link MapboxConstants#DEFAULT_FONT}.
+     * </p>
      * @param fontFamily font family for local ideograph generation.
      * @return the mutated {@link Options}
      */
     @NonNull
     public Options withLocalIdeographFontFamily(String fontFamily) {
-      this.localIdeographFontFamily = fontFamily;
+      this.localIdeographFontFamily = FontUtils.extractValidFont(fontFamily);
+      return this;
+    }
+
+    /**
+     * Set a font family from range of font families for generating glyphs locally for ideographs in the
+     * &#x27;CJK Unified Ideographs&#x27; and &#x27;Hangul Syllables&#x27; ranges.
+     * <p>
+     * The font families are checked against the default system fonts defined in
+     * &#x27;/system/etc/fonts.xml&#x27;. Default font for local ideograph font family is
+     * {@link MapboxConstants#DEFAULT_FONT}.
+     * </p>
+     * @param fontFamilies font families for local ideograph generation.
+     * @return the mutated {@link Options}
+     */
+    @NonNull
+    public Options withLocalIdeographFontFamily(String... fontFamilies) {
+      this.localIdeographFontFamily = FontUtils.extractValidFont(fontFamilies);
       return this;
     }
 
@@ -274,7 +294,7 @@ public CameraPosition getCameraPosition() {
 
     /**
      * @return the font family used for locally generating ideographs,
-     * Default font for local ideograph font family is "sans-serif".
+     * Default font for local ideograph font family is {@link MapboxConstants#DEFAULT_FONT}.
      */
     public String getLocalIdeographFontFamily() {
       return localIdeographFontFamily;

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/utils/FontUtils.java

@@ -0,0 +1,64 @@
+package com.mapbox.mapboxsdk.utils;
+
+import android.graphics.Typeface;
+
+import com.mapbox.mapboxsdk.MapStrictMode;
+import com.mapbox.mapboxsdk.log.Logger;
+
+import java.lang.reflect.Field;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+import static com.mapbox.mapboxsdk.constants.MapboxConstants.DEFAULT_FONT;
+
+/**
+ * Utility class to select a font from a range of font names based on the availability of fonts on the device.
+ */
+public class FontUtils {
+
+  private static final String TAG = "Mbgl-FontUtils";
+
+  private FontUtils() {
+    // no instance
+  }
+
+  /**
+   * Select a font from a range of font names to match the availability of fonts on the device.
+   *
+   * @param fontNames the range of font names to select from
+   * @return the selected fon
+   */
+  public static String extractValidFont(String... fontNames) {
+    if (fontNames == null) {
+      return null;
+    }
+
+    List<String> validFonts = getAvailableFonts();
+    for (String fontName : fontNames) {
+      if (validFonts.contains(fontName)) {
+        return fontName;
+      }
+    }
+
+    Logger.i(TAG, String.format(
+      "Couldn't map font family for local ideograph, using %s instead", DEFAULT_FONT)
+    );
+    return DEFAULT_FONT;
+  }
+
+  private static List<String> getAvailableFonts() {
+    List<String> fonts = new ArrayList<>();
+    try {
+      Typeface typeface = Typeface.create(Typeface.DEFAULT, Typeface.NORMAL);
+      Field f = Typeface.class.getDeclaredField("sSystemFontMap");
+      f.setAccessible(true);
+      Map<String, Typeface> fontMap = (Map<String, Typeface>) f.get(typeface);
+      fonts.addAll(fontMap.keySet());
+    } catch (Exception exception) {
+      Logger.e(TAG,"Couldn't load fonts from Typeface", exception);
+      MapStrictMode.strictModeViolation("Couldn't load fonts from Typeface", exception);
+    }
+    return fonts;
+  }
+}

platform/android/MapboxGLAndroidSDK/src/test/java/com/mapbox/mapboxsdk/maps/MapboxMapOptionsTest.java

@@ -180,7 +180,7 @@ public void testCrossSourceCollisions() {
   @Test
   public void testLocalIdeographFontFamily_enabledByDefault() {
     MapboxMapOptions options = MapboxMapOptions.createFromAttributes(RuntimeEnvironment.application, null);
-    assertEquals("sans-serif", options.getLocalIdeographFontFamily());
+    assertEquals(MapboxConstants.DEFAULT_FONT, options.getLocalIdeographFontFamily());
   }
 }
 

platform/android/MapboxGLAndroidSDKTestApp/src/androidTest/java/com/mapbox/mapboxsdk/utils/FontUtilsTest.java

@@ -0,0 +1,43 @@
+package com.mapbox.mapboxsdk.utils;
+
+import android.support.test.runner.AndroidJUnit4;
+
+import com.mapbox.mapboxsdk.constants.MapboxConstants;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+@RunWith(AndroidJUnit4.class)
+public class FontUtilsTest {
+
+  @Test
+  public void testExtractedFontShouldMatchDefault() {
+    String[] fonts = new String[] {"foo", "bar"};
+    String actual = FontUtils.extractValidFont(fonts);
+    assertEquals("Selected font should match", MapboxConstants.DEFAULT_FONT, actual);
+  }
+
+  @Test
+  public void testExtractedFontShouldMatchMonospace() {
+    String expected = "monospace";
+    String[] fonts = new String[] {"foo", expected};
+    String actual = FontUtils.extractValidFont(fonts);
+    assertEquals("Selected font should match", expected, actual);
+  }
+
+  @Test
+  public void testExtractedFontArrayShouldBeNull() {
+    String[] fonts = null;
+    String actual = FontUtils.extractValidFont(fonts);
+    assertNull(actual);
+  }
+
+  @Test
+  public void testExtractedFontShouldBeNull() {
+    String actual = FontUtils.extractValidFont(null);
+    assertNull(actual);
+  }
+}

platform/android/MapboxGLAndroidSDKTestApp/src/main/java/com/mapbox/mapboxsdk/testapp/activity/snapshot/MapSnapshotterActivity.java

@@ -7,6 +7,7 @@
 import android.widget.ImageView;
 
 import com.mapbox.mapboxsdk.camera.CameraPosition;
+import com.mapbox.mapboxsdk.constants.MapboxConstants;
 import com.mapbox.mapboxsdk.maps.Style;
 import com.mapbox.mapboxsdk.geometry.LatLng;
 import com.mapbox.mapboxsdk.geometry.LatLngBounds;
@@ -68,7 +69,7 @@ private void startSnapShot(final int row, final int column) {
 
       // Optionally the style
       .withStyle((column + row) % 2 == 0 ? Style.MAPBOX_STREETS : Style.DARK)
-      .withLocalIdeographFontFamily("sans-serif");
+      .withLocalIdeographFontFamily(MapboxConstants.DEFAULT_FONT);
 
     // Optionally the visible region
     if (row % 2 == 0) {