Allow specifying multiple fonts or font families for local font rendering

[1ec5]

Removed MGLIdeographicFontFamilyName validation from MGLRendererConfiguration, since mbgl::LocalGlyphRasterizer performs more robust validation. Removed C++ from MGLRendererConfiguration interface, implementation, and tests and simplified the logic.

Pass all the specified font and font family names into mbgl so that mbgl::LocalGlyphRasterizer can form a full font cascade list.

• Plumb through font name list
• Clean up MGLRendererConfiguration
• Remove font family validation from MGLRendererConfiguration
• Clean up MGLIdeographicFontFamilyName documentation
• Plumb through an array of strings instead of a line-delimited string
• Update submodule

Fixes #105. Depends on #280, mapbox/mapbox-gl-native#16253, and mapbox/mapbox-gl-native#16428.

/cc @mapbox/maps-ios

[1ec5]

#105 (comment) has some screenshots of boldfaced CJK.

To demonstrate per-character font substitution, I made the following modifications to specify a font cascade list and override road labels:

diff --git a/platform/macos/app/Info.plist b/platform/macos/app/Info.plist
index 21b86bfc7..6b85554dc 100644
--- a/platform/macos/app/Info.plist
+++ b/platform/macos/app/Info.plist
@@ -54,5 +54,11 @@
        <string>NSApplication</string>
        <key>NSSupportsAutomaticGraphicsSwitching</key>
        <true/>
+       <key>MGLIdeographicFontFamilyName</key>
+       <array>
+               <string>HAN NOM A</string>
+               <string>Noto Sans CJK JP Black</string>
+               <string>Hiragino Sans W5</string>
+       </array>
 </dict>
 </plist>
diff --git a/platform/macos/app/MapDocument.m b/platform/macos/app/MapDocument.m
index 1ab8b690b..859b53aa0 100644
--- a/platform/macos/app/MapDocument.m
+++ b/platform/macos/app/MapDocument.m
@@ -496,6 +496,8 @@ NSArray<id <MGLAnnotation>> *MBXFlattenedShapes(NSArray<id <MGLAnnotation>> *sha
 
 - (void)updateLabels {
     [self.mapView.style localizeLabelsIntoLocale:_isLocalizingLabels ? nil : [NSLocale localeWithLocaleIdentifier:@"mul"]];
+    MGLSymbolStyleLayer *roadLayer = (MGLSymbolStyleLayer *)[self.mapView.style layerWithIdentifier:@"road-label"];
+    roadLayer.text = [NSExpression expressionForConstantValue:@"日本語 ㋿元年 浮亭鿍"];
 }
 
 - (void)applyPendingState {

All roads are labeled with the nonsensical string “日本語 ㋿元年 浮亭鿍”. The font families were chosen to require font substitution: HAN NOM A predates Unicode 8.0 and thus lacks both ㋿ (Reiwa era) and 鿍 (hill), while Noto Sans CJK JP predates Unicode 11.0 and thus lacks 鿍. The font faces were chosen to differ in weights, to highlight the substitution: HAN NOM A is the faintest character, while Hiragino Sans W5 is medium and Noto Sans CJK JP Black is extra bold.

In the absence of mapbox/mapbox-gl-js#9362, I cheated a bit by enabling local font rendering for the Enclosed CJK Letters and Months block that contains ㋿.

diff --git a/src/mbgl/util/i18n.cpp b/src/mbgl/util/i18n.cpp
index 885c8ec3d..c8fd08c5a 100644
--- a/src/mbgl/util/i18n.cpp
+++ b/src/mbgl/util/i18n.cpp
@@ -418,7 +418,8 @@ bool allowsIdeographicBreaking(char16_t chr) {
 bool allowsFixedWidthGlyphGeneration(char16_t chr) {
     // Mirrors conservative set of characters used in glyph_manager.js/_tinySDF
     return isInCJKUnifiedIdeographs(chr) || isInHangulSyllables(chr)
-        || isInKatakana(chr) || isInHiragana(chr);
+        || isInKatakana(chr) || isInHiragana(chr)
+        || isInEnclosedCJKLettersandMonths(chr);
 }
 
 bool allowsVerticalWritingMode(const std::u16string& string) {

[julianrex]

Looks good - thank you!

[1ec5]

I’ve added a snapshot test of local glyph rasterization, since mbgl’s UnitTestApp has proven so difficult to test on a device: mapbox/mapbox-gl-native#16259 (comment).