Expose font index in AbstractFont

src/Magnum/Text/AbstractFont.cpp

@@ -108,7 +108,11 @@ void AbstractFont::setFileCallback(Containers::Optional<Containers::ArrayView<co
 
 void AbstractFont::doSetFileCallback(Containers::Optional<Containers::ArrayView<const char>>(*)(const std::string&, InputFileCallbackPolicy, void*), void*) {}
 
-bool AbstractFont::openData(Containers::ArrayView<const void> data, const Float size) {
+bool AbstractFont::openData(const Containers::ArrayView<const void> data, const Float size) {
+    return openData(data, size, 0);
+}
+
+bool AbstractFont::openData(Containers::ArrayView<const void> data, const Float size, const UnsignedInt fontIndex) {
     CORRADE_ASSERT(features() & FontFeature::OpenData,
         "Text::AbstractFont::openData(): feature not supported", false);
 
@@ -116,16 +120,19 @@ bool AbstractFont::openData(Containers::ArrayView<const void> data, const Float
        the check doesn't be done on the plugin side) because for some file
        formats it could be valid (MagnumFont in particular). */
     close();
+    _fontIndex = fontIndex;
     const Properties properties = doOpenData(Containers::arrayCast<const char>(data), size);
 
     /* If opening succeeded, save the returned values. If not, the values were
        set to their default values by close() already. */
     if(isOpened()) {
+        CORRADE_INTERNAL_ASSERT(!properties.fontCount || fontIndex < properties.fontCount);
         _size = properties.size;
         _ascent = properties.ascent;
         _descent = properties.descent;
         _lineHeight = properties.lineHeight;
         _glyphCount = properties.glyphCount;
+        _fontCount = properties.fontCount ? properties.fontCount : 1;
         return true;
     }
 
@@ -137,7 +144,12 @@ auto AbstractFont::doOpenData(Containers::ArrayView<const char>, Float) -> Prope
 }
 
 bool AbstractFont::openFile(const Containers::StringView filename, const Float size) {
+    return openFile(filename, size, 0);
+}
+
+bool AbstractFont::openFile(const Containers::StringView filename, const Float size, const UnsignedInt fontIndex) {
     close();
+    _fontIndex = fontIndex;
     Properties properties;
 
     /* If file loading callbacks are not set or the font implementation
@@ -174,11 +186,13 @@ bool AbstractFont::openFile(const Containers::StringView filename, const Float s
     /* If opening succeeded, save the returned values. If not, the values were
        set to their default values by close() already. */
     if(isOpened()) {
+        CORRADE_INTERNAL_ASSERT(!properties.fontCount || fontIndex < properties.fontCount);
         _size = properties.size;
         _ascent = properties.ascent;
         _descent = properties.descent;
         _lineHeight = properties.lineHeight;
         _glyphCount = properties.glyphCount;
+        _fontCount = properties.fontCount ? properties.fontCount : 1;
         return true;
     }
 
@@ -228,6 +242,13 @@ void AbstractFont::close() {
     _lineHeight = {};
     _descent = {};
     _lineHeight = {};
+    _fontIndex = {};
+    _fontCount = {};
+}
+
+UnsignedInt AbstractFont::fontCount() const {
+    CORRADE_ASSERT(isOpened(), "Text::AbstractFont::fontCount(): no font opened", {});
+    return _fontCount;
 }
 
 Float AbstractFont::size() const {

src/Magnum/Text/AbstractFont.h

@@ -400,28 +400,40 @@ class MAGNUM_TEXT_EXPORT AbstractFont: public PluginManager::AbstractPlugin {
          * @brief Open raw data
          * @param data          File data
          * @param size          Font size in points
+         * @param fontIndex     Font index to open
          *
          * Closes previous file, if it was opened, and tries to open given
-         * raw data. Available only if @ref FontFeature::OpenData is supported.
-         * On failure prints a message to @relativeref{Magnum,Error} and
-         * returns @cpp false @ce.
-         * @see @ref features(), @ref openFile()
+         * raw data. The @p fontIndex is useful for opening a particular font
+         * from a collection such as TrueType Collection (`*.ttc`) files.
+         * Available only if @ref FontFeature::OpenData is supported. On
+         * failure prints a message to @relativeref{Magnum,Error} and returns
+         * @cpp false @ce.
+         * @see @ref features(), @ref openFile(), @ref fontIndex(),
+         *      @ref fontCount()
          */
+        bool openData(Containers::ArrayView<const void> data, Float size, UnsignedInt fontIndex);
+        /** @overload */
         bool openData(Containers::ArrayView<const void> data, Float size);
 
         /**
          * @brief Open a file
          * @param filename      Font file
          * @param size          Size to open the font in, in points
+         * @param fontIndex     Font index to open
          *
          * Closes previous file, if it was opened, and tries to open given
-         * file. On failure prints a message to @relativeref{Magnum,Error} and
-         * returns @cpp false @ce. If file loading callbacks are set via
+         * file. The @p fontIndex is useful for opening a particular font from
+         * a collection such as TrueType Collection (`*.ttc`) files. On
+         * failure prints a message to @relativeref{Magnum,Error} and returns
+         * @cpp false @ce. If file loading callbacks are set via
          * @ref setFileCallback() and @ref FontFeature::OpenData is supported,
          * this function uses the callback to load the file and passes the
          * memory view to @ref openData() instead. See @ref setFileCallback()
          * for more information.
+         * @see @ref fontIndex(), @ref fontCount()
          */
+        bool openFile(Containers::StringView filename, Float size, UnsignedInt fontIndex);
+        /** @overload */
         bool openFile(Containers::StringView filename, Float size);
 
         /**
@@ -437,6 +449,28 @@ class MAGNUM_TEXT_EXPORT AbstractFont: public PluginManager::AbstractPlugin {
          */
         void close();
 
+        /**
+         * @brief Opened font index
+         * @m_since_latest
+         *
+         * Returns the font index passed to @ref openFile() or @ref openData().
+         * For files containing just one font, this value is @cpp 0 @ce.
+         * @see @ref fontCount()
+         */
+        UnsignedInt fontIndex() const { return _fontIndex; }
+
+        /**
+         * @brief Count of fonts in the opened file
+         * @m_since_latest
+         *
+         * For files containing just one font, this value is @cpp 1 @ce. For
+         * font collections such as TrueType Collection (`*.ttc`) files, this
+         * is the count of fonts in the collection. Expects that a font is
+         * opened.
+         * @see @ref fontIndex()
+         */
+        UnsignedInt fontCount() const;
+
         /**
          * @brief Font size in points
          *
@@ -655,11 +689,8 @@ class MAGNUM_TEXT_EXPORT AbstractFont: public PluginManager::AbstractPlugin {
          * Returned from @ref doOpenFile(), @ref doOpenData().
          */
         struct Properties {
-            #if defined(CORRADE_TARGET_GCC) && !defined(CORRADE_TARGET_CLANG) && __GNUC__ < 5
-            /* Otherwise GCC 4.8 loudly complains about missing initializers */
-            constexpr /*implicit*/ Properties() noexcept: size{}, ascent{}, descent{}, lineHeight{}, glyphCount{} {}
-            constexpr /*implicit*/ Properties(Float size, Float ascent, Float descent, Float lineHeight, UnsignedInt glyphCount) noexcept: size{size}, ascent{ascent}, descent{descent}, lineHeight{lineHeight}, glyphCount{glyphCount} {}
-            #endif
+            constexpr /*implicit*/ Properties() noexcept: size{}, ascent{}, descent{}, lineHeight{}, glyphCount{}, fontCount{} {}
+            constexpr /*implicit*/ Properties(Float size, Float ascent, Float descent, Float lineHeight, UnsignedInt glyphCount, UnsignedInt fontCount = 0) noexcept: size{size}, ascent{ascent}, descent{descent}, lineHeight{lineHeight}, glyphCount{glyphCount}, fontCount{fontCount} {}
 
             /**
              * Font size in points
@@ -691,6 +722,17 @@ class MAGNUM_TEXT_EXPORT AbstractFont: public PluginManager::AbstractPlugin {
              * @m_since_latest
              */
             UnsignedInt glyphCount;
+
+            /**
+             * Count of fonts in the opened file
+             *
+             * If left at @cpp 0 @ce by an implementation, the public
+             * @ref fontCount() reports @cpp 1 @ce. Implementations supporting
+             * font collections should return the real count.
+             * @see @ref fontCount()
+             * @m_since_latest
+             */
+            UnsignedInt fontCount;
         };
 
     protected:
@@ -823,7 +865,7 @@ class MAGNUM_TEXT_EXPORT AbstractFont: public PluginManager::AbstractPlugin {
         #endif
 
         Float _size{}, _ascent{}, _descent{}, _lineHeight{};
-        UnsignedInt _glyphCount{};
+        UnsignedInt _glyphCount{}, _fontIndex{}, _fontCount{};
 };
 
 #ifdef MAGNUM_BUILD_DEPRECATED
@@ -917,7 +959,7 @@ updated interface string.
 */
 /* Silly indentation to make the string appear in pluginInterface() docs */
 #define MAGNUM_TEXT_ABSTRACTFONT_PLUGIN_INTERFACE /* [interface] */ \
-"cz.mosra.magnum.Text.AbstractFont/0.3.7"
+"cz.mosra.magnum.Text.AbstractFont/0.3.8"
 /* [interface] */
 
 #ifndef DOXYGEN_GENERATING_OUTPUT

src/Magnum/Text/Test/AbstractFontTest.cpp

@@ -57,6 +57,7 @@ struct AbstractFontTest: TestSuite::Tester {
     void construct();
 
     void openData();
+    void openDataFontIndex();
     void openFileAsData();
     void openFileAsDataNotFound();
 
@@ -131,6 +132,7 @@ AbstractFontTest::AbstractFontTest() {
     addTests({&AbstractFontTest::construct,
 
               &AbstractFontTest::openData,
+              &AbstractFontTest::openDataFontIndex,
               &AbstractFontTest::openFileAsData,
               &AbstractFontTest::openFileAsDataNotFound,
 
@@ -250,6 +252,41 @@ void AbstractFontTest::openData() {
     CORRADE_COMPARE(font.descent(), 2.0f);
     CORRADE_COMPARE(font.lineHeight(), 3.0f);
     CORRADE_COMPARE(font.glyphCount(), 15);
+    CORRADE_COMPARE(font.fontIndex(), 0);
+    CORRADE_COMPARE(font.fontCount(), 1);
+}
+
+void AbstractFontTest::openDataFontIndex() {
+    struct: AbstractFont {
+        FontFeatures doFeatures() const override { return FontFeature::OpenData; }
+        bool doIsOpened() const override { return _opened; }
+        void doClose() override {}
+
+        Properties doOpenData(const Containers::ArrayView<const char> data, Float size) override {
+            CORRADE_COMPARE(fontIndex(), 2);
+            _opened = (data.size() == 1 && data[0] == '\xa5');
+            return {size, 1.0f, 2.0f, 3.0f, 15, 3};
+        }
+
+        void doGlyphIdsInto(const Containers::StridedArrayView1D<const char32_t>&, const Containers::StridedArrayView1D<UnsignedInt>&) override {}
+        Vector2 doGlyphSize(UnsignedInt) override { return {}; }
+        Vector2 doGlyphAdvance(UnsignedInt) override { return {}; }
+        Containers::Pointer<AbstractShaper> doCreateShaper() override { return {}; }
+
+        bool _opened = false;
+    } font;
+
+    CORRADE_VERIFY(!font.isOpened());
+    const char a5 = '\xa5';
+    font.openData({&a5, 1}, 13.0f, 2);
+    CORRADE_VERIFY(font.isOpened());
+    CORRADE_COMPARE(font.size(), 13.0f);
+    CORRADE_COMPARE(font.ascent(), 1.0f);
+    CORRADE_COMPARE(font.descent(), 2.0f);
+    CORRADE_COMPARE(font.lineHeight(), 3.0f);
+    CORRADE_COMPARE(font.glyphCount(), 15);
+    CORRADE_COMPARE(font.fontIndex(), 2);
+    CORRADE_COMPARE(font.fontCount(), 3);
 }
 
 void AbstractFontTest::openFileAsData() {
@@ -280,6 +317,8 @@ void AbstractFontTest::openFileAsData() {
     CORRADE_COMPARE(font.descent(), 2.0f);
     CORRADE_COMPARE(font.lineHeight(), 3.0f);
     CORRADE_COMPARE(font.glyphCount(), 15);
+    CORRADE_COMPARE(font.fontIndex(), 0);
+    CORRADE_COMPARE(font.fontCount(), 1);
 }
 
 void AbstractFontTest::openFileAsDataNotFound() {
@@ -811,12 +850,14 @@ void AbstractFontTest::propertiesNoFont() {
     font.descent();
     font.lineHeight();
     font.glyphCount();
+    font.fontCount();
     CORRADE_COMPARE(out,
         "Text::AbstractFont::size(): no font opened\n"
         "Text::AbstractFont::ascent(): no font opened\n"
         "Text::AbstractFont::descent(): no font opened\n"
         "Text::AbstractFont::lineHeight(): no font opened\n"
-        "Text::AbstractFont::glyphCount(): no font opened\n");
+        "Text::AbstractFont::glyphCount(): no font opened\n"
+        "Text::AbstractFont::fontCount(): no font opened\n");
 }
 
 void AbstractFontTest::glyphId() {