Text: initial support for line height in AbstractFont.

Got finally pissed with the requirement of setting AbstractFont::_size
manually and took this as opportunity to rework the internal plugin API
in a better way. Bumped the interface version, as this is binary
incompatible. MagnumFont doesn't support lineHeight yet.

src/Plugins/MagnumFont/MagnumFont.cpp

@@ -67,11 +67,11 @@ auto MagnumFont::doFeatures() const -> Features { return Feature::OpenData|Featu
 
 bool MagnumFont::doIsOpened() const { return _opened; }
 
-void MagnumFont::doOpenData(const std::vector<std::pair<std::string, Containers::ArrayReference<const unsigned char>>>& data, const Float) {
+std::pair<Float, Float> MagnumFont::doOpenData(const std::vector<std::pair<std::string, Containers::ArrayReference<const unsigned char>>>& data, const Float) {
     /* We need just the configuration file and image file */
     if(data.size() != 2) {
         Error() << "Text::MagnumFont::openData(): wanted two files, got" << data.size();
-        return;
+        return {};
     }
 
     /* Open the configuration file */
@@ -79,51 +79,51 @@ void MagnumFont::doOpenData(const std::vector<std::pair<std::string, Containers:
     Utility::Configuration conf(in, Utility::Configuration::Flag::SkipComments);
     if(!conf.isValid() || conf.isEmpty()) {
         Error() << "Text::MagnumFont::openData(): cannot open file" << data[0].first;
-        return;
+        return {};
     }
 
     /* Check version */
     if(conf.value<UnsignedInt>("version") != 1) {
         Error() << "Text::MagnumFont::openData(): unsupported file version, expected 1 but got"
                 << conf.value<UnsignedInt>("version");
-        return;
+        return {};
     }
 
     /* Check that we have also the image file */
     if(conf.value("image") != data[1].first) {
         Error() << "Text::MagnumFont::openData(): expected file"
                 << conf.value("image") << "but got" << data[1].first;
-        return;
+        return {};
     }
 
     /* Open and load image file */
     Trade::TgaImporter importer;
     if(!importer.openData(data[1].second)) {
         Error() << "Text::MagnumFont::openData(): cannot open image file";
-        return;
+        return {};
     }
     std::optional<Trade::ImageData2D> image = importer.image2D(0);
     if(!image) {
         Error() << "Text::MagnumFont::openData(): cannot load image file";
-        return;
+        return {};
     }
 
-    openInternal(std::move(conf), std::move(*image));
+    return openInternal(std::move(conf), std::move(*image));
 }
 
-void MagnumFont::doOpenFile(const std::string& filename, Float) {
+std::pair<Float, Float> MagnumFont::doOpenFile(const std::string& filename, Float) {
     /* Open the configuration file */
     Utility::Configuration conf(filename, Utility::Configuration::Flag::ReadOnly|Utility::Configuration::Flag::SkipComments);
     if(!conf.isValid() || conf.isEmpty()) {
         Error() << "Text::MagnumFont::openFile(): cannot open file" << filename << conf.isValid();
-        return;
+        return {};
     }
 
     /* Check version */
     if(conf.value<UnsignedInt>("version") != 1) {
         Error() << "Text::MagnumFont::openFile(): unsupported file version, expected 1 but got"
                 << conf.value<UnsignedInt>("version");
-        return;
+        return {};
     }
 
     /* Open and load image file */
@@ -131,21 +131,20 @@ void MagnumFont::doOpenFile(const std::string& filename, Float) {
     Trade::TgaImporter importer;
     if(!importer.openFile(imageFilename)) {
         Error() << "Text::MagnumFont::openFile(): cannot open image file" << imageFilename;
-        return;
+        return {};
     }
     std::optional<Trade::ImageData2D> image = importer.image2D(0);
     if(!image) {
         Error() << "Text::MagnumFont::openFile(): cannot load image file";
-        return;
+        return {};
     }
 
-    openInternal(std::move(conf), std::move(*image));
+    return openInternal(std::move(conf), std::move(*image));
 }
 
-void MagnumFont::openInternal(Utility::Configuration&& conf, Trade::ImageData2D&& image) {
+std::pair<Float, Float> MagnumFont::openInternal(Utility::Configuration&& conf, Trade::ImageData2D&& image) {
     /* Everything okay, save the data internally */
     _opened = new Data{std::move(conf), std::move(image), {}, {}};
-    _size = _opened->conf.value<Float>("fontSize");
 
     /* Glyph advances */
     const std::vector<Utility::ConfigurationGroup*> glyphs = _opened->conf.groups("glyph");
@@ -160,6 +159,8 @@ void MagnumFont::openInternal(Utility::Configuration&& conf, Trade::ImageData2D&
         CORRADE_INTERNAL_ASSERT(glyphId < _opened->glyphAdvance.size());
         _opened->glyphId.emplace(c->value<char32_t>("unicode"), glyphId);
     }
+
+    return {_opened->conf.value<Float>("fontSize"), 0};
 }
 
 void MagnumFont::doClose() {

src/Plugins/MagnumFont/MagnumFont.h

@@ -115,9 +115,9 @@ class MagnumFont: public AbstractFont {
 
         bool doIsOpened() const override;
 
-        void doOpenData(const std::vector<std::pair<std::string, Containers::ArrayReference<const unsigned char>>>& data, Float) override;
+        std::pair<Float, Float> doOpenData(const std::vector<std::pair<std::string, Containers::ArrayReference<const unsigned char>>>& data, Float) override;
 
-        void doOpenFile(const std::string& filename, Float) override;
+        std::pair<Float, Float> doOpenFile(const std::string& filename, Float) override;
 
         void doClose() override;
 
@@ -129,9 +129,9 @@ class MagnumFont: public AbstractFont {
 
         std::unique_ptr<AbstractLayouter> doLayout(const GlyphCache& cache, Float size, const std::string& text) override;
 
-        Data* _opened;
+        std::pair<Float, Float> openInternal(Utility::Configuration&& conf, Trade::ImageData2D&& image);
 
-        void openInternal(Utility::Configuration&& conf, Trade::ImageData2D&& image);
+        Data* _opened;
 };
 
 }}

src/Plugins/MagnumFont/pluginRegistrationMagnumFont.cpp

@@ -25,4 +25,4 @@
 #include "MagnumFont/MagnumFont.h"
 
 CORRADE_PLUGIN_REGISTER(MagnumFont, Magnum::Text::MagnumFont,
-    "cz.mosra.magnum.Text.AbstractFont/0.2.1")
+    "cz.mosra.magnum.Text.AbstractFont/0.2.2")

src/Plugins/MagnumFontConverter/Test/MagnumFontConverterTest.cpp

@@ -60,11 +60,15 @@ void MagnumFontConverterTest::exportFont() {
     /* Fake font with fake cache */
     class FakeFont: public Text::AbstractFont {
         public:
-            explicit FakeFont() { _size = 16.0f; }
+            explicit FakeFont(): _opened(false) {}
 
         private:
-            void doClose() {}
-            bool doIsOpened() const { return true; }
+            void doClose() { _opened = false; }
+            bool doIsOpened() const { return _opened; }
+            std::pair<Float, Float> doOpenFile(const std::string&, Float) {
+                _opened = true;
+                return {16.0f, 0};
+            }
             Features doFeatures() const { return {}; }
             std::unique_ptr<AbstractLayouter> doLayout(const GlyphCache&, Float, const std::string&) { return nullptr; }
 
@@ -86,7 +90,10 @@ void MagnumFontConverterTest::exportFont() {
 
                 CORRADE_ASSERT_UNREACHABLE();
             }
+
+            bool _opened;
     } font;
+    font.openFile({}, {});
 
     /* Create fake cache */
     MAGNUM_ASSERT_EXTENSION_SUPPORTED(Extensions::GL::ARB::texture_rg);

src/Text/AbstractFont.cpp

@@ -34,7 +34,7 @@ namespace Magnum { namespace Text {
 
 AbstractFont::AbstractFont(): _size(0.0f) {}
 
-AbstractFont::AbstractFont(PluginManager::AbstractManager* manager, std::string plugin): AbstractPlugin(manager, std::move(plugin)), _size(0.0f) {}
+AbstractFont::AbstractFont(PluginManager::AbstractManager* manager, std::string plugin): AbstractPlugin(manager, std::move(plugin)), _size(0.0f), _lineHeight(0.0f) {}
 
 bool AbstractFont::openData(const std::vector<std::pair<std::string, Containers::ArrayReference<const unsigned char>>>& data, const Float size) {
     CORRADE_ASSERT(features() & Feature::OpenData,
@@ -43,18 +43,19 @@ bool AbstractFont::openData(const std::vector<std::pair<std::string, Containers:
         "Text::AbstractFont::openData(): no data passed", false);
 
     close();
-    doOpenData(data, size);
+    std::tie(_size, _lineHeight) = doOpenData(data, size);
+    CORRADE_INTERNAL_ASSERT(isOpened() || (_size == 0.0f && _lineHeight == 0.0f));
     return isOpened();
 }
 
-void AbstractFont::doOpenData(const std::vector<std::pair<std::string, Containers::ArrayReference<const unsigned char>>>& data, const Float size) {
+std::pair<Float, Float> AbstractFont::doOpenData(const std::vector<std::pair<std::string, Containers::ArrayReference<const unsigned char>>>& data, const Float size) {
     CORRADE_ASSERT(!(features() & Feature::MultiFile),
-        "Text::AbstractFont::openData(): feature advertised but not implemented", );
+        "Text::AbstractFont::openData(): feature advertised but not implemented", {});
     CORRADE_ASSERT(data.size() == 1,
-        "Text::AbstractFont::openData(): expected just one file for single-file format", );
+        "Text::AbstractFont::openData(): expected just one file for single-file format", {});
 
     close();
-    doOpenSingleData(data[0].second, size);
+    return doOpenSingleData(data[0].second, size);
 }
 
 bool AbstractFont::openSingleData(const Containers::ArrayReference<const unsigned char> data, const Float size) {
@@ -64,29 +65,31 @@ bool AbstractFont::openSingleData(const Containers::ArrayReference<const unsigne
         "Text::AbstractFont::openSingleData(): the format is not single-file", false);
 
     close();
-    doOpenSingleData(data, size);
+    std::tie(_size, _lineHeight) = doOpenSingleData(data, size);
+    CORRADE_INTERNAL_ASSERT(isOpened() || (_size == 0.0f && _lineHeight == 0.0f));
     return isOpened();
 }
 
-void AbstractFont::doOpenSingleData(Containers::ArrayReference<const unsigned char>, Float) {
-    CORRADE_ASSERT(false, "Text::AbstractFont::openSingleData(): feature advertised but not implemented", );
+std::pair<Float, Float> AbstractFont::doOpenSingleData(Containers::ArrayReference<const unsigned char>, Float) {
+    CORRADE_ASSERT(false, "Text::AbstractFont::openSingleData(): feature advertised but not implemented", {});
 }
 
 bool AbstractFont::openFile(const std::string& filename, const Float size) {
     close();
-    doOpenFile(filename, size);
+    std::tie(_size, _lineHeight) = doOpenFile(filename, size);
+    CORRADE_INTERNAL_ASSERT(isOpened() || (_size == 0.0f && _lineHeight == 0.0f));
     return isOpened();
 }
 
-void AbstractFont::doOpenFile(const std::string& filename, const Float size) {
+std::pair<Float, Float> AbstractFont::doOpenFile(const std::string& filename, const Float size) {
     CORRADE_ASSERT(features() & Feature::OpenData && !(features() & Feature::MultiFile),
-        "Text::AbstractFont::openFile(): not implemented", );
+        "Text::AbstractFont::openFile(): not implemented", {});
 
     /* Open file */
     std::ifstream in(filename.data(), std::ios::binary);
     if(!in.good()) {
         Error() << "Trade::AbstractFont::openFile(): cannot open file" << filename;
-        return;
+        return {};
     }
 
     /* Create array to hold file contents */
@@ -98,12 +101,14 @@ void AbstractFont::doOpenFile(const std::string& filename, const Float size) {
     in.read(reinterpret_cast<char*>(data.begin()), data.size());
     in.close();
 
-    doOpenSingleData(data, size);
+    return doOpenSingleData(data, size);
 }
 
 void AbstractFont::close() {
     if(isOpened()) {
         doClose();
+        _size = 0.0f;
+        _lineHeight = 0.0f;
         CORRADE_INTERNAL_ASSERT(!isOpened());
     }
 }

src/Text/AbstractFont.h

@@ -67,7 +67,7 @@ checked by the implementation:
     there is any file opened.
 */
 class MAGNUM_TEXT_EXPORT AbstractFont: public PluginManager::AbstractPlugin {
-    CORRADE_PLUGIN_INTERFACE("cz.mosra.magnum.Text.AbstractFont/0.2.1")
+    CORRADE_PLUGIN_INTERFACE("cz.mosra.magnum.Text.AbstractFont/0.2.2")
 
     public:
         /**
@@ -150,6 +150,9 @@ class MAGNUM_TEXT_EXPORT AbstractFont: public PluginManager::AbstractPlugin {
         /** @brief Font size */
         Float size() const { return _size; }
 
+        /** @brief Line height */
+        Float lineHeight() const { return _lineHeight; }
+
         /**
          * @brief Glyph ID for given character
          *
@@ -199,13 +202,6 @@ class MAGNUM_TEXT_EXPORT AbstractFont: public PluginManager::AbstractPlugin {
          */
         std::unique_ptr<AbstractLayouter> layout(const GlyphCache& cache, Float size, const std::string& text);
 
-    #ifdef DOXYGEN_GENERATING_OUTPUT
-    private:
-    #else
-    protected:
-    #endif
-        Float _size;
-
     #ifdef DOXYGEN_GENERATING_OUTPUT
     protected:
     #else
@@ -220,22 +216,29 @@ class MAGNUM_TEXT_EXPORT AbstractFont: public PluginManager::AbstractPlugin {
         /**
          * @brief Implementation for @ref openData()
          *
-         * If the plugin doesn't have @ref Feature::MultiFile, default
-         * implementation calls @ref doOpenSingleData().
+         * Return size and line height of opened font on successful opening,
+         * zeros otherwise. If the plugin doesn't have @ref Feature::MultiFile,
+         * default implementation calls @ref doOpenSingleData().
          */
-        virtual void doOpenData(const std::vector<std::pair<std::string, Containers::ArrayReference<const unsigned char>>>& data, Float size);
+        virtual std::pair<Float, Float> doOpenData(const std::vector<std::pair<std::string, Containers::ArrayReference<const unsigned char>>>& data, Float size);
 
-        /** @brief Implementation for @ref openSingleData() */
-        virtual void doOpenSingleData(Containers::ArrayReference<const unsigned char> data, Float size);
+        /**
+         * @brief Implementation for @ref openSingleData()
+         *
+         * Return size and line height of opened font on successful opening,
+         * zeros otherwise.
+         */
+        virtual std::pair<Float, Float> doOpenSingleData(Containers::ArrayReference<const unsigned char> data, Float size);
 
         /**
          * @brief Implementation for @ref openFile()
          *
-         * If @ref Feature::OpenData is supported and the plugin doesn't have
-         * @ref Feature::MultiFile, default implementation opens the file and
-         * calls @ref doOpenSingleData() with its contents.
+         * Return size and line height of opened font on successful opening,
+         * zeros otherwise. If @ref Feature::OpenData is supported and the
+         * plugin doesn't have @ref Feature::MultiFile, default implementation
+         * opens the file and calls @ref doOpenSingleData() with its contents.
          */
-        virtual void doOpenFile(const std::string& filename, Float size);
+        virtual std::pair<Float, Float> doOpenFile(const std::string& filename, Float size);
 
         /** @brief Implementation for @ref close() */
         virtual void doClose() = 0;
@@ -266,6 +269,11 @@ class MAGNUM_TEXT_EXPORT AbstractFont: public PluginManager::AbstractPlugin {
 
         /** @brief Implementation for @ref layout() */
         virtual std::unique_ptr<AbstractLayouter> doLayout(const GlyphCache& cache, Float size, const std::string& text) = 0;
+
+    #ifdef DOXYGEN_GENERATING_OUTPUT
+    private:
+    #endif
+        Float _size, _lineHeight;
 };
 
 CORRADE_ENUMSET_OPERATORS(AbstractFont::Features)

src/Text/Test/AbstractFontTest.cpp

@@ -55,8 +55,9 @@ class SingleDataFont: public Text::AbstractFont {
         bool doIsOpened() const override { return opened; }
         void doClose() override {}
 
-        void doOpenSingleData(const Containers::ArrayReference<const unsigned char> data, Float) override {
+        std::pair<Float, Float> doOpenSingleData(const Containers::ArrayReference<const unsigned char> data, Float) override {
             opened = (data.size() == 1 && data[0] == 0xa5);
+            return {};
         }
 
         UnsignedInt doGlyphId(char32_t) override { return 0; }