tdf#58941 implement retrieving font features and structures

This adds the following:
- Retrieving of features using HarfBuzz
- Retrieving of feature definitions from graphite fonts
- Adds description texts of OpenType features
- Tests for retrieving features (Linux Libertine G graphite font)
and making sure the features and definitions are what we
expect.

Change-Id: I51573fe086e59c6228cb546bbfac95ac53824c47
Reviewed-on: https://gerrit.libreoffice.org/55892
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>

2 files changed, 105 insertions, 0 deletions

diff --git a/include/vcl/font/Feature.hxx b/include/vcl/font/Feature.hxx
new file mode 100644
index 000000000000..0fa8f6d5bb70
--- /dev/null
+++ b/include/vcl/font/Feature.hxx
@@ -0,0 +1,99 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#ifndef INCLUDED_VCL_FONT_FEATURE_HXX
+#define INCLUDED_VCL_FONT_FEATURE_HXX
+
+#include <vcl/dllapi.h>
+#include <rtl/ustring.hxx>
+#include <rtl/string.hxx>
+#include <memory>
+#include <vector>
+#include <unordered_map>
+
+namespace vcl
+{
+namespace font
+{
+constexpr sal_uInt32 featureCode(const char sFeature[4])
+{
+    return sFeature[0] << 24 | sFeature[1] << 16 | sFeature[2] << 8 | sFeature[3] << 0;
+}
+
+VCL_DLLPUBLIC OUString featureCodeAsString(sal_uInt32 nFeature);
+
+enum class FeatureParameterType
+{
+    BOOL,
+    ENUM
+};
+
+struct VCL_DLLPUBLIC FeatureParameter
+{
+private:
+    sal_uInt32 m_nCode;
+    OUString m_sDescription;
+    const char* m_pDescriptionID;
+
+public:
+    FeatureParameter(sal_uInt32 nCode, OUString aDescription);
+    FeatureParameter(sal_uInt32 nCode, const char* pDescriptionID);
+
+    sal_uInt32 getCode() const;
+    OUString getDescription() const;
+};
+
+class VCL_DLLPUBLIC FeatureDefinition
+{
+private:
+    sal_uInt32 m_nCode;
+    OUString m_sDescription;
+    const char* m_pDescriptionID;
+    FeatureParameterType m_eType;
+    // the index of the parameter defines the enum value, string is the description
+    std::vector<FeatureParameter> m_aEnumParameters;
+
+public:
+    FeatureDefinition();
+    FeatureDefinition(sal_uInt32 nCode, OUString const& rDescription,
+                      FeatureParameterType eType = FeatureParameterType::BOOL,
+                      std::vector<FeatureParameter> const& rEnumParameters
+                      = std::vector<FeatureParameter>{});
+    FeatureDefinition(sal_uInt32 nCode, const char* pDescriptionID);
+    FeatureDefinition(sal_uInt32 nCode, const char* pDescriptionID,
+                      std::vector<FeatureParameter> aEnumParameters);
+
+    const std::vector<FeatureParameter>& getEnumParameters() const;
+    OUString getDescription() const;
+    sal_uInt32 getCode() const;
+    FeatureParameterType getType() const;
+
+    operator bool() const;
+};
+
+struct VCL_DLLPUBLIC FeatureID
+{
+    sal_uInt32 m_aFeatureCode;
+    sal_uInt32 m_aScriptCode;
+    sal_uInt32 m_aLanguageCode;
+};
+
+struct VCL_DLLPUBLIC Feature
+{
+    FeatureID m_aID;
+    FeatureDefinition m_aDefinition;
+};
+
+} // end font namespace
+
+} // end vcl namespace
+
+#endif // INCLUDED_VCL_FONT_FEATURE_HXX
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/include/vcl/outdev.hxx b/include/vcl/outdev.hxx
index 5cff1915b602..96fd4246a070 100644
--- a/include/vcl/outdev.hxx
+++ b/include/vcl/outdev.hxx
@@ -101,6 +101,9 @@ namespace vcl
     class TextLayoutCache;
     class Window;
     class FontInfo;
+    namespace font {
+        struct Feature;
+    }
 }
 
 namespace com { namespace sun { namespace star { namespace rendering {
@@ -1218,6 +1221,9 @@ public:
     bool                        GetFontCharMap( FontCharMapRef& rxFontCharMap ) const;
     bool                        GetFontCapabilities( vcl::FontCapabilities& rFontCapabilities ) const;
 
+    bool GetFontFeatures(std::vector<vcl::font::Feature>& rFontFeatures) const;
+
+
     /** Retrieve detailed font information in platform independent structure
 
         @param  nFallbacklevel      Fallback font level (0 = best matching font)