DocumentStyle: fixes for font issues

This commit should hopefully fix all the font problems we were having. Instead of using font substitution for emojis, we just instead call QFont::setFamilies. Builds with Qt versions below 5.13 will not have proper emoji support.

0) emojis seem to work fine at least in my environment
1) when selecting theme with font that is not on the system, a respectable default is used instead
2) custom fonts now work great on Windows (seems to be due to the removal of insertSubstitutions, which didn't seem to work in my build)
3) the dodgey 'Kristall XX' stuff was removed, as it seems like we don't need it

1 files changed, 50 insertions, 54 deletions

diff --git a/src/documentstyle.cpp b/src/documentstyle.cpp
index 815a647..5edef73 100644
--- a/src/documentstyle.cpp
+++ b/src/documentstyle.cpp
@@ -4,6 +4,7 @@
 #include <QDebug>
 #include <QString>
 #include <QStringList>
+#include <QFontDatabase>
 
 #include <QCryptographicHash>
 #include <QDebug>
@@ -156,49 +157,27 @@ DocumentStyle::DocumentStyle(bool do_init) : theme(Fixed),
 
 void DocumentStyle::initialiseDefaultFonts()
 {
-    // Setup default fonts
-#ifdef Q_OS_WIN32
-    // Windows
-    static const QString FONT_NORMAL = "Segoe UI";
-    static const QString FONT_MONO = "Consolas";
-//#elif defined Q_OS_DARWIN
-    // Mac (No idea what they use)
-    // static const QString FONT_NORMAL = "???";
-    // static const QString FONT_MONO = "???";
-#else
-    // Ganoo slash linooks
-    static const QString FONT_NORMAL = kristall::default_font_family;
-    static const QString FONT_MONO = kristall::default_font_family_fixed;
-#endif
-
-    preformatted_font.setFamily(FONT_MONO);
-    preformatted_font.setPointSizeF(10.0);
-
-    standard_font.setFamily(FONT_NORMAL);
-    standard_font.setPointSizeF(10.0);
-
-    h1_font.setFamily(FONT_NORMAL);
+    preformatted_font.setFamily(kristall::default_font_family_fixed);
+    preformatted_font.setPointSizeF(12.0);
+
+    standard_font.setFamily(kristall::default_font_family);
+    standard_font.setPointSizeF(12.0);
+
+    h1_font.setFamily(kristall::default_font_family);
     h1_font.setBold(true);
-    h1_font.setPointSizeF(20.0);
+    h1_font.setPointSizeF(22.0);
 
-    h2_font.setFamily(FONT_NORMAL);
+    h2_font.setFamily(kristall::default_font_family);
     h2_font.setBold(true);
-    h2_font.setPointSizeF(15.0);
+    h2_font.setPointSizeF(17.0);
 
-    h3_font.setFamily(FONT_NORMAL);
+    h3_font.setFamily(kristall::default_font_family);
     h3_font.setBold(true);
-    h3_font.setPointSizeF(12.0);
+    h3_font.setPointSizeF(14.0);
 
-    blockquote_font.setFamily(FONT_NORMAL);
+    blockquote_font.setFamily(kristall::default_font_family);
     blockquote_font.setItalic(true);
-    blockquote_font.setPointSizeF(10.0);
-
-    this->cookie = []() {
-        QByteArray arr(8, ' ');
-        for(auto & b : arr)
-            b = rand();
-        return arr.toBase64();
-    }();
+    blockquote_font.setPointSizeF(12.0);
 }
 
 QString DocumentStyle::createFileNameFromName(const QString &src, int index)
@@ -437,14 +416,10 @@ DocumentStyle DocumentStyle::derive(const QUrl &url) const
     DocumentStyle themed = *this;
 
     // Patch font lists to allow improved emoji display:
-    // Now this is a bit tricky to get right:
-    // 1. We need a list of fonts that provide emojis. This is `emojiFonts`
-    // 2. We need our own unique font name (This is "Kristall XX" + cookie)
-    // 3. We need to substitutions for that unique random name so Qt will look up missing symbols
-    // 4. We MUST NOT use a system font name as we would replace the user interface font (which we don't want to touch)
 
     static QStringList emojiFonts = {
         "<PLACEHOLDER>",
+        "<FALLBACK>",
         "Apple Color Emoji",
         "Segoe UI Emoji",
         "Twitter Color Emoji",
@@ -452,23 +427,44 @@ DocumentStyle DocumentStyle::derive(const QUrl &url) const
         "JoyPixels",
     };
 
-    auto const patchup_font = [this](QFont & font, QString custom_family)
+    auto const patchup_font = [](QFont & font, bool fixed=false)
     {
-        emojiFonts.front() = font.family();
-        QFont::insertSubstitutions(custom_family + cookie, emojiFonts);
-        font.setFamily(custom_family + cookie);
+        // Set the "fallback" font, just to be absolutely sure.
+        // (fixes *nix default font issues)
+        emojiFonts[1] = fixed
+            ? kristall::default_font_family_fixed
+            : kristall::default_font_family;
+
+        // Set the primary font as the preferred font.
+        // We ensure that the font family is available first,
+        // so that we don't get an ugly default font
+        // (fixes Windows' default font)
+        QFontDatabase db;
+        if (!db.families().contains(font.family()))
+        {
+            emojiFonts.front() = fixed
+                ? kristall::default_font_family_fixed
+                : kristall::default_font_family;
+        }
+        else
+        {
+            emojiFonts.front() = font.family();
+        }
 
-        // from docs:
-        // > After substituting a font, you must trigger the updating of the font by destroying and re-creating all QFont objects.
-        font.fromString(font.toString());
+        // We don't support emoji fonts on lower than Qt 5.13
+    #if QT_VERSION < QT_VERSION_CHECK(5, 13, 0)
+        font.setFamily(emojiFonts.front());
+    #else
+        font.setFamilies(emojiFonts);
+    #endif
     };
 
-    patchup_font(themed.h1_font, "Kristall H1");
-    patchup_font(themed.h2_font, "Kristall H2");
-    patchup_font(themed.h3_font, "Kristall H3");
-    patchup_font(themed.standard_font, "Kristall Standard");
-    patchup_font(themed.preformatted_font, "Kristall Monospace");
-    patchup_font(themed.blockquote_font, "Kristall Blockquote");
+    patchup_font(themed.h1_font);
+    patchup_font(themed.h2_font);
+    patchup_font(themed.h3_font);
+    patchup_font(themed.standard_font);
+    patchup_font(themed.preformatted_font, true);
+    patchup_font(themed.blockquote_font);
 
     if (this->theme == Fixed)
         return themed;