LibGfx: Add Font::AllowInexactSizeMatch parameter to font lookup

This allows bitmap font lookup to return the best matching size instead
of failing completely. The previous behavior (exact matches only)
remains the default.

Userland/Libraries/LibGfx/Font.h

@@ -95,6 +95,11 @@ struct FontMetrics {
 
 class Font : public RefCounted<Font> {
 public:
+    enum class AllowInexactSizeMatch {
+        No,
+        Yes,
+    };
+
     virtual NonnullRefPtr<Font> clone() const = 0;
     virtual ~Font() {};
 

Userland/Libraries/LibGfx/FontDatabase.cpp

@@ -164,20 +164,20 @@ RefPtr<Gfx::Font> FontDatabase::get_by_name(StringView name)
     return it->value;
 }
 
-RefPtr<Gfx::Font> FontDatabase::get(const String& family, unsigned size, unsigned weight, unsigned slope)
+RefPtr<Gfx::Font> FontDatabase::get(String const& family, unsigned size, unsigned weight, unsigned slope, Font::AllowInexactSizeMatch allow_inexact_size_match)
 {
     for (auto typeface : m_private->typefaces) {
         if (typeface->family() == family && typeface->weight() == weight && typeface->slope() == slope)
-            return typeface->get_font(size);
+            return typeface->get_font(size, allow_inexact_size_match);
     }
     return nullptr;
 }
 
-RefPtr<Gfx::Font> FontDatabase::get(const String& family, const String& variant, unsigned size)
+RefPtr<Gfx::Font> FontDatabase::get(String const& family, const String& variant, unsigned size, Font::AllowInexactSizeMatch allow_inexact_size_match)
 {
     for (auto typeface : m_private->typefaces) {
         if (typeface->family() == family && typeface->variant() == variant)
-            return typeface->get_font(size);
+            return typeface->get_font(size, allow_inexact_size_match);
     }
     return nullptr;
 }

Userland/Libraries/LibGfx/FontDatabase.h

@@ -44,8 +44,8 @@ public:
     static void set_fixed_width_font_query(String);
     static void set_default_fonts_lookup_path(String);
 
-    RefPtr<Gfx::Font> get(const String& family, unsigned size, unsigned weight, unsigned slope);
-    RefPtr<Gfx::Font> get(const String& family, const String& variant, unsigned size);
+    RefPtr<Gfx::Font> get(const String& family, unsigned size, unsigned weight, unsigned slope, Font::AllowInexactSizeMatch = Font::AllowInexactSizeMatch::No);
+    RefPtr<Gfx::Font> get(const String& family, const String& variant, unsigned size, Font::AllowInexactSizeMatch = Font::AllowInexactSizeMatch::No);
     RefPtr<Gfx::Font> get_by_name(StringView);
     void for_each_font(Function<void(const Gfx::Font&)>);
     void for_each_fixed_width_font(Function<void(const Gfx::Font&)>);

Userland/Libraries/LibGfx/Typeface.cpp

@@ -48,13 +48,28 @@ void Typeface::set_ttf_font(RefPtr<TTF::Font> font)
     m_ttf_font = move(font);
 }
 
-RefPtr<Font> Typeface::get_font(unsigned size) const
+RefPtr<Font> Typeface::get_font(unsigned size, Font::AllowInexactSizeMatch allow_inexact_size_match) const
 {
+    VERIFY(size < NumericLimits<int>::max());
+
+    RefPtr<BitmapFont> best_match;
+    int best_delta = NumericLimits<int>::max();
+
     for (auto font : m_bitmap_fonts) {
         if (font->presentation_size() == size)
             return font;
+        if (allow_inexact_size_match == Font::AllowInexactSizeMatch::Yes) {
+            int delta = static_cast<int>(font->presentation_size()) - static_cast<int>(size);
+            if (abs(delta) < best_delta) {
+                best_match = font;
+                best_delta = abs(delta);
+            }
+        }
     }
 
+    if (allow_inexact_size_match == Font::AllowInexactSizeMatch::Yes && best_match)
+        return best_match;
+
     if (m_ttf_font)
         return adopt_ref(*new TTF::ScaledFont(*m_ttf_font, size, size));
 

Userland/Libraries/LibGfx/Typeface.h

@@ -36,7 +36,7 @@ public:
     void add_bitmap_font(RefPtr<BitmapFont>);
     void set_ttf_font(RefPtr<TTF::Font>);
 
-    RefPtr<Font> get_font(unsigned size) const;
+    RefPtr<Font> get_font(unsigned size, Font::AllowInexactSizeMatch = Font::AllowInexactSizeMatch::No) const;
 
 private:
     String m_family;