Add font reload utility

modules/core/inc/tactile/core/ui/fonts.hpp

@@ -0,0 +1,25 @@
+// Copyright (C) 2023 Albin Johansson (GNU General Public License v3.0)
+
+#pragma once
+
+#include "tactile/core/api.hpp"
+#include "tactile/foundation/prelude.hpp"
+
+namespace tactile {
+
+class IRenderer;
+
+/**
+ * \brief Attempts to reload the Dear ImGui font texture atlas.
+ *
+ * \note This function does nothing if the renderer doesn't support font reloading.
+ *
+ * \param renderer          the active renderer.
+ * \param font_size         the current font size.
+ * \param framebuffer_scale the current display framebuffer scale.
+ */
+TACTILE_CORE_API void try_reload_imgui_fonts(IRenderer& renderer,
+                                             float font_size,
+                                             float framebuffer_scale);
+
+}  // namespace tactile

modules/core/src/tactile/core/editor_app.cpp

@@ -5,6 +5,7 @@
 #include <imgui.h>
 #include <imgui_internal.h>
 
+#include "tactile/core/ui/fonts.hpp"
 #include "tactile/foundation/debug/validation.hpp"
 
 namespace tactile {
@@ -48,6 +49,7 @@ void EditorApp::on_update()
 
 void EditorApp::on_framebuffer_scale_changed(const float framebuffer_scale)
 {
+  try_reload_imgui_fonts(*mRenderer, 13.0f, framebuffer_scale);
 }
 
 }  // namespace tactile

modules/core/src/tactile/core/ui/fonts.cpp

@@ -0,0 +1,57 @@
+// Copyright (C) 2023 Albin Johansson (GNU General Public License v3.0)
+
+#include "tactile/core/ui/fonts.hpp"
+
+#include <IconsFontAwesome6.h>
+#include <imgui.h>
+
+#include "tactile/foundation/container/array.hpp"
+#include "tactile/foundation/log/logger.hpp"
+#include "tactile/foundation/render/renderer.hpp"
+
+namespace tactile {
+namespace {
+
+inline constexpr Array<ImWchar, 3> kFontIconRange {ICON_MIN_FA, ICON_MAX_FA, 0};
+
+}  // namespace
+
+void try_reload_imgui_fonts(IRenderer& renderer,
+                            const float font_size,
+                            const float framebuffer_scale)
+{
+  if (renderer.can_reload_fonts_texture()) {
+    TACTILE_LOG_TRACE("Reloading fonts...");
+
+    auto& io = ImGui::GetIO();
+    io.Fonts->Clear();
+
+    ImFontConfig roboto_config {};
+    roboto_config.SizePixels = font_size * framebuffer_scale;
+    io.Fonts->AddFontFromFileTTF("assets/fonts/roboto/Roboto-Regular.ttf",
+                                 roboto_config.SizePixels,
+                                 &roboto_config);
+
+    // The global scale is 1 on most platforms, and 0.5 on macOS.
+    io.FontGlobalScale = 1.0f / framebuffer_scale;
+
+    ImFontConfig icon_config {};
+    icon_config.MergeMode = true;
+    icon_config.SizePixels = font_size * framebuffer_scale;
+    icon_config.GlyphMinAdvanceX = icon_config.SizePixels;
+    icon_config.GlyphMaxAdvanceX = icon_config.GlyphMinAdvanceX;
+    icon_config.GlyphOffset = {0, 2};
+    io.Fonts->AddFontFromFileTTF("assets/fonts/fa/" FONT_ICON_FILE_NAME_FAS,
+                                 icon_config.GlyphMinAdvanceX,
+                                 &icon_config,
+                                 kFontIconRange.data());
+
+    io.Fonts->Build();
+
+    renderer.reload_fonts_texture();
+
+    ImGui::GetStyle().ScaleAllSizes(1.0f);
+  }
+}
+
+}  // namespace tactile