Font: Added io.FontDefault in ImGuiIO structure to make it easier to change default font from third-party or demo code

imgui.cpp

@@ -658,6 +658,7 @@ static float            GetDraggedColumnOffset(int column_index);
 
 static bool             IsKeyPressedMap(ImGuiKey key, bool repeat = true);
 
+static ImFont*          GetDefaultFont();
 static void             SetCurrentFont(ImFont* font);
 static void             SetCurrentWindow(ImGuiWindow* window);
 static void             SetWindowScrollY(ImGuiWindow* window, float new_scroll_y);
@@ -809,6 +810,7 @@ ImGuiIO::ImGuiIO()
     LogFilename = "imgui_log.txt";
     Fonts = &GImDefaultFontAtlas;
     FontGlobalScale = 1.0f;
+    FontDefault = NULL;
     DisplayFramebufferScale = ImVec2(1.0f, 1.0f);
     MousePos = ImVec2(-1,-1);
     MousePosPrev = ImVec2(-1,-1);
@@ -2106,7 +2108,8 @@ void ImGui::NewFrame()
         g.Initialized = true;
     }
 
-    SetCurrentFont(g.IO.Fonts->Fonts[0]);
+    SetCurrentFont(GetDefaultFont());
+    IM_ASSERT(g.Font->IsLoaded());
 
     g.Time += g.IO.DeltaTime;
     g.FrameCount += 1;
@@ -4586,6 +4589,12 @@ float ImGui::CalcItemWidth()
     return w;
 }
 
+static ImFont* GetDefaultFont()
+{
+    ImGuiContext& g = *GImGui;
+    return g.IO.FontDefault ? g.IO.FontDefault : g.IO.Fonts->Fonts[0];
+}
+
 static void SetCurrentFont(ImFont* font)
 {
     ImGuiContext& g = *GImGui;
@@ -4601,7 +4610,7 @@ void ImGui::PushFont(ImFont* font)
 {
     ImGuiContext& g = *GImGui;
     if (!font)
-        font = g.IO.Fonts->Fonts[0];
+        font = GetDefaultFont();
     SetCurrentFont(font);
     g.FontStack.push_back(font);
     g.CurrentWindow->DrawList->PushTextureID(font->ContainerAtlas->TexID);
@@ -4612,7 +4621,7 @@ void  ImGui::PopFont()
     ImGuiContext& g = *GImGui;
     g.CurrentWindow->DrawList->PopTextureID();
     g.FontStack.pop_back();
-    SetCurrentFont(g.FontStack.empty() ? g.IO.Fonts->Fonts[0] : g.FontStack.back());
+    SetCurrentFont(g.FontStack.empty() ? GetDefaultFont() : g.FontStack.back());
 }
 
 void ImGui::PushAllowKeyboardFocus(bool allow_keyboard_focus)

imgui.h

@@ -739,6 +739,7 @@ struct ImGuiIO
     ImFontAtlas*  Fonts;                    // <auto>               // Load and assemble one or more fonts into a single tightly packed texture. Output to Fonts array.
     float         FontGlobalScale;          // = 1.0f               // Global scale all fonts
     bool          FontAllowUserScaling;     // = false              // Allow user scaling text of individual window with CTRL+Wheel.
+    ImFont*       FontDefault;              // = NULL               // Font to use on NewFrame(). Use NULL to uses Fonts->Fonts[0].
     ImVec2        DisplayFramebufferScale;  // = (1.0f,1.0f)        // For retina display or other situations where window coordinates are different from framebuffer coordinates. User storage only, presently not used by ImGui.
     ImVec2        DisplayVisibleMin;        // <unset> (0.0f,0.0f)  // If you use DisplaySize as a virtual space larger than your screen, set DisplayVisibleMin/Max to the visible area.
     ImVec2        DisplayVisibleMax;        // <unset> (0.0f,0.0f)  // If the values are the same, we defaults to Min=(0.0f) and Max=DisplaySize

imgui_demo.cpp

@@ -1721,7 +1721,8 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
     if (ImGui::TreeNode("Fonts", "Fonts (%d)", ImGui::GetIO().Fonts->Fonts.Size))
     {
         ImGui::SameLine(); ShowHelpMarker("Tip: Load fonts with io.Fonts->AddFontFromFileTTF()\nbefore calling io.Fonts->GetTex* functions.");
-        ImFontAtlas* atlas = ImGui::GetIO().Fonts;
+        ImGuiIO& io = ImGui::GetIO();
+        ImFontAtlas* atlas = io.Fonts;
         if (ImGui::TreeNode("Atlas texture", "Atlas texture (%dx%d pixels)", atlas->TexWidth, atlas->TexHeight))
         {
             ImGui::Image(atlas->TexID, ImVec2((float)atlas->TexWidth, (float)atlas->TexHeight), ImVec2(0,0), ImVec2(1,1), ImColor(255,255,255,255), ImColor(255,255,255,128));
@@ -1733,7 +1734,7 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
             ImFont* font = atlas->Fonts[i];
             ImGui::BulletText("Font %d: \'%s\', %.2f px, %d glyphs", i, font->ConfigData ? font->ConfigData[0].Name : "", font->FontSize, font->Glyphs.Size);
             ImGui::TreePush((void*)(intptr_t)i);
-            if (i > 0) { ImGui::SameLine(); if (ImGui::SmallButton("Set as default")) { atlas->Fonts[i] = atlas->Fonts[0]; atlas->Fonts[0] = font; } }
+            ImGui::SameLine(); if (ImGui::SmallButton("Set as default")) io.FontDefault = font;
             ImGui::PushFont(font);
             ImGui::Text("The quick brown fox jumps over the lazy dog");
             ImGui::PopFont();