From 1979baf619025cd8bb1c7524e69e93546e9bba48 Mon Sep 17 00:00:00 2001
From: Vojtech Kral <vojtech@kral.hk>
Date: Tue, 2 Apr 2019 13:26:22 +0200
Subject: [PATCH] imgui: Fix font size and scaling on Windows

---
 src/slic3r/GUI/GLCanvas3D.cpp   |  6 +++---
 src/slic3r/GUI/ImGuiWrapper.cpp | 11 +++++++----
 src/slic3r/GUI/ImGuiWrapper.hpp |  2 +-
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/src/slic3r/GUI/GLCanvas3D.cpp b/src/slic3r/GUI/GLCanvas3D.cpp
index ca3f6261b..a600f9ce1 100644
--- a/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/src/slic3r/GUI/GLCanvas3D.cpp
@@ -4405,12 +4405,12 @@ void GLCanvas3D::_resize(unsigned int w, unsigned int h)
 
     auto *imgui = wxGetApp().imgui();
     imgui->set_display_size((float)w, (float)h);
+    const float font_size = 1.5f * wxGetApp().em_unit();
 #if ENABLE_RETINA_GL
-    const float scaling = m_retina_helper->get_scale_factor();
+    imgui->set_scaling(font_size, 1.0f, m_retina_helper->get_scale_factor());
 #else
-    const float scaling = m_canvas->GetContentScaleFactor();
+    imgui->set_scaling(font_size, m_canvas->GetContentScaleFactor(), 1.0f);
 #endif
-    imgui->set_scaling(m_canvas->GetFont().GetPixelSize().y, scaling);
 
     // ensures that this canvas is current
     _set_current();
diff --git a/src/slic3r/GUI/ImGuiWrapper.cpp b/src/slic3r/GUI/ImGuiWrapper.cpp
index b008c17a7..1b4d4edf9 100644
--- a/src/slic3r/GUI/ImGuiWrapper.cpp
+++ b/src/slic3r/GUI/ImGuiWrapper.cpp
@@ -92,16 +92,19 @@ void ImGuiWrapper::set_display_size(float w, float h)
     io.DisplayFramebufferScale = ImVec2(1.0f, 1.0f);
 }
 
-void ImGuiWrapper::set_scaling(float font_size, float scaling)
+void ImGuiWrapper::set_scaling(float font_size, float scale_style, float scale_both)
 {
-    if (m_font_size == font_size && m_style_scaling == scaling) {
+    font_size *= scale_both;
+    scale_style *= scale_both;
+
+    if (m_font_size == font_size && m_style_scaling == scale_style) {
         return;
     }
 
     m_font_size = font_size;
 
-    ImGui::GetStyle().ScaleAllSizes(scaling / m_style_scaling);
-    m_style_scaling = scaling;
+    ImGui::GetStyle().ScaleAllSizes(scale_style / m_style_scaling);
+    m_style_scaling = scale_style;
 
     destroy_font();
 }
diff --git a/src/slic3r/GUI/ImGuiWrapper.hpp b/src/slic3r/GUI/ImGuiWrapper.hpp
index 84a60e3d1..c1bf491e1 100644
--- a/src/slic3r/GUI/ImGuiWrapper.hpp
+++ b/src/slic3r/GUI/ImGuiWrapper.hpp
@@ -35,7 +35,7 @@ public:
 
     void set_language(const std::string &language);
     void set_display_size(float w, float h);
-    void set_scaling(float font_size, float scaling);
+    void set_scaling(float font_size, float scale_style, float scale_both);
     bool update_mouse_data(wxMouseEvent &evt);
     bool update_key_data(wxKeyEvent &evt);