DPI scaling (#326)

* Add option for dpiScale to globalContext and scale font with dpiScale factor

* Scale everthing with the dpiScale factor

* set GLFW_SCALE_TO_MONITOR for proper windows size on start up

* Make sure the dpiScale factor is in a reasonable range (1x-10x)

* some refactor/renaming, plus bugfixes for nested context push

* remove global font atlas engine pointer

* autoset uiscale and restore from prefs file

* disable GLFW_SCALE_TO_MONITOR

* remove debug code

* set uiScale on non-glfw backends

* fix imgui init calls for non-GLFW backends

---------

Co-authored-by: Nicholas Sharp <[email protected]>

Author: BruegelN

examples/demo-app/demo_app.cpp

@@ -780,7 +780,7 @@ void callback() {
   static int loadedMat = 1;
   static bool depthClick = false;
 
-  ImGui::PushItemWidth(100);
+  ImGui::PushItemWidth(100 * polyscope::options::uiScale);
 
   ImGui::InputInt("num points", &numPoints);
   ImGui::InputFloat("param value", &param);

include/polyscope/options.h

@@ -93,6 +93,9 @@ extern std::string screenshotExtension; // sets the extension used for automatic
 // SSAA scaling in pixel multiples
 extern int ssaaFactor;
 
+// DPI scaling to scale the UI on high-resolutoin screens
+extern float uiScale;
+
 // Transparency settings for the renderer
 extern TransparencyMode transparencyMode;
 extern int transparencyRenderPasses;

include/polyscope/parameterization_quantity.ipp

@@ -61,7 +61,7 @@ ParameterizationQuantity<QuantityT>::ParameterizationQuantity(QuantityT& quantit
 template <typename QuantityT>
 void ParameterizationQuantity<QuantityT>::buildParameterizationUI() {
 
-  ImGui::PushItemWidth(100);
+  ImGui::PushItemWidth(100 * options::uiScale);
 
   // Modulo stripey width
   if (ImGui::DragFloat("period", &checkerSize.get(), .001, 0.0001, 1.0, "%.4f",
@@ -82,7 +82,7 @@ void ParameterizationQuantity<QuantityT>::buildParameterizationUI() {
       setCheckerColors(getCheckerColors());
     break;
   case ParamVizStyle::CHECKER_ISLANDS:
-    ImGui::PushItemWidth(100);
+    ImGui::PushItemWidth(100 * options::uiScale);
     if (ImGui::DragFloat("alt darkness", &altDarkness.get(), 0.01, 0., 1.)) {
       altDarkness.manuallyChanged();
       requestRedraw();
@@ -103,7 +103,7 @@ void ParameterizationQuantity<QuantityT>::buildParameterizationUI() {
   case ParamVizStyle::LOCAL_CHECK:
   case ParamVizStyle::LOCAL_RAD: {
     // Angle slider
-    ImGui::PushItemWidth(100);
+    ImGui::PushItemWidth(100 * options::uiScale);
     ImGui::SliderAngle("angle shift", &localRot, -180,
                        180); // displays in degrees, works in radians TODO refresh/update/persist
     if (ImGui::DragFloat("alt darkness", &altDarkness.get(), 0.01, 0., 1.)) {

include/polyscope/render/engine.h

@@ -518,7 +518,6 @@ class Engine {
   virtual void ImGuiRender() = 0;
 
   void setImGuiStyle();
-  ImFontAtlas* getImGuiGlobalFontAtlas();
 
   // Display an ImGui window showing a texture
   // WARNING: you must ensure that the texture buffer pointer stays valid until after the ImGui frame is rendered, which
@@ -629,7 +628,7 @@ class Engine {
   bool useAltDisplayBuffer = false; // if true, push final render results offscreen to the alt buffer instead
 
   // Internal windowing and engine details
-  ImFontAtlas* globalFontAtlas = nullptr;
+  virtual void configureImGui() {}; // generates font things
   ImFont* regularFont = nullptr;
   ImFont* monoFont = nullptr;
   FrameBuffer* currRenderFramebuffer = nullptr;
@@ -658,7 +657,6 @@ class Engine {
   TransparencyMode currLightingTransparencyMode = TransparencyMode::None;
 
   // Helpers
-  void configureImGui();
   void loadDefaultMaterials();
   void loadDefaultMaterial(std::string name);
   std::shared_ptr<TextureBuffer> loadMaterialTexture(float* data, int width, int height);

include/polyscope/render/mock_opengl/mock_gl_engine.h

@@ -358,6 +358,7 @@ class MockGLEngine : public Engine {
 
   // ImGui
   void initializeImGui() override;
+  void configureImGui() override;
   void shutdownImGui() override;
   void ImGuiNewFrame() override;
   void ImGuiRender() override;

include/polyscope/render/opengl/gl_engine_egl.h

@@ -69,6 +69,7 @@ class GLEngineEGL : public GLEngine {
   // === ImGui
 
   void initializeImGui() override;
+  void configureImGui() override;
   void shutdownImGui() override;
   void ImGuiNewFrame() override;
   void ImGuiRender() override;

include/polyscope/render/opengl/gl_engine_glfw.h

@@ -77,10 +77,13 @@ class GLEngineGLFW : public GLEngine {
   void shutdownImGui() override;
   void ImGuiNewFrame() override;
   void ImGuiRender() override;
+  void configureImGui() override;
 
 protected:
   // Internal windowing and engine details
   GLFWwindow* mainWindow = nullptr;
+
+  void setUIScaleFromSystemDPI();
 };
 
 } // namespace backend_openGL3

include/polyscope/scalar_quantity.ipp

@@ -147,7 +147,7 @@ void ScalarQuantity<QuantityT>::buildScalarUI() {
   // Isolines
   if (isolinesEnabled.get()) {
 
-    ImGui::PushItemWidth(100);
+    ImGui::PushItemWidth(100 * options::uiScale);
 
 
     auto styleName = [](const IsolineStyle& m) -> std::string {

src/camera_view.cpp

@@ -386,7 +386,7 @@ void CameraView::buildCustomUI() {
 
 void CameraView::buildCustomOptionsUI() {
 
-  ImGui::PushItemWidth(150);
+  ImGui::PushItemWidth(150 * options::uiScale);
 
   if (widgetFocalLengthUpper == -777) widgetFocalLengthUpper = 2. * (*widgetFocalLength.get().getValuePtr());
   if (ImGui::SliderFloat("widget focal length", widgetFocalLength.get().getValuePtr(), 0, widgetFocalLengthUpper,

src/curve_network.cpp

@@ -411,7 +411,7 @@ void CurveNetwork::buildCustomUI() {
     setColor(getColor());
   }
   ImGui::SameLine();
-  ImGui::PushItemWidth(100);
+  ImGui::PushItemWidth(100 * options::uiScale);
   if (ImGui::SliderFloat("Radius", radius.get().getValuePtr(), 0.0, .1, "%.5f",
                          ImGuiSliderFlags_Logarithmic | ImGuiSliderFlags_NoRoundToFormat)) {
     radius.manuallyChanged();