rework high-dpi auto-setting to fix it on macOS (#347)

* rework high-dpi handling for macOS

* always start with default style in config

Author: nmwsharp

examples/demo-app/demo_app.cpp

@@ -879,7 +879,7 @@ int main(int argc, char** argv) {
   // polyscope::view::windowWidth = 600;
   // polyscope::view::windowHeight = 800;
   // polyscope::options::maxFPS = -1;
-  polyscope::options::verbosity = 100;
+  polyscope::options::verbosity = 101;
   polyscope::options::enableRenderErrorChecks = true;
   polyscope::options::allowHeadlessBackends = true;
 

src/imgui_config.cpp

@@ -16,13 +16,16 @@ const unsigned int* getLatoRegularCompressedData();
 
 void configureImGuiStyle() {
 
-  // Style
   ImGuiStyle* style = &ImGui::GetStyle();
-  style->WindowRounding = 1 * options::uiScale;
-  style->FrameRounding = 1 * options::uiScale;
-  style->FramePadding.y = 4 * options::uiScale;
-  style->ScrollbarRounding = 1 * options::uiScale;
-  style->ScrollbarSize = 20 * options::uiScale;
+  *style = ImGuiStyle(); // apply the default style as a starting point
+
+  // Style
+  style->WindowRounding = 1;
+  style->FrameRounding = 1;
+  style->FramePadding.y = 4;
+  style->ScrollbarRounding = 1;
+  style->ScrollbarSize = 20;
+  style->ScaleAllSizes(options::uiScale);
 
 
   // Colors
@@ -77,21 +80,32 @@ std::tuple<ImFontAtlas*, ImFont*, ImFont*> prepareImGuiFonts() {
 
   ImGuiIO& io = ImGui::GetIO();
 
+  ImVec2 windowSize{static_cast<float>(view::windowWidth), static_cast<float>(view::windowHeight)};
+  ImVec2 bufferSize{static_cast<float>(view::bufferWidth), static_cast<float>(view::bufferHeight)};
+  ImVec2 imguiCoordScale = {bufferSize.x / windowSize.x, bufferSize.y / windowSize.y};
+
   // outputs
   ImFontAtlas* fontAtlas;
   ImFont* regularFont;
   ImFont* monoFont;
 
+  float fontSize = 16.0 * options::uiScale;
+  fontSize = std::max(1.0f, std::roundf(fontSize));
+
   { // add regular font
     ImFontConfig config;
+    config.RasterizerDensity = std::max(imguiCoordScale.x, imguiCoordScale.y);
     regularFont = io.Fonts->AddFontFromMemoryCompressedTTF(render::getLatoRegularCompressedData(),
-                                                           render::getLatoRegularCompressedSize(), options::uiScale*18.0f, &config);
+                                                           render::getLatoRegularCompressedSize(),
+                                                           options::uiScale * 18.0f, &config);
   }
 
   { // add mono font
     ImFontConfig config;
+    config.RasterizerDensity = std::max(imguiCoordScale.x, imguiCoordScale.y);
     monoFont = io.Fonts->AddFontFromMemoryCompressedTTF(render::getCousineRegularCompressedData(),
-                                                        render::getCousineRegularCompressedSize(), options::uiScale*16.0f, &config);
+                                                        render::getCousineRegularCompressedSize(),
+                                                        options::uiScale * 16.0f, &config);
   }
 
   // io.Fonts->AddFontFromFileTTF("test-font-name.ttf", 16);

src/render/opengl/gl_engine.cpp

@@ -1078,7 +1078,7 @@ void GLCompiledProgram::compileGLProgram(const std::vector<ShaderStageSpecificat
       if (options::verbosity > 2) {
         printShaderInfoLog(h);
       }
-      if (options::verbosity > 100) {
+      if (options::verbosity > 200) {
         std::cout << "Program text:" << std::endl;
         std::cout << s.src.c_str() << std::endl;
       }

src/render/opengl/gl_engine_glfw.cpp

@@ -51,7 +51,7 @@ void GLEngineGLFW::initialize() {
   glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
 
   // This tells GLFW to scale window size/positioning/content based on the system-reported DPI scaling factor
-  // However, it can lead to some confusing behaviors, for instance, on linux with scaling=200%, if the user 
+  // However, it can lead to some confusing behaviors, for instance, on linux with scaling=200%, if the user
   // sets view::windowWidth = 1280, they might get back a window with windowWidth == bufferWidth == 2560,
   // which is quite confusing.
   // For this reason we _do not_ set this hint. If desired, the user can specify a windowWidth = 1280*uiScale,
@@ -80,14 +80,6 @@ void GLEngineGLFW::initialize() {
 
   setWindowResizable(view::windowResizable);
 
-  // Set the UI scale to account for system-requested DPI scaling
-  // Currently we do *not* watch for changes of this value e.g. if a window moves between
-  // monitors with different DPI behaviors. We could, but it would require some logic to
-  // avoid overwriting values that a user might have set.
-  if(options::uiScale < 0) { // only set from system if the value is -1, meaning not set yet
-    setUIScaleFromSystemDPI();
-  }
-
 // === Initialize openGL
 // Load openGL functions (using GLAD)
 #ifndef __APPLE__
@@ -117,18 +109,39 @@ void GLEngineGLFW::initialize() {
     // glClearDepth(1.);
   }
 
+  // Set the UI scale to account for system-requested DPI scaling
+  // Currently we do *not* watch for changes of this value e.g. if a window moves between
+  // monitors with different DPI behaviors. We could, but it would require some logic to
+  // avoid overwriting values that a user might have set.
+  if (options::uiScale < 0) { // only set from system if the value is -1, meaning not set yet
+    setUIScaleFromSystemDPI();
+  }
+
   populateDefaultShadersAndRules();
 }
 
 void GLEngineGLFW::setUIScaleFromSystemDPI() {
-  
-  float xScale, dont_use_yScale;
-  glfwGetWindowContentScale(mainWindow, &xScale, &dont_use_yScale);
 
-  // clamp to values within [1x,4x] scaling
-  xScale = std::fmin(std::fmax(xScale, 1.0f), 4.0f);
+  // logic adapted from a helpful imgui issue here: https://github.com/ocornut/imgui/issues/6967#issuecomment-2833882081
+
+  ImVec2 windowSize{static_cast<float>(view::windowWidth), static_cast<float>(view::windowHeight)};
+  ImVec2 bufferSize{static_cast<float>(view::bufferWidth), static_cast<float>(view::bufferHeight)};
+  ImVec2 imguiCoordScale = {bufferSize.x / windowSize.x, bufferSize.y / windowSize.y};
 
-  options::uiScale = xScale;
+  ImVec2 contentScale;
+  glfwGetWindowContentScale(mainWindow, &contentScale.x, &contentScale.y);
+
+  float sx = contentScale.x / imguiCoordScale.x;
+  float sy = contentScale.y / imguiCoordScale.y;
+  options::uiScale = std::max(sx, sy);
+  // clamp to values within [0.5x,4x] scaling
+  options::uiScale = std::fmin(std::fmax(options::uiScale, 0.5f), 4.0f);
+
+  info(100, "window size: " + std::to_string(view::windowWidth) + "," + std::to_string(view::windowHeight));
+  info(100, "buffer size: " + std::to_string(view::bufferWidth) + "," + std::to_string(view::bufferHeight));
+  info(100, "imguiCoordScale: " + std::to_string(imguiCoordScale.x) + "," + std::to_string(imguiCoordScale.y));
+  info(100, "contentScale: " + std::to_string(contentScale.x) + "," + std::to_string(contentScale.y));
+  info(100, "computed uiScale: " + std::to_string(options::uiScale));
 }
 
 void GLEngineGLFW::initializeImGui() {
@@ -146,7 +159,7 @@ void GLEngineGLFW::initializeImGui() {
 
 void GLEngineGLFW::configureImGui() {
 
-  if(options::uiScale < 0){
+  if (options::uiScale < 0) {
     exception("uiScale is < 0. Perhaps it wasn't initialized?");
   }
 
@@ -161,7 +174,7 @@ void GLEngineGLFW::configureImGui() {
 
     ImFontAtlas* _unused;
     std::tie(_unused, regularFont, monoFont) = options::prepareImGuiFontsCallback();
-    
+
     ImGui_ImplOpenGL3_CreateFontsTexture();
   }
 
@@ -172,7 +185,6 @@ void GLEngineGLFW::configureImGui() {
 }
 
 
-
 void GLEngineGLFW::shutdown() {
   checkError();
   shutdownImGui();