Dynamic DPI scaling (#1980)

* DPI scaling
 1. Add the ability to query the operating system's DPI scaling values
 2. Expose those values through a new Lua function
 3. Add an asset that sets the CEF gui and the Dashboard font sizes and placements based on the DPI scaling
 4. Add that new asset into the base_blank asset
* Add message when including the dpiscaling

apps/OpenSpace/main.cpp

@@ -28,6 +28,7 @@
 #include <openspace/engine/openspaceengine.h>
 #include <openspace/engine/windowdelegate.h>
 #include <openspace/interaction/joystickinputstate.h>
+#include <openspace/scripting/scriptengine.h>
 #include <openspace/util/keys.h>
 #include <ghoul/ghoul.h>
 #include <ghoul/filesystem/filesystem.h>
@@ -810,6 +811,36 @@ void setSgctDelegateFunctions() {
         vec2 scale = currentWindow->scale();
         return glm::vec2(scale.x, scale.y);
     };
+    sgctDelegate.osDpiScaling = []() {
+        ZoneScoped
+            
+        // Detect which DPI scaling to use
+        // 1. If there is a GUI window, use the GUI window's content scale value
+        const Window* dpiWindow = nullptr;
+        for (const std::unique_ptr<Window>& window : Engine::instance().windows()) {
+            if (window->hasTag("GUI")) {
+                dpiWindow = window.get();
+                break;
+            }
+        }
+
+        // 2. If there isn't a GUI window, use the first window's value
+        if (!dpiWindow) {
+            dpiWindow = Engine::instance().windows().front().get();
+        }
+
+        glm::vec2 scale = glm::vec2(1.f, 1.f);
+        glfwGetWindowContentScale(dpiWindow->windowHandle(), &scale.x, &scale.y);
+
+        if (scale.x != scale.y) {
+            LWARNING(fmt::format(
+                "Non-square window scaling detected ({0}x{1}), using {0}x{0} instead",
+                scale.x, scale.y
+            ));
+        }
+
+        return scale.x;
+    };
     sgctDelegate.hasGuiWindow = []() {
         ZoneScoped
 

data/assets/base_blank.asset

@@ -5,13 +5,16 @@ local propertyHelper = asset.require("util/property_helper")
 -- Specifying which other assets should be loaded in this scene
 asset.require("spice/base")
 
--- Load default key bindings applicable to most scenes
 asset.require("dashboard/default_dashboard")
+-- Load default key bindings applicable to most scenes
 asset.require("util/default_keybindings")
 
 -- Load web gui
 local webGui = asset.require("util/webgui")
 
+-- Scale the different UI components based on the operating system's DPI scaling value
+asset.require("util/dpiscaling")
+
 local toggle_trails = {
   Identifier = "os_default.toggle_trails",
   Name = "Toggle Trails",

data/assets/util/dpiscaling.asset

@@ -0,0 +1,37 @@
+asset.onInitialize(function ()
+  local scale = openspace.dpiScaling()
+  openspace.printInfo("Setting the DPI scaling factor to " .. tostring(scale))
+
+
+  if openspace.modules.isLoaded("CefWebGui") then
+  openspace.setPropertyValueSingle(
+      "Modules.CefWebGui.GuiScale",
+      openspace.getPropertyValue("Modules.CefWebGui.GuiScale") * scale
+    )
+  end
+
+  local dashboards = openspace.getProperty("Dashboard.*.FontSize");
+  for _, v in ipairs(dashboards) do
+    openspace.setPropertyValueSingle(
+      v,
+      openspace.getPropertyValue(v) * scale
+    )
+  end
+
+  local offset = openspace.getPropertyValue("Dashboard.StartPositionOffset")
+  openspace.setPropertyValueSingle(
+    "Dashboard.StartPositionOffset",
+    { offset[1] * scale, offset[2] * scale }
+  )
+end)
+
+asset.meta = {
+  Name = "DPI Scaling",
+  Version = "1.0",
+  Description = [[ Retrieves the DPI scaling from the operating system and applies it to 
+  a few selected places to make them scale better on "large resolution but small size"
+  monitors ]],
+  Author = "OpenSpace Team",
+  URL = "http://openspaceproject.com",
+  License = "MIT license"
+}

include/openspace/engine/windowdelegate.h

@@ -64,6 +64,8 @@ struct WindowDelegate {
 
     glm::vec2 (*dpiScaling)() = []() { return glm::vec2(1.f); };
 
+    float (*osDpiScaling)() = []() { return 1.f; };
+
     bool (*hasGuiWindow)() = []() { return false; };
 
     bool (*isGuiWindow)() = []() { return false; };

src/rendering/renderengine.cpp

@@ -1072,7 +1072,8 @@ scripting::LuaLibrary RenderEngine::luaLibrary() {
         {
             codegen::lua::AddScreenSpaceRenderable,
             codegen::lua::RemoveScreenSpaceRenderable,
-            codegen::lua::TakeScreenshot
+            codegen::lua::TakeScreenshot,
+            codegen::lua::DpiScaling
         }
     };
 }

src/rendering/renderengine_lua.inl

@@ -67,6 +67,12 @@ namespace {
     return static_cast<int>(screenshotNumber);
 }
 
+// Extracts the DPI scaling for either the GUI window or if there is no dedicated GUI
+// window, the first window.
+[[codegen::luawrap]] float dpiScaling() {
+    return openspace::global::windowDelegate->osDpiScaling();
+}
+
 #include "renderengine_lua_codegen.cpp"
 
 } // namespace