GUI: detect UI scale factor when moving window

src/gui/gui.cpp

@@ -3491,6 +3491,7 @@ bool FurnaceGUI::loop() {
               scrX=ev.window.data1;
               scrY=ev.window.data2;
               updateWindow=true;
+              shallDetectScale=2;
               logV("window moved to %dx%d",scrX,scrY);
               break;
             case SDL_WINDOWEVENT_SIZE_CHANGED:
@@ -6140,7 +6141,38 @@ bool FurnaceGUI::loop() {
     if (shallDetectScale) {
       if (--shallDetectScale<1) {
         if (settings.dpiScale<0.5f) {
-          applyUISettings();
+          const char* videoBackend=SDL_GetCurrentVideoDriver();      
+          double newScale=getScaleFactor(videoBackend,sdlWin);
+          if (newScale<0.1f) {
+            logW("scale what?");
+            newScale=1.0f;
+          }
+
+          if (newScale!=dpiScale) {
+            logD("auto UI scale changed (%f != %f) - applying settings...",newScale,dpiScale);
+            ImGui::GetIO().Fonts->Clear();
+
+            applyUISettings();
+
+            if (rend) rend->destroyFontsTexture();
+            if (!ImGui::GetIO().Fonts->Build()) {
+              logE("error while building font atlas!");
+              showError("error while loading fonts! please check your settings.");
+              ImGui::GetIO().Fonts->Clear();
+              mainFont=ImGui::GetIO().Fonts->AddFontDefault();
+              patFont=mainFont;
+              bigFont=mainFont;
+              headFont=mainFont;
+              if (rend) rend->destroyFontsTexture();
+              if (!ImGui::GetIO().Fonts->Build()) {
+                logE("error again while building font atlas!");
+              } else {
+                rend->createFontsTexture();
+              }
+            } else {
+              rend->createFontsTexture();
+            }
+          }
         }
       }
     }
@@ -6368,7 +6400,7 @@ bool FurnaceGUI::init() {
     dpiScale=settings.dpiScale;
   } else {
     logD("auto-detecting UI scale factor.");
-    dpiScale=getScaleFactor(videoBackend);
+    dpiScale=getScaleFactor(videoBackend,sdlWin);
     logD("scale factor: %f",dpiScale);
     if (dpiScale<0.1f) {
       logW("scale what?");

src/gui/macstuff.h

@@ -17,4 +17,4 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-double getMacDPIScale();
+double getMacDPIScale(void* sysWin, unsigned char isUIKit);

src/gui/macstuff.m

@@ -20,7 +20,28 @@
 #include <Cocoa/Cocoa.h>
 #include "macstuff.h"
 
-double getMacDPIScale() {
-  CGFloat val=[[NSScreen mainScreen] backingScaleFactor];
+double getMacDPIScale(void* sysWin, unsigned char isUIKit) {
+  NSScreen* screen=nil;
+  if (sysWin!=NULL) {
+    if (isUIKit) {
+      UIWindow* win=(UIWindow*)sysWin;
+      UIWindowScene* winScene=[win windowScene];
+      if (winScene!=nil) {
+        UIScreen* winScreen=[winScene screen];
+        CGFloat ret=[winScreen scale];
+        return (double)ret;
+      }
+    } else {
+      NSWindow* win=(NSWindow*)sysWin;
+      screen=[win screen];
+    }
+  }
+  if (screen==nil) {
+    screen=[NSScreen mainScreen];
+  }
+  if (screen==nil) {
+    return 1.0;
+  }
+  CGFloat val=[screen backingScaleFactor];
   return (double)val;
 }

src/gui/scaling.cpp

@@ -42,14 +42,23 @@ typedef int (*XDS)(void*);
 typedef int (*XDW)(void*,int);
 #endif
 
-double getScaleFactor(const char* driverHint) {
+double getScaleFactor(const char* driverHint, void* windowHint) {
   double ret=1.0;
 
   // Windows
 #ifdef _WIN32
   POINT nullPoint;
-  nullPoint.x=-1;
-  nullPoint.y=-1;
+  if (windowHint!=NULL) {
+    int px=0;
+    int py=0;
+
+    SDL_GetWindowPosition((SDL_Window*)windowHint,&px,&py);
+    nullPoint.x=px;
+    nullPoint.y=py;
+  } else {
+    nullPoint.x=-1;
+    nullPoint.y=-1;
+  }
   HMONITOR disp=MonitorFromPoint(nullPoint,MONITOR_DEFAULTTOPRIMARY);
 
   if (disp==NULL) {
@@ -93,12 +102,30 @@ double getScaleFactor(const char* driverHint) {
   return ret;
 #endif
 
-  // macOS - backingScaleFactor
+  // macOS
 #ifdef __APPLE__
   if (driverHint==NULL) {
-    return getMacDPIScale();
-  } else if (strcmp(driverHint,"cocoa")==0 || strcmp(driverHint,"uikit")==0) {
-    return getMacDPIScale();
+    return getMacDPIScale(NULL,false);
+  } else if (strcmp(driverHint,"cocoa")==0) {
+    void* nsWindow=NULL;
+    SDL_SysWMinfo wmInfo;
+    if (windowHint!=NULL) {
+      SDL_VERSION(&info.version)
+      if (SDL_GetWindowWMInfo((SDL_Window*)windowHint,&wmInfo)==SDL_TRUE) {
+        nsWindow=wmInfo.cocoa.window;
+      }
+    }
+    return getMacDPIScale(nsWindow,false);
+  } else if (strcmp(driverHint,"uikit")==0) {
+    void* uiWindow=NULL;
+    SDL_SysWMinfo wmInfo;
+    if (windowHint!=NULL) {
+      SDL_VERSION(&info.version)
+      if (SDL_GetWindowWMInfo((SDL_Window*)windowHint,&wmInfo)==SDL_TRUE) {
+        uiWindow=wmInfo.cocoa.window;
+      }
+    }
+    return getMacDPIScale(uiWindow,true);
   }
 #endif
 

src/gui/scaling.h

@@ -17,4 +17,4 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-double getScaleFactor(const char* driverHint);
+double getScaleFactor(const char* driverHint, void* windowHint);

src/gui/settings.cpp

@@ -4153,18 +4153,20 @@ void FurnaceGUI::applyUISettings(bool updateFonts) {
   setupLabel(settings.emptyLabel.c_str(),emptyLabel,3);
   setupLabel(settings.emptyLabel2.c_str(),emptyLabel2,2);
 
-  // get scale factor
-  const char* videoBackend=SDL_GetCurrentVideoDriver();
-  if (settings.dpiScale>=0.5f) {
-    logD("setting UI scale factor from config (%f).",settings.dpiScale);
-    dpiScale=settings.dpiScale;
-  } else {
-    logD("auto-detecting UI scale factor.");
-    dpiScale=getScaleFactor(videoBackend);
-    logD("scale factor: %f",dpiScale);
-    if (dpiScale<0.1f) {
-      logW("scale what?");
-      dpiScale=1.0f;
+  if (updateFonts) {
+    // get scale factor
+    const char* videoBackend=SDL_GetCurrentVideoDriver();
+    if (settings.dpiScale>=0.5f) {
+      logD("setting UI scale factor from config (%f).",settings.dpiScale);
+      dpiScale=settings.dpiScale;
+    } else {
+      logD("auto-detecting UI scale factor.");
+      dpiScale=getScaleFactor(videoBackend,sdlWin);
+      logD("scale factor: %f",dpiScale);
+      if (dpiScale<0.1f) {
+        logW("scale what?");
+        dpiScale=1.0f;
+      }
     }
   }