Internally scale VST2 UI size if host doesnt inform of scale factor

distrho/src/DistrhoPluginVST2.cpp

@@ -189,7 +189,8 @@ public:
               nullptr, // TODO file request
               nullptr,
               plugin->getInstancePointer(),
-              scaleFactor)
+              scaleFactor),
+          fHasScaleFactor(d_isNotZero(scaleFactor))
 # if !DISTRHO_PLUGIN_HAS_EXTERNAL_UI
         , fKeyboardModifiers(0)
 # endif
@@ -228,11 +229,21 @@ public:
         return fUI.getHeight();
     }
 
+    double getScaleFactor() const
+    {
+        return fUI.getScaleFactor();
+    }
+
     void setSampleRate(const double newSampleRate)
     {
         fUI.setSampleRate(newSampleRate, true);
     }
 
+    void notifyScaleFactorChanged(const double scaleFactor)
+    {
+        fUI.notifyScaleFactorChanged(scaleFactor);
+    }
+
     // -------------------------------------------------------------------
     // functions called from the plugin side, may block
 
@@ -387,9 +398,15 @@ protected:
         hostCallback(audioMasterAutomate, index, 0, nullptr, perValue);
     }
 
-    void setSize(const uint width, const uint height)
+    void setSize(uint width, uint height)
     {
-        // fUI.setWindowSize(width, height);
+        // figure out scale factor ourselves if the host doesn't support it
+        if (! fHasScaleFactor)
+        {
+            const double scaleFactor = fUI.getScaleFactor();
+            width /= scaleFactor;
+            height /= scaleFactor;
+        }
         hostCallback(audioMasterSizeWindow, width, height);
     }
 
@@ -421,6 +438,7 @@ private:
 
     // Plugin UI
     UIExporter fUI;
+    const bool fHasScaleFactor;
 # if !DISTRHO_PLUGIN_HAS_EXTERNAL_UI
     uint16_t fKeyboardModifiers;
 # endif
@@ -499,7 +517,7 @@ public:
         fVstRect.left    = 0;
         fVstRect.bottom  = 0;
         fVstRect.right   = 0;
-        fLastScaleFactor = 1.0f;
+        fLastScaleFactor = 0.0f;
 
         if (parameterCount != 0)
         {
@@ -670,6 +688,13 @@ public:
             {
                 fVstRect.right  = fVstUI->getWidth();
                 fVstRect.bottom = fVstUI->getHeight();
+                // figure out scale factor ourselves if the host doesn't support it
+                if (fLastScaleFactor == 0.0f)
+                {
+                    const double scaleFactor = fVstUI->getScaleFactor();
+                    fVstRect.right /= scaleFactor;
+                    fVstRect.bottom /= scaleFactor;
+                }
             }
             else
             {
@@ -678,6 +703,13 @@ public:
                                  fPlugin.getInstancePointer(), fLastScaleFactor);
                 fVstRect.right  = tmpUI.getWidth();
                 fVstRect.bottom = tmpUI.getHeight();
+                // figure out scale factor ourselves if the host doesn't support it
+                if (fLastScaleFactor == 0.0f)
+                {
+                    const double scaleFactor = tmpUI.getScaleFactor();
+                    fVstRect.right /= scaleFactor;
+                    fVstRect.bottom /= scaleFactor;
+                }
                 tmpUI.quit();
             }
             *(ERect**)ptr = &fVstRect;
@@ -998,7 +1030,15 @@ public:
         case effVendorSpecific:
 #if DISTRHO_PLUGIN_HAS_UI
             if (index == CCONST('P', 'r', 'e', 'S') && value == CCONST('A', 'e', 'C', 's'))
+            {
+                if (d_isEqual(fLastScaleFactor, opt))
+                    break;
+
                 fLastScaleFactor = opt;
+
+                if (fVstUI != nullptr)
+                    fVstUI->notifyScaleFactorChanged(opt);
+            }
 #endif
             break;
 

distrho/src/DistrhoUIInternal.hpp

@@ -59,7 +59,7 @@ public:
                const fileRequestFunc fileRequestCall,
                const char* const bundlePath = nullptr,
                void* const dspPtr = nullptr,
-               const double scaleFactor = 1.0,
+               const double scaleFactor = 0.0,
                const uint32_t bgColor = 0,
                const uint32_t fgColor = 0xffffffff)
         : ui(nullptr),
@@ -128,6 +128,11 @@ public:
         return uiData->window->getHeight();
     }
 
+    double getScaleFactor() const noexcept
+    {
+        return uiData->window->getScaleFactor();
+    }
+
     bool isVisible() const noexcept
     {
         return uiData->window->isVisible();
@@ -340,6 +345,13 @@ public:
 
     // -------------------------------------------------------------------
 
+    void notifyScaleFactorChanged(const double scaleFactor)
+    {
+        DISTRHO_SAFE_ASSERT_RETURN(ui != nullptr,);
+
+        ui->uiScaleFactorChanged(scaleFactor);
+    }
+
     void setSampleRate(const double sampleRate, const bool doCallback = false)
     {
         DISTRHO_SAFE_ASSERT_RETURN(ui != nullptr,);