tdf#138122 Detect window scaling for multi display configurations on macOS

(1) Activate window scaling when at least one retina display is connected

(2) Remove environment variable VCL_MACOS_FORCE_WINDOW_SCALING

(3) Disable related unit tests unless bitmap scaling has been implemented

Change-Id: I218119a21e319e22bf17c609608724fce180f000
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/111267
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

2 files changed, 26 insertions, 28 deletions

diff --git a/vcl/osx/salgdiutils.cxx b/vcl/osx/salgdiutils.cxx
index 01626d348999..f3ddd946f699 100644
--- a/vcl/osx/salgdiutils.cxx
+++ b/vcl/osx/salgdiutils.cxx
@@ -35,37 +35,35 @@
 #include <osx/salframe.h>
 #include <osx/saldata.hxx>
 
-float AquaSalGraphics::GetWindowScaling()
-{
-    float fScale = 1.0f;
-
-#ifdef MACOSX
-
-    // Window scaling independent from main display may be forced by setting VCL_MACOS_FORCE_WINDOW_SCALING environment variable
-    // whose setting is stored in mbWindowScaling. After implementation of full support of scaled displays window scaling will be
-    // set to 2.0f for macOS as default. This will allow moving of windows between non retina and retina displays without blurry
-    // text and graphics.
+// TODO: Scale will be set to 2.0f as default after implementation of full scaled display support . This will allow moving of
+// windows between non retina and retina displays without blurry text and graphics. Static variables have to be removed thereafter.
 
-    // TODO: After implementation of full support of scaled displays code has to be modified to set a scaling of 2.0f as default.
-
-    if (mbWindowScaling)
-    {
-        fScale = 2.0f;
-        return fScale;
-    }
+// Currently scaled display support is not implemented for bitmaps. This will cause a slight performance degradation on displays
+// with single precision. To preserve performance for now, window scaling is only activated if at least one display with double
+// precision is present. Moving windows between displays is then possible without blurry text and graphics too. Adapting window
+// scaling when displays are added while application is running is not supported.
 
-#endif
+static bool  bWindowScaling = false;
+static float fWindowScale = 1.0f;
 
-    AquaSalFrame *pSalFrame = mpFrame;
-    if (!pSalFrame)
-        pSalFrame = static_cast<AquaSalFrame *>(GetSalData()->mpInstance->anyFrame());
-    if (pSalFrame)
+float AquaSalGraphics::GetWindowScaling()
+{
+    if (!bWindowScaling)
     {
-        NSWindow *pNSWindow = pSalFrame->getNSWindow();
-        if (pNSWindow)
-            fScale = [pNSWindow backingScaleFactor];
+        NSArray *aScreens = [NSScreen screens];
+        if (aScreens != nullptr)
+        {
+            int nScreens = [aScreens count];
+            for (int i = 0; i < nScreens; i++)
+            {
+                float fScale = [[aScreens objectAtIndex:i] backingScaleFactor];
+                if (fScale > fWindowScale)
+                  fWindowScale = fScale;
+            }
+            bWindowScaling = true;
+        }
     }
-    return fScale;
+    return fWindowScale;
 }
 
 void AquaSalGraphics::SetWindowGraphics( AquaSalFrame* pFrame )
diff --git a/vcl/osx/salmacos.cxx b/vcl/osx/salmacos.cxx
index 0f41dd9e8c4a..f6403dea2725 100644
--- a/vcl/osx/salmacos.cxx
+++ b/vcl/osx/salmacos.cxx
@@ -19,7 +19,7 @@
 
 // This file contains the macOS-specific versions of the functions which were touched in the commit
 // to fix tdf#138122. The iOS-specific versions of these functions are kept (for now, when this
-// comment is written) as they were before that commit in vcl/isx/salios.cxx.
+// comment is written) as they were before that commit in vcl/ios/salios.cxx.
 
 #include <sal/config.h>
 #include <sal/log.hxx>
@@ -331,7 +331,7 @@ bool AquaSalVirtualDevice::SetSize(tools::Long nDX, tools::Long nDY)
 
     mnWidth = nDX;
     mnHeight = nDY;
-    fScale = mpGraphics->GetWindowScaling();
+    fScale = AquaSalGraphics::GetWindowScaling();
     CGColorSpaceRef aColorSpace;
     uint32_t nFlags;
     if (mnBitmapDepth && (mnBitmapDepth < 16))