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

This reverts commit f318b856ed055f1952276355f811153f6b29c93e.
It appears this reliably causes CppunitTest_vcl_backend_test to fail on macOS on
at least tb69, see e.g. <https://ci.libreoffice.org/job/gerrit_mac/82587/
consoleFull#-500134232d893063f-7f3d-4b7e-b56f-4e0f225817cd> and
<https://ci.libreoffice.org/job/gerrit_mac/82592/
consoleFull#-500134232d893063f-7f3d-4b7e-b56f-4e0f225817cd>,

[_RUN_____] BackendTest::testDrawBlendExtended
/Users/tdf/lode/jenkins/workspace/lo_gerrit/Config/macosx_clang_dbgutil/vcl/qa/cppunit/BackendTest.cxx:688:BackendTest::testDrawBlendExtended
equality assertion failed
- Expected: c[000080ff]
- Actual  : c[ffffffff]

BackendTest::testDrawBlendExtended finished in: 1ms
[_RUN_____] BackendTest::testDrawAlphaBitmapMirrored
/Users/tdf/lode/jenkins/workspace/lo_gerrit/Config/macosx_clang_dbgutil/vcl/qa/cppunit/BackendTest.cxx:749:BackendTest::testDrawAlphaBitmapMirrored
equality assertion failed
- Expected: c[ff0000ff]
- Actual  : c[000000ff]

BackendTest::testDrawAlphaBitmapMirrored finished in: 1ms
[_RUN_____] BackendTest::testTdf124848
/Users/tdf/lode/jenkins/workspace/lo_gerrit/Config/macosx_clang_dbgutil/vcl/qa/cppunit/BackendTest.cxx:808:BackendTest::testTdf124848
equality assertion failed
- Expected: c[000000ff]
- Actual  : c[ffffffff]

And it also causes my local macOS 11.1 ARM64 build to consistently fail that
way, both the original patch set 1 (with the older parent) and the submitted
patch set 2 (with a newer parent).

Change-Id: I2c36fada271e8bc300b6caa19370d8e8bb1e7599
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/110055
Reviewed-by: Tor Lillqvist <tml@collabora.com>
Tested-by: Jenkins

4 files changed, 36 insertions, 25 deletions

diff --git a/vcl/inc/quartz/salgdi.h b/vcl/inc/quartz/salgdi.h
index 4897d96c6089..69b735787bdc 100644
--- a/vcl/inc/quartz/salgdi.h
+++ b/vcl/inc/quartz/salgdi.h
@@ -174,6 +174,7 @@ class AquaSalGraphics : public SalGraphics
 #ifdef MACOSX
     /// is this a window graphics
     bool                                    mbWindow;
+    bool                                    mbWindowScaling;
 
 #else // IOS
 
diff --git a/vcl/osx/salgdiutils.cxx b/vcl/osx/salgdiutils.cxx
index f3ddd946f699..01626d348999 100644
--- a/vcl/osx/salgdiutils.cxx
+++ b/vcl/osx/salgdiutils.cxx
@@ -35,35 +35,37 @@
 #include <osx/salframe.h>
 #include <osx/saldata.hxx>
 
-// 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.
+float AquaSalGraphics::GetWindowScaling()
+{
+    float fScale = 1.0f;
 
-// 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.
+#ifdef MACOSX
 
-static bool  bWindowScaling = false;
-static float fWindowScale = 1.0f;
+    // 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.
 
-float AquaSalGraphics::GetWindowScaling()
-{
-    if (!bWindowScaling)
+    // 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)
     {
-        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;
-        }
+        fScale = 2.0f;
+        return fScale;
+    }
+
+#endif
+
+    AquaSalFrame *pSalFrame = mpFrame;
+    if (!pSalFrame)
+        pSalFrame = static_cast<AquaSalFrame *>(GetSalData()->mpInstance->anyFrame());
+    if (pSalFrame)
+    {
+        NSWindow *pNSWindow = pSalFrame->getNSWindow();
+        if (pNSWindow)
+            fScale = [pNSWindow backingScaleFactor];
     }
-    return fWindowScale;
+    return fScale;
 }
 
 void AquaSalGraphics::SetWindowGraphics( AquaSalFrame* pFrame )
diff --git a/vcl/osx/salmacos.cxx b/vcl/osx/salmacos.cxx
index 5b1265130cd0..0f41dd9e8c4a 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/ios/salios.cxx.
+// comment is written) as they were before that commit in vcl/isx/salios.cxx.
 
 #include <sal/config.h>
 #include <sal/log.hxx>
diff --git a/vcl/quartz/salgdi.cxx b/vcl/quartz/salgdi.cxx
index ae6a40cfd4e2..8dd9ec9222ad 100644
--- a/vcl/quartz/salgdi.cxx
+++ b/vcl/quartz/salgdi.cxx
@@ -205,6 +205,14 @@ AquaSalGraphics::AquaSalGraphics()
     , mbVirDev( false )
 #ifdef MACOSX
     , mbWindow( false )
+
+    // Window scaling independent from main display may be forced by setting VCL_MACOS_FORCE_WINDOW_SCALING environment variable. If
+    // unset window scaling from main display will be used. After implementation of full support of scaled displays window scaling
+    // will be set to 2.0f for macOS as default.
+
+    // TODO: After implementation of full support of scaled displays VCL_FORCE_WINDOW_SCALING control has to be removed.
+
+    , mbWindowScaling( getenv("VCL_MACOS_FORCE_WINDOW_SCALING") )
 #else
     , mbForeignContext( false )
 #endif