From e902050002dae11871eff89151dec7a8a895f3a6 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Thu, 6 Aug 2020 23:58:05 +0200
Subject: [PATCH] Return "logical" PPI from wxDisplay::GetPPI() in wxGTK3

Just scale the standard PPI by the scaling factor instead of trying to
compute the actual physical PPI, as the latter is not useful and is
incompatible with the value used by all the other applications.
---
 src/gtk/display.cpp | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/gtk/display.cpp b/src/gtk/display.cpp
index b1bdacb196..b21a0c2295 100644
--- a/src/gtk/display.cpp
+++ b/src/gtk/display.cpp
@@ -350,7 +350,17 @@ double wxDisplayImplGTK::GetScaleFactor() const
 
     return 1.0;
 }
-#endif // GTK+ 3.10
+
+wxSize wxDisplayImplGTK::GetPPI() const
+{
+    // The useful value of PPI is the scaled value of the default PPI and not
+    // the actual PPI computed by dividing the number of pixels by the physical
+    // screen size: this is what everyone else uses, and so we should do it
+    // too.
+    return wxDisplay::GetStdPPI()*GetScaleFactor();
+}
+
+#else // GTK+ < 3.10
 
 wxSize wxDisplayImplGTK::GetPPI() const
 {
@@ -370,6 +380,8 @@ wxSize wxDisplayImplGTK::GetPPI() const
     return ppi;
 }
 
+#endif // GTK+ 3.10
+
 wxSize wxDisplayImplGTK::GetSizeMM() const
 {
     wxSize sizeMM;