From 7a0b17c0d39fbda40df65e7c2e4b917c31bf77c2 Mon Sep 17 00:00:00 2001
From: reuk <reuk@users.noreply.github.com>
Date: Wed, 3 Mar 2021 16:52:10 +0000
Subject: [PATCH] LinuxComponentPeer:  Fix scaling in custom windows created by
 plugins

Previously, things like PopupMenus which were created in their own
windows were not being scaled correctly on HiDPI displays on Linux.

This patch forces the display scale to 1.0 in plugins, meaning that
the transform applied to the main plugin window is the sole source
of truth for component scaling in plugins.
---
 .../native/juce_linux_Windowing.cpp           | 22 +++++++++----------
 .../native/x11/juce_linux_XWindowSystem.cpp   |  6 ++---
 .../native/x11/juce_linux_XWindowSystem.h     |  2 +-
 3 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/modules/juce_gui_basics/native/juce_linux_Windowing.cpp b/modules/juce_gui_basics/native/juce_linux_Windowing.cpp
index ea597e3347..453abc8417 100644
--- a/modules/juce_gui_basics/native/juce_linux_Windowing.cpp
+++ b/modules/juce_gui_basics/native/juce_linux_Windowing.cpp
@@ -85,8 +85,8 @@ public:
 
         updateScaleFactorFromNewBounds (bounds, false);
 
-        auto physicalBounds = (parentWindow == 0 ? Desktop::getInstance().getDisplays().logicalToPhysical (bounds)
-                               : bounds * currentScaleFactor);
+        auto physicalBounds = parentWindow == 0 ? Desktop::getInstance().getDisplays().logicalToPhysical (bounds)
+                                                : bounds * currentScaleFactor;
 
         WeakReference<Component> deletionChecker (&component);
 
@@ -103,13 +103,16 @@ public:
 
     Point<int> getScreenPosition (bool physical) const
     {
-        auto parentPosition = XWindowSystem::getInstance()->getParentScreenPosition();
+        auto physicalParentPosition = XWindowSystem::getInstance()->getPhysicalParentScreenPosition();
+        auto parentPosition = parentWindow == 0 ? Desktop::getInstance().getDisplays().physicalToLogical (physicalParentPosition)
+                                                : physicalParentPosition / currentScaleFactor;
 
-        auto screenBounds = (parentWindow == 0 ? bounds
-                                               : bounds.translated (parentPosition.x, parentPosition.y));
+        auto screenBounds = parentWindow == 0 ? bounds
+                                              : bounds.translated (parentPosition.x, parentPosition.y);
 
         if (physical)
-            return Desktop::getInstance().getDisplays().logicalToPhysical (screenBounds.getTopLeft());
+            return parentWindow == 0 ? Desktop::getInstance().getDisplays().logicalToPhysical (screenBounds.getTopLeft())
+                                     : screenBounds.getTopLeft() * currentScaleFactor;
 
         return screenBounds.getTopLeft();
     }
@@ -314,8 +317,8 @@ public:
 
             updateScaleFactorFromNewBounds (physicalBounds, true);
 
-            bounds = (parentWindow == 0 ? Desktop::getInstance().getDisplays().physicalToLogical (physicalBounds)
-                                        : physicalBounds / currentScaleFactor);
+            bounds = parentWindow == 0 ? Desktop::getInstance().getDisplays().physicalToLogical (physicalBounds)
+                                       : physicalBounds / currentScaleFactor;
         }
     }
 
@@ -433,9 +436,6 @@ private:
     //==============================================================================
     void updateScaleFactorFromNewBounds (const Rectangle<int>& newBounds, bool isPhysical)
     {
-        if (! JUCEApplicationBase::isStandaloneApp())
-            return;
-
         Point<int> translation = (parentWindow != 0 ? getScreenPosition (isPhysical) : Point<int>());
         const auto& desktop = Desktop::getInstance();
 
diff --git a/modules/juce_gui_basics/native/x11/juce_linux_XWindowSystem.cpp b/modules/juce_gui_basics/native/x11/juce_linux_XWindowSystem.cpp
index b8e6e0c7ed..4d0c06a390 100644
--- a/modules/juce_gui_basics/native/x11/juce_linux_XWindowSystem.cpp
+++ b/modules/juce_gui_basics/native/x11/juce_linux_XWindowSystem.cpp
@@ -1799,14 +1799,14 @@ Rectangle<int> XWindowSystem::getWindowBounds (::Window windowH, ::Window parent
         }
         else
         {
-            parentScreenPosition = Desktop::getInstance().getDisplays().physicalToLogical (Point<int> (rootX, rootY));
+            parentScreenPosition = Point<int> (rootX, rootY);
         }
     }
 
     return { wx, wy, (int) ww, (int) wh };
 }
 
-Point<int> XWindowSystem::getParentScreenPosition() const
+Point<int> XWindowSystem::getPhysicalParentScreenPosition() const
 {
     return parentScreenPosition;
 }
@@ -2424,7 +2424,7 @@ Array<Displays::Display> XWindowSystem::findDisplays (float masterScale) const
                                                   + ((static_cast<double> (crtc->height) * 25.4 * 0.5) / static_cast<double> (output->mm_height));
 
                                         auto scale = DisplayHelpers::getDisplayScale (output->name, d.dpi);
-                                        scale = (scale <= 0.1 ? 1.0 : scale);
+                                        scale = (scale <= 0.1 || ! JUCEApplicationBase::isStandaloneApp()) ? 1.0 : scale;
 
                                         d.scale = masterScale * scale;
 
diff --git a/modules/juce_gui_basics/native/x11/juce_linux_XWindowSystem.h b/modules/juce_gui_basics/native/x11/juce_linux_XWindowSystem.h
index 3f804a2fc6..dda192484d 100644
--- a/modules/juce_gui_basics/native/x11/juce_linux_XWindowSystem.h
+++ b/modules/juce_gui_basics/native/x11/juce_linux_XWindowSystem.h
@@ -109,7 +109,7 @@ public:
 
     BorderSize<int> getBorderSize   (::Window) const;
     Rectangle<int>  getWindowBounds (::Window, ::Window parentWindow);
-    Point<int> getParentScreenPosition() const;
+    Point<int> getPhysicalParentScreenPosition() const;
 
     bool contains (::Window, Point<int> localPos) const;