From f12d29899c80551ce7cbff524ffc5901301bb9f7 Mon Sep 17 00:00:00 2001
From: reuk <reuk@users.noreply.github.com>
Date: Mon, 20 Jan 2025 12:56:28 +0000
Subject: [PATCH] Direct2D: Remove SetDpi call in startFrame

Previously, plugins and standalone apps could produce slightly different
visual results, particularly anti-aliasing, when displaying on a display
with native scaling applied. The discrepancy was caused by SetDpi being
called with a larger-than-default value (e.g. 192 DPI on a 200% scaled
display) in a standalone app, whereas SetDpi would always be called with
the default value of 96 in a plugin.

Keeping the default value seems to produce better results, so standalone
apps will now retain the default DPI.
---
 .../native/juce_Direct2DGraphicsContext_windows.cpp        | 7 ++-----
 .../native/juce_Direct2DHwndContext_windows.cpp            | 4 ++--
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/modules/juce_graphics/native/juce_Direct2DGraphicsContext_windows.cpp b/modules/juce_graphics/native/juce_Direct2DGraphicsContext_windows.cpp
index 1417c64cd3..e0cc632802 100644
--- a/modules/juce_graphics/native/juce_Direct2DGraphicsContext_windows.cpp
+++ b/modules/juce_graphics/native/juce_Direct2DGraphicsContext_windows.cpp
@@ -610,7 +610,7 @@ public:
         popAllSavedStates();
     }
 
-    virtual SavedState* startFrame (float dpiScale)
+    virtual SavedState* startFrame()
     {
         prepare();
 
@@ -636,9 +636,6 @@ public:
         // Init device context transform
         resetTransform (deviceContext);
 
-        const auto effectiveDpi = USER_DEFAULT_SCREEN_DPI * dpiScale;
-        deviceContext->SetDpi (effectiveDpi, effectiveDpi);
-
         // Start drawing
         deviceContext->SetTarget (getDeviceContextTarget());
         deviceContext->BeginDraw();
@@ -899,7 +896,7 @@ bool Direct2DGraphicsContext::startFrame (float dpiScale)
 {
     const auto pimpl = getPimpl();
     const auto paintAreas = pimpl->getPaintAreas();
-    currentState = pimpl->startFrame (dpiScale);
+    currentState = pimpl->startFrame();
 
     if (currentState == nullptr)
         return false;
diff --git a/modules/juce_graphics/native/juce_Direct2DHwndContext_windows.cpp b/modules/juce_graphics/native/juce_Direct2DHwndContext_windows.cpp
index 0e1c7b356d..afea108853 100644
--- a/modules/juce_graphics/native/juce_Direct2DHwndContext_windows.cpp
+++ b/modules/juce_graphics/native/juce_Direct2DHwndContext_windows.cpp
@@ -258,11 +258,11 @@ public:
         JUCE_TRACE_EVENT_INT_RECT (etw::repaint, etw::paintKeyword, snappedRectangle);
     }
 
-    SavedState* startFrame (float dpiScale) override
+    SavedState* startFrame() override
     {
         setSize (getClientRect());
 
-        auto* savedState = Pimpl::startFrame (dpiScale);
+        auto* savedState = Pimpl::startFrame();
 
         if (savedState == nullptr)
             return nullptr;