From f0a08826a3984e5bc5d794fcbf6f1864942e8c13 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Benoi=CC=82t=20Rouleau?= <benoit.rouleau@icloud.com>
Date: Sat, 25 Jul 2026 22:27:24 -0400
Subject: [PATCH] ios: honour Conf::high_dpi on the Metal path
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`create_metal_view` took `_high_dpi` and never used it. `MTKView`
sizes its drawable from `bounds * contentScaleFactor`, which
defaults to the screen's native scale, so `high_dpi: false` had no
effect and the drawable was always native resolution.

The display-size branch that reads `contentScaleFactor` then
reported that same native size, so the two agreed only because
neither honoured the flag.

Applied once the view is in a window rather than at creation, for
two reasons. Moving a view into a window re-derives its
`contentScaleFactor` from that window's screen, so a value set at
creation does not survive. And changing it resizes the drawable,
whose `drawableSizeWillChange:` reaches for `NATIVE_DISPLAY` —
which at creation time the backend has not initialized yet.

Placed after `makeKeyAndVisible`, this covers the OpenGL view as
well, which sets the scale at creation and loses it the same way.
---
 src/native/ios.rs | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/native/ios.rs b/src/native/ios.rs
index 78ba78dd..2913666f 100644
--- a/src/native/ios.rs
+++ b/src/native/ios.rs
@@ -503,7 +503,7 @@ unsafe fn create_opengl_view(screen_rect: NSRect, _sample_count: i32, high_dpi:
     }
 }
 
-unsafe fn create_metal_view(screen_rect: NSRect, sample_count: i32, _high_dpi: bool) -> View {
+unsafe fn create_metal_view(screen_rect: NSRect, sample_count: i32) -> View {
     let mtk_view_obj: ObjcId = msg_send![define_glk_or_mtk_view(class!(MTKView)), alloc];
     let mtk_view_obj: ObjcId = msg_send![mtk_view_obj, initWithFrame: screen_rect];
 
@@ -586,7 +586,7 @@ pub fn define_app_delegate() -> *const Class {
                     create_opengl_view(screen_rect, conf.sample_count, conf.high_dpi)
                 }
                 AppleGfxApi::Metal => {
-                    create_metal_view(screen_rect, conf.sample_count, conf.high_dpi)
+                    create_metal_view(screen_rect, conf.sample_count)
                 }
             };
 
@@ -728,6 +728,14 @@ pub fn define_app_delegate() -> *const Class {
             msg_send_![window, addSubview: view];
             msg_send_![window, setRootViewController: view_ctrl];
             msg_send_![window, makeKeyAndVisible];
+
+            // `MTKView` loses a `contentScaleFactor` set before it has a window: moving it in
+            // re-derives the scale from that window's screen. A no-op for `GLKView`, which keeps
+            // what `create_opengl_view` set. Here rather than at creation because the resize this
+            // triggers reaches the backend, which is initialized by now.
+            if !crate::native_display().lock().unwrap().high_dpi {
+                msg_send_![view, setContentScaleFactor: 1.0];
+            }
         }
     }