Part of #1459: the window's surface may be as large as the graphics adapter allows

apps/vectorcraft/src/gpu.rs

@@ -113,6 +113,13 @@ pub fn backends(default: Backends, env_set: bool) -> Backends {
     if cfg!(windows) && !env_set { Backends::DX12 | Backends::GL } else { default }
 }
 
+/// The largest texture side to ask the device for, which bounds the window's surface: the
+/// adapter's own limit when it is above eframe's `default` (8192 px), so a window larger than
+/// that keeps its surface (#1459). Never below `default`, which is what was asked for before.
+pub fn surface_limit(default: u32, adapter: u32) -> u32 {
+    default.max(adapter)
+}
+
 /// One adapter, as [`adapter_order`] sees it.
 #[derive(Clone, Debug)]
 pub struct Candidate {
@@ -547,6 +554,14 @@ mod tests {
         Candidate { key: format!("{backend:?}:{name}"), name: name.into(), backend, device_type, pci: (0, 0), presents: true }
     }
 
+    /// #1459: a 9048 px wide window (two display scales' ratio past 8192) fits an adapter that
+    /// takes 16384 px textures; an adapter with less than eframe asks for changes nothing.
+    #[test]
+    fn the_surface_may_be_as_large_as_the_adapter_allows() {
+        assert_eq!(surface_limit(8192, 16384), 16384);
+        assert_eq!(surface_limit(8192, 4096), 8192);
+    }
+
     fn names(c: &[Candidate], order: &[usize]) -> Vec<String> {
         order.iter().map(|&i| c[i].name.clone()).collect()
     }

apps/vectorcraft/src/main.rs

@@ -752,6 +752,16 @@ fn main() -> std::process::ExitCode {
             // losing the device before the first frame (#1194). `WGPU_DX12_COMPILER` picks another.
             create.instance_descriptor.backend_options.dx12.shader_compiler =
                 eframe::wgpu::Dx12Compiler::from_env().unwrap_or(eframe::wgpu::Dx12Compiler::Fxc);
+            // The window's surface may be as large as the adapter allows, not eframe's fixed
+            // 8192 px: a window stretched over several monitors, or grown by a display scale
+            // change, otherwise fails to configure its surface and the app closes (#1459).
+            let device = create.device_descriptor.clone();
+            create.device_descriptor = std::sync::Arc::new(move |adapter: &eframe::wgpu::Adapter| {
+                let mut descriptor = device(adapter);
+                let limit = &mut descriptor.required_limits.max_texture_dimension_2d;
+                *limit = gpu::surface_limit(*limit, adapter.limits().max_texture_dimension_2d);
+                descriptor
+            });
         }
         options
     };