feat(core): Expose descriptor validation separately from create_texture

Author: andyleiserson

CHANGELOG.md

@@ -47,7 +47,7 @@ Bottom level categories:
 #### General
 
 - Support the `wasm64-unknown-unknown` target for the web backend. Building for wasm64 requires a nightly toolchain with `-Z build-std=std,panic_abort`. By @nickbabcock in [#9836](https://github.com/gfx-rs/wgpu/pull/9836).
-- `wgpu-core` now exposes a `validate_device_descriptor` function that validates a device descriptor as `request_device` would. This may be useful in conjunction with `create_device_from_hal`. By @andyleiserson in [#9967](https://github.com/gfx-rs/wgpu/pull/9967).
+- `wgpu-core` now exposes `validate_device_descriptor` and `validate_texture_descriptor` functions that perform the same descriptor validation the corresponding resource creation APIs would, without actually creating a resource. This may be useful in conjunction with hal raw APIs. By @andyleiserson in [#9967](https://github.com/gfx-rs/wgpu/pull/9967) and TBD.
 
 #### Hal
 

wgpu-core/src/device/global.rs

@@ -254,6 +254,18 @@ impl Global {
         (id, error)
     }
 
+    pub fn device_validate_texture_descriptor(
+        &self,
+        device_id: DeviceId,
+        desc: &resource::TextureDescriptor,
+    ) -> Option<resource::CreateTextureError> {
+        self.hub
+            .devices
+            .get(device_id)
+            .validate_texture_descriptor(desc)
+            .err()
+    }
+
     /// # Safety
     ///
     /// - `hal_texture` must be created from `device_id` corresponding raw handle.

wgpu-core/src/device/resource.rs

@@ -1662,13 +1662,20 @@ impl Device {
         }
     }
 
-    fn create_texture_inner(
+    pub fn validate_texture_descriptor(
         self: &Arc<Self>,
         desc: &resource::TextureDescriptor,
-    ) -> Result<Arc<Texture>, resource::CreateTextureError> {
-        use resource::{CreateTextureError, TextureDimensionError};
+    ) -> Result<(), resource::CreateTextureError> {
+        self.validate_texture_descriptor_inner(desc)?;
+        Ok(())
+    }
 
-        self.check_is_valid()?;
+    fn validate_texture_descriptor_inner(
+        self: &Arc<Self>,
+        desc: &resource::TextureDescriptor,
+    ) -> Result<(wgt::TextureFormatFeatures, Vec<TextureFormat>), resource::CreateTextureError>
+    {
+        use resource::{CreateTextureError, TextureDimensionError};
 
         if desc.usage.is_empty() || desc.usage.contains_unknown_bits() {
             return Err(CreateTextureError::InvalidUsage(desc.usage));
@@ -1939,6 +1946,17 @@ impl Device {
             self.require_downlevel_flags(wgt::DownlevelFlags::VIEW_FORMATS)?;
         }
 
+        Ok((format_features, hal_view_formats))
+    }
+
+    fn create_texture_inner(
+        self: &Arc<Self>,
+        desc: &resource::TextureDescriptor,
+    ) -> Result<Arc<Texture>, resource::CreateTextureError> {
+        self.check_is_valid()?;
+
+        let (format_features, hal_view_formats) = self.validate_texture_descriptor_inner(desc)?;
+
         let hal_usage = conv::map_texture_usage_for_texture(desc, &format_features);
 
         let hal_desc = hal::TextureDescriptor {