feat(core): Expose descriptor validation separately from create_texture (gfx-rs#9979)

Author: andyleiserson

CHANGELOG.md

@@ -47,8 +47,8 @@ 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).
 - Many types now offer `pub const fn default()` in addition to implementing the `Default` trait, allowing constants to make use of default values. By @kpreid in [#9929](https://github.com/gfx-rs/wgpu/pull/9929).
+- `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 [#9979](https://github.com/gfx-rs/wgpu/pull/9979).
 
 #### 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

@@ -1517,6 +1517,8 @@ impl Device {
         desc: &resource::TextureDescriptor,
         initial_state: wgt::TextureUses,
     ) -> Result<Arc<Texture>, resource::CreateTextureError> {
+        self.check_is_valid()?;
+
         let format_features = self
             .describe_format_features(desc.format)
             .map_err(|error| resource::CreateTextureError::MissingFeatures(desc.format, error))?;
@@ -1662,10 +1664,29 @@ impl Device {
         }
     }
 
-    fn create_texture_inner(
+    /// Validate a texture descriptor.
+    ///
+    /// This applies the same validation as [`Self::create_texture`], without
+    /// actually creating a texture.
+    pub fn validate_texture_descriptor(
         self: &Arc<Self>,
         desc: &resource::TextureDescriptor,
-    ) -> Result<Arc<Texture>, resource::CreateTextureError> {
+    ) -> Result<(), resource::CreateTextureError> {
+        self.validate_texture_descriptor_inner(desc)?;
+        Ok(())
+    }
+
+    /// Validate a texture descriptor.
+    ///
+    /// Implements the [validating GPUTextureDescriptor] algorithm, with some
+    /// `wgpu` extensions.
+    ///
+    /// [validating GPUTextureDescriptor]: https://www.w3.org/TR/webgpu/#abstract-opdef-validating-gputexturedescriptor
+    fn validate_texture_descriptor_inner(
+        self: &Arc<Self>,
+        desc: &resource::TextureDescriptor,
+    ) -> Result<(wgt::TextureFormatFeatures, Vec<TextureFormat>), resource::CreateTextureError>
+    {
         use resource::{CreateTextureError, TextureDimensionError};
 
         self.check_is_valid()?;
@@ -1939,6 +1960,15 @@ 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> {
+        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 {