Implement queue.copy_external_image_to_texture for WebGL2 and improve WebGPU Impl

CHANGELOG.md

@@ -103,6 +103,10 @@ Additionally `Surface::get_default_config` now returns an Option and returns Non
 
 `Instance::create_surface()` now returns `Result<Surface, CreateSurfaceError>` instead of `Surface`. This allows an error to be returned instead of panicking if the given window is a HTML canvas and obtaining a WebGPU or WebGL 2 context fails. (No other platforms currently report any errors through this path.) By @kpreid in [#3052](https://github.com/gfx-rs/wgpu/pull/3052/)
 
+#### `Queue::copy_external_image_to_texture` on WebAssembly
+
+There's a new api `Queue::copy_external_image_to_texture` which allows you to create wgpu textures from various web image primitives. Specificically from HtmlVideoElement, HtmlCanvasElement, OffscreenCanvas, and ImageBitmap. This provides multiple low-copy ways of interacting with the browser. WebGL is also supported, though WebGL has some additional restrictions, represented by the UNRESTRICTED_EXTERNAL_IMAGE_COPIES downlevel flag. By @cwfitzgerald in [#3288](https://github.com/gfx-rs/wgpu/pull/3288)
+
 #### Instance creation now takes `InstanceDescriptor` instead of `Backends`
 
 `Instance::new()` and `hub::Global::new()` now take an `InstanceDescriptor` struct which cointains both the existing `Backends` selection as well as a new `Dx12Compiler` field for selecting which Dx12 shader compiler to use.
@@ -300,14 +304,12 @@ let texture = device.create_texture(&wgpu::TextureDescriptor {
 
 - Don't use a pointer to a local copy of a `PhysicalDeviceDriverProperties` struct after it has gone out of scope. In fact, don't make a local copy at all. Introduce a helper function for building `CStr`s from C character arrays, and remove some `unsafe` blocks. By @jimblandy in [#3076](https://github.com/gfx-rs/wgpu/pull/3076).
 
-
 ## wgpu-0.14.2 (2022-11-28)
 
 ### Bug Fixes
 
 - Fix incorrect offset in `get_mapped_range` by @nical in [#3233](https://github.com/gfx-rs/wgpu/pull/3233)
 
-
 ## wgpu-0.14.1 (2022-11-02)
 
 ### Bug Fixes

Cargo.toml

@@ -57,6 +57,7 @@ env_logger = "0.9"
 futures-intrusive = "0.4"
 fxhash = "0.2.1"
 glam = "0.21.3"
+image = { version = "0.24", default-features = false, features = ["png"] }
 libloading = "0.7"
 libc = "0.2"
 log = "0.4"

wgpu-core/src/command/transfer.rs

@@ -24,6 +24,7 @@ use std::iter;
 
 pub type ImageCopyBuffer = wgt::ImageCopyBuffer<BufferId>;
 pub type ImageCopyTexture = wgt::ImageCopyTexture<TextureId>;
+pub type ImageCopyTextureTagged = wgt::ImageCopyTextureTagged<TextureId>;
 
 #[derive(Clone, Copy, Debug)]
 pub enum CopySide {
@@ -44,6 +45,8 @@ pub enum TransferError {
     MissingCopySrcUsageFlag,
     #[error("destination buffer/texture is missing the `COPY_DST` usage flag")]
     MissingCopyDstUsageFlag(Option<BufferId>, Option<TextureId>),
+    #[error("destination texture is missing the `RENDER_ATTACHMENT` usage flag")]
+    MissingRenderAttachmentUsageFlag(TextureId),
     #[error("copy of {start_offset}..{end_offset} would end up overrunning the bounds of the {side:?} buffer of size {buffer_size}")]
     BufferOverrun {
         start_offset: BufferAddress,
@@ -66,6 +69,8 @@ pub enum TransferError {
     },
     #[error("unable to select texture mip level {level} out of {total}")]
     InvalidTextureMipLevel { level: u32, total: u32 },
+    #[error("texture dimension must be 2D when copying from an external texture")]
+    InvalidDimensionExternal(TextureId),
     #[error("buffer offset {0} is not aligned to block size or `COPY_BUFFER_ALIGNMENT`")]
     UnalignedBufferOffset(BufferAddress),
     #[error("copy size {0} does not respect `COPY_BUFFER_ALIGNMENT`")]
@@ -102,6 +107,10 @@ pub enum TransferError {
         format: wgt::TextureFormat,
         aspect: wgt::TextureAspect,
     },
+    #[error(
+        "copying to textures with format {0:?} is forbidden when copying from external texture"
+    )]
+    ExternalCopyToForbiddenTextureFormat(wgt::TextureFormat),
     #[error("the entire texture must be copied when copying from depth texture")]
     InvalidDepthTextureExtent,
     #[error(
@@ -701,8 +710,8 @@ impl<G: GlobalIdentityHandlerFactory> Global<G> {
         #[cfg(feature = "trace")]
         if let Some(ref mut list) = cmd_buf.commands {
             list.push(TraceCommand::CopyBufferToTexture {
-                src: source.clone(),
-                dst: destination.clone(),
+                src: *source,
+                dst: *destination,
                 size: *copy_size,
             });
         }
@@ -837,8 +846,8 @@ impl<G: GlobalIdentityHandlerFactory> Global<G> {
         #[cfg(feature = "trace")]
         if let Some(ref mut list) = cmd_buf.commands {
             list.push(TraceCommand::CopyTextureToBuffer {
-                src: source.clone(),
-                dst: destination.clone(),
+                src: *source,
+                dst: *destination,
                 size: *copy_size,
             });
         }
@@ -1002,8 +1011,8 @@ impl<G: GlobalIdentityHandlerFactory> Global<G> {
         #[cfg(feature = "trace")]
         if let Some(ref mut list) = cmd_buf.commands {
             list.push(TraceCommand::CopyTextureToTexture {
-                src: source.clone(),
-                dst: destination.clone(),
+                src: *source,
+                dst: *destination,
                 size: *copy_size,
             });
         }

wgpu-core/src/conv.rs

@@ -33,6 +33,30 @@ pub fn is_valid_copy_dst_texture_format(
     }
 }
 
+#[cfg_attr(
+    any(not(target_arch = "wasm32"), feature = "emscripten"),
+    allow(unused)
+)]
+pub fn is_valid_external_image_copy_dst_texture_format(format: wgt::TextureFormat) -> bool {
+    use wgt::TextureFormat as Tf;
+    match format {
+        Tf::R8Unorm
+        | Tf::R16Float
+        | Tf::R32Float
+        | Tf::Rg8Unorm
+        | Tf::Rg16Float
+        | Tf::Rg32Float
+        | Tf::Rgba8Unorm
+        | Tf::Rgba8UnormSrgb
+        | Tf::Bgra8Unorm
+        | Tf::Bgra8UnormSrgb
+        | Tf::Rgb10a2Unorm
+        | Tf::Rgba16Float
+        | Tf::Rgba32Float => true,
+        _ => false,
+    }
+}
+
 pub fn map_buffer_usage(usage: wgt::BufferUsages) -> hal::BufferUses {
     let mut u = hal::BufferUses::empty();
     u.set(