gpui: Add support for animated images (#13809)

This PR adds support for animated images. The image requires a id for it
to actually animate across frames.

Currently it only has support for `GIF`, I tried adding decoding a
animated `WebP` into frames but it seems to error. This issue in the
image crate seems to document this
https://github.com/image-rs/image/issues/2263.

Not sure if this is the best way or the desired way for animated images
to work in GPUI but I would really like support for animated images.
Open to feedback.

Example Video:


https://github.com/zed-industries/zed/assets/76515905/011f790f-d070-499b-96c9-bbff141fb002



Closes https://github.com/zed-industries/zed/issues/9993

Release Notes:

- N/A

---------

Co-authored-by: Antonio Scandurra <me@as-cii.com>
Co-authored-by: Nathan <nathan@zed.dev>

crates/gpui/src/assets.rs

@@ -1,6 +1,7 @@
 use crate::{size, DevicePixels, Result, SharedString, Size};
+use smallvec::SmallVec;
 
-use image::RgbaImage;
+use image::{Delay, Frame};
 use std::{
     borrow::Cow,
     fmt,
@@ -34,43 +35,54 @@ pub struct ImageId(usize);
 #[derive(PartialEq, Eq, Hash, Clone)]
 pub(crate) struct RenderImageParams {
     pub(crate) image_id: ImageId,
+    pub(crate) frame_index: usize,
 }
 
 /// A cached and processed image.
 pub struct ImageData {
     /// The ID associated with this image
     pub id: ImageId,
-    data: RgbaImage,
+    data: SmallVec<[Frame; 1]>,
 }
 
 impl ImageData {
     /// Create a new image from the given data.
-    pub fn new(data: RgbaImage) -> Self {
+    pub fn new(data: impl Into<SmallVec<[Frame; 1]>>) -> Self {
         static NEXT_ID: AtomicUsize = AtomicUsize::new(0);
 
         Self {
             id: ImageId(NEXT_ID.fetch_add(1, SeqCst)),
-            data,
+            data: data.into(),
         }
     }
 
     /// Convert this image into a byte slice.
-    pub fn as_bytes(&self) -> &[u8] {
-        &self.data
+    pub fn as_bytes(&self, frame_index: usize) -> &[u8] {
+        &self.data[frame_index].buffer()
     }
 
-    /// Get the size of this image, in pixels
-    pub fn size(&self) -> Size<DevicePixels> {
-        let (width, height) = self.data.dimensions();
+    /// Get the size of this image, in pixels.
+    pub fn size(&self, frame_index: usize) -> Size<DevicePixels> {
+        let (width, height) = self.data[frame_index].buffer().dimensions();
         size(width.into(), height.into())
     }
+
+    /// Get the delay of this frame from the previous
+    pub fn delay(&self, frame_index: usize) -> Delay {
+        self.data[frame_index].delay()
+    }
+
+    /// Get the number of frames for this image.
+    pub fn frame_count(&self) -> usize {
+        self.data.len()
+    }
 }
 
 impl fmt::Debug for ImageData {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("ImageData")
             .field("id", &self.id)
-            .field("size", &self.data.dimensions())
+            .field("size", &self.size(0))
             .finish()
     }
 }