introduce gif animation

Signed-off-by: kernelkind <kernelkind@gmail.com>

crates/notedeck/src/imgcache.rs

@@ -7,6 +7,7 @@ use egui::ColorImage;
 
 use std::collections::HashMap;
 use std::fs::{create_dir_all, File};
+use std::sync::mpsc::Receiver;
 use std::time::{Duration, Instant, SystemTime};
 
 use hex::ToHex;
@@ -20,6 +21,37 @@ pub type MediaCacheMap = HashMap<String, MediaCacheValue>;
 
 pub enum TexturedImage {
     Static(TextureHandle),
+    Animated(Animation),
+}
+
+pub struct Animation {
+    pub first_frame: TextureFrame,
+    pub other_frames: Vec<TextureFrame>,
+    pub receiver: Option<Receiver<TextureFrame>>,
+}
+
+impl Animation {
+    pub fn get_frame(&self, index: usize) -> Option<&TextureFrame> {
+        if index == 0 {
+            Some(&self.first_frame)
+        } else {
+            self.other_frames.get(index - 1)
+        }
+    }
+
+    pub fn num_frames(&self) -> usize {
+        self.other_frames.len() + 1
+    }
+}
+
+pub struct TextureFrame {
+    pub delay: Duration,
+    pub texture: TextureHandle,
+}
+
+pub struct ImageFrame {
+    pub delay: Duration,
+    pub image: ColorImage,
 }
 
 pub struct MediaCache {
@@ -146,6 +178,7 @@ impl MediaCache {
 pub fn get_texture(textured_image: &TexturedImage) -> &TextureHandle {
     match textured_image {
         TexturedImage::Static(texture_handle) => texture_handle,
+        TexturedImage::Animated(_animation) => todo!(), // Temporary...
     }
 }