Provide thumbnailing

src/thumbnail.rs

@@ -0,0 +1,46 @@
+use cosmic::iced_core::image::Data;
+use iced_video_player::{Position, Video};
+use image::{DynamicImage, ImageFormat, RgbaImage};
+use std::{error::Error, num::NonZero, path::Path, time::Duration};
+use url::Url;
+
+pub fn main(
+    input: &Url,
+    output: &Path,
+    size_opt: Option<(u32, u32)>,
+) -> Result<(), Box<dyn Error>> {
+    let mut image = {
+        let thumbnails = {
+            let mut video = Video::new(input)?;
+            let duration = video.duration();
+            //TODO: how best to decide time?
+            let position = if duration.as_secs_f64() < 20.0 {
+                // If less than 20 seconds, divide duration by 2
+                Position::Time(duration / 2)
+            } else {
+                // If more than 20 seconds, thumbnail at 10 seconds
+                Position::Time(Duration::new(10, 0))
+            };
+            video.thumbnails([position], NonZero::new(1).unwrap())?
+        };
+        //TODO: do not require clone of pixels data
+        match thumbnails[0].data() {
+            Data::Rgba {
+                width,
+                height,
+                pixels,
+            } => RgbaImage::from_raw(*width, *height, pixels.to_vec())
+                .map(DynamicImage::ImageRgba8)
+                .ok_or_else(|| format!("failed to convert thumbnail")),
+            _ => Err(format!("unsupported thumbnail handle {:?}", thumbnails[0])),
+        }
+    }?;
+
+    if let Some((width, height)) = size_opt {
+        image = image.thumbnail(width, height);
+    }
+
+    image.save_with_format(output, ImageFormat::Png)?;
+
+    Ok(())
+}