add image sizes to emoji

crates/treehouse/src/config.rs

@@ -1,7 +1,8 @@
 use std::{collections::HashMap, ffi::OsStr, fs::File, io::BufReader, path::Path};
 
 use anyhow::Context;
-use log::debug;
+use image::ImageError;
+use log::{debug, error, warn};
 use serde::{Deserialize, Serialize};
 use walkdir::WalkDir;
 
@@ -180,32 +181,43 @@ impl Config {
 /// Data derived from the config.
 #[derive(Debug, Clone, Default)]
 pub struct ConfigDerivedData {
-    pub pic_sizes: HashMap<String, Option<PicSize>>,
+    pub image_sizes: HashMap<String, Option<ImageSize>>,
 }
 
-/// Picture size. This is useful for emitting <img> elements with a specific size to eliminate layout shifting.
+/// Image size. This is useful for emitting <img> elements with a specific size to eliminate
+/// layout shifting.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub struct PicSize {
+pub struct ImageSize {
     pub width: u32,
     pub height: u32,
 }
 
 impl ConfigDerivedData {
-    fn read_pic_size(config: &Config, pic_id: &str) -> Option<PicSize> {
-        let pic_filename = config.pics.get(pic_id)?;
-        let (width, height) = image::io::Reader::new(BufReader::new(
-            File::open(format!("static/pic/{pic_filename}")).ok()?,
-        ))
-        .into_dimensions()
-        .ok()?;
-        Some(PicSize { width, height })
+    fn read_image_size(filename: &str) -> Option<ImageSize> {
+        let (width, height) = image::io::Reader::new(BufReader::new(File::open(filename).ok()?))
+            .with_guessed_format()
+            .map_err(ImageError::from)
+            .and_then(|i| i.into_dimensions())
+            // NOTE: Not being able to determine the image size is not the end of the world,
+            // so just warn the user if we couldn't do it.
+            // For example, currently SVG is not supported at all, which causes this to fail.
+            .inspect_err(|e| warn!("cannot read image size of {filename}: {e}"))
+            .ok()?;
+        Some(ImageSize { width, height })
     }
 
-    pub fn pic_size(&mut self, config: &Config, pic_id: &str) -> Option<PicSize> {
-        if !self.pic_sizes.contains_key(pic_id) {
-            self.pic_sizes
-                .insert(pic_id.to_owned(), Self::read_pic_size(config, pic_id));
+    pub fn image_size(&mut self, filename: &str) -> Option<ImageSize> {
+        if !self.image_sizes.contains_key(filename) {
+            self.image_sizes
+                .insert(filename.to_owned(), Self::read_image_size(filename));
         }
-        self.pic_sizes.get(pic_id).copied().flatten()
+        self.image_sizes.get(filename).copied().flatten()
+    }
+
+    pub fn pic_size(&mut self, config: &Config, pic_id: &str) -> Option<ImageSize> {
+        config
+            .pics
+            .get(pic_id)
+            .and_then(|pic_filename| self.image_size(&format!("static/pic/{pic_filename}")))
     }
 }

crates/treehouse/src/html/markdown.rs

@@ -30,7 +30,7 @@ use pulldown_cmark::escape::{escape_href, escape_html, StrWrite};
 use pulldown_cmark::{Alignment, CodeBlockKind, Event, LinkType, Tag};
 use pulldown_cmark::{CowStr, Event::*};
 
-use crate::config::{Config, ConfigDerivedData, PicSize};
+use crate::config::{Config, ConfigDerivedData, ImageSize};
 use crate::html::highlight::highlight;
 use crate::state::Treehouse;
 
@@ -281,15 +281,13 @@ where
 
                                 if let LiterateCodeKind::Output { placeholder_pic_id } = kind {
                                     if !placeholder_pic_id.is_empty() {
-                                        self.write(
-                                                            "<img class=\"placeholder-image\" loading=\"lazy\" src=\"",
-                                                        )?;
+                                        self.write("<img class=\"placeholder-image\" loading=\"lazy\" src=\"")?;
                                         escape_html(
                                             &mut self.writer,
                                             &self.config.pic_url(placeholder_pic_id),
                                         )?;
                                         self.write("\"")?;
-                                        if let Some(PicSize { width, height }) = self
+                                        if let Some(ImageSize { width, height }) = self
                                             .config_derived_data
                                             .pic_size(self.config, placeholder_pic_id)
                                         {
@@ -552,6 +550,7 @@ where
                                 escape_html(&mut self.writer, &branch.attributes.id)?;
                                 self.writer.write_str("\">")?;
                             }
+
                             self.writer
                                 .write_str("<img data-cast=\"emoji\" title=\":")?;
                             escape_html(&mut self.writer, name)?;
@@ -561,7 +560,18 @@ where
                             escape_html(&mut self.writer, filename)?;
                             self.writer.write_str("\" alt=\"")?;
                             escape_html(&mut self.writer, name)?;
+                            if let Some(image_size) = self
+                                .config_derived_data
+                                .image_size(&format!("static/emoji/{filename}"))
+                            {
+                                write!(
+                                    self.writer,
+                                    "\" width=\"{}\" height=\"{}",
+                                    image_size.width, image_size.height
+                                )?;
+                            }
                             self.writer.write_str("\">")?;
+
                             if branch_id.is_some() {
                                 self.writer.write_str("</a>")?;
                             }