1 files changed, 59 insertions, 74 deletions

diff --git a/src/image.rs b/src/image.rs
index f6574045..a7b62503 100644
--- a/src/image.rs
+++ b/src/image.rs
@@ -1,6 +1,7 @@
 //! Image handling.
 
 use std::collections::{hash_map::Entry, HashMap};
+use std::ffi::OsStr;
 use std::fmt::{self, Debug, Formatter};
 use std::io;
 use std::path::Path;
@@ -9,7 +10,6 @@ use std::rc::Rc;
 use image::io::Reader as ImageReader;
 use image::{DynamicImage, GenericImageView, ImageFormat};
 use serde::{Deserialize, Serialize};
-use usvg::{Error as USvgError, Tree};
 
 use crate::loading::{FileHash, Loader};
 
@@ -66,7 +66,8 @@ impl ImageStore {
             Entry::Occupied(entry) => entry.into_mut(),
             Entry::Vacant(entry) => {
                 let buffer = self.loader.load(path)?;
-                let image = Image::parse(&buffer)?;
+                let ext = path.extension().and_then(OsStr::to_str).unwrap_or_default();
+                let image = Image::parse(&buffer, &ext)?;
                 let id = ImageId(self.images.len() as u32);
                 if let Some(callback) = &self.on_load {
                     callback(id, &image);
@@ -91,21 +92,32 @@ impl ImageStore {
 /// A loaded image.
 #[derive(Debug)]
 pub enum Image {
+    /// A pixel raster format, like PNG or JPEG.
     Raster(RasterImage),
+    /// An SVG vector graphic.
     Svg(Svg),
 }
 
 impl Image {
-    /// Parse an image from raw data. This will prioritize SVG images and then
-    /// try to decode a supported raster format.
-    pub fn parse(data: &[u8]) -> io::Result<Self> {
+    /// Parse an image from raw data. The file extension is used as a hint for
+    /// which error message describes the problem best.
+    pub fn parse(data: &[u8], ext: &str) -> io::Result<Self> {
         match Svg::parse(data) {
-            Ok(svg) => Ok(Self::Svg(svg)),
-            Err(e) if e.kind() == io::ErrorKind::InvalidData => {
-                Ok(Self::Raster(RasterImage::parse(data)?))
-            }
-            Err(e) => Err(e),
+            Ok(svg) => return Ok(Self::Svg(svg)),
+            Err(err) if matches!(ext, "svg" | "svgz") => return Err(err),
+            Err(_) => {}
         }
+
+        match RasterImage::parse(data) {
+            Ok(raster) => return Ok(Self::Raster(raster)),
+            Err(err) if matches!(ext, "png" | "jpg" | "jpeg") => return Err(err),
+            Err(_) => {}
+        }
+
+        Err(io::Error::new(
+            io::ErrorKind::InvalidData,
+            "unknown image format",
+        ))
     }
 
     /// The width of the image in pixels.
@@ -123,67 +135,6 @@ impl Image {
             Self::Svg(image) => image.height(),
         }
     }
-
-    pub fn is_vector(&self) -> bool {
-        match self {
-            Self::Raster(_) => false,
-            Self::Svg(_) => true,
-        }
-    }
-}
-
-/// An SVG image, supported through the usvg crate.
-pub struct Svg(pub Tree);
-
-impl Svg {
-    /// Parse an SVG file from a data buffer. This also handles `.svgz`
-    /// compressed files.
-    pub fn parse(data: &[u8]) -> io::Result<Self> {
-        let usvg_opts = usvg::Options::default();
-        let tree = Tree::from_data(data, &usvg_opts.to_ref()).map_err(|e| match e {
-            USvgError::NotAnUtf8Str => {
-                io::Error::new(io::ErrorKind::InvalidData, "file is not valid utf-8")
-            }
-            USvgError::MalformedGZip => io::Error::new(
-                io::ErrorKind::InvalidData,
-                "could not extract gzipped SVG",
-            ),
-            USvgError::ElementsLimitReached => io::Error::new(
-                io::ErrorKind::Other,
-                "SVG file has more than 1 million elements",
-            ),
-            USvgError::InvalidSize => io::Error::new(
-                io::ErrorKind::InvalidData,
-                "SVG width or height not greater than zero",
-            ),
-            USvgError::ParsingFailed(error) => io::Error::new(
-                io::ErrorKind::InvalidData,
-                format!("SVG parsing error: {}", error.to_string()),
-            ),
-        })?;
-
-        Ok(Self(tree))
-    }
-
-    /// The width of the image in rounded-up nominal SVG pixels.
-    pub fn width(&self) -> u32 {
-        self.0.svg_node().size.width().ceil() as u32
-    }
-
-    /// The height of the image in rounded-up nominal SVG pixels.
-    pub fn height(&self) -> u32 {
-        self.0.svg_node().size.height().ceil() as u32
-    }
-}
-
-impl Debug for Svg {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.debug_struct("Svg")
-            .field("width", &self.0.svg_node().size.width())
-            .field("height", &self.0.svg_node().size.height())
-            .field("viewBox", &self.0.svg_node().view_box)
-            .finish()
-    }
 }
 
 /// A raster image, supported through the image crate.
@@ -201,9 +152,9 @@ impl RasterImage {
     pub fn parse(data: &[u8]) -> io::Result<Self> {
         let cursor = io::Cursor::new(data);
         let reader = ImageReader::new(cursor).with_guessed_format()?;
-        let format = reader.format().ok_or_else(|| {
-            io::Error::new(io::ErrorKind::InvalidData, "unknown image format")
-        })?;
+        let format = reader
+            .format()
+            .ok_or_else(|| io::Error::from(io::ErrorKind::InvalidData))?;
 
         let buf = reader
             .decode()
@@ -233,3 +184,37 @@ impl Debug for RasterImage {
             .finish()
     }
 }
+
+/// An SVG image, supported through the usvg crate.
+pub struct Svg(pub usvg::Tree);
+
+impl Svg {
+    /// Parse an SVG file from a data buffer. This also handles `.svgz`
+    /// compressed files.
+    pub fn parse(data: &[u8]) -> io::Result<Self> {
+        let usvg_opts = usvg::Options::default();
+        usvg::Tree::from_data(data, &usvg_opts.to_ref())
+            .map(Self)
+            .map_err(|err| io::Error::new(io::ErrorKind::InvalidData, err))
+    }
+
+    /// The width of the image in rounded-up nominal SVG pixels.
+    pub fn width(&self) -> u32 {
+        self.0.svg_node().size.width().ceil() as u32
+    }
+
+    /// The height of the image in rounded-up nominal SVG pixels.
+    pub fn height(&self) -> u32 {
+        self.0.svg_node().size.height().ceil() as u32
+    }
+}
+
+impl Debug for Svg {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.debug_struct("Svg")
+            .field("width", &self.0.svg_node().size.width())
+            .field("height", &self.0.svg_node().size.height())
+            .field("viewBox", &self.0.svg_node().view_box)
+            .finish()
+    }
+}