Don't change DPI in resvg (#4354)

crates/typst/src/visualize/image/mod.rs

@@ -329,6 +329,9 @@ impl Image {
     /// if the image doesn't contain DPI metadata.
     pub const DEFAULT_DPI: f64 = 72.0;
 
+    /// Should always be the same as the default DPI used by usvg.
+    pub const USVG_DEFAULT_DPI: f64 = 96.0;
+
     /// Create an image from a buffer and a format.
     #[comemo::memoize]
     #[typst_macros::time(name = "load image")]
@@ -407,7 +410,7 @@ impl Image {
     pub fn dpi(&self) -> Option<f64> {
         match &self.0.kind {
             ImageKind::Raster(raster) => raster.dpi(),
-            ImageKind::Svg(_) => None,
+            ImageKind::Svg(_) => Some(Image::USVG_DEFAULT_DPI),
         }
     }
 

crates/typst/src/visualize/image/svg.rs

@@ -12,7 +12,6 @@ use crate::layout::Axes;
 use crate::text::{
     Font, FontBook, FontFlags, FontStretch, FontStyle, FontVariant, FontWeight,
 };
-use crate::visualize::Image;
 use crate::World;
 
 /// A decoded SVG.
@@ -102,9 +101,10 @@ fn base_options() -> usvg::Options<'static> {
         // Disable usvg's default to "Times New Roman".
         font_family: String::new(),
 
-        // We override the DPI here so that we get the correct the size when
-        // scaling the image to its natural size.
-        dpi: Image::DEFAULT_DPI as f32,
+        // We don't override the DPI here, because we already
+        // force the image into the corresponding DPI by setting
+        // the width and height. Changing the DPI only trips up
+        // the logic in `resvg`.
 
         // Override usvg's resource loading defaults.
         resources_dir: None,