Merge main into #2200

crates/engine/src/canvas/tools/click.rs

@@ -360,8 +360,13 @@ impl Session {
     pub(super) fn eyedrop(&mut self, ev: &PointerEvent) -> Result<()> {
         let ds = self.ds()?;
         let doc = ds.doc.clone();
-        let view = figcraft_render::View { origin: (ev.x, ev.y), scale: ev.zoom.max(0.01), width: 1, height: 1 };
-        let Some(pix) = figcraft_render::render_view(&doc, ds.page, &view, &Default::default()) else { return Ok(()) };
+        // One screen pixel centred on the pointer (its top left half a pixel up and to the left).
+        let scale = ev.zoom.max(0.01);
+        let view = figcraft_render::View { origin: (ev.x - 0.5 / scale, ev.y - 0.5 / scale), scale, width: 1, height: 1 };
+        // As the canvas draws it: an image magnified past 2x shows its pixels, so the colour picked
+        // is the pixel under the pointer, not a blend with its neighbours (#2189).
+        let opts = figcraft_render::Options { magnified_image_pixels: true, ..Default::default() };
+        let Some(pix) = figcraft_render::render_view(&doc, ds.page, &view, &opts) else { return Ok(()) };
         let rgba = figcraft_render::to_rgba8(&pix);
         let c = figcraft_color::Color::from_rgba8(
             rgba.first().copied().unwrap_or(0),

crates/engine/src/eyedropper_image_tests.rs

@@ -0,0 +1,42 @@
+//! #2189: the eyedropper picks the colour the canvas shows under the pointer. A magnified image
+//! draws its pixels on the canvas (`magnified_image_pixels`), so the picked colour is that pixel's,
+//! not a blend with its neighbours.
+
+use base64::Engine as _;
+use serde_json::json;
+
+use crate::Session;
+use crate::tools::{PointerEvent, PointerKind};
+
+/// A 9 x 9 image of `back` with a 1 px vertical line of `line` in column 4 (a thin border in a
+/// screenshot, as in the report).
+fn line_png(back: [u8; 3], line: [u8; 3]) -> Vec<u8> {
+    let mut p = figcraft_render::Pixmap::new(9, 9).unwrap();
+    for (i, px) in p.data_mut().chunks_exact_mut(4).enumerate() {
+        let c = if i % 9 == 4 { line } else { back };
+        px.copy_from_slice(&[c[0], c[1], c[2], 255]);
+    }
+    figcraft_render::encode_png(&p).unwrap()
+}
+
+/// The colour the eyedropper picks at page point (x, y) at `zoom`.
+fn picked(png: &[u8], x: f64, y: f64, zoom: f64) -> String {
+    let mut s = Session::new();
+    let data = base64::engine::general_purpose::STANDARD.encode(png);
+    s.execute("image.place", &json!({"data": data, "x": 0, "y": 0})).unwrap();
+    s.execute("edit.pickColor", &json!({"apply": false})).unwrap();
+    s.pointer(&PointerEvent::at(PointerKind::Down, x, y, zoom)).unwrap();
+    s.tool.picked.map(|c| c.to_hex()).unwrap_or_default()
+}
+
+#[test]
+fn the_eyedropper_picks_a_magnified_images_pixel_not_a_blend_with_its_neighbours() {
+    // The reporter's colours: a #3D444D border, 1 px wide, beside a darker background.
+    let png = line_png([0x15, 0x1B, 0x23], [0x3D, 0x44, 0x4D]);
+    for zoom in [2.0, 8.0, 20.0] {
+        assert_eq!(picked(&png, 4.5, 4.5, zoom), "3D444D", "on the line at {zoom}x");
+        assert_eq!(picked(&png, 2.5, 4.5, zoom), "151B23", "beside it at {zoom}x");
+    }
+    // At 1:1 the canvas pixel is the image's pixel too.
+    assert_eq!(picked(&png, 4.5, 4.5, 1.0), "3D444D", "on the line at 1x");
+}

crates/engine/src/lib.rs

@@ -327,6 +327,8 @@ mod extended_chain_tests;
 #[cfg(test)]
 mod eyedropper_create_tests;
 #[cfg(test)]
+mod eyedropper_image_tests;
+#[cfg(test)]
 mod facilitate_tests;
 #[cfg(test)]
 mod fig_export_assets_tests;