Stop DIMTMOVE 2 text taking the DIMTAD 1 clearance twice (#2302)

Fixes #2222

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: Brandon Thomas <echelon@gmail.com>

crates/render/src/dim/linear.rs

@@ -150,11 +150,13 @@ fn position_linear_text(config: &DimConfig<'_>, state: &mut LinearDimState) {
     };
     state.side_out = if (config.dimension.defpt.xy() - state.p1).dot(state.n) >= 0.0 { state.n } else { -state.n };
     state.text_axis = Vec2::from_angle(state.angle);
-    let off_along = |axis: Vec2| {
-        let glyph_extent = state.text_width * state.text_axis.dot(axis).abs() / 2.0
-            + state.text_height * state.text_axis.perp().dot(axis).abs() * if st.text_above == 1 { 0.6 } else { 0.5 };
-        config.gap + glyph_extent
+    let clearance = |axis: Vec2, across: f64| {
+        config.gap
+            + state.text_width * state.text_axis.dot(axis).abs() / 2.0
+            + state.text_height * state.text_axis.perp().dot(axis).abs() * across
     };
+    // Empirical #2004 match: 0.595× height with SHX and 0.601× with TrueType.
+    let off_along = |axis: Vec2| clearance(axis, if st.text_above == 1 { 0.6 } else { 0.5 });
     let above = if state.angle.abs() < 1e-12 && state.n.y.abs() > 1e-9 {
         if state.n.y > 0.0 { state.n } else { -state.n }
     } else if state.angle.abs() < 1e-12 {
@@ -181,11 +183,13 @@ fn position_linear_text(config: &DimConfig<'_>, state: &mut LinearDimState) {
             + outward * (config.gap + state.text_height / 2.0);
     } else if state.moved {
         let mid = state.f1.mid(state.f2);
-        let lift = off_along(state.side_out) + 2.0 * config.arrow_size.max(config.tick_size);
+        // Half the text height either way, whatever DIMTAD says (#2222).
+        let clear = clearance(state.side_out, 0.5);
+        let lift = clear + 2.0 * config.arrow_size.max(config.tick_size);
         state.text_mid = if st.text_move == 1 {
             mid + state.side_out * lift + state.u * state.half_extent
         } else {
-            mid + state.side_out * (lift + off_along(state.side_out))
+            mid + state.side_out * (lift + clear)
         };
     } else if !config.dimension.user_text_pos {
         state.text_mid = state.along_center + state.offset;

crates/render/src/dim/tests.rs

@@ -233,6 +233,29 @@ fn text_that_does_not_fit_follows_dimtmove_2() {
     assert!(g.lines_of(LineRole::Dim).flatten().all(|p| p.x <= 0.5 + 1e-9 && p.y >= 5.0 - 1e-9), "no leader, no line out to the text");
 }
 
+#[test]
+fn dimtmove_2_text_clearance_matches_autocad() {
+    // #2222: the 0.10 dimension of #1998 in the #2004 1:50 style. AutoCAD 2026 recomputes the
+    // moved text at about 0.358 from the dimension line (0.658214, 0.05).
+    let st = st_with(|s| {
+        s.scale = 50.0;
+        s.text_height = 0.0025;
+        s.text_gap = 0.0008;
+        s.arrow_size = 0.0015;
+        s.text_above = 1;
+        s.text_inside_horizontal = false;
+        s.text_outside_horizontal = false;
+        s.decimals = 2;
+        s.text_move = 2;
+    });
+    let d = lin((0.0, 0.0), (0.0, 0.10), (0.30, 0.0), std::f64::consts::FRAC_PI_2);
+    let g = dimension_geometry(&d, &st, 50.0);
+    assert!(g.text_pos.dist(Vec2::new(0.658214, 0.05)) < 0.005, "vertical: {:?}", g.text_pos);
+    let d = lin((0.0, 0.0), (0.10, 0.0), (0.0, -0.30), 0.0);
+    let g = dimension_geometry(&d, &st, 50.0);
+    assert!(g.text_pos.dist(Vec2::new(0.05, -0.658214)) < 0.005, "horizontal: {:?}", g.text_pos);
+}
+
 #[test]
 fn text_that_does_not_fit_follows_dimtmove_1() {
     // Moved off the line with a leader from the middle of the dimension line.