Add popup help to elements

crates/synth-visualiser/src/patchbay.rs

@@ -141,6 +141,13 @@ impl Module {
             && y >= self.y && y <= self.y + MOD_HEADER
     }
 
+    /// Hit-test the `?` help badge drawn in the top-right of the header.
+    fn hit_help_badge(&self, x: f32, y: f32) -> bool {
+        let bx = self.x + MOD_W - 10.0;
+        let by = self.y + MOD_HEADER / 2.0;
+        hypot(x - bx, y - by) <= 9.0
+    }
+
     fn hit_body(&self, x: f32, y: f32) -> bool {
         x >= self.x && x <= self.x + MOD_W
             && y >= self.y && y <= self.y + self.height()
@@ -490,6 +497,18 @@ impl PatchBay {
         }
     }
 
+    /// Returns the markdown description for the module whose `?` badge is at
+    /// (x, y), or an empty string if none is hovered.  JS calls this on every
+    /// `mousemove` over the patch bay canvas to drive the tooltip overlay.
+    pub fn get_tooltip_at(&self, x: f32, y: f32) -> String {
+        for m in self.modules.iter().rev() {
+            if m.hit_help_badge(x, y) {
+                return m.descriptor().description.to_string();
+            }
+        }
+        String::new()
+    }
+
     /// Double-click removes the topmost module under the cursor.
     pub fn on_double_click(&mut self, x: f32, y: f32) {
         if y < PALETTE_H { return; }
@@ -685,7 +704,25 @@ impl PatchBay {
             (m.y + MOD_HEADER * 0.70) as f64,
         );
 
+        // ? help badge — top-right corner of every module header
+        {
+            let bx = (m.x + MOD_W - 10.0) as f64;
+            let by = (m.y + MOD_HEADER / 2.0) as f64;
+            ctx.begin_path();
+            let _ = ctx.arc(bx, by, 7.0, 0.0, core::f64::consts::TAU);
+            ctx.set_fill_style_str("rgba(0,0,0,0.30)");
+            ctx.fill();
+            ctx.set_stroke_style_str("rgba(255,255,255,0.25)");
+            ctx.set_line_width(1.0);
+            ctx.stroke();
+            ctx.set_fill_style_str("rgba(255,255,255,0.70)");
+            ctx.set_font("bold 9px sans-serif");
+            ctx.set_text_align("center");
+            let _ = ctx.fill_text("?", bx, by + 3.5);
+        }
+
         // Output node: LIVE / UNPATCHED badge on the right of the header
+        // (shifted left to clear the ? badge)
         if is_out {
             if has_signal {
                 ctx.set_fill_style_str("#22c55e");
@@ -693,7 +730,7 @@ impl PatchBay {
                 ctx.set_text_align("right");
                 let _ = ctx.fill_text(
                     "● LIVE",
-                    (m.x + MOD_W - 6.0) as f64,
+                    (m.x + MOD_W - 24.0) as f64,
                     (m.y + MOD_HEADER * 0.70) as f64,
                 );
             } else {
@@ -702,7 +739,7 @@ impl PatchBay {
                 ctx.set_text_align("right");
                 let _ = ctx.fill_text(
                     "unpatched",
-                    (m.x + MOD_W - 6.0) as f64,
+                    (m.x + MOD_W - 24.0) as f64,
                     (m.y + MOD_HEADER * 0.70) as f64,
                 );
             }