From c2ba6b0e331a7f8283a515e21366f44a8b9eb736 Mon Sep 17 00:00:00 2001
From: Calixte Denizet <calixte.denizet@gmail.com>
Date: Thu, 26 Mar 2026 15:51:37 +0100
Subject: [PATCH] Update the canvas detail view only when drawing is done

And remove the canvas from the view once it's destroyed.
---
 web/internal/canvas_context_details_view.js | 32 +++++++++++++++++----
 web/internal/page_view.js                   | 13 +++++++--
 2 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/web/internal/canvas_context_details_view.js b/web/internal/canvas_context_details_view.js
index 5ec4f59cc..4f1ddd725 100644
--- a/web/internal/canvas_context_details_view.js
+++ b/web/internal/canvas_context_details_view.js
@@ -110,10 +110,12 @@ class CanvasContextDetailsView {
     this.#ctxStates.set(label, state);
     this.#ctxStateStacks.set(label, []);
     this.#ctxStackViewIdx.set(label, null);
-    // If the panel is already visible (stepping in progress), rebuild it so
-    // the new context section is added and its live-update entries are
-    // registered.
-    if (this.#gfxStateValueElements.size > 0) {
+    // If the panel is already visible and we're at a pause point, rebuild it
+    // so the new context section is added and its live-update entries are
+    // registered. Skip the rebuild while frozen (execution is in progress
+    // between pauses) — the next build() call from #onStepped() will pick it
+    // up.
+    if (!this.#frozen && this.#gfxStateValueElements.size > 0) {
       this.build();
     }
 
@@ -303,9 +305,29 @@ class CanvasContextDetailsView {
     }
   }
 
-  /** Hide the panel. */
+  /**
+   * Remove the section for a single context from the panel and all internal
+   * state maps. Called when a temporary canvas is destroyed.
+   */
+  removeContext(label) {
+    this.#ctxStates.delete(label);
+    this.#ctxStateStacks.delete(label);
+    this.#ctxStackViewIdx.delete(label);
+    this.#gfxStateValueElements.delete(label);
+    this.#gfxStateNavElements.delete(label);
+    this.#panel
+      .querySelector(
+        `.gfx-state-section[data-ctx-label="${CSS.escape(label)}"]`
+      )
+      ?.remove();
+  }
+
+  /** Hide the panel and discard all DOM state so no live updates occur. */
   hide() {
     this.#panel.hidden = true;
+    this.#gfxStateValueElements.clear();
+    this.#gfxStateNavElements.clear();
+    this.#panel.replaceChildren();
   }
 
   /**
diff --git a/web/internal/page_view.js b/web/internal/page_view.js
index e840cd213..397dad8c4 100644
--- a/web/internal/page_view.js
+++ b/web/internal/page_view.js
@@ -355,7 +355,9 @@ class PageView {
       destroy(canvasAndCtx) {
         const idx = this.#alive.findIndex(e => e.canvasAndCtx === canvasAndCtx);
         if (idx !== -1) {
-          this.#alive[idx].wrapper.remove();
+          const { wrapper, ctxLabel } = this.#alive[idx];
+          wrapper.remove();
+          gfxStateComp.removeContext(ctxLabel);
           this.#alive.splice(idx, 1);
         }
         super.destroy(canvasAndCtx);
@@ -393,7 +395,7 @@ class PageView {
         checker.className = "canvas-checker";
         checker.append(canvasAndCtx.canvas);
         wrapper.append(labelEl, checker);
-        const entry = { canvasAndCtx, wrapper, labelEl };
+        const entry = { canvasAndCtx, wrapper, labelEl, ctxLabel };
         this.#alive.push(entry);
         this.#attachWrapper(entry);
       }
@@ -482,7 +484,10 @@ class PageView {
     });
 
     this.#stepButton.addEventListener("click", () => {
-      globalThis.StepperManager._active?.stepNext();
+      if (globalThis.StepperManager._active) {
+        this.#gfxStateComp.freeze();
+        globalThis.StepperManager._active.stepNext();
+      }
     });
 
     this.#continueButton.addEventListener("click", () => {
@@ -580,9 +585,11 @@ class PageView {
       }
       if (e.key === "s") {
         e.preventDefault();
+        this.#gfxStateComp.freeze();
         stepper.stepNext();
       } else if (e.key === "c") {
         e.preventDefault();
+        this.#gfxStateComp.freeze();
         stepper.continueToBreakpoint();
       }
     });