From 531342825095e0703d251c38e382e293289b263b Mon Sep 17 00:00:00 2001
From: Ad5001 <mail@ad5001.eu>
Date: Tue, 15 Oct 2024 03:52:06 +0200
Subject: [PATCH] Improving stability of asynchronous LaTeX renderer.

---
 common/src/module/canvas.mjs                     | 16 +++++++++++-----
 common/src/preferences/general.mjs               |  2 +-
 runtime-pyside6/LogarithmPlotter/util/promise.py |  7 ++++++-
 3 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/common/src/module/canvas.mjs b/common/src/module/canvas.mjs
index c46c9a1..62649cf 100644
--- a/common/src/module/canvas.mjs
+++ b/common/src/module/canvas.mjs
@@ -30,16 +30,18 @@ class CanvasAPI extends Module {
     #canvas = null
     /** @type {CanvasRenderingContext2D} */
     #ctx = null
+    /** Lock to prevent asynchronous stuff from printing stuff that is outdated. */
+    #redrawCount = 0
     /** @type {{show(string, string, string)}} */
     #drawingErrorDialog = null
-    
-    
+
+
     constructor() {
         super("Canvas", {
             canvas: CanvasInterface,
             drawingErrorDialog: DialogInterface
         })
-        
+
         /**
          *
          * @type {Object.<string, {expression: Expression, value: number, maxDraw: number}>}
@@ -207,6 +209,7 @@ class CanvasAPI extends Module {
      */
     redraw() {
         if(!this.initialized) throw new Error("Attempting redraw before initialize!")
+        this.#redrawCount = (this.#redrawCount + 1) % 10000
         this.#ctx = this.#canvas.getContext("2d")
         this._computeAxes()
         this._reset()
@@ -519,15 +522,18 @@ class CanvasAPI extends Module {
      * @param {function(LatexRenderResult|{width: number, height: number, source: string})} callback
      */
     renderLatexImage(ltxText, color, callback) {
+        const currentRedrawCount = this.#redrawCount
         const onRendered = (imgData) => {
             if(!this.#canvas.isImageLoaded(imgData.source) && !this.#canvas.isImageLoading(imgData.source)) {
                 // Wait until the image is loaded to callback.
                 this.#canvas.loadImageAsync(imgData.source).then(() => {
-                    callback(imgData)
+                    if(this.#redrawCount === currentRedrawCount)
+                        callback(imgData)
                 })
             } else {
                 // Callback directly
-                callback(imgData)
+                if(this.#redrawCount === currentRedrawCount)
+                    callback(imgData)
             }
         }
         const prerendered = Latex.findPrerendered(ltxText, this.textsize, color)
diff --git a/common/src/preferences/general.mjs b/common/src/preferences/general.mjs
index 4a1098f..a6957c6 100644
--- a/common/src/preferences/general.mjs
+++ b/common/src/preferences/general.mjs
@@ -47,7 +47,7 @@ class EnableLatex extends BoolSetting {
 }
 
 const ENABLE_LATEX_ASYNC = new BoolSetting(
-    qsTranslate("general", "Enable asynchronous LaTeX renderer (experimental)"),
+    qsTranslate("general", "Enable asynchronous LaTeX renderer"),
     "enable_latex_async",
     "new"
 )
diff --git a/runtime-pyside6/LogarithmPlotter/util/promise.py b/runtime-pyside6/LogarithmPlotter/util/promise.py
index 6868432..f129d41 100644
--- a/runtime-pyside6/LogarithmPlotter/util/promise.py
+++ b/runtime-pyside6/LogarithmPlotter/util/promise.py
@@ -53,7 +53,12 @@ class PyPromiseRunner(QRunnable):
                 raise InvalidReturnValue("Must return either a primitive, a valid QObject, JS Value, or None.")
             self.promise.finished.emit(data)
         except Exception as e:
-            self.promise.errored.emit(repr(e))
+            try:
+                self.promise.errored.emit(repr(e))
+            except RuntimeError as e2:
+                # Happens when the PyPromise has already been garbage collected.
+                # In other words, nothing to report to nowhere.
+                pass
 
 
 class PyPromise(QObject):