From fbb06457b1ae178ac4d2db49d4c67aca3f2ff6bc Mon Sep 17 00:00:00 2001
From: shunby <25155092+shunby@users.noreply.github.com>
Date: Wed, 25 Sep 2024 00:50:31 +0900
Subject: [PATCH] Suppress re-rendering of callout widgets

---
 main.ts | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/main.ts b/main.ts
index c43c461..fca4a2e 100644
--- a/main.ts
+++ b/main.ts
@@ -3,10 +3,20 @@ import { Plugin } from "obsidian";
 import { around } from "monkey-around";
 
 type CalloutWidgetType = WidgetType & {
-	clazz?: string;
-	text?: string;
+	clazz: string;
+	text: string;
 };
 
+function isCallout(
+	widget: (WidgetType & { clazz?: unknown; text?: unknown }) | undefined
+): widget is CalloutWidgetType {
+	return (
+		widget !== undefined &&
+		widget.clazz === "cm-callout" &&
+		typeof widget.text === "string"
+	);
+}
+
 function makeFootrefHTML(tag: string) {
 	const span1 = document.createElement("span");
 	span1.className =
@@ -27,17 +37,19 @@ function makeFootrefHTML(tag: string) {
 
 // If `spec.widget` is a callout widget, replace its inner "[^tag]"s with HTML generated by `makeFootrefHTML`.
 function modifyCallout(spec: Parameters<typeof Decoration.replace>[0]) {
-	const widget: CalloutWidgetType | undefined = spec.widget;
-	if (
-		widget &&
-		widget.clazz === "cm-callout" &&
-		widget.text &&
-		typeof widget.text === "string"
-	) {
+	const widget = spec.widget;
+	if (isCallout(widget)) {
 		const footrefRegex = /\[\^([^\]]+)\]/g;
 		widget.text = widget.text.replace(footrefRegex, (_, tag) =>
 			makeFootrefHTML(tag)
 		);
+
+		// Modifying `widget.text` causes an inconsistency between `widget.text` and the document,
+		// leading Obsidian to recreate the widget. The eq method tells that the recreated widget
+		// is equivallent to the original one, preventeing unnecessary re-rendering.
+		widget.eq = function (other) {
+			return isCallout(other) && this.text === other.text;
+		};
 	}
 }