From 489eadb352123bd220029b098e5f80fb72c4e9c8 Mon Sep 17 00:00:00 2001
From: Henrik Giesel <hengiesel@gmail.com>
Date: Tue, 11 Jan 2022 23:39:41 +0100
Subject: [PATCH] Fix IME input after tab (#1584)

* Avoid initial call of mirror-dom

* Disable updateFocus from OldEditorAdapter

* fixes IME input duplication bug

* Fix saving of latestLocation for ContentEditable

* Fix IME after calling placeCaretAfterContent

* Export other libraries from domlib/index.ts

* Remove dead code

+ Uncomment code which was mistakenly left commmented
---
 ts/domlib/index.ts                            |  6 +-
 ts/editable/ContentEditable.svelte            |  4 +-
 ts/editable/content-editable.ts               | 50 ++++++++----
 ts/editor/OldEditorAdapter.svelte             | 11 +--
 ts/editor/RichTextInput.svelte                |  1 -
 .../mathjax-overlay/MathjaxHandle.svelte      |  3 +-
 ts/sveltelib/mirror-dom.ts                    | 77 ++++++++++---------
 ts/sveltelib/node-store.ts                    | 11 +--
 ts/sveltelib/store-subscribe.ts               |  4 +-
 9 files changed, 90 insertions(+), 77 deletions(-)

diff --git a/ts/domlib/index.ts b/ts/domlib/index.ts
index b530593ab..4808c7ce5 100644
--- a/ts/domlib/index.ts
+++ b/ts/domlib/index.ts
@@ -1,5 +1,7 @@
 // Copyright: Ankitects Pty Ltd and contributors
 // License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
-export * as location from "./location";
-export * as surround from "./surround";
+export * from "./location";
+export * from "./surround";
+export * from "./move-nodes";
+export * from "./place-caret";
diff --git a/ts/editable/ContentEditable.svelte b/ts/editable/ContentEditable.svelte
index 3a4b39415..d1a6bb02b 100644
--- a/ts/editable/ContentEditable.svelte
+++ b/ts/editable/ContentEditable.svelte
@@ -12,7 +12,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     import actionList from "../sveltelib/action-list";
     import contentEditableAPI, {
         saveLocation,
-        prepareFocusHandling,
+        initialFocusHandling,
         preventBuiltinContentEditableShortcuts,
     } from "./content-editable";
     import type { ContentEditableAPI } from "./content-editable";
@@ -40,7 +40,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     contenteditable="true"
     use:resolve
     use:saveLocation
-    use:prepareFocusHandling
+    use:initialFocusHandling
     use:preventBuiltinContentEditableShortcuts
     use:mirrorAction={mirrorOptions}
     use:managerAction={{}}
diff --git a/ts/editable/content-editable.ts b/ts/editable/content-editable.ts
index 6c755aa9b..3f2582bb7 100644
--- a/ts/editable/content-editable.ts
+++ b/ts/editable/content-editable.ts
@@ -17,30 +17,42 @@ function flushLocation(): void {
     }
 }
 
-let latestLocation: SelectionLocation | null = null;
+function safePlaceCaretAfterContent(editable: HTMLElement): void {
+    /**
+     * Workaround: If you try to invoke an IME after calling
+     * `placeCaretAfterContent` on a cE element, the IME will immediately
+     * end and the input character will be duplicated
+     */
+    placeCaretAfterContent(editable);
+    restoreSelection(editable, saveSelection(editable)!);
+}
 
-function onFocus(this: HTMLElement): void {
-    if (!latestLocation) {
-        placeCaretAfterContent(this);
-        return;
-    }
+function onFocus(location: SelectionLocation | null): () => void {
+    return function (this: HTMLElement): void {
+        if (!location) {
+            safePlaceCaretAfterContent(this);
+            return;
+        }
 
-    try {
-        restoreSelection(this, latestLocation);
-    } catch {
-        placeCaretAfterContent(this);
-    }
+        try {
+            restoreSelection(this, location);
+        } catch {
+            safePlaceCaretAfterContent(this);
+        }
+    };
 }
 
 function onBlur(this: HTMLElement): void {
-    prepareFocusHandling(this);
-    latestLocation = saveSelection(this);
+    prepareFocusHandling(this, saveSelection(this));
 }
 
-let removeOnFocus: () => void;
-
-export function prepareFocusHandling(editable: HTMLElement): void {
-    removeOnFocus = on(editable, "focus", onFocus, { once: true });
+function prepareFocusHandling(
+    editable: HTMLElement,
+    latestLocation: SelectionLocation | null = null,
+): void {
+    const removeOnFocus = on(editable, "focus", onFocus(latestLocation), {
+        once: true,
+    });
 
     locationEvents.push(
         removeOnFocus,
@@ -48,6 +60,10 @@ export function prepareFocusHandling(editable: HTMLElement): void {
     );
 }
 
+export function initialFocusHandling(editable: HTMLElement): void {
+    prepareFocusHandling(editable);
+}
+
 /* Must execute before DOMMirror */
 export function saveLocation(editable: HTMLElement): { destroy(): void } {
     const removeOnBlur = on(editable, "blur", onBlur);
diff --git a/ts/editor/OldEditorAdapter.svelte b/ts/editor/OldEditorAdapter.svelte
index fd88db316..dae07472e 100644
--- a/ts/editor/OldEditorAdapter.svelte
+++ b/ts/editor/OldEditorAdapter.svelte
@@ -8,7 +8,6 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     import type { PlainTextInputAPI } from "./PlainTextInput.svelte";
     import type { EditorToolbarAPI } from "./EditorToolbar.svelte";
 
-    import { registerShortcut } from "../lib/shortcuts";
     import contextProperty from "../sveltelib/context-property";
     import { writable, get } from "svelte/store";
 
@@ -27,15 +26,6 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
     const activeInput = writable<RichTextInputAPI | PlainTextInputAPI | null>(null);
     const currentField = writable<EditorFieldAPI | null>(null);
-
-    function updateFocus() {
-        get(activeInput)?.moveCaretToEnd();
-    }
-
-    registerShortcut(
-        () => document.addEventListener("focusin", updateFocus, { once: true }),
-        "Shift?+Tab",
-    );
 </script>
 
 <script lang="ts">
@@ -67,6 +57,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     import { onMount, onDestroy } from "svelte";
     import type { Writable } from "svelte/store";
     import { bridgeCommand } from "../lib/bridgecommand";
+    import { registerShortcut } from "../lib/shortcuts";
     import { isApplePlatform } from "../lib/platform";
     import { ChangeTimer } from "./change-timer";
     import { alertIcon } from "./icons";
diff --git a/ts/editor/RichTextInput.svelte b/ts/editor/RichTextInput.svelte
index 7aa4f0bac..0ff7efde9 100644
--- a/ts/editor/RichTextInput.svelte
+++ b/ts/editor/RichTextInput.svelte
@@ -110,7 +110,6 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
         /* we need createContextualFragment so that customElements are initialized */
         const fragment = range.createContextualFragment(adjustInputHTML(html));
         adjustInputFragment(fragment);
-
         nodes.setUnprocessed(fragment);
     }
 
diff --git a/ts/editor/mathjax-overlay/MathjaxHandle.svelte b/ts/editor/mathjax-overlay/MathjaxHandle.svelte
index b783d43d7..28e10e3a3 100644
--- a/ts/editor/mathjax-overlay/MathjaxHandle.svelte
+++ b/ts/editor/mathjax-overlay/MathjaxHandle.svelte
@@ -40,6 +40,8 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     let selectAll = false;
 
     function placeHandle(after: boolean): void {
+        flushLocation();
+
         if (after) {
             (mathjaxElement as any).placeCaretAfter();
         } else {
@@ -48,7 +50,6 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     }
 
     async function resetHandle(): Promise<void> {
-        flushLocation();
         selectAll = false;
 
         if (activeImage && mathjaxElement) {
diff --git a/ts/sveltelib/mirror-dom.ts b/ts/sveltelib/mirror-dom.ts
index 646710e28..18fc594be 100644
--- a/ts/sveltelib/mirror-dom.ts
+++ b/ts/sveltelib/mirror-dom.ts
@@ -4,7 +4,7 @@
 import { writable } from "svelte/store";
 import type { Writable } from "svelte/store";
 import storeSubscribe from "./store-subscribe";
-// import { getSelection } from "../lib/cross-browser";
+import { on } from "../lib/events";
 
 const config = {
     childList: true,
@@ -14,7 +14,7 @@ const config = {
 };
 
 export type MirrorAction = (
-    element: Element,
+    element: HTMLElement,
     params: { store: Writable<DocumentFragment> },
 ) => { destroy(): void };
 
@@ -23,10 +23,22 @@ interface DOMMirrorAPI {
     preventResubscription(): () => void;
 }
 
+function cloneNode(node: Node): DocumentFragment {
+    /**
+     * Creates a deep clone
+     * This seems to be less buggy than node.cloneNode(true)
+     */
+    const range = document.createRange();
+
+    range.selectNodeContents(node);
+    return range.cloneContents();
+}
+
 /**
  * Allows you to keep an element's inner HTML bidirectionally
  * in sync with a store containing a DocumentFragment.
  * While the element has focus, this connection is tethered.
+ * In practice, this will sync changes from PlainTextInput to RichTextInput.
  */
 function getDOMMirror(): DOMMirrorAPI {
     const allowResubscription = writable(true);
@@ -40,68 +52,58 @@ function getDOMMirror(): DOMMirrorAPI {
     }
 
     function mirror(
-        element: Element,
+        element: HTMLElement,
         { store }: { store: Writable<DocumentFragment> },
     ): { destroy(): void } {
         function saveHTMLToStore(): void {
-            const range = document.createRange();
-
-            range.selectNodeContents(element);
-            const contents = range.cloneContents();
-
-            store.set(contents);
+            store.set(cloneNode(element));
         }
 
         const observer = new MutationObserver(saveHTMLToStore);
         observer.observe(element, config);
 
-        function mirrorToNode(node: Node): void {
+        function mirrorToElement(node: Node): void {
             observer.disconnect();
-            const clone = node.cloneNode(true);
-
-            /* TODO use Element.replaceChildren */
+            // element.replaceChildren(...node.childNodes); // TODO use once available
             while (element.firstChild) {
                 element.firstChild.remove();
             }
 
-            while (clone.firstChild) {
-                element.appendChild(clone.firstChild);
+            while (node.firstChild) {
+                element.appendChild(node.firstChild);
             }
-
             observer.observe(element, config);
         }
 
-        const { subscribe, unsubscribe } = storeSubscribe(store, mirrorToNode);
-        // const selection = getSelection(element)!;
-
-        function doSubscribe(): void {
-            // Might not be needed after all:
-            // /**
-            //  * Focused element and caret are two independent things in the browser.
-            //  * When the ContentEditable calls blur, it will still have the selection inside of it.
-            //  * Some elements (e.g. FrameElement) need to figure whether the intended focus is still
-            //  * in the contenteditable or elsewhere because they might change the selection.
-            //  */
-            // selection.removeAllRanges();
-
-            subscribe();
+        function mirrorFromFragment(fragment: DocumentFragment): void {
+            mirrorToElement(cloneNode(fragment));
         }
 
+        const { subscribe, unsubscribe } = storeSubscribe(
+            store,
+            mirrorFromFragment,
+            false,
+        );
+
         /* do not update when focused as it will reset caret */
-        element.addEventListener("focus", unsubscribe);
+        const removeFocus = on(element, "focus", unsubscribe);
+        let removeBlur: (() => void) | undefined;
 
         const unsubResubscription = allowResubscription.subscribe(
             (allow: boolean): void => {
                 if (allow) {
-                    element.addEventListener("blur", doSubscribe);
+                    if (!removeBlur) {
+                        removeBlur = on(element, "blur", subscribe);
+                    }
 
                     const root = element.getRootNode() as Document | ShadowRoot;
 
                     if (root.activeElement !== element) {
-                        doSubscribe();
+                        subscribe();
                     }
-                } else {
-                    element.removeEventListener("blur", doSubscribe);
+                } else if (removeBlur) {
+                    removeBlur();
+                    removeBlur = undefined;
                 }
             },
         );
@@ -110,9 +112,8 @@ function getDOMMirror(): DOMMirrorAPI {
             destroy() {
                 observer.disconnect();
 
-                // removes blur event listener
-                allowResubscription.set(false);
-                element.removeEventListener("focus", unsubscribe);
+                removeFocus();
+                removeBlur?.();
 
                 unsubscribe();
                 unsubResubscription();
diff --git a/ts/sveltelib/node-store.ts b/ts/sveltelib/node-store.ts
index e78f20c25..bf18fc6d5 100644
--- a/ts/sveltelib/node-store.ts
+++ b/ts/sveltelib/node-store.ts
@@ -15,12 +15,13 @@ export function nodeStore<T extends Node>(
     const subscribers: Set<Subscriber<T>> = new Set();
 
     function setUnprocessed(newNode: T): void {
-        if (!node || !node.isEqualNode(newNode)) {
-            node = newNode;
+        if (node && node.isEqualNode(newNode)) {
+            return;
+        }
 
-            for (const subscriber of subscribers) {
-                subscriber(node);
-            }
+        node = newNode;
+        for (const subscriber of subscribers) {
+            subscriber(node);
         }
     }
 
diff --git a/ts/sveltelib/store-subscribe.ts b/ts/sveltelib/store-subscribe.ts
index dcc8ade99..3cb086286 100644
--- a/ts/sveltelib/store-subscribe.ts
+++ b/ts/sveltelib/store-subscribe.ts
@@ -8,7 +8,9 @@ interface StoreAccessors {
     unsubscribe: () => void;
 }
 
-// Prevent double subscriptions / unsubscriptions
+/**
+ * Helper function to prevent double (un)subscriptions
+ */
 function storeSubscribe<T>(
     store: Readable<T>,
     callback: (value: T) => void,