Add RTE keyboard navigation in editing (#9980)

Add Keyboard navigation in editing

src/components/views/rooms/wysiwyg_composer/utils/event.ts

@@ -0,0 +1,46 @@
+/*
+Copyright 2023 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { MatrixClient, MatrixEvent } from "matrix-js-sdk/src/matrix";
+
+import EditorStateTransfer from "../../../../../utils/EditorStateTransfer";
+import { IRoomState } from "../../../../structures/RoomView";
+
+// From EditMessageComposer private get events(): MatrixEvent[]
+export function getEventsFromEditorStateTransfer(
+    editorStateTransfer: EditorStateTransfer,
+    roomContext: IRoomState,
+    mxClient: MatrixClient,
+): MatrixEvent[] | undefined {
+    const liveTimelineEvents = roomContext.liveTimeline?.getEvents();
+    if (!liveTimelineEvents) {
+        return;
+    }
+
+    const roomId = editorStateTransfer.getEvent().getRoomId();
+    if (!roomId) {
+        return;
+    }
+
+    const room = mxClient.getRoom(roomId);
+    if (!room) {
+        return;
+    }
+
+    const pendingEvents = room.getPendingEvents();
+    const isInThread = Boolean(editorStateTransfer.getEvent().getThread());
+    return liveTimelineEvents.concat(isInThread ? [] : pendingEvents);
+}

src/components/views/rooms/wysiwyg_composer/utils/selection.ts

@@ -39,3 +39,50 @@ export function isSelectionEmpty(): boolean {
     const selection = document.getSelection();
     return Boolean(selection?.isCollapsed);
 }
+
+export function isCaretAtStart(editor: HTMLElement): boolean {
+    const selection = document.getSelection();
+
+    // No selection or the caret is not at the beginning of the selected element
+    if (!selection || selection.anchorOffset !== 0) {
+        return false;
+    }
+
+    // In case of nested html elements (list, code blocks), we are going through all the first child
+    let child = editor.firstChild;
+    do {
+        if (child === selection.anchorNode) {
+            return true;
+        }
+    } while ((child = child?.firstChild || null));
+
+    return false;
+}
+
+export function isCaretAtEnd(editor: HTMLElement): boolean {
+    const selection = document.getSelection();
+
+    if (!selection) {
+        return false;
+    }
+
+    // When we are cycling across all the timeline message with the keyboard
+    // The caret is on the last text element but focusNode and anchorNode refers to the editor div
+    // In this case, the focusOffset & anchorOffset match the index + 1 of the selected text
+    const isOnLastElement = selection.focusNode === editor && selection.focusOffset === editor.childNodes?.length;
+    if (isOnLastElement) {
+        return true;
+    }
+
+    // In case of nested html elements (list, code blocks), we are going through all the last child
+    // The last child of the editor is always a <br> tag, we skip it
+    let child: ChildNode | null = editor.childNodes.item(editor.childNodes.length - 2);
+    do {
+        if (child === selection.focusNode) {
+            // Checking that the cursor is at end of the selected text
+            return selection.focusOffset === child.textContent?.length;
+        }
+    } while ((child = child.lastChild));
+
+    return false;
+}