force pasting as plain text in new composer

src/components/views/rooms/BasicMessageComposer.js

@@ -25,10 +25,12 @@ import {
     formatRangeAsQuote,
     formatRangeAsCode,
     formatInline,
+    replaceRangeAndMoveCaret,
 } from '../../../editor/operations';
 import {getCaretOffsetAndText, getRangeForSelection} from '../../../editor/dom';
 import Autocomplete from '../rooms/Autocomplete';
 import {autoCompleteCreator} from '../../../editor/parts';
+import {parsePlainTextMessage} from '../../../editor/deserialize';
 import {renderModel} from '../../../editor/render';
 import {Room} from 'matrix-js-sdk';
 import TypingStore from "../../../stores/TypingStore";
@@ -169,6 +171,18 @@ export default class BasicMessageEditor extends React.Component {
         this._onInput({inputType: "insertCompositionText"});
     }
 
+    _onPaste = (event) => {
+        const {model} = this.props;
+        const {partCreator} = model;
+        const text = event.clipboardData.getData("text/plain");
+        if (text) {
+            const range = getRangeForSelection(this._editorRef, model, document.getSelection());
+            const parts = parsePlainTextMessage(text, partCreator);
+            replaceRangeAndMoveCaret(range, parts);
+            event.preventDefault();
+        }
+    }
+
     _onInput = (event) => {
         // ignore any input while doing IME compositions
         if (this._isIMEComposing) {
@@ -492,6 +506,7 @@ export default class BasicMessageEditor extends React.Component {
                 tabIndex="1"
                 onBlur={this._onBlur}
                 onFocus={this._onFocus}
+                onPaste={this._onPaste}
                 onKeyDown={this._onKeyDown}
                 ref={ref => this._editorRef = ref}
                 aria-label={this.props.label}

src/editor/deserialize.js

@@ -232,7 +232,7 @@ function parseHtmlMessage(html, partCreator, isQuotedMessage) {
     return parts;
 }
 
-function parsePlainTextMessage(body, partCreator, isQuotedMessage) {
+export function parsePlainTextMessage(body, partCreator, isQuotedMessage) {
     const lines = body.split("\n");
     const parts = lines.reduce((parts, line, i) => {
         if (isQuotedMessage) {

src/editor/operations.js

@@ -18,7 +18,8 @@ limitations under the License.
  * Some common queries and transformations on the editor model
  */
 
-export function replaceRangeAndExpandSelection(model, range, newParts) {
+export function replaceRangeAndExpandSelection(range, newParts) {
+    const {model} = range;
     model.transform(() => {
         const oldLen = range.length;
         const addedLen = range.replace(newParts);
@@ -28,6 +29,17 @@ export function replaceRangeAndExpandSelection(model, range, newParts) {
     });
 }
 
+export function replaceRangeAndMoveCaret(range, newParts) {
+    const {model} = range;
+    model.transform(() => {
+        const oldLen = range.length;
+        const addedLen = range.replace(newParts);
+        const firstOffset = range.start.asOffset(model);
+        const lastOffset = firstOffset.add(oldLen + addedLen);
+        return lastOffset.asPosition(model);
+    });
+}
+
 export function rangeStartsAtBeginningOfLine(range) {
     const {model} = range;
     const startsWithPartial = range.start.offset !== 0;
@@ -63,7 +75,7 @@ export function formatRangeAsQuote(range) {
     }
 
     parts.push(partCreator.newline());
-    replaceRangeAndExpandSelection(model, range, parts);
+    replaceRangeAndExpandSelection(range, parts);
 }
 
 export function formatRangeAsCode(range) {
@@ -85,7 +97,7 @@ export function formatRangeAsCode(range) {
         parts.unshift(partCreator.plain("`"));
         parts.push(partCreator.plain("`"));
     }
-    replaceRangeAndExpandSelection(model, range, parts);
+    replaceRangeAndExpandSelection(range, parts);
 }
 
 export function formatInline(range, prefix, suffix = prefix) {
@@ -93,5 +105,5 @@ export function formatInline(range, prefix, suffix = prefix) {
     const {partCreator} = model;
     parts.unshift(partCreator.plain(prefix));
     parts.push(partCreator.plain(suffix));
-    replaceRangeAndExpandSelection(model, range, parts);
+    replaceRangeAndExpandSelection(range, parts);
 }