Don't anchor scroll position to bottom if the editor isn't scrolled

FIX: Fix a bug where adding content to the editor could inappropriately move the scroll position. Closes codemirror/dev#1200
codemirror · Jul 4, 2023 · 94ba222 · 94ba222
1 parent 5bd7ac0
commit 94ba222
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Showing 3 changed files with 9 additions and 4 deletions.
diff --git a/src/dom.ts b/src/dom.ts
@@ -314,3 +314,7 @@ export function atElementStart(doc: HTMLElement, selection: SelectionRange) {
     }
   }
 }
+
+export function isScrolledToBottom(elt: HTMLElement) {
+  return elt.scrollTop > Math.max(1, elt.scrollHeight - elt.clientHeight - 4)
+}
diff --git a/src/editorview.ts b/src/editorview.ts
@@ -5,7 +5,8 @@ import {StyleModule, StyleSpec} from "style-mod"
 import {DocView} from "./docview"
 import {ContentView} from "./contentview"
 import {InputState, focusChangeTransaction, isFocusChange} from "./input"
-import {Rect, focusPreventScroll, flattenRect, getRoot, ScrollStrategy, dispatchKey} from "./dom"
+import {Rect, focusPreventScroll, flattenRect, getRoot, ScrollStrategy,
+        isScrolledToBottom, dispatchKey} from "./dom"
 import {posAtCoords, moveByChar, moveToLineBoundary, byGroup, moveVertically, skipAtoms} from "./cursor"
 import {BlockInfo} from "./heightmap"
 import {ViewState} from "./viewstate"
@@ -384,7 +385,7 @@ export class EditorView {
     try {
       for (let i = 0;; i++) {
         if (scrollAnchorHeight < 0) {
-          if (scrollTop > sDOM.scrollHeight - sDOM.clientHeight - 4) {
+          if (isScrolledToBottom(sDOM)) {
             scrollAnchorPos = -1
             scrollAnchorHeight = this.viewState.heightMap.height
           } else {

diff --git a/src/viewstate.ts b/src/viewstate.ts
@@ -1,5 +1,5 @@
 import {Text, EditorState, ChangeSet, ChangeDesc, RangeSet, EditorSelection} from "@codemirror/state"
-import {Rect} from "./dom"
+import {Rect, isScrolledToBottom} from "./dom"
 import {HeightMap, HeightOracle, BlockInfo, MeasuredHeights, QueryType, heightRelevantDecoChanges} from "./heightmap"
 import {decorations, ViewUpdate, UpdateFlag, ChangedRange, ScrollTarget, nativeSelectionHidden,
         contentAttributes} from "./extension"
@@ -263,7 +263,7 @@ export class ViewState {
       this.scrollAnchorHeight = -1
       this.scrollTop = view.scrollDOM.scrollTop
     }
-    this.scrolledToBottom = this.scrollTop > view.scrollDOM.scrollHeight - view.scrollDOM.clientHeight - 4
+    this.scrolledToBottom = isScrolledToBottom(view.scrollDOM)
 
     // Pixel viewport
     let pixelViewport = (this.printing ? fullPixelRange : visiblePixelRange)(dom, this.paddingTop)
-Original file line number
+Diff line change
@@ Expand Up @@
         }
       }
     }
+    export function isScrolledToBottom(elt: HTMLElement) {
+      return elt.scrollTop > Math.max(1, elt.scrollHeight - elt.clientHeight - 4)
+    }