From 20c1f1a5f72233ba542e12d4dea0560ab69eff90 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Breitbart?= <jerch@rockborn.de>
Date: Wed, 28 Sep 2022 12:14:09 +0200
Subject: [PATCH] fix resize edge cases: always report cleanup state

---
 src/common/Types.d.ts           |  2 +-
 src/common/buffer/BufferLine.ts | 13 +++++++++----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/common/Types.d.ts b/src/common/Types.d.ts
index d44bb197..bbf00f1b 100644
--- a/src/common/Types.d.ts
+++ b/src/common/Types.d.ts
@@ -205,7 +205,7 @@ export interface IBufferLine {
   insertCells(pos: number, n: number, ch: ICellData, eraseAttr?: IAttributeData): void;
   deleteCells(pos: number, n: number, fill: ICellData, eraseAttr?: IAttributeData): void;
   replaceCells(start: number, end: number, fill: ICellData, eraseAttr?: IAttributeData, respectProtect?: boolean): void;
-  resize(cols: number, fill: ICellData): void;
+  resize(cols: number, fill: ICellData): boolean;
   fill(fillCellData: ICellData, respectProtect?: boolean): void;
   copyFrom(line: IBufferLine): void;
   clone(): IBufferLine;
diff --git a/src/common/buffer/BufferLine.ts b/src/common/buffer/BufferLine.ts
index dc7ab51c..f6279f9d 100644
--- a/src/common/buffer/BufferLine.ts
+++ b/src/common/buffer/BufferLine.ts
@@ -338,10 +338,16 @@ export class BufferLine implements IBufferLine {
     }
   }
 
+  /**
+   * Resize BufferLine to `cols` filling excess cells with `fillCellData`.
+   * The underlying array buffer will not change if there is still enough space
+   * to hold the new buffer line data.
+   * Returns a boolean indicating, whether a `cleanBuffer` call would free
+   * excess memory (after shrinking > CLEANUP_THRESHOLD).
+   */
   public resize(cols: number, fillCellData: ICellData): boolean {
-    let needsCleanup = false;
     if (cols === this.length) {
-      return needsCleanup;
+      return this._data.length * 4 < this._data.buffer.byteLength * CLEANUP_THRESHOLD;
     }
     const fourByteCells = cols * CELL_SIZE;
     if (cols > this.length) {
@@ -362,7 +368,6 @@ export class BufferLine implements IBufferLine {
     } else {
       // optimization: just shrink the view on existing buffer
       this._data = this._data.subarray(0, fourByteCells);
-      needsCleanup = fourByteCells * 4 < this._data.buffer.byteLength * CLEANUP_THRESHOLD;
       // Remove any cut off combined data
       const keys = Object.keys(this._combined);
       for (let i = 0; i < keys.length; i++) {
@@ -381,7 +386,7 @@ export class BufferLine implements IBufferLine {
       }
     }
     this.length = cols;
-    return needsCleanup;
+    return fourByteCells * 4 < this._data.buffer.byteLength * CLEANUP_THRESHOLD;
   }
 
   /**