Separate image storage per mechanism (sixel, iip)

addons/addon-image/src/IIPHandler.ts

@@ -4,7 +4,8 @@
  */
 import { IImageAddonOptions, IOscHandler, IResetHandler, ITerminalExt } from './Types';
 import { ImageRenderer } from './ImageRenderer';
-import { ImageStorage, CELL_SIZE_DEFAULT } from './ImageStorage';
+import { IIPImageStorage } from './IIPImageStorage';
+import { CELL_SIZE_DEFAULT } from './ImageStorage';
 import Base64Decoder from 'xterm-wasm-parts/lib/base64/Base64Decoder.wasm';
 import { HeaderParser, IHeaderFields, HeaderState } from './IIPHeaderParser';
 import { imageType, UNSUPPORTED_TYPE } from './IIPMetrics';
@@ -40,7 +41,7 @@ export class IIPHandler implements IOscHandler, IResetHandler {
   constructor(
     private readonly _opts: IImageAddonOptions,
     private readonly _renderer: ImageRenderer,
-    private readonly _storage: ImageStorage,
+    private readonly _storage: IIPImageStorage,
     private readonly _coreTerminal: ITerminalExt
   ) {
     const maxEncodedBytes = Math.ceil(this._opts.iipSizeLimit * 4 / 3);

addons/addon-image/src/IIPImageStorage.ts

@@ -0,0 +1,26 @@
+/**
+ * Copyright (c) 2023 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { ImageStorage } from './ImageStorage';
+
+/**
+ * IIP (iTerm Image Protocol) specific image storage controller.
+ *
+ * Wraps the shared ImageStorage with IIP protocol semantics:
+ * - Always uses scrolling mode (cursor advances with image)
+ */
+export class IIPImageStorage {
+  constructor(
+    private readonly _storage: ImageStorage
+  ) {}
+
+  /**
+   * Add an IIP image to storage.
+   * Always uses scrolling mode — cursor advances past the image.
+   */
+  public addImage(img: HTMLCanvasElement | ImageBitmap): void {
+    this._storage.addImage(img, true);
+  }
+}

addons/addon-image/src/ImageAddon.ts

@@ -9,6 +9,8 @@ import { IIPHandler } from './IIPHandler';
 import { ImageRenderer } from './ImageRenderer';
 import { ImageStorage, CELL_SIZE_DEFAULT } from './ImageStorage';
 import { SixelHandler } from './SixelHandler';
+import { SixelImageStorage } from './SixelImageStorage';
+import { IIPImageStorage } from './IIPImageStorage';
 import { ITerminalExt, IImageAddonOptions, IResetHandler } from './Types';
 
 // default values of addon ctor options
@@ -129,7 +131,8 @@ export class ImageAddon implements ITerminalAddon, IImageApi {
 
     // SIXEL handler
     if (this._opts.sixelSupport) {
-      const sixelHandler = new SixelHandler(this._opts, this._storage!, terminal);
+      const sixelStorage = new SixelImageStorage(this._storage!, this._opts, this._renderer!, terminal);
+      const sixelHandler = new SixelHandler(this._opts, sixelStorage, terminal);
       this._handlers.set('sixel', sixelHandler);
       this._disposeLater(
         terminal._core._inputHandler._parser.registerDcsHandler({ final: 'q' }, sixelHandler)
@@ -138,7 +141,8 @@ export class ImageAddon implements ITerminalAddon, IImageApi {
 
     // iTerm IIP handler
     if (this._opts.iipSupport) {
-      const iipHandler = new IIPHandler(this._opts, this._renderer!, this._storage!, terminal);
+      const iipStorage = new IIPImageStorage(this._storage!);
+      const iipHandler = new IIPHandler(this._opts, this._renderer!, iipStorage, terminal);
       this._handlers.set('iip', iipHandler);
       this._disposeLater(
         terminal._core._inputHandler._parser.registerOscHandler(1337, iipHandler)

addons/addon-image/src/ImageStorage.ts

@@ -216,28 +216,14 @@ export class ImageStorage implements IDisposable {
     this._fullyCleared = false;
   }
 
-  /**
-   * Only advance text cursor.
-   * This is an edge case from empty sixels carrying only a height but no pixels.
-   * Partially fixes https://github.com/jerch/xterm-addon-image/issues/37.
-   */
-  public advanceCursor(height: number): void {
-    if (this._opts.sixelScrolling) {
-      let cellSize = this._renderer.cellSize;
-      if (cellSize.width === -1 || cellSize.height === -1) {
-        cellSize = CELL_SIZE_DEFAULT;
-      }
-      const rows = Math.ceil(height / cellSize.height);
-      for (let i = 1; i < rows; ++i) {
-        this._terminal._core._inputHandler.lineFeed();
-      }
-    }
-  }
-
   /**
    * Method to add an image to the storage.
+   * @param img - The image to add (canvas or bitmap).
+   * @param scrolling - When true, cursor advances with the image (lineFeed per row).
+   *   When false, image is placed at (0,0) and cursor is restored (DECSET 80 / sixel origin mode).
+   * @returns The internal image ID assigned to the stored image.
    */
-  public addImage(img: HTMLCanvasElement | ImageBitmap): void {
+  public addImage(img: HTMLCanvasElement | ImageBitmap, scrolling: boolean): number {
     // never allow storage to exceed memory limit
     this._evictOldest(img.width * img.height);
 
@@ -259,7 +245,7 @@ export class ImageStorage implements IDisposable {
     let offset = originX;
     let tileCount = 0;
 
-    if (!this._opts.sixelScrolling) {
+    if (!scrolling) {
       buffer.x = 0;
       buffer.y = 0;
       offset = 0;
@@ -273,7 +259,7 @@ export class ImageStorage implements IDisposable {
         this._writeToCell(line as IBufferLineExt, offset + col, imageId, row * cols + col);
         tileCount++;
       }
-      if (this._opts.sixelScrolling) {
+      if (scrolling) {
         if (row < rows - 1) this._terminal._core._inputHandler.lineFeed();
       } else {
         if (++buffer.y >= termRows) break;
@@ -283,7 +269,7 @@ export class ImageStorage implements IDisposable {
     this._terminal._core._inputHandler._dirtyRowTracker.markDirty(buffer.y);
 
     // cursor positioning modes
-    if (this._opts.sixelScrolling) {
+    if (scrolling) {
       buffer.x = offset;
     } else {
       buffer.x = originX;
@@ -331,6 +317,7 @@ export class ImageStorage implements IDisposable {
 
     // finally add the image
     this._images.set(imageId, imgSpec);
+    return imageId;
   }
 
 

addons/addon-image/src/SixelHandler.ts

@@ -3,7 +3,7 @@
  * @license MIT
  */
 
-import { ImageStorage } from './ImageStorage';
+import { SixelImageStorage } from './SixelImageStorage';
 import { IDcsHandler, IParams, IImageAddonOptions, ITerminalExt, AttributeData, IResetHandler, ReadonlyColorSet } from './Types';
 import { toRGBA8888, BIG_ENDIAN, PALETTE_ANSI_256, PALETTE_VT340_COLOR } from 'sixel/lib/Colors';
 import { RGBA8888 } from 'sixel/lib/Types';
@@ -26,7 +26,7 @@ export class SixelHandler implements IDcsHandler, IResetHandler {
 
   constructor(
     private readonly _opts: IImageAddonOptions,
-    private readonly _storage: ImageStorage,
+    private readonly _storage: SixelImageStorage,
     private readonly _coreTerminal: ITerminalExt
   ) {
     DecoderAsync({

addons/addon-image/src/SixelImageStorage.ts

@@ -0,0 +1,50 @@
+/**
+ * Copyright (c) 2020 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { ImageStorage, CELL_SIZE_DEFAULT } from './ImageStorage';
+import { IImageAddonOptions, ITerminalExt } from './Types';
+import { ImageRenderer } from './ImageRenderer';
+
+/**
+ * Sixel-specific image storage controller.
+ *
+ * Wraps the shared ImageStorage with sixel protocol semantics:
+ * - Cursor behavior governed by DECSET 80 (sixelScrolling option)
+ * - advanceCursor for empty sixels carrying only height
+ */
+export class SixelImageStorage {
+  constructor(
+    private readonly _storage: ImageStorage,
+    private readonly _opts: IImageAddonOptions,
+    private readonly _renderer: ImageRenderer,
+    private readonly _terminal: ITerminalExt
+  ) {}
+
+  /**
+   * Add a sixel image to storage.
+   * Cursor behavior depends on the sixelScrolling option (DECSET 80).
+   */
+  public addImage(img: HTMLCanvasElement | ImageBitmap): void {
+    this._storage.addImage(img, this._opts.sixelScrolling);
+  }
+
+  /**
+   * Only advance text cursor.
+   * This is an edge case from empty sixels carrying only a height but no pixels.
+   * Partially fixes https://github.com/jerch/xterm-addon-image/issues/37.
+   */
+  public advanceCursor(height: number): void {
+    if (this._opts.sixelScrolling) {
+      let cellSize = this._renderer.cellSize;
+      if (cellSize.width === -1 || cellSize.height === -1) {
+        cellSize = CELL_SIZE_DEFAULT;
+      }
+      const rows = Math.ceil(height / cellSize.height);
+      for (let i = 1; i < rows; ++i) {
+        this._terminal._core._inputHandler.lineFeed();
+      }
+    }
+  }
+}