From b7d73f63cd730bd8aeb48121ee29d9f8f1c7dc2e Mon Sep 17 00:00:00 2001
From: tisilent <tisilent@163.com>
Date: Wed, 19 Apr 2023 15:48:12 +0800
Subject: [PATCH] Add smoothScroll to scrollLines

---
 src/browser/Terminal.ts | 76 +++++++++++++++++++++++++++++++++++++++--
 src/browser/Types.d.ts  | 10 ++++++
 src/browser/Viewport.ts |  8 +----
 3 files changed, 85 insertions(+), 9 deletions(-)

diff --git a/src/browser/Terminal.ts b/src/browser/Terminal.ts
index fe19f9546e..37a4eca136 100644
--- a/src/browser/Terminal.ts
+++ b/src/browser/Terminal.ts
@@ -21,7 +21,7 @@
  *   http://linux.die.net/man/7/urxvt
  */
 
-import { ICompositionHelper, ITerminal, IBrowser, CustomKeyEventHandler, IViewport, ILinkifier2, CharacterJoinerHandler, IBufferRange, IBufferElementProvider } from 'browser/Types';
+import { ICompositionHelper, ITerminal, IBrowser, CustomKeyEventHandler, IViewport, ILinkifier2, CharacterJoinerHandler, IBufferRange, IBufferElementProvider, ISmoothScrollProgressState } from 'browser/Types';
 import { IRenderer } from 'browser/renderer/shared/Types';
 import { CompositionHelper } from 'browser/input/CompositionHelper';
 import { Viewport } from 'browser/Viewport';
@@ -122,6 +122,13 @@ export class Terminal extends CoreTerminal implements ITerminal {
   private _compositionHelper: ICompositionHelper | undefined;
   private _accessibilityManager: AccessibilityManager | undefined;
 
+  private _smoothScrollProgressState: ISmoothScrollProgressState = {
+    startTime: 0,
+    origin: 0,
+    target: 0,
+    progress: 0
+  };
+
   private readonly _onCursorMove = this.register(new EventEmitter<void>());
   public readonly onCursorMove = this._onCursorMove.event;
   private readonly _onKey = this.register(new EventEmitter<{ key: string, domEvent: KeyboardEvent }>());
@@ -869,11 +876,76 @@ export class Terminal extends CoreTerminal implements ITerminal {
     }
   }
 
-  public scrollLines(disp: number, suppressScrollEvent?: boolean, source = ScrollSource.TERMINAL): void {
+  private _scrollLines(disp: number, suppressScrollEvent?: boolean, source = ScrollSource.TERMINAL): void {
     super.scrollLines(disp, suppressScrollEvent, source);
     this.refresh(0, this.rows - 1);
   }
 
+  public scrollLines(disp: number, suppressScrollEvent?: boolean, source = ScrollSource.TERMINAL): void {
+    if (source === ScrollSource.VIEWPORT) {
+      this._scrollLines(disp, suppressScrollEvent, source);
+    } else {
+      if (!this.optionsService.rawOptions.smoothScrollDuration) {
+        this._scrollLines(disp, suppressScrollEvent, source);
+      } else {
+        this._smoothScrollProgressState.startTime = Date.now();
+        if (this._smoothScrollPercent() < 1) {
+          this._smoothScrollProgressState.origin = 0;
+          this._smoothScrollProgressState.target = disp;
+          this._smoothScrollProgressState.progress = 0;
+          this._smoothScroll(suppressScrollEvent, source);
+        } else {
+          this._clearSmoothScrollState();
+        }
+      }
+    }
+  }
+
+  private _smoothScrollPercent(): number {
+    if (!this.optionsService.rawOptions.smoothScrollDuration || !this._smoothScrollProgressState.startTime) {
+      return 1;
+    }
+    return Math.max(Math.min((Date.now() - this._smoothScrollProgressState.startTime) / this.optionsService.rawOptions.smoothScrollDuration, 1), 0);
+  }
+
+  private _isSmoothScrollEnd(): boolean {
+    if (this._smoothScrollProgressState.target < 0) {
+      if (this._smoothScrollProgressState.progress > this._smoothScrollProgressState.target) {
+        return false;
+      }
+    } else if (this._smoothScrollProgressState.target > 0) {
+      if (this._smoothScrollProgressState.progress < this._smoothScrollProgressState.target) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  private _smoothScroll(suppressScrollEvent?: boolean, source = ScrollSource.TERMINAL): void {
+    if (this._smoothScrollProgressState.startTime === 0 || this._isSmoothScrollEnd()) {
+      return;
+    }
+
+    const percent = this._smoothScrollPercent();
+    const step = Math.round(percent * (this._smoothScrollProgressState.target - this._smoothScrollProgressState.origin)) - this._smoothScrollProgressState.progress;
+    this._smoothScrollProgressState.progress += step;
+    this._scrollLines(step, suppressScrollEvent, source);
+
+    if (this._isSmoothScrollEnd()) {
+      this._clearSmoothScrollState();
+      return;
+    }
+
+    this._coreBrowserService?.window.requestAnimationFrame(() => this._smoothScroll(suppressScrollEvent, source));
+  }
+
+  private _clearSmoothScrollState(): void {
+    this._smoothScrollProgressState.origin = 0;
+    this._smoothScrollProgressState.target = 0;
+    this._smoothScrollProgressState.progress = 0;
+    this._smoothScrollProgressState.startTime = 0;
+  }
+
   public paste(data: string): void {
     paste(data, this.textarea!, this.coreService);
   }
diff --git a/src/browser/Types.d.ts b/src/browser/Types.d.ts
index 5f2ed89952..93236e69f3 100644
--- a/src/browser/Types.d.ts
+++ b/src/browser/Types.d.ts
@@ -150,6 +150,16 @@ export interface IViewport extends IDisposable {
   handleTouchMove(ev: TouchEvent): boolean;
 }
 
+export interface ISmoothScrollState {
+  startTime: number;
+  origin: number;
+  target: number;
+}
+
+export interface ISmoothScrollProgressState extends ISmoothScrollState {
+  progress: number;
+}
+
 export interface ILinkifierEvent {
   x1: number;
   y1: number;
diff --git a/src/browser/Viewport.ts b/src/browser/Viewport.ts
index 25757bcac4..b5fa722d12 100644
--- a/src/browser/Viewport.ts
+++ b/src/browser/Viewport.ts
@@ -5,7 +5,7 @@
 
 import { Disposable } from 'common/Lifecycle';
 import { addDisposableDomListener } from 'browser/Lifecycle';
-import { IColorSet, IViewport, ReadonlyColorSet } from 'browser/Types';
+import { IColorSet, ISmoothScrollState, IViewport, ReadonlyColorSet } from 'browser/Types';
 import { ICharSizeService, ICoreBrowserService, IRenderService, IThemeService } from 'browser/services/Services';
 import { IBufferService, IOptionsService } from 'common/services/Services';
 import { IBuffer } from 'common/buffer/Types';
@@ -13,12 +13,6 @@ import { IRenderDimensions } from 'browser/renderer/shared/Types';
 
 const FALLBACK_SCROLL_BAR_WIDTH = 15;
 
-interface ISmoothScrollState {
-  startTime: number;
-  origin: number;
-  target: number;
-}
-
 /**
  * Represents the viewport of a terminal, the visible area within the larger buffer of output.
  * Logic for the virtual scroll bar is included in this object.