Prevent blink interval from running unless needed

Part of #944

src/browser/renderer/dom/DomRenderer.ts

@@ -47,6 +47,8 @@ export class DomRenderer extends Disposable implements IRenderer {
   private _selectionRenderModel: ISelectionRenderModel = createSelectionRenderModel();
   private _cursorBlinkStateManager: CursorBlinkStateManager;
   private _textBlinkStateManager: TextBlinkStateManager;
+  private _rowHasBlinkingCells: boolean[] = [];
+  private _rowHasBlinkingCellsCount: number = 0;
 
   public dimensions: IRenderDimensions;
 
@@ -329,10 +331,14 @@ export class DomRenderer extends Disposable implements IRenderer {
       const row = this._document.createElement('div');
       this._rowContainer.appendChild(row);
       this._rowElements.push(row);
+      this._rowHasBlinkingCells.push(false);
     }
     // Remove excess elements
     while (this._rowElements.length > rows) {
       this._rowContainer.removeChild(this._rowElements.pop()!);
+      if (this._rowHasBlinkingCells.pop()) {
+        this._rowHasBlinkingCellsCount--;
+      }
     }
   }
 
@@ -360,6 +366,10 @@ export class DomRenderer extends Disposable implements IRenderer {
     this.renderRows(this._bufferService.buffer.y, this._bufferService.buffer.y);
   }
 
+  public handleViewportVisibilityChange(isVisible: boolean): void {
+    this._textBlinkStateManager.setViewportVisible(isVisible);
+  }
+
   public handleSelectionChanged(start: [number, number] | undefined, end: [number, number] | undefined, columnSelectMode: boolean): void {
     // Remove all selections
     this._selectionContainer.replaceChildren();
@@ -461,6 +471,11 @@ export class DomRenderer extends Disposable implements IRenderer {
        */
       e.replaceChildren();
     }
+    if (this._rowHasBlinkingCellsCount > 0) {
+      this._rowHasBlinkingCells.fill(false);
+      this._rowHasBlinkingCellsCount = 0;
+      this._textBlinkStateManager.setNeedsBlinkInViewport(false);
+    }
   }
 
   public renderRows(start: number, end: number): void {
@@ -470,6 +485,7 @@ export class DomRenderer extends Disposable implements IRenderer {
     const cursorBlink = this._coreService.decPrivateModes.cursorBlink ?? this._optionsService.rawOptions.cursorBlink;
     const cursorStyle = this._coreService.decPrivateModes.cursorStyle ?? this._optionsService.rawOptions.cursorStyle;
     const cursorInactiveStyle = this._optionsService.rawOptions.cursorInactiveStyle;
+    const rowInfo = { hasBlinkingCells: false };
 
     for (let y = start; y <= end; y++) {
       const row = y + buffer.ydisp;
@@ -491,10 +507,13 @@ export class DomRenderer extends Disposable implements IRenderer {
           this.dimensions.css.cell.width,
           this._widthCache,
           -1,
-          -1
+          -1,
+          rowInfo
         )
       );
+      this._setRowBlinkState(y, rowInfo.hasBlinkingCells);
     }
+    this._updateTextBlinkState();
   }
 
   private get _terminalSelector(): string {
@@ -539,6 +558,7 @@ export class DomRenderer extends Disposable implements IRenderer {
     const cursorBlink = this._optionsService.rawOptions.cursorBlink;
     const cursorStyle = this._optionsService.rawOptions.cursorStyle;
     const cursorInactiveStyle = this._optionsService.rawOptions.cursorInactiveStyle;
+    const rowInfo = { hasBlinkingCells: false };
 
     // refresh rows within link range
     for (let i = y; i <= y2; ++i) {
@@ -561,10 +581,26 @@ export class DomRenderer extends Disposable implements IRenderer {
           this.dimensions.css.cell.width,
           this._widthCache,
           enabled ? (i === y ? x : 0) : -1,
-          enabled ? ((i === y2 ? x2 : cols) - 1) : -1
+          enabled ? ((i === y2 ? x2 : cols) - 1) : -1,
+          rowInfo
         )
       );
+      this._setRowBlinkState(i, rowInfo.hasBlinkingCells);
     }
+    this._updateTextBlinkState();
+  }
+
+  private _setRowBlinkState(row: number, hasBlinkingCells: boolean): void {
+    const previous = this._rowHasBlinkingCells[row];
+    if (previous === hasBlinkingCells) {
+      return;
+    }
+    this._rowHasBlinkingCells[row] = hasBlinkingCells;
+    this._rowHasBlinkingCellsCount += hasBlinkingCells ? 1 : -1;
+  }
+
+  private _updateTextBlinkState(): void {
+    this._textBlinkStateManager.setNeedsBlinkInViewport(this._rowHasBlinkingCellsCount > 0);
   }
 }
 

src/browser/renderer/dom/DomRendererRowFactory.ts

@@ -71,10 +71,14 @@ export class DomRendererRowFactory {
     cellWidth: number,
     widthCache: WidthCache,
     linkStart: number,
-    linkEnd: number
+    linkEnd: number,
+    rowInfo?: { hasBlinkingCells: boolean }
   ): HTMLSpanElement[] {
 
     const elements: HTMLSpanElement[] = [];
+    if (rowInfo) {
+      rowInfo.hasBlinkingCells = false;
+    }
     const joinedRanges = this._characterJoinerService.getJoinedCharacters(row);
     const colors = this._themeService.colors;
 
@@ -155,6 +159,9 @@ export class DomRendererRowFactory {
       const isInSelection = this._isCellInSelection(x, row);
       const isCursorCell = isCursorRow && x === cursorX;
       const isLinkHover = hasHover && x >= linkStart && x <= linkEnd;
+      if (rowInfo && cell.isBlink()) {
+        rowInfo.hasBlinkingCells = true;
+      }
       const isBlinkHidden = !blinkOn && cell.isBlink();
       if (isBlinkHidden) {
         classes.push(RowCss.BLINK_HIDDEN_CLASS);