Start fixed width terminals

Scroll bars don't work yet and only a command for discovery

Part of #74501

src/vs/workbench/contrib/terminal/browser/terminal.ts

@@ -717,8 +717,12 @@ export interface ITerminalInstance {
 
 	waitForTitle(): Promise<string>;
 
+	// TODO: Clarify name
 	setDimensions(dimensions: ITerminalDimensions): void;
 
+	// TODO: Doc
+	setFixedDimensions(): Promise<void>;
+
 	addDisposable(disposable: IDisposable): void;
 
 	toggleEscapeSequenceLogging(): void;

src/vs/workbench/contrib/terminal/browser/terminalActions.ts

@@ -1793,6 +1793,21 @@ export function registerTerminalActions() {
 		}
 	});
 
+	registerAction2(class extends Action2 {
+		constructor() {
+			super({
+				id: TerminalCommandId.SetDimensions,
+				title: { value: localize('workbench.action.terminal.setFixedDimensions', "Set Fixed Dimensions"), original: 'Set Fixed Dimensions' },
+				f1: true,
+				category,
+				precondition: TerminalContextKeys.isOpen
+			});
+		}
+		async run(accessor: ServicesAccessor) {
+			await accessor.get(ITerminalService).doWithActiveInstance(t => t.setFixedDimensions());
+		}
+	});
+
 	// Some commands depend on platform features
 	if (BrowserFeatures.clipboard.writeText) {
 		registerAction2(class extends Action2 {

src/vs/workbench/contrib/terminal/browser/terminalInstance.ts

@@ -135,6 +135,8 @@ export class TerminalInstance extends Disposable implements ITerminalInstance {
 	private _terminalA11yTreeFocusContextKey: IContextKey<boolean>;
 	private _cols: number = 0;
 	private _rows: number = 0;
+	private _fixedCols: number | undefined = undefined;
+	private _fixedRows: number | undefined = undefined;
 	private _dimensionsOverride: ITerminalDimensionsOverride | undefined;
 	private _xtermReadyPromise: Promise<XTermTerminal>;
 	private _titleReadyPromise: Promise<string>;
@@ -166,6 +168,9 @@ export class TerminalInstance extends Disposable implements ITerminalInstance {
 	get instanceId(): number { return this._instanceId; }
 	get resource(): URI { return this._resource; }
 	get cols(): number {
+		if (this._fixedCols !== undefined) {
+			return this._fixedCols;
+		}
 		if (this._dimensionsOverride && this._dimensionsOverride.cols) {
 			if (this._dimensionsOverride.forceExactSize) {
 				return this._dimensionsOverride.cols;
@@ -175,6 +180,9 @@ export class TerminalInstance extends Disposable implements ITerminalInstance {
 		return this._cols;
 	}
 	get rows(): number {
+		if (this._fixedRows !== undefined) {
+			return this._fixedRows;
+		}
 		if (this._dimensionsOverride && this._dimensionsOverride.rows) {
 			if (this._dimensionsOverride.forceExactSize) {
 				return this._dimensionsOverride.rows;
@@ -1795,6 +1803,41 @@ export class TerminalInstance extends Disposable implements ITerminalInstance {
 		}
 	}
 
+	async setFixedDimensions(): Promise<void> {
+		const cols = await this._quickInputService.input({
+			// TODO: nls
+			title: 'Set Fixed Dimensions: Column',
+			placeHolder: 'Enter a number or leave empty size automatically',
+			validateInput: async (text) => text.length > 0 && !text.match(/^\d+$/) ? { content: 'Enter a number or leave empty size automatically', severity: Severity.Error } : undefined
+		});
+		if (cols === undefined) {
+			return;
+		}
+		this._fixedCols = this._parseFixedDimension(cols);
+		const rows = await this._quickInputService.input({
+			// TODO: nls
+			title: 'Set Fixed Dimensions: Row',
+			placeHolder: 'Enter a number or leave empty size automatically',
+			validateInput: async (text) => text.length > 0 && !text.match(/^\d+$/) ? { content: 'Enter a number or leave empty size automatically', severity: Severity.Error } : undefined
+		});
+		if (rows === undefined) {
+			return;
+		}
+		this._fixedRows = this._parseFixedDimension(rows);
+		this._resize();
+	}
+
+	private _parseFixedDimension(value: string): number | undefined {
+		if (value === '') {
+			return undefined;
+		}
+		const parsed = parseInt(value);
+		if (parsed <= 0) {
+			throw new Error(`Could not parse dimension "${value}"`);
+		}
+		return parsed;
+	}
+
 	private _setResolvedShellLaunchConfig(shellLaunchConfig: IShellLaunchConfig): void {
 		this._shellLaunchConfig.args = shellLaunchConfig.args;
 		this._shellLaunchConfig.cwd = shellLaunchConfig.cwd;

src/vs/workbench/contrib/terminal/common/terminal.ts

@@ -444,6 +444,7 @@ export const enum TerminalCommandId {
 	MoveToEditor = 'workbench.action.terminal.moveToEditor',
 	MoveToEditorInstance = 'workbench.action.terminal.moveToEditorInstance',
 	MoveToTerminalPanel = 'workbench.action.terminal.moveToTerminalPanel',
+	SetDimensions = 'workbench.action.terminal.setDimensions',
 }
 
 export const DEFAULT_COMMANDS_TO_SKIP_SHELL: string[] = [