feat(material/select): add input to control the panel width

src/material/legacy-select/public-api.ts

@@ -8,7 +8,12 @@
 
 export {MatLegacySelectModule} from './select-module';
 export {matLegacySelectAnimations} from './select-animations';
-export {MatLegacySelectChange, MatLegacySelect, MatLegacySelectTrigger} from './select';
+export {
+  MatLegacySelectChange,
+  MatLegacySelect,
+  MatLegacySelectTrigger,
+  MatLegacySelectConfig,
+} from './select';
 
 export {
   /**
@@ -40,10 +45,4 @@ export {
    * @breaking-change 17.0.0
    */
   MAT_SELECT_TRIGGER as MAT_LEGACY_SELECT_TRIGGER,
-
-  /**
-   * @deprecated Use `MatSelectConfig` from `@angular/material/select` instead. See https://material.angular.io/guide/mdc-migration for information about migrating.
-   * @breaking-change 17.0.0
-   */
-  MatSelectConfig as MatLegacySelectConfig,
 } from '@angular/material/select';

src/material/legacy-select/select.ts

@@ -25,7 +25,7 @@ import {
   MatLegacyOption,
   MatLegacyOptgroup,
 } from '@angular/material/legacy-core';
-import {MAT_SELECT_TRIGGER, _MatSelectBase} from '@angular/material/select';
+import {MAT_SELECT_TRIGGER, _MatSelectBase, MatSelectConfig} from '@angular/material/select';
 import {MatLegacyFormFieldControl} from '@angular/material/legacy-form-field';
 import {take, takeUntil} from 'rxjs/operators';
 import {matLegacySelectAnimations} from './select-animations';
@@ -101,6 +101,12 @@ export class MatLegacySelectChange {
   ) {}
 }
 
+/**
+ * @deprecated Use `MatSelectConfig` from `@angular/material/select` instead. See https://material.angular.io/guide/mdc-migration for information about migrating.
+ * @breaking-change 17.0.0
+ */
+export type MatLegacySelectConfig = Omit<MatSelectConfig, 'panelWidth'>;
+
 /**
  * Allows the user to customize the trigger that is displayed when the select has a value.
  * @deprecated Use `MatSelectTrigger` from `@angular/material/select` instead. See https://material.angular.io/guide/mdc-migration for information about migrating.

src/material/select/select.spec.ts

@@ -1524,6 +1524,42 @@ describe('MDC-based MatSelect', () => {
         expect(parseInt(pane.style.width || '0')).toBeGreaterThan(initialWidth);
       }));
 
+      it('should be able to set a custom width on the select panel', fakeAsync(() => {
+        fixture.componentInstance.panelWidth = '42px';
+        fixture.detectChanges();
+
+        trigger.click();
+        fixture.detectChanges();
+        flush();
+
+        const pane = overlayContainerElement.querySelector('.cdk-overlay-pane') as HTMLElement;
+        expect(pane.style.width).toBe('42px');
+      }));
+
+      it('should not set a width on the panel if panelWidth is null', fakeAsync(() => {
+        fixture.componentInstance.panelWidth = null;
+        fixture.detectChanges();
+
+        trigger.click();
+        fixture.detectChanges();
+        flush();
+
+        const pane = overlayContainerElement.querySelector('.cdk-overlay-pane') as HTMLElement;
+        expect(pane.style.width).toBeFalsy();
+      }));
+
+      it('should not set a width on the panel if panelWidth is an empty string', fakeAsync(() => {
+        fixture.componentInstance.panelWidth = '';
+        fixture.detectChanges();
+
+        trigger.click();
+        fixture.detectChanges();
+        flush();
+
+        const pane = overlayContainerElement.querySelector('.cdk-overlay-pane') as HTMLElement;
+        expect(pane.style.width).toBeFalsy();
+      }));
+
       it('should not attempt to open a select that does not have any options', fakeAsync(() => {
         fixture.componentInstance.foods = [];
         fixture.detectChanges();
@@ -4430,6 +4466,7 @@ describe('MDC-based MatSelect', () => {
             disableOptionCentering: true,
             typeaheadDebounceInterval: 1337,
             overlayPanelClass: 'test-panel-class',
+            panelWidth: null,
           } as MatSelectConfig,
         },
       ],
@@ -4444,6 +4481,7 @@ describe('MDC-based MatSelect', () => {
     expect(select.disableOptionCentering).toBe(true);
     expect(select.typeaheadDebounceInterval).toBe(1337);
     expect(document.querySelector('.cdk-overlay-pane')?.classList).toContain('test-panel-class');
+    expect(select.panelWidth).toBeNull();
   }));
 
   it('should be able to hide checkmark icon through an injection token', () => {
@@ -4542,7 +4580,8 @@ describe('MDC-based MatSelect', () => {
         [tabIndex]="tabIndexOverride" [aria-describedby]="ariaDescribedBy"
         [aria-label]="ariaLabel" [aria-labelledby]="ariaLabelledby"
         [panelClass]="panelClass" [disableRipple]="disableRipple"
-        [typeaheadDebounceInterval]="typeaheadDebounceInterval">
+        [typeaheadDebounceInterval]="typeaheadDebounceInterval"
+        [panelWidth]="panelWidth">
         <mat-option *ngFor="let food of foods" [value]="food.value" [disabled]="food.disabled">
           {{ capitalize ? food.viewValue.toUpperCase() : food.viewValue }}
         </mat-option>
@@ -4577,6 +4616,7 @@ class BasicSelect {
   disableRipple: boolean;
   typeaheadDebounceInterval: number;
   capitalize = false;
+  panelWidth: string | null | number = 'auto';
 
   @ViewChild(MatSelect, {static: true}) select: MatSelect;
   @ViewChildren(MatOption) options: QueryList<MatOption>;

src/material/select/select.ts

@@ -138,6 +138,12 @@ export interface MatSelectConfig {
 
   /** Wheter icon indicators should be hidden for single-selection. */
   hideSingleSelectionIndicator?: boolean;
+
+  /**
+   * Width of the panel. If set to `auto`, the panel will match the trigger width.
+   * If set to null or an empty string, the panel will grow to match the longest option's text.
+   */
+  panelWidth?: string | number | null;
 }
 
 /** Injection token that can be used to provide the default options the select module. */
@@ -1282,6 +1288,15 @@ export class MatSelect extends _MatSelectBase<MatSelectChange> implements OnInit
   @ContentChildren(MAT_OPTGROUP, {descendants: true}) optionGroups: QueryList<MatOptgroup>;
   @ContentChild(MAT_SELECT_TRIGGER) customTrigger: MatSelectTrigger;
 
+  /**
+   * Width of the panel. If set to `auto`, the panel will match the trigger width.
+   * If set to null or an empty string, the panel will grow to match the longest option's text.
+   */
+  @Input() panelWidth: string | number | null =
+    this._defaultOptions && typeof this._defaultOptions.panelWidth !== 'undefined'
+      ? this._defaultOptions.panelWidth
+      : 'auto';
+
   _positions: ConnectedPosition[] = [
     {
       originX: 'start',
@@ -1302,7 +1317,7 @@ export class MatSelect extends _MatSelectBase<MatSelectChange> implements OnInit
   _preferredOverlayOrigin: CdkOverlayOrigin | ElementRef | undefined;
 
   /** Width of the overlay panel. */
-  _overlayWidth: number;
+  _overlayWidth: string | number;
 
   override get shouldLabelFloat(): boolean {
     // Since the panel doesn't overlap the trigger, we
@@ -1378,12 +1393,16 @@ export class MatSelect extends _MatSelectBase<MatSelectChange> implements OnInit
   }
 
   /** Gets how wide the overlay panel should be. */
-  private _getOverlayWidth() {
-    const refToMeasure =
-      this._preferredOverlayOrigin instanceof CdkOverlayOrigin
-        ? this._preferredOverlayOrigin.elementRef
-        : this._preferredOverlayOrigin || this._elementRef;
-    return refToMeasure.nativeElement.getBoundingClientRect().width;
+  private _getOverlayWidth(): string | number {
+    if (this.panelWidth === 'auto') {
+      const refToMeasure =
+        this._preferredOverlayOrigin instanceof CdkOverlayOrigin
+          ? this._preferredOverlayOrigin.elementRef
+          : this._preferredOverlayOrigin || this._elementRef;
+      return refToMeasure.nativeElement.getBoundingClientRect().width;
+    }
+
+    return this.panelWidth === null ? '' : this.panelWidth;
   }
 
   /** Whether checkmark indicator for single-selection options is hidden. */

tools/public_api_guard/material/legacy-select.md

@@ -20,8 +20,8 @@ import { MAT_SELECT_SCROLL_STRATEGY_PROVIDER_FACTORY as MAT_LEGACY_SELECT_SCROLL
 import { MAT_SELECT_TRIGGER as MAT_LEGACY_SELECT_TRIGGER } from '@angular/material/select';
 import { MatLegacyOptgroup } from '@angular/material/legacy-core';
 import { MatLegacyOption } from '@angular/material/legacy-core';
-import { MatSelectConfig as MatLegacySelectConfig } from '@angular/material/select';
 import { _MatSelectBase } from '@angular/material/select';
+import { MatSelectConfig } from '@angular/material/select';
 import { OnInit } from '@angular/core';
 import { QueryList } from '@angular/core';
 
@@ -83,7 +83,8 @@ export class MatLegacySelectChange {
     value: any;
 }
 
-export { MatLegacySelectConfig }
+// @public @deprecated (undocumented)
+export type MatLegacySelectConfig = Omit<MatSelectConfig, 'panelWidth'>;
 
 // @public @deprecated (undocumented)
 export class MatLegacySelectModule {

tools/public_api_guard/material/select.md

@@ -95,7 +95,8 @@ export class MatSelect extends _MatSelectBase<MatSelectChange> implements OnInit
     optionGroups: QueryList<MatOptgroup>;
     // (undocumented)
     options: QueryList<MatOption>;
-    _overlayWidth: number;
+    _overlayWidth: string | number;
+    panelWidth: string | number | null;
     // (undocumented)
     protected _positioningSettled(): void;
     // (undocumented)
@@ -108,7 +109,7 @@ export class MatSelect extends _MatSelectBase<MatSelectChange> implements OnInit
     protected _skipPredicate: (option: MatOption) => boolean;
     _syncParentProperties(): void;
     // (undocumented)
-    static ɵcmp: i0.ɵɵComponentDeclaration<MatSelect, "mat-select", ["matSelect"], { "disabled": { "alias": "disabled"; "required": false; }; "disableRipple": { "alias": "disableRipple"; "required": false; }; "tabIndex": { "alias": "tabIndex"; "required": false; }; "hideSingleSelectionIndicator": { "alias": "hideSingleSelectionIndicator"; "required": false; }; }, {}, ["customTrigger", "options", "optionGroups"], ["mat-select-trigger", "*"], false, never>;
+    static ɵcmp: i0.ɵɵComponentDeclaration<MatSelect, "mat-select", ["matSelect"], { "disabled": { "alias": "disabled"; "required": false; }; "disableRipple": { "alias": "disableRipple"; "required": false; }; "tabIndex": { "alias": "tabIndex"; "required": false; }; "panelWidth": { "alias": "panelWidth"; "required": false; }; "hideSingleSelectionIndicator": { "alias": "hideSingleSelectionIndicator"; "required": false; }; }, {}, ["customTrigger", "options", "optionGroups"], ["mat-select-trigger", "*"], false, never>;
     // (undocumented)
     static ɵfac: i0.ɵɵFactoryDeclaration<MatSelect, never>;
 }
@@ -242,6 +243,7 @@ export interface MatSelectConfig {
     disableOptionCentering?: boolean;
     hideSingleSelectionIndicator?: boolean;
     overlayPanelClass?: string | string[];
+    panelWidth?: string | number | null;
     typeaheadDebounceInterval?: number;
 }