feat(material/paginator): add input for configuring the underlying select

Since we hide the underlying `MatSelect` inside the `MatPaginator`, the user doesn't have the ability to configure some of the inputs. These changes introduce an input that proxy some of the supported properties to the select.

Fixes #13646.

Author: crisbeto

src/material-experimental/mdc-paginator/paginator.html

@@ -14,6 +14,8 @@
           [value]="pageSize"
           [disabled]="disabled"
           [aria-labelledby]="_pageSizeLabelId"
+          [panelClass]="selectConfig.panelClass || ''"
+          [disableOptionCentering]="selectConfig.disableOptionCentering"
           (selectionChange)="_changePageSize($event.value)">
           <mat-option *ngFor="let pageSizeOption of _displayedPageSizeOptions" [value]="pageSizeOption">
             {{pageSizeOption}}

src/material-experimental/mdc-paginator/public-api.ts

@@ -13,4 +13,5 @@ export {
   MAT_PAGINATOR_INTL_PROVIDER_FACTORY,
   MAT_PAGINATOR_INTL_PROVIDER,
   PageEvent,
+  MatPaginatorSelectConfig,
 } from '@angular/material/paginator';

src/material/paginator/paginator.html

@@ -13,6 +13,8 @@
         <mat-select
           [value]="pageSize"
           [disabled]="disabled"
+          [panelClass]="selectConfig.panelClass || ''"
+          [disableOptionCentering]="selectConfig.disableOptionCentering"
           [aria-label]="_intl.itemsPerPageLabel"
           (selectionChange)="_changePageSize($event.value)">
           <mat-option *ngFor="let pageSizeOption of _displayedPageSizeOptions" [value]="pageSizeOption">

src/material/paginator/paginator.md

@@ -16,7 +16,11 @@ any associated data view.
 The paginator displays a dropdown of page sizes for the user to choose from. The options for this
 dropdown can be set via `pageSizeOptions`
 
-The current pageSize will always appear in the dropdown, even if it is not included in pageSizeOptions.
+The current pageSize will always appear in the dropdown, even if it is not included in
+pageSizeOptions.
+
+If you want to customize some of the optional of the `mat-select` inside the `mat-paginator`, you
+can use the `selectConfig` input.
 
 ### Internationalization
 The labels for the paginator can be customized by providing your own instance of `MatPaginatorIntl`.
@@ -30,5 +34,5 @@ The paginator uses `role="group"` to semantically group its child controls. You
 `aria-label` or `aria-labelledby` attribute to `<mat-paginator>` with a label that describes
 the content controlled by the pagination control.
 
-You can set the `aria-label` attributes for the button and select controls within the paginator in 
+You can set the `aria-label` attributes for the button and select controls within the paginator in
 `MatPaginatorIntl`.

src/material/paginator/paginator.spec.ts

@@ -6,7 +6,11 @@ import {ThemePalette} from '@angular/material/core';
 import {MatSelect} from '@angular/material/select';
 import {By} from '@angular/platform-browser';
 import {MatPaginator, MatPaginatorIntl, MatPaginatorModule} from './index';
-import {MAT_PAGINATOR_DEFAULT_OPTIONS, MatPaginatorDefaultOptions} from './paginator';
+import {
+  MAT_PAGINATOR_DEFAULT_OPTIONS,
+  MatPaginatorDefaultOptions,
+  MatPaginatorSelectConfig,
+} from './paginator';
 
 describe('MatPaginator', () => {
   function createComponent<T>(type: Type<T>, providers: Provider[] = []): ComponentFixture<T> {
@@ -210,6 +214,24 @@ describe('MatPaginator', () => {
     expect(formField.classList).not.toContain('mat-accent');
   });
 
+  it('should be able to pass options to the underlying mat-select', () => {
+    const fixture = createComponent(MatPaginatorApp);
+    fixture.detectChanges();
+    const select: MatSelect = fixture.debugElement.query(By.directive(MatSelect)).componentInstance;
+
+    expect(select.disableOptionCentering).toBe(false);
+    expect(select.panelClass).toBeFalsy();
+
+    fixture.componentInstance.selectConfig = {
+      disableOptionCentering: true,
+      panelClass: 'custom-class',
+    };
+    fixture.detectChanges();
+
+    expect(select.disableOptionCentering).toBe(true);
+    expect(select.panelClass).toBe('custom-class');
+  });
+
   describe('when showing the first and last button', () => {
     let fixture: ComponentFixture<MatPaginatorApp>;
     let component: MatPaginatorApp;
@@ -537,6 +559,7 @@ function getLastButton(fixture: ComponentFixture<any>) {
                    [pageSize]="pageSize"
                    [pageSizeOptions]="pageSizeOptions"
                    [hidePageSize]="hidePageSize"
+                   [selectConfig]="selectConfig"
                    [showFirstLastButtons]="showFirstLastButtons"
                    [length]="length"
                    [color]="color"
@@ -555,6 +578,7 @@ class MatPaginatorApp {
   disabled: boolean;
   pageEvent = jasmine.createSpy('page event');
   color: ThemePalette;
+  selectConfig: MatPaginatorSelectConfig = {};
 
   @ViewChild(MatPaginator) paginator: MatPaginator;
 

src/material/paginator/paginator.ts

@@ -89,6 +89,15 @@ export const MAT_PAGINATOR_DEFAULT_OPTIONS = new InjectionToken<MatPaginatorDefa
 /** @docs-private */
 const _MatPaginatorMixinBase = mixinDisabled(mixinInitialized(class {}));
 
+/** Object that can used to configure the underlying `MatSelect` inside a `MatPaginator`. */
+export interface MatPaginatorSelectConfig {
+  /** Whether to center the active option over the trigger. */
+  disableOptionCentering?: boolean;
+
+  /** Classes to be passed to the select panel. */
+  panelClass?: string | string[] | Set<string> | {[key: string]: any};
+}
+
 /**
  * Base class with all of the `MatPaginator` functionality.
  * @docs-private
@@ -175,6 +184,9 @@ export abstract class _MatPaginatorBase<
   }
   private _showFirstLastButtons = false;
 
+  /** Used to configure the underlying `MatSelect` inside the paginator. */
+  @Input() selectConfig: MatPaginatorSelectConfig = {};
+
   /** Event emitted when the paginator changes the page size or page index. */
   @Output() readonly page: EventEmitter<PageEvent> = new EventEmitter<PageEvent>();