ipsos-components
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Material Design components for Angular
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text/typescript
/**
* @license
* Copyright Google LLC All Rights Reserved.
*
* Use of this source code is governed by an MIT-style license that can be
* found in the LICENSE file at https://angular.io/license
*/
import {ActiveDescendantKeyManager} from '@angular/cdk/a11y';
import {Directionality} from '@angular/cdk/bidi';
import {coerceBooleanProperty} from '@angular/cdk/coercion';
import {SelectionModel} from '@angular/cdk/collections';
import {DOWN_ARROW, END, ENTER, HOME, SPACE, UP_ARROW} from '@angular/cdk/keycodes';
import {
CdkConnectedOverlay,
Overlay,
RepositionScrollStrategy,
ScrollStrategy,
ViewportRuler,
} from '@angular/cdk/overlay';
import {filter} from 'rxjs/operators/filter';
import {take} from 'rxjs/operators/take';
import {map} from 'rxjs/operators/map';
import {startWith} from 'rxjs/operators/startWith';
import {takeUntil} from 'rxjs/operators/takeUntil';
import {
AfterContentInit,
Attribute,
ChangeDetectionStrategy,
ChangeDetectorRef,
Component,
ContentChild,
ContentChildren,
Directive,
DoCheck,
ElementRef,
EventEmitter,
Inject,
InjectionToken,
Input,
isDevMode,
NgZone,
OnChanges,
OnDestroy,
OnInit,
Optional,
Output,
QueryList,
Self,
SimpleChanges,
ViewChild,
ViewEncapsulation,
} from '@angular/core';
import {
ControlValueAccessor,
FormGroupDirective,
NgControl,
NgForm
} from '@angular/forms';
import {
CanDisable,
ErrorStateMatcher,
CanUpdateErrorState,
mixinErrorState,
HasTabIndex,
MatOptgroup,
MatOption,
MatOptionSelectionChange,
mixinDisabled,
mixinTabIndex,
MAT_OPTION_PARENT_COMPONENT,
} from '@angular/material/core';
import {MatFormField, MatFormFieldControl} from '@angular/material/form-field';
import {Observable} from 'rxjs/Observable';
import {merge} from 'rxjs/observable/merge';
import {Subject} from 'rxjs/Subject';
import {fadeInContent, transformPanel} from './select-animations';
import {
getMatSelectDynamicMultipleError,
getMatSelectNonArrayValueError,
getMatSelectNonFunctionValueError,
} from './select-errors';
let nextUniqueId = 0;
/**
* The following style constants are necessary to save here in order
* to properly calculate the alignment of the selected option over
* the trigger element.
*/
/** The max height of the select's overlay panel */
export const SELECT_PANEL_MAX_HEIGHT = 256;
/** The panel's padding on the x-axis */
export const SELECT_PANEL_PADDING_X = 16;
/** The panel's x axis padding if it is indented (e.g. there is an option group). */
export const SELECT_PANEL_INDENT_PADDING_X = SELECT_PANEL_PADDING_X * 2;
/** The height of the select items in `em` units. */
export const SELECT_ITEM_HEIGHT_EM = 3;
/**
* Distance between the panel edge and the option text in
* multi-selection mode.
*
* (SELECT_PANEL_PADDING_X * 1.5) + 20 = 44
* The padding is multiplied by 1.5 because the checkbox's margin is half the padding.
* The checkbox width is 20px.
*/
export const SELECT_MULTIPLE_PANEL_PADDING_X = SELECT_PANEL_PADDING_X * 1.5 + 20;
/**
* The select panel will only "fit" inside the viewport if it is positioned at
* this value or more away from the viewport boundary.
*/
export const SELECT_PANEL_VIEWPORT_PADDING = 8;
/** Injection token that determines the scroll handling while a select is open. */
export const MAT_SELECT_SCROLL_STRATEGY =
new InjectionToken<() => ScrollStrategy>('mat-select-scroll-strategy');
/** @docs-private */
export function MAT_SELECT_SCROLL_STRATEGY_PROVIDER_FACTORY(overlay: Overlay):
() => RepositionScrollStrategy {
return () => overlay.scrollStrategies.reposition();
}
/** @docs-private */
export const MAT_SELECT_SCROLL_STRATEGY_PROVIDER = {
provide: MAT_SELECT_SCROLL_STRATEGY,
deps: [Overlay],
useFactory: MAT_SELECT_SCROLL_STRATEGY_PROVIDER_FACTORY,
};
/** Change event object that is emitted when the select value has changed. */
export class MatSelectChange {
constructor(
/** Reference to the select that emitted the change event. */
public source: MatSelect,
/** Current value of the select that emitted the event. */
public value: any) { }
}
// Boilerplate for applying mixins to MatSelect.
/** @docs-private */
export class MatSelectBase {
constructor(public _elementRef: ElementRef,
public _defaultErrorStateMatcher: ErrorStateMatcher,
public _parentForm: NgForm,
public _parentFormGroup: FormGroupDirective,
public ngControl: NgControl) {}
}
export const _MatSelectMixinBase = mixinTabIndex(mixinDisabled(mixinErrorState(MatSelectBase)));
/**
* Allows the user to customize the trigger that is displayed when the select has a value.
*/
export class MatSelectTrigger {}
export class MatSelect extends _MatSelectMixinBase implements AfterContentInit, OnChanges,
OnDestroy, OnInit, DoCheck, ControlValueAccessor, CanDisable, HasTabIndex,
MatFormFieldControl<any>, CanUpdateErrorState {
/** Whether or not the overlay panel is open. */
private _panelOpen = false;
/** Whether filling out the select is required in the form. */
private _required: boolean = false;
/** The scroll position of the overlay panel, calculated to center the selected option. */
private _scrollTop = 0;
/** The placeholder displayed in the trigger of the select. */
private _placeholder: string;
/** Whether the component is in multiple selection mode. */
private _multiple: boolean = false;
/** Comparison function to specify which option is displayed. Defaults to object equality. */
private _compareWith = (o1: any, o2: any) => o1 === o2;
/** Unique id for this input. */
private _uid = `mat-select-${nextUniqueId++}`;
/** Emits whenever the component is destroyed. */
private _destroy = new Subject<void>();
/** The last measured value for the trigger's client bounding rect. */
_triggerRect: ClientRect;
/** The aria-describedby attribute on the select for improved a11y. */
_ariaDescribedby: string;
/** The cached font-size of the trigger element. */
_triggerFontSize = 0;
/** Deals with the selection logic. */
_selectionModel: SelectionModel<MatOption>;
/** Manages keyboard events for options in the panel. */
_keyManager: ActiveDescendantKeyManager<MatOption>;
/** View -> model callback called when value changes */
_onChange: (value: any) => void = () => {};
/** View -> model callback called when select has been touched */
_onTouched = () => {};
/** The IDs of child options to be passed to the aria-owns attribute. */
_optionIds: string = '';
/** The value of the select panel's transform-origin property. */
_transformOrigin: string = 'top';
/** Whether the panel's animation is done. */
_panelDoneAnimating: boolean = false;
/** Strategy that will be used to handle scrolling while the select panel is open. */
_scrollStrategy = this._scrollStrategyFactory();
/**
* The y-offset of the overlay panel in relation to the trigger's top start corner.
* This must be adjusted to align the selected option text over the trigger text.
* when the panel opens. Will change based on the y-position of the selected option.
*/
_offsetY = 0;
/**
* This position config ensures that the top "start" corner of the overlay
* is aligned with with the top "start" of the origin by default (overlapping
* the trigger completely). If the panel cannot fit below the trigger, it
* will fall back to a position above the trigger.
*/
_positions = [
{
originX: 'start',
originY: 'top',
overlayX: 'start',
overlayY: 'top',
},
{
originX: 'start',
originY: 'bottom',
overlayX: 'start',
overlayY: 'bottom',
},
];
/** Whether the select is focused. */
focused = false;
/** A name for this control that can be used by `mat-form-field`. */
controlType = 'mat-select';
/** Trigger that opens the select. */
trigger: ElementRef;
/** Panel containing the select options. */
panel: ElementRef;
/** Overlay pane containing the options. */
overlayDir: CdkConnectedOverlay;
/** All of the defined select options. */
options: QueryList<MatOption>;
/** All of the defined groups of options. */
optionGroups: QueryList<MatOptgroup>;
/** Classes to be passed to the select panel. Supports the same syntax as `ngClass`. */
panelClass: string|string[]|Set<string>|{[key: string]: any};
/** User-supplied override of the trigger element. */
customTrigger: MatSelectTrigger;
/** Placeholder to be shown if no value has been selected. */
get placeholder() { return this._placeholder; }
set placeholder(value: string) {
this._placeholder = value;
this.stateChanges.next();
}
/** Whether the component is required. */
get required() { return this._required; }
set required(value: any) {
this._required = coerceBooleanProperty(value);
this.stateChanges.next();
}
/** Whether the user should be allowed to select multiple options. */
get multiple(): boolean { return this._multiple; }
set multiple(value: boolean) {
if (this._selectionModel) {
throw getMatSelectDynamicMultipleError();
}
this._multiple = coerceBooleanProperty(value);
}
/**
* A function to compare the option values with the selected values. The first argument
* is a value from an option. The second is a value from the selection. A boolean
* should be returned.
*/
get compareWith() { return this._compareWith; }
set compareWith(fn: (o1: any, o2: any) => boolean) {
if (typeof fn !== 'function') {
throw getMatSelectNonFunctionValueError();
}
this._compareWith = fn;
if (this._selectionModel) {
// A different comparator means the selection could change.
this._initializeSelection();
}
}
/** Value of the select control. */
get value() { return this._value; }
set value(newValue: any) {
if (newValue !== this._value) {
this.writeValue(newValue);
this._value = newValue;
}
}
private _value: any;
/** Whether ripples for all options in the select are disabled. */
get disableRipple(): boolean { return this._disableRipple; }
set disableRipple(value: boolean) {
this._disableRipple = coerceBooleanProperty(value);
}
private _disableRipple: boolean = false;
/** Aria label of the select. If not specified, the placeholder will be used as label. */
ariaLabel: string = '';
/** Input that can be used to specify the `aria-labelledby` attribute. */
ariaLabelledby: string;
/** An object used to control when error messages are shown. */
errorStateMatcher: ErrorStateMatcher;
/** Unique id of the element. */
get id() { return this._id; }
set id(value: string) {
this._id = value || this._uid;
this.stateChanges.next();
}
private _id: string;
/** Combined stream of all of the child options' change events. */
get optionSelectionChanges(): Observable<MatOptionSelectionChange> {
return merge(...this.options.map(option => option.onSelectionChange));
}
/** Event emitted when the select has been opened. */
openedChange: EventEmitter<boolean> = new EventEmitter<boolean>();
/** Event emitted when the select has been opened. */
get _openedStream(): Observable<void> {
return this.openedChange.pipe(filter(o => o), map(() => {}));
}
/** Event emitted when the select has been closed. */
get _closedStream(): Observable<void> {
return this.openedChange.pipe(filter(o => !o), map(() => {}));
}
/**
* Event emitted when the select has been opened.
* @deprecated Use `openedChange` instead.
*/
onOpen: Observable<void> = this._openedStream;
/**
* Event emitted when the select has been closed.
* @deprecated Use `openedChange` instead.
*/
onClose: Observable<void> = this._closedStream;
/** Event emitted when the selected value has been changed by the user. */
selectionChange: EventEmitter<MatSelectChange> = new EventEmitter<MatSelectChange>();
/**
* Event emitted when the selected value has been changed by the user.
* @deprecated Use `selectionChange` instead.
*/
change: EventEmitter<MatSelectChange> = this.selectionChange;
/**
* Event that emits whenever the raw value of the select changes. This is here primarily
* to facilitate the two-way binding for the `value` input.
* @docs-private
*/
valueChange = new EventEmitter<any>();
constructor(
private _viewportRuler: ViewportRuler,
private _changeDetectorRef: ChangeDetectorRef,
private _ngZone: NgZone,
_defaultErrorStateMatcher: ErrorStateMatcher,
elementRef: ElementRef,
private _dir: Directionality,
_parentForm: NgForm,
_parentFormGroup: FormGroupDirective,
private _parentFormField: MatFormField,
public ngControl: NgControl,
tabIndex: string,
private _scrollStrategyFactory) {
super(elementRef, _defaultErrorStateMatcher, _parentForm,
_parentFormGroup, ngControl);
if (this.ngControl) {
this.ngControl.valueAccessor = this;
}
this.tabIndex = parseInt(tabIndex) || 0;
// Force setter to be called in case id was not specified.
this.id = this.id;
}
ngOnInit() {
this._selectionModel = new SelectionModel<MatOption>(this.multiple, undefined, false);
this.stateChanges.next();
}
ngAfterContentInit() {
this._initKeyManager();
this.options.changes.pipe(startWith(null), takeUntil(this._destroy)).subscribe(() => {
this._resetOptions();
this._initializeSelection();
});
}
ngDoCheck() {
if (this.ngControl) {
this.updateErrorState();
}
}
ngOnChanges(changes: SimpleChanges) {
// Updating the disabled state is handled by `mixinDisabled`, but we need to additionally let
// the parent form field know to run change detection when the disabled state changes.
if (changes.disabled) {
this.stateChanges.next();
}
}
ngOnDestroy() {
this._destroy.next();
this._destroy.complete();
}
/** Toggles the overlay panel open or closed. */
toggle(): void {
this.panelOpen ? this.close() : this.open();
}
/** Opens the overlay panel. */
open(): void {
if (this.disabled || !this.options || !this.options.length) {
return;
}
this._triggerRect = this.trigger.nativeElement.getBoundingClientRect();
// Note: The computed font-size will be a string pixel value (e.g. "16px").
// `parseInt` ignores the trailing 'px' and converts this to a number.
this._triggerFontSize = parseInt(getComputedStyle(this.trigger.nativeElement)['font-size']);
this._panelOpen = true;
this._calculateOverlayPosition();
this._highlightCorrectOption();
this._changeDetectorRef.markForCheck();
// Set the font size on the panel element once it exists.
this._ngZone.onStable.asObservable().pipe(take(1)).subscribe(() => {
if (this._triggerFontSize && this.overlayDir.overlayRef &&
this.overlayDir.overlayRef.overlayElement) {
this.overlayDir.overlayRef.overlayElement.style.fontSize = `${this._triggerFontSize}px`;
}
});
}
/** Closes the overlay panel and focuses the host element. */
close(): void {
if (this._panelOpen) {
this._panelOpen = false;
this._changeDetectorRef.markForCheck();
this.focus();
}
}
/**
* Sets the select's value. Part of the ControlValueAccessor interface
* required to integrate with Angular's core forms API.
*
* @param value New value to be written to the model.
*/
writeValue(value: any): void {
if (this.options) {
this._setSelectionByValue(value);
}
}
/**
* Saves a callback function to be invoked when the select's value
* changes from user input. Part of the ControlValueAccessor interface
* required to integrate with Angular's core forms API.
*
* @param fn Callback to be triggered when the value changes.
*/
registerOnChange(fn: (value: any) => void): void {
this._onChange = fn;
}
/**
* Saves a callback function to be invoked when the select is blurred
* by the user. Part of the ControlValueAccessor interface required
* to integrate with Angular's core forms API.
*
* @param fn Callback to be triggered when the component has been touched.
*/
registerOnTouched(fn: () => {}): void {
this._onTouched = fn;
}
/**
* Disables the select. Part of the ControlValueAccessor interface required
* to integrate with Angular's core forms API.
*
* @param isDisabled Sets whether the component is disabled.
*/
setDisabledState(isDisabled: boolean): void {
this.disabled = isDisabled;
this._changeDetectorRef.markForCheck();
this.stateChanges.next();
}
/** Whether or not the overlay panel is open. */
get panelOpen(): boolean {
return this._panelOpen;
}
/** The currently selected option. */
get selected(): MatOption | MatOption[] {
return this.multiple ? this._selectionModel.selected : this._selectionModel.selected[0];
}
/** The value displayed in the trigger. */
get triggerValue(): string {
if (this.empty) {
return '';
}
if (this._multiple) {
const selectedOptions = this._selectionModel.selected.map(option => option.viewValue);
if (this._isRtl()) {
selectedOptions.reverse();
}
// TODO(crisbeto): delimiter should be configurable for proper localization.
return selectedOptions.join(', ');
}
return this._selectionModel.selected[0].viewValue;
}
/** Whether the element is in RTL mode. */
_isRtl(): boolean {
return this._dir ? this._dir.value === 'rtl' : false;
}
/** Handles all keydown events on the select. */
_handleKeydown(event: KeyboardEvent): void {
if (!this.disabled) {
this.panelOpen ? this._handleOpenKeydown(event) : this._handleClosedKeydown(event);
}
}
/** Handles keyboard events while the select is closed. */
private _handleClosedKeydown(event: KeyboardEvent): void {
const keyCode = event.keyCode;
const isArrowKey = keyCode === DOWN_ARROW || keyCode === UP_ARROW;
const isOpenKey = keyCode === ENTER || keyCode === SPACE;
if (isOpenKey || (this.multiple && isArrowKey)) {
event.preventDefault(); // prevents the page from scrolling down when pressing space
this.open();
} else if (!this.multiple) {
this._keyManager.onKeydown(event);
}
}
/** Handles keyboard events when the selected is open. */
private _handleOpenKeydown(event: KeyboardEvent): void {
const keyCode = event.keyCode;
if (keyCode === HOME || keyCode === END) {
event.preventDefault();
keyCode === HOME ? this._keyManager.setFirstItemActive() :
this._keyManager.setLastItemActive();
} else if ((keyCode === ENTER || keyCode === SPACE) && this._keyManager.activeItem) {
event.preventDefault();
this._keyManager.activeItem._selectViaInteraction();
} else {
this._keyManager.onKeydown(event);
}
}
/**
* When the panel element is finished transforming in (though not fading in), it
* emits an event and focuses an option if the panel is open.
*/
_onPanelDone(): void {
if (this.panelOpen) {
this._scrollTop = 0;
this.openedChange.emit(true);
} else {
this.openedChange.emit(false);
this._panelDoneAnimating = false;
this.overlayDir.offsetX = 0;
this._changeDetectorRef.markForCheck();
}
}
/**
* When the panel content is done fading in, the _panelDoneAnimating property is
* set so the proper class can be added to the panel.
*/
_onFadeInDone(): void {
this._panelDoneAnimating = this.panelOpen;
this._changeDetectorRef.markForCheck();
}
_onFocus() {
if (!this.disabled) {
this.focused = true;
this.stateChanges.next();
}
}
/**
* Calls the touched callback only if the panel is closed. Otherwise, the trigger will
* "blur" to the panel when it opens, causing a false positive.
*/
_onBlur() {
if (!this.disabled && !this.panelOpen) {
this.focused = false;
this._onTouched();
this._changeDetectorRef.markForCheck();
this.stateChanges.next();
}
}
/**
* Callback that is invoked when the overlay panel has been attached.
*/
_onAttached(): void {
this.overlayDir.positionChange.pipe(take(1)).subscribe(() => {
this._changeDetectorRef.detectChanges();
this._calculateOverlayOffsetX();
this.panel.nativeElement.scrollTop = this._scrollTop;
});
}
/** Returns the theme to be used on the panel. */
_getPanelTheme(): string {
return this._parentFormField ? `mat-${this._parentFormField.color}` : '';
}
/** Whether the select has a value. */
get empty(): boolean {
return !this._selectionModel || this._selectionModel.isEmpty();
}
private _initializeSelection(): void {
// Defer setting the value in order to avoid the "Expression
// has changed after it was checked" errors from Angular.
Promise.resolve().then(() => {
this._setSelectionByValue(this.ngControl ? this.ngControl.value : this._value);
});
}
/**
* Sets the selected option based on a value. If no option can be
* found with the designated value, the select trigger is cleared.
*/
private _setSelectionByValue(value: any | any[], isUserInput = false): void {
if (this.multiple && value) {
if (!Array.isArray(value)) {
throw getMatSelectNonArrayValueError();
}
this._clearSelection();
value.forEach((currentValue: any) => this._selectValue(currentValue, isUserInput));
this._sortValues();
} else {
this._clearSelection();
const correspondingOption = this._selectValue(value, isUserInput);
// Shift focus to the active item. Note that we shouldn't do this in multiple
// mode, because we don't know what option the user interacted with last.
if (correspondingOption) {
this._keyManager.setActiveItem(this.options.toArray().indexOf(correspondingOption));
}
}
this._changeDetectorRef.markForCheck();
}
/**
* Finds and selects and option based on its value.
* @returns Option that has the corresponding value.
*/
private _selectValue(value: any, isUserInput = false): MatOption | undefined {
const correspondingOption = this.options.find((option: MatOption) => {
try {
// Treat null as a special reset value.
return option.value != null && this._compareWith(option.value, value);
} catch (error) {
if (isDevMode()) {
// Notify developers of errors in their comparator.
console.warn(error);
}
return false;
}
});
if (correspondingOption) {
isUserInput ? correspondingOption._selectViaInteraction() : correspondingOption.select();
this._selectionModel.select(correspondingOption);
this.stateChanges.next();
}
return correspondingOption;
}
/**
* Clears the select trigger and deselects every option in the list.
* @param skip Option that should not be deselected.
*/
private _clearSelection(skip?: MatOption): void {
this._selectionModel.clear();
this.options.forEach(option => {
if (option !== skip) {
option.deselect();
}
});
this.stateChanges.next();
}
/** Sets up a key manager to listen to keyboard events on the overlay panel. */
private _initKeyManager() {
this._keyManager = new ActiveDescendantKeyManager<MatOption>(this.options).withTypeAhead();
this._keyManager.tabOut.pipe(takeUntil(this._destroy)).subscribe(() => this.close());
this._keyManager.change.pipe(takeUntil(this._destroy)).subscribe(() => {
if (this._panelOpen && this.panel) {
this._scrollActiveOptionIntoView();
} else if (!this._panelOpen && !this.multiple && this._keyManager.activeItem) {
this._keyManager.activeItem._selectViaInteraction();
}
});
}
/** Drops current option subscriptions and IDs and resets from scratch. */
private _resetOptions(): void {
this.optionSelectionChanges.pipe(
takeUntil(merge(this._destroy, this.options.changes)),
filter(event => event.isUserInput)
).subscribe(event => {
this._onSelect(event.source);
if (!this.multiple) {
this.close();
}
});
this._setOptionIds();
}
/** Invoked when an option is clicked. */
private _onSelect(option: MatOption): void {
const wasSelected = this._selectionModel.isSelected(option);
// TODO(crisbeto): handle blank/null options inside multi-select.
if (this.multiple) {
this._selectionModel.toggle(option);
this.stateChanges.next();
wasSelected ? option.deselect() : option.select();
this._sortValues();
} else {
this._clearSelection(option.value == null ? undefined : option);
if (option.value == null) {
this._propagateChanges(option.value);
} else {
this._selectionModel.select(option);
this.stateChanges.next();
}
}
if (wasSelected !== this._selectionModel.isSelected(option)) {
this._propagateChanges();
}
}
/**
* Sorts the model values, ensuring that they keep the same
* order that they have in the panel.
*/
private _sortValues(): void {
if (this._multiple) {
this._selectionModel.clear();
this.options.forEach(option => {
if (option.selected) {
this._selectionModel.select(option);
}
});
this.stateChanges.next();
}
}
/** Emits change event to set the model value. */
private _propagateChanges(fallbackValue?: any): void {
let valueToEmit: any = null;
if (this.multiple) {
valueToEmit = (this.selected as MatOption[]).map(option => option.value);
} else {
valueToEmit = this.selected ? (this.selected as MatOption).value : fallbackValue;
}
this._value = valueToEmit;
this._onChange(valueToEmit);
this.selectionChange.emit(new MatSelectChange(this, valueToEmit));
this.valueChange.emit(valueToEmit);
this._changeDetectorRef.markForCheck();
}
/** Records option IDs to pass to the aria-owns property. */
private _setOptionIds() {
this._optionIds = this.options.map(option => option.id).join(' ');
}
/**
* Highlights the selected item. If no option is selected, it will highlight
* the first item instead.
*/
private _highlightCorrectOption(): void {
if (this._keyManager) {
if (this.empty) {
this._keyManager.setFirstItemActive();
} else {
this._keyManager.setActiveItem(this._getOptionIndex(this._selectionModel.selected[0])!);
}
}
}
/** Scrolls the active option into view. */
private _scrollActiveOptionIntoView(): void {
const itemHeight = this._getItemHeight();
const activeOptionIndex = this._keyManager.activeItemIndex || 0;
const labelCount = MatOption.countGroupLabelsBeforeOption(activeOptionIndex,
this.options, this.optionGroups);
const scrollOffset = (activeOptionIndex + labelCount) * itemHeight;
const panelTop = this.panel.nativeElement.scrollTop;
if (scrollOffset < panelTop) {
this.panel.nativeElement.scrollTop = scrollOffset;
} else if (scrollOffset + itemHeight > panelTop + SELECT_PANEL_MAX_HEIGHT) {
this.panel.nativeElement.scrollTop =
Math.max(0, scrollOffset - SELECT_PANEL_MAX_HEIGHT + itemHeight);
}
}
/** Focuses the select element. */
focus(): void {
this._elementRef.nativeElement.focus();
}
/** Gets the index of the provided option in the option list. */
private _getOptionIndex(option: MatOption): number | undefined {
return this.options.reduce((result: number, current: MatOption, index: number) => {
return result === undefined ? (option === current ? index : undefined) : result;
}, undefined);
}
/** Calculates the scroll position and x- and y-offsets of the overlay panel. */
private _calculateOverlayPosition(): void {
const itemHeight = this._getItemHeight();
const items = this._getItemCount();
const panelHeight = Math.min(items * itemHeight, SELECT_PANEL_MAX_HEIGHT);
const scrollContainerHeight = items * itemHeight;
// The farthest the panel can be scrolled before it hits the bottom
const maxScroll = scrollContainerHeight - panelHeight;
// If no value is selected we open the popup to the first item.
let selectedOptionOffset =
this.empty ? 0 : this._getOptionIndex(this._selectionModel.selected[0])!;
selectedOptionOffset += MatOption.countGroupLabelsBeforeOption(selectedOptionOffset,
this.options, this.optionGroups);
// We must maintain a scroll buffer so the selected option will be scrolled to the
// center of the overlay panel rather than the top.
const scrollBuffer = panelHeight / 2;
this._scrollTop = this._calculateOverlayScroll(selectedOptionOffset, scrollBuffer, maxScroll);
this._offsetY = this._calculateOverlayOffsetY(selectedOptionOffset, scrollBuffer, maxScroll);
this._checkOverlayWithinViewport(maxScroll);
}
/**
* Calculates the scroll position of the select's overlay panel.
*
* Attempts to center the selected option in the panel. If the option is
* too high or too low in the panel to be scrolled to the center, it clamps the
* scroll position to the min or max scroll positions respectively.
*/
_calculateOverlayScroll(selectedIndex: number, scrollBuffer: number,
maxScroll: number): number {
const itemHeight = this._getItemHeight();
const optionOffsetFromScrollTop = itemHeight * selectedIndex;
const halfOptionHeight = itemHeight / 2;
// Starts at the optionOffsetFromScrollTop, which scrolls the option to the top of the
// scroll container, then subtracts the scroll buffer to scroll the option down to
// the center of the overlay panel. Half the option height must be re-added to the
// scrollTop so the option is centered based on its middle, not its top edge.
const optimalScrollPosition = optionOffsetFromScrollTop - scrollBuffer + halfOptionHeight;
return Math.min(Math.max(0, optimalScrollPosition), maxScroll);
}
/** Returns the aria-label of the select component. */
get _ariaLabel(): string | null {
// If an ariaLabelledby value has been set, the select should not overwrite the
// `aria-labelledby` value by setting the ariaLabel to the placeholder.
return this.ariaLabelledby ? null : this.ariaLabel || this.placeholder;
}
/** Determines the `aria-activedescendant` to be set on the host. */
_getAriaActiveDescendant(): string | null {
if (this.panelOpen && this._keyManager && this._keyManager.activeItem) {
return this._keyManager.activeItem.id;
}
return null;
}
/**
* Sets the x-offset of the overlay panel in relation to the trigger's top start corner.
* This must be adjusted to align the selected option text over the trigger text when
* the panel opens. Will change based on LTR or RTL text direction. Note that the offset
* can't be calculated until the panel has been attached, because we need to know the
* content width in order to constrain the panel within the viewport.
*/
private _calculateOverlayOffsetX(): void {
const overlayRect = this.overlayDir.overlayRef.overlayElement.getBoundingClientRect();
const viewportSize = this._viewportRuler.getViewportSize();
const isRtl = this._isRtl();
const paddingWidth = this.multiple ? SELECT_MULTIPLE_PANEL_PADDING_X + SELECT_PANEL_PADDING_X :
SELECT_PANEL_PADDING_X * 2;
let offsetX: number;
// Adjust the offset, depending on the option padding.
if (this.multiple) {
offsetX = SELECT_MULTIPLE_PANEL_PADDING_X;
} else {
let selected = this._selectionModel.selected[0] || this.options.first;
offsetX = selected && selected.group ? SELECT_PANEL_INDENT_PADDING_X : SELECT_PANEL_PADDING_X;
}
// Invert the offset in LTR.
if (!isRtl) {
offsetX *= -1;
}
// Determine how much the select overflows on each side.
const leftOverflow = 0 - (overlayRect.left + offsetX - (isRtl ? paddingWidth : 0));
const rightOverflow = overlayRect.right + offsetX - viewportSize.width
+ (isRtl ? 0 : paddingWidth);
// If the element overflows on either side, reduce the offset to allow it to fit.
if (leftOverflow > 0) {
offsetX += leftOverflow + SELECT_PANEL_VIEWPORT_PADDING;
} else if (rightOverflow > 0) {
offsetX -= rightOverflow + SELECT_PANEL_VIEWPORT_PADDING;
}
// Set the offset directly in order to avoid having to go through change detection and
// potentially triggering "changed after it was checked" errors.
this.overlayDir.offsetX = offsetX;
this.overlayDir.overlayRef.updatePosition();
}
/**
* Calculates the y-offset of the select's overlay panel in relation to the
* top start corner of the trigger. It has to be adjusted in order for the
* selected option to be aligned over the trigger when the panel opens.
*/
private _calculateOverlayOffsetY(selectedIndex: number, scrollBuffer: number,
maxScroll: number): number {
const itemHeight = this._getItemHeight();
const optionHeightAdjustment = (itemHeight - this._triggerRect.height) / 2;
const maxOptionsDisplayed = Math.floor(SELECT_PANEL_MAX_HEIGHT / itemHeight);
let optionOffsetFromPanelTop: number;
if (this._scrollTop === 0) {
optionOffsetFromPanelTop = selectedIndex * itemHeight;
} else if (this._scrollTop === maxScroll) {
const firstDisplayedIndex = this._getItemCount() - maxOptionsDisplayed;
const selectedDisplayIndex = selectedIndex - firstDisplayedIndex;
// The first item is partially out of the viewport. Therefore we need to calculate what
// portion of it is shown in the viewport and account for it in our offset.
let partialItemHeight =
itemHeight - (this._getItemCount() * itemHeight - SELECT_PANEL_MAX_HEIGHT) % itemHeight;
// Because the panel height is longer than the height of the options alone,
// there is always extra padding at the top or bottom of the panel. When
// scrolled to the very bottom, this padding is at the top of the panel and
// must be added to the offset.
optionOffsetFromPanelTop = selectedDisplayIndex * itemHeight + partialItemHeight;
} else {
// If the option was scrolled to the middle of the panel using a scroll buffer,
// its offset will be the scroll buffer minus the half height that was added to
// center it.
optionOffsetFromPanelTop = scrollBuffer - itemHeight / 2;
}
// The final offset is the option's offset from the top, adjusted for the height
// difference, multiplied by -1 to ensure that the overlay moves in the correct
// direction up the page.
return optionOffsetFromPanelTop * -1 - optionHeightAdjustment;
}
/**
* Checks that the attempted overlay position will fit within the viewport.
* If it will not fit, tries to adjust the scroll position and the associated
* y-offset so the panel can open fully on-screen. If it still won't fit,
* sets the offset back to 0 to allow the fallback position to take over.
*/
private _checkOverlayWithinViewport(maxScroll: number): void {
const itemHeight = this._getItemHeight();
const viewportSize = this._viewportRuler.getViewportSize();
const topSpaceAvailable = this._triggerRect.top - SELECT_PANEL_VIEWPORT_PADDING;
const bottomSpaceAvailable =
viewportSize.height - this._triggerRect.bottom - SELECT_PANEL_VIEWPORT_PADDING;
const panelHeightTop = Math.abs(this._offsetY);
const totalPanelHeight =
Math.min(this._getItemCount() * itemHeight, SELECT_PANEL_MAX_HEIGHT);
const panelHeightBottom = totalPanelHeight - panelHeightTop - this._triggerRect.height;
if (panelHeightBottom > bottomSpaceAvailable) {
this._adjustPanelUp(panelHeightBottom, bottomSpaceAvailable);
} else if (panelHeightTop > topSpaceAvailable) {
this._adjustPanelDown(panelHeightTop, topSpaceAvailable, maxScroll);
} else {
this._transformOrigin = this._getOriginBasedOnOption();
}
}
/** Adjusts the overlay panel up to fit in the viewport. */
private _adjustPanelUp(panelHeightBottom: number, bottomSpaceAvailable: number) {
// Browsers ignore fractional scroll offsets, so we need to round.
const distanceBelowViewport = Math.round(panelHeightBottom - bottomSpaceAvailable);
// Scrolls the panel up by the distance it was extending past the boundary, then
// adjusts the offset by that amount to move the panel up into the viewport.
this._scrollTop -= distanceBelowViewport;
this._offsetY -= distanceBelowViewport;
this._transformOrigin = this._getOriginBasedOnOption();
// If the panel is scrolled to the very top, it won't be able to fit the panel
// by scrolling, so set the offset to 0 to allow the fallback position to take
// effect.
if (this._scrollTop <= 0) {
this._scrollTop = 0;
this._offsetY = 0;
this._transformOrigin = `50% bottom 0px`;
}
}
/** Adjusts the overlay panel down to fit in the viewport. */
private _adjustPanelDown(panelHeightTop: number, topSpaceAvailable: number,
maxScroll: number) {
// Browsers ignore fractional scroll offsets, so we need to round.
const distanceAboveViewport = Math.round(panelHeightTop - topSpaceAvailable);
// Scrolls the panel down by the distance it was extending past the boundary, then
// adjusts the offset by that amount to move the panel down into the viewport.
this._scrollTop += distanceAboveViewport;
this._offsetY += distanceAboveViewport;
this._transformOrigin = this._getOriginBasedOnOption();
// If the panel is scrolled to the very bottom, it won't be able to fit the
// panel by scrolling, so set the offset to 0 to allow the fallback position
// to take effect.
if (this._scrollTop >= maxScroll) {
this._scrollTop = maxScroll;
this._offsetY = 0;
this._transformOrigin = `50% top 0px`;
return;
}
}
/** Sets the transform origin point based on the selected option. */
private _getOriginBasedOnOption(): string {
const itemHeight = this._getItemHeight();
const optionHeightAdjustment = (itemHeight - this._triggerRect.height) / 2;
const originY = Math.abs(this._offsetY) - optionHeightAdjustment + itemHeight / 2;
return `50% ${originY}px 0px`;
}
/** Calculates the amount of items in the select. This includes options and group labels. */
private _getItemCount(): number {
return this.options.length + this.optionGroups.length;
}
/** Calculates the height of the select's options. */
private _getItemHeight(): number {
return this._triggerFontSize * SELECT_ITEM_HEIGHT_EM;
}
// Implemented as part of MatFormFieldControl.
setDescribedByIds(ids: string[]) {
this._ariaDescribedby = ids.join(' ');
}
// Implemented as part of MatFormFieldControl.
onContainerClick() {
this.focus();
this.open();
}
// Implemented as part of MatFormFieldControl.
get shouldLabelFloat(): boolean {
return this._panelOpen || !this.empty;
}
}