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fix(expansion-panel): header animating on init when using non-default height #16122

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Merged
merged 1 commit into from
Jun 19, 2019
Merged

fix(expansion-panel): header animating on init when using non-default height #16122

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17 changes: 17 additions & 0 deletions src/material/expansion/expansion-panel-header.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,8 @@ import {
'[class.mat-expanded]': '_isExpanded()',
'(click)': '_toggle()',
'(keydown)': '_keydown($event)',
'[@.disabled]': '_animationsDisabled',
'(@expansionHeight.start)': '_animationStarted()',
'[@expansionHeight]': `{
value: _getExpandedState(),
params: {
Expand All @@ -70,6 +72,9 @@ import {
export class MatExpansionPanelHeader implements OnDestroy, FocusableOption {
private _parentChangeSubscription = Subscription.EMPTY;

/** Whether Angular animations in the panel header should be disabled. */
_animationsDisabled = true;

constructor(
@Host() public panel: MatExpansionPanel,
private _element: ElementRef,
Expand Down Expand Up @@ -108,6 +113,18 @@ export class MatExpansionPanelHeader implements OnDestroy, FocusableOption {
}
}

_animationStarted() {
// Currently the `expansionHeight` animation has a `void => collapsed` transition which is
// there to work around a bug in Angular (see #13088), however this introduces a different
// issue. The new transition will cause the header to animate in on init (see #16067), if the
// consumer has set a header height that is different from the default one. We work around it
// by disabling animations on the header and re-enabling them after the first animation has run.
// Note that Angular dispatches animation events even if animations are disabled. Ideally this
// wouldn't be necessary if we remove the `void => collapsed` transition, but we have to wait
// for https://github.com/angular/angular/issues/18847 to be resolved.
this._animationsDisabled = false;
}

/** Height of the header while the panel is expanded. */
@Input() expandedHeight: string;

Expand Down
2 changes: 2 additions & 0 deletions tools/public_api_guard/material/expansion.d.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -70,11 +70,13 @@ export declare class MatExpansionPanelDescription {
}

export declare class MatExpansionPanelHeader implements OnDestroy, FocusableOption {
_animationsDisabled: boolean;
collapsedHeight: string;
readonly disabled: any;
expandedHeight: string;
panel: MatExpansionPanel;
constructor(panel: MatExpansionPanel, _element: ElementRef, _focusMonitor: FocusMonitor, _changeDetectorRef: ChangeDetectorRef, defaultOptions?: MatExpansionPanelDefaultOptions);
_animationStarted(): void;
_getExpandedState(): string;
_getPanelId(): string;
_isExpanded(): boolean;
Expand Down