How to hide onScroll header in ionic 4? - ionic4

Question

I want to hide the header on scroll in Ionic 4 Beta 5.
I tried all the directives solutions, but none of them work for me.
So, are there any methods that work?

Answer 1

Use below directive
import { IonContent, DomController } from '#ionic/angular';
import { Directive, ElementRef, Input, Renderer2, SimpleChanges } from '#angular/core';
#Directive({
selector: '[scrollHide]'
})
export class ScrollHideDirective {
#Input('scrollHide') config: ScrollHideConfig;
#Input('scrollContent') scrollContent: IonContent;
contentHeight: number;
scrollHeight: number;
lastScrollPosition: number;
lastValue: number = 0;
constructor(private element: ElementRef, private renderer: Renderer2, private domCtrl: DomController) {
}
ngOnChanges(changes: SimpleChanges) {
if(this.scrollContent && this.config) {
this.scrollContent.scrollEvents = true;
let scrollStartFunc = async (ev) => {
const el = await this.scrollContent.getScrollElement();
this.contentHeight = el.offsetHeight;
this.scrollHeight = el.scrollHeight;
if (this.config.maxValue === undefined) {
this.config.maxValue = this.element.nativeElement.offsetHeight;
}
this.lastScrollPosition = el.scrollTop;
};
if(this.scrollContent && this.scrollContent instanceof IonContent) {
this.scrollContent.ionScrollStart.subscribe(scrollStartFunc);
this.scrollContent.ionScroll.subscribe(async (ev) => this.adjustElementOnScroll(ev));
this.scrollContent.ionScrollEnd.subscribe(async (ev) => this.adjustElementOnScroll(ev));
} else if(this.scrollContent instanceof HTMLElement) {
(this.scrollContent as HTMLElement).addEventListener('ionScrollStart', scrollStartFunc);
(this.scrollContent as HTMLElement).addEventListener('ionScroll',async (ev) => this.adjustElementOnScroll(ev));
(this.scrollContent as HTMLElement).addEventListener('ionScrollEnd',async (ev) => this.adjustElementOnScroll(ev));
}
}
}
private adjustElementOnScroll(ev) {
if (ev) {
this.domCtrl.write(async () => {
const el = await this.scrollContent.getScrollElement();
let scrollTop: number = el.scrollTop > 0 ? el.scrollTop : 0;
let scrolldiff: number = scrollTop - this.lastScrollPosition;
this.lastScrollPosition = scrollTop;
let newValue = this.lastValue + scrolldiff;
newValue = Math.max(0, Math.min(newValue, this.config.maxValue));
this.renderer.setStyle(this.element.nativeElement, this.config.cssProperty, `-${newValue}px`);
this.lastValue = newValue;
});
}
}
}
export interface ScrollHideConfig {
cssProperty: string;
maxValue: number;
}
Steps to use:
In your HTML
<ion-header [scrollHide]="headerScrollConfig" [scrollContent]="pageContent">
.
.
.
<ion-content #pageContent>
In your controller: Add config variables
footerScrollConfig: ScrollHideConfig = { cssProperty: 'margin-bottom', maxValue: undefined };
headerScrollConfig: ScrollHideConfig = { cssProperty: 'margin-top', maxValue: 54 };