implementing advanced grid rendering (on scroll render more images)

fixing slow image load

frontend/app/gallery/grid/grid.gallery.component.ts

@@ -8,7 +8,8 @@ import {
     ViewChild,
     ViewChildren,
     QueryList,
-    AfterViewInit
+    AfterViewInit,
+    HostListener
 } from "@angular/core";
 import {Photo} from "../../../../common/entities/Photo";
 import {GridRowBuilder} from "./GridRowBuilder";
@@ -41,56 +42,24 @@ export class GalleryGridComponent implements OnChanges,AfterViewInit {
     }
 
     ngOnChanges() {
-        this.renderPhotos();
+        this.onPhotosChanged();
     }
 
     onResize() {
-        this.renderPhotos();
+        this.onPhotosChanged();
     }
 
     ngAfterViewInit() {
         this.lightbox.gridPhotoQL = this.gridPhotoQL;
 
         //TODO: implement scroll detection
-        /*   this.gridPhotoQL.changes.subscribe(
-         (x)=> {
-         console.log("changed");
-         if (!this.directory || this.gridPhotoQL.length < this.directory.photos.length) {
-         console.log("bad");
-         console.log(this.directory ? this.gridPhotoQL.length + " < "+this.directory.photos.length : "no dir");
-         return;
-         }
-         if (this.renderedContainerWidth != this.getContainerWidth()) {
-         this.renderPhotos();
-         }
-         },
-         (err) => {
-         console.log('Error: %s', err);
-         },
-         () =>{
-         console.log('Completed');
-         }
-
-         ); */
 
 
-        setImmediate(() => {
+        this.onPhotosChanged();
-            this.renderPhotos();
-        });
     }
 
 
-    private renderedContainerWidth = 0;
+    private onPhotosChanged() {
-
-    private renderPhotos() {
-        if (this.getContainerWidth() == 0) {
-            return;
-        }
-        let maxRowHeight = window.innerHeight / this.MIN_ROW_COUNT;
-        let minRowHeight = window.innerHeight / this.MAX_ROW_COUNT;
-        let containerWidth = this.getContainerWidth();
-        this.renderedContainerWidth = containerWidth;
-
         this.photos.sort((a:Photo, b:Photo) => {
             if (a.metadata.creationDate > b.metadata.creationDate) {
                 return 1;
@@ -101,13 +70,28 @@ export class GalleryGridComponent implements OnChanges,AfterViewInit {
             // a must be equal to b
             return 0;
         });
-        
         this.photosToRender = [];
-        let i = 0;
+        this.renderedPhotoIndex = 0;
+        setImmediate(() => {
+            this.renderPhotos();
+        });
+    }
 
-        while (i < this.photos.length) {
+    private renderedPhotoIndex:number = 0;
 
-            let photoRowBuilder = new GridRowBuilder(this.photos, i, this.IMAGE_MARGIN, containerWidth);
+    private renderPhotos() {
+        if (this.getContainerWidth() == 0 || this.renderedPhotoIndex >= this.photos.length || !this.shouldRenderMore()) {
+            return;
+        }
+
+        let maxRowHeight = window.innerHeight / this.MIN_ROW_COUNT;
+        let minRowHeight = window.innerHeight / this.MAX_ROW_COUNT;
+
+        let renderedContentHeight = 0;
+
+        while (this.renderedPhotoIndex < this.photos.length && this.shouldRenderMore(renderedContentHeight)) {
+
+            let photoRowBuilder = new GridRowBuilder(this.photos, this.renderedPhotoIndex, this.IMAGE_MARGIN, this.getContainerWidth());
             photoRowBuilder.addPhotos(this.TARGET_COL_COUNT);
             photoRowBuilder.adjustRowHeightBetween(minRowHeight, maxRowHeight);
 
@@ -119,11 +103,24 @@ export class GalleryGridComponent implements OnChanges,AfterViewInit {
                 this.photosToRender.push(new GridPhoto(photo, imageWidth, imageHeight));
             });
 
-            i += photoRowBuilder.getPhotoRow().length;
+            renderedContentHeight += rowHeight;
+            this.renderedPhotoIndex += photoRowBuilder.getPhotoRow().length;
+        
         }
     }
 
 
+    private shouldRenderMore(offset:number = 0):boolean {
+        return document.body.scrollTop >= (document.body.clientHeight + offset - window.innerHeight) * 0.7
+            || document.body.clientHeight + offset < window.innerHeight;
+
+    }
+
+    @HostListener('window:scroll')
+    onScroll() {
+        this.renderPhotos();
+    }
+
     private getContainerWidth():number {
         if (!this.gridContainer) {
             return 0;

frontend/app/gallery/grid/photo/photo.grid.gallery.component.html

@@ -1,5 +1,5 @@
 <div #photoContainer class="photo-container" (mouseover)="hover()" (mouseout)="mouseOut()">
-    <img #img [src]="image.src" [hidden]="!image.show">
+    <img #img [src]="image.src" [hidden]="!image.show || loading.show" (load)="onImageLoad()">
 
     <gallery-grid-photo-loading [animate]="loading.animate" *ngIf="loading.show">
     </gallery-grid-photo-loading>

frontend/app/gallery/grid/photo/photo.grid.gallery.component.ts

@@ -1,6 +1,6 @@
 ///<reference path="../../../../browser.d.ts"/>
 
-import {Component, Input, ElementRef, ViewChild, OnInit, AfterViewInit, OnDestroy, HostListener} from "@angular/core";
+import {Component, Input, ElementRef, ViewChild, OnInit, AfterViewInit, OnDestroy, Renderer} from "@angular/core";
 import {IRenderable, Dimension} from "../../../model/IRenderable";
 import {GridPhoto} from "../GridPhoto";
 import {SearchTypes} from "../../../../../common/entities/AutoCompleteItem";
@@ -34,7 +34,7 @@ export class GalleryPhotoComponent implements IRenderable, OnInit, AfterViewInit
 
     loading = {
         animate: false,
-        show: false
+        show: true
     };
 
     thumbnailTask:ThumbnailTaskEntity = null;
@@ -47,9 +47,13 @@ export class GalleryPhotoComponent implements IRenderable, OnInit, AfterViewInit
     SearchTypes:any = [];
     searchEnabled:boolean = true;
 
-    constructor(private thumbnailService:ThumbnailLoaderService) {
+    scrollListener = null;
+
+    constructor(private thumbnailService:ThumbnailLoaderService, private renderer:Renderer) {
         this.SearchTypes = SearchTypes;
         this.searchEnabled = Config.Client.Search.searchEnabled;
+
+
     }
 
     ngOnInit() {
@@ -57,7 +61,7 @@ export class GalleryPhotoComponent implements IRenderable, OnInit, AfterViewInit
         if (this.gridPhoto.isThumbnailAvailable()) {
             this.image.src = this.gridPhoto.getThumbnailPath();
             this.image.show = true;
-            this.loading.show = false;
+            //  this.loading.show = false;
 
         } else {
             if (this.gridPhoto.isReplacementThumbnailAvailable()) {
@@ -84,15 +88,23 @@ export class GalleryPhotoComponent implements IRenderable, OnInit, AfterViewInit
                         this.image.show = true;
                         this.loading.show = false;
                         this.thumbnailTask = null;
+                        if (this.scrollListener) {
+                            this.scrollListener();
+                        }
                     },
                     onError: (error)=> {//onError
                         this.thumbnailTask = null;
+                        if (this.scrollListener) {
+                            this.scrollListener();
+                        }
                         //TODO: handle error
                         console.error("something bad happened");
                         console.error(error);
                     }
                 };
-
+                this.scrollListener = this.renderer.listenGlobal('window', 'scroll', () => {
+                    this.onScroll();
+                });
                 if (this.gridPhoto.isReplacementThumbnailAvailable()) {
                     this.thumbnailTask = this.thumbnailService.loadImage(this.gridPhoto, ThumbnailLoadingPriority.medium, listener);
                 } else {
@@ -117,7 +129,6 @@ export class GalleryPhotoComponent implements IRenderable, OnInit, AfterViewInit
             && document.body.scrollTop + window.innerHeight > this.container.nativeElement.offsetTop;
     }
 
-    @HostListener('window:scroll')
     onScroll() {
         if (this.thumbnailTask != null) {
             if (this.isInView() == true) {
@@ -157,6 +168,10 @@ export class GalleryPhotoComponent implements IRenderable, OnInit, AfterViewInit
 
     }
 
+    onImageLoad() {
+        this.loading.show = false;
+    }
+
     public getDimension():Dimension {
         return new Dimension(this.imageRef.nativeElement.offsetTop,
             this.imageRef.nativeElement.offsetLeft,