[ADF-2137] Document Thumbnail Pane (#2943)

* pdf thumbnails

* update TestBed declarations

* add PdfViewerService to TestBed

* content projection

* update TestBed declaration

* update TestBed

* update TestBed

* docs

* pristine

* added doc component image

* use global PDFJS instance fro tests

lib/core/viewer/components/pdfViewer-thumb.component.ts

@@ -0,0 +1,62 @@
+/*!
+ * @license
+ * Copyright 2016 Alfresco Software, Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { Component, Input, OnInit, ElementRef, ViewEncapsulation } from '@angular/core';
+import { DomSanitizer } from '@angular/platform-browser';
+
+@Component({
+    selector: 'adf-pdf-thumb',
+    templateUrl: './pdfViewer-thumb.component.html',
+    encapsulation: ViewEncapsulation.None
+})
+export class PdfThumbComponent implements OnInit {
+    @Input('page') page: any = null;
+
+    image$: Promise<string>;
+
+    constructor(
+        private element: ElementRef, private sanitizer: DomSanitizer) {}
+
+    ngOnInit() {
+        this.image$ = this.page.getPage().then((page) => this.getThumb(page));
+    }
+
+    private getThumb(page): Promise<string> {
+        const canvas = this.getCanvas();
+        const viewport = page.getViewport(1);
+        const scale = Math.min((canvas.height / viewport.height), (canvas.width / viewport.width));
+
+        return page.render({
+            canvasContext: canvas.getContext('2d'),
+            viewport: page.getViewport(scale)
+        })
+        .then(() => {
+            const imageSource = canvas.toDataURL();
+            return this.sanitizer.bypassSecurityTrustUrl(imageSource);
+        });
+    }
+
+    private getCanvas(): HTMLCanvasElement {
+        const elementRect = this.element.nativeElement.getBoundingClientRect();
+        const canvas = document.createElement('canvas');
+
+        canvas.width = elementRect.width;
+        canvas.height = elementRect.height;
+
+        return canvas;
+    }
+}