PLT-3642 Add PDF previewer (#3812)

* Added a PDF previewer

* PLT-3900 - Improving UI for the pdf max pages (#3800)

2 files changed, 213 insertions, 11 deletions

diff --git a/webapp/components/pdf_preview.jsx b/webapp/components/pdf_preview.jsx
new file mode 100644
index 000000000..fd1ca7758
--- /dev/null
+++ b/webapp/components/pdf_preview.jsx
@@ -0,0 +1,189 @@
+// Copyright (c) 2016 Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+import FileInfoPreview from './file_info_preview.jsx';
+
+import * as Utils from 'utils/utils.jsx';
+
+import loadingGif from 'images/load.gif';
+
+import React from 'react';
+import PDFJS from 'pdfjs-dist';
+import {FormattedMessage} from 'react-intl';
+
+const MAX_PDF_PAGES = 5;
+
+export default class PDFPreview extends React.Component {
+    constructor(props) {
+        super(props);
+
+        this.updateStateFromProps = this.updateStateFromProps.bind(this);
+        this.onDocumentLoad = this.onDocumentLoad.bind(this);
+        this.onPageLoad = this.onPageLoad.bind(this);
+        this.renderPDFPage = this.renderPDFPage.bind(this);
+
+        this.pdfPagesRendered = {};
+
+        this.state = {
+            pdf: null,
+            pdfPages: {},
+            pdfPagesLoaded: {},
+            numPages: 0,
+            loading: true,
+            success: false
+        };
+    }
+
+    componentDidMount() {
+        this.updateStateFromProps(this.props);
+    }
+
+    componentWillReceiveProps(nextProps) {
+        if (this.props.fileUrl !== nextProps.fileUrl) {
+            this.updateStateFromProps(nextProps);
+            this.pdfPagesRendered = {};
+        }
+    }
+
+    componentDidUpdate() {
+        if (this.state.success) {
+            for (let i = 0; i < this.state.numPages; i++) {
+                this.renderPDFPage(i);
+            }
+        }
+    }
+
+    renderPDFPage(pageIndex) {
+        if (this.pdfPagesRendered[pageIndex] || !this.state.pdfPagesLoaded[pageIndex]) {
+            return;
+        }
+
+        const canvas = this.refs['pdfCanvas' + pageIndex];
+        const context = canvas.getContext('2d');
+        const viewport = this.state.pdfPages[pageIndex].getViewport(1);
+
+        canvas.height = viewport.height;
+        canvas.width = viewport.width;
+
+        const renderContext = {
+            canvasContext: context,
+            viewport
+        };
+
+        this.state.pdfPages[pageIndex].render(renderContext);
+        this.pdfPagesRendered[pageIndex] = true;
+    }
+
+    updateStateFromProps(props) {
+        this.setState({
+            pdf: null,
+            pdfPages: {},
+            pdfPagesLoaded: {},
+            numPages: 0,
+            loading: true,
+            success: false
+        });
+
+        PDFJS.getDocument(window.mm_config.SiteURL + props.fileUrl).then(this.onDocumentLoad);
+    }
+
+    onDocumentLoad(pdf) {
+        const numPages = pdf.numPages <= MAX_PDF_PAGES ? pdf.numPages : MAX_PDF_PAGES;
+        this.setState({pdf, numPages});
+        for (let i = 1; i <= pdf.numPages; i++) {
+            pdf.getPage(i).then(this.onPageLoad);
+        }
+    }
+
+    onPageLoad(page) {
+        const pdfPages = Object.assign({}, this.state.pdfPages);
+        pdfPages[page.pageIndex] = page;
+
+        const pdfPagesLoaded = Object.assign({}, this.state.pdfPagesLoaded);
+        pdfPagesLoaded[page.pageIndex] = true;
+
+        this.setState({pdfPages, pdfPagesLoaded});
+
+        if (page.pageIndex === 0) {
+            this.setState({success: true, loading: false});
+        }
+    }
+
+    static support(filename) {
+        const fileInfo = Utils.splitFileLocation(filename);
+        const ext = fileInfo.ext;
+        if (!ext) {
+            return false;
+        }
+
+        if (ext === 'pdf') {
+            return true;
+        }
+
+        return false;
+    }
+
+    render() {
+        if (this.state.loading) {
+            return (
+                <div className='view-image__loading'>
+                    <img
+                        className='loader-image'
+                        src={loadingGif}
+                    />
+                </div>
+            );
+        }
+
+        if (!this.state.success) {
+            return (
+                <FileInfoPreview
+                    filename={this.props.filename}
+                    fileUrl={this.props.fileUrl}
+                    fileInfo={this.props.fileInfo}
+                    formatMessage={this.props.formatMessage}
+                />
+            );
+        }
+
+        const pdfCanvases = [];
+        for (let i = 0; i < this.state.numPages; i++) {
+            pdfCanvases.push(
+                <canvas
+                    ref={'pdfCanvas' + i}
+                    key={'previewpdfcanvas' + i}
+                />
+            );
+
+            if (i < this.state.numPages - 1 && this.state.numPages > 1) {
+                pdfCanvases.push(
+                    <div className='pdf-preview-spacer'/>
+                );
+            }
+        }
+
+        if (this.state.pdf.numPages > MAX_PDF_PAGES) {
+            pdfCanvases.push(
+                <div className='pdf-max-pages'>
+                    <FormattedMessage
+                        id='pdf_preview.max_pages'
+                        defaultMessage='PDF previews only show the first five pages.'
+                    />
+                </div>
+            );
+        }
+
+        return (
+            <div className='post-code'>
+                {pdfCanvases}
+            </div>
+        );
+    }
+}
+
+PDFPreview.propTypes = {
+    filename: React.PropTypes.string.isRequired,
+    fileUrl: React.PropTypes.string.isRequired,
+    fileInfo: React.PropTypes.object.isRequired,
+    formatMessage: React.PropTypes.func.isRequired
+};
diff --git a/webapp/components/view_image.jsx b/webapp/components/view_image.jsx
index 7b827ac0e..c9f558725 100644
--- a/webapp/components/view_image.jsx
+++ b/webapp/components/view_image.jsx
@@ -1,23 +1,29 @@
 // Copyright (c) 2015 Mattermost, Inc. All Rights Reserved.
 // See License.txt for license information.
 
-import $ from 'jquery';
-import * as AsyncClient from 'utils/async_client.jsx';
-import * as GlobalActions from 'actions/global_actions.jsx';
-import * as Utils from 'utils/utils.jsx';
 import AudioVideoPreview from './audio_video_preview.jsx';
-import Constants from 'utils/constants.jsx';
 import CodePreview from './code_preview.jsx';
+import PDFPreview from './pdf_preview.jsx';
 import FileInfoPreview from './file_info_preview.jsx';
-import FileStore from 'stores/file_store.jsx';
 import ViewImagePopoverBar from './view_image_popover_bar.jsx';
-import loadingGif from 'images/load.gif';
 
-import {intlShape, injectIntl, defineMessages} from 'react-intl';
+import * as GlobalActions from 'actions/global_actions.jsx';
 
-import {Modal} from 'react-bootstrap';
+import FileStore from 'stores/file_store.jsx';
+
+import * as AsyncClient from 'utils/async_client.jsx';
+import * as Utils from 'utils/utils.jsx';
+
+import Constants from 'utils/constants.jsx';
 const KeyCodes = Constants.KeyCodes;
 
+import $ from 'jquery';
+import React from 'react';
+import {intlShape, injectIntl, defineMessages} from 'react-intl';
+import {Modal} from 'react-bootstrap';
+
+import loadingGif from 'images/load.gif';
+
 const holders = defineMessages({
     loading: {
         id: 'view_image.loading',
@@ -25,8 +31,6 @@ const holders = defineMessages({
     }
 });
 
-import React from 'react';
-
 class ViewImageModal extends React.Component {
     constructor(props) {
         super(props);
@@ -241,6 +245,15 @@ class ViewImageModal extends React.Component {
                         formatMessage={this.props.intl.formatMessage}
                     />
                 );
+            } else if (PDFPreview.support(filename)) {
+                content = (
+                    <PDFPreview
+                        filename={filename}
+                        fileUrl={fileUrl}
+                        fileInfo={fileInfo}
+                        formatMessage={this.props.intl.formatMessage}
+                    />
+                );
             } else if (CodePreview.support(filename)) {
                 content = (
                     <CodePreview