From 2e22966289ff8d4a9a4e25b4a114d9c25ec31c48 Mon Sep 17 00:00:00 2001
From: Dmitry S <dsagal+git@gmail.com>
Date: Thu, 19 Nov 2020 21:05:55 -0500
Subject: [PATCH] (core) Revamp attachment editor + preview UI, and support
 more types, including PDFs.

Summary:
- New UI for the modal look mostly following the design prepared previously.
- Use <object> for rendering PDFs (on a Mac works on Firefox, Chrome, Safari; needs checking on Windows)
- While we are at it, use <video> and <audio> for relevant files (object would
  render them too, but without the option to disable autoplay).
- Use <object> for unknown types, except for text/html (unsafe) and other text
  types (need more work to render well).
- Fix skipping save on Escape or when attachments are unsaved (previously a
  noop action was emitted, creating surprises with undo).
- Display extension for files without preview, both in-cell and in the modal.
- Replace tiny "eye" icon to preview particular attachment with double-clicking.
- As an accidental feature, a particular attachment can be previewed by typing 1, 2, 3, etc into cell.
- Renamed PreviewsWidget/PreviewModel to AttachmentsWidget/AttachmentsEditor.

Test Plan: Unified old and new tests for attachments, added new test cases.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D2667
---
 app/client/ui2018/modals.ts                   |   8 +-
 app/client/widgets/AttachmentsEditor.ts       | 447 ++++++++++++++++++
 ...eviewsWidget.css => AttachmentsWidget.css} |   0
 ...PreviewsWidget.ts => AttachmentsWidget.ts} | 128 ++---
 app/client/widgets/FieldEditor.ts             |   3 +-
 app/client/widgets/PreviewModal.ts            | 405 ----------------
 app/client/widgets/UserType.js                |   8 +-
 app/client/widgets/UserTypeImpl.js            |   7 +-
 8 files changed, 510 insertions(+), 496 deletions(-)
 create mode 100644 app/client/widgets/AttachmentsEditor.ts
 rename app/client/widgets/{PreviewsWidget.css => AttachmentsWidget.css} (100%)
 rename app/client/widgets/{PreviewsWidget.ts => AttachmentsWidget.ts} (71%)
 delete mode 100644 app/client/widgets/PreviewModal.ts

diff --git a/app/client/ui2018/modals.ts b/app/client/ui2018/modals.ts
index ee4e580e..841d52fa 100644
--- a/app/client/ui2018/modals.ts
+++ b/app/client/ui2018/modals.ts
@@ -47,9 +47,11 @@ export type ModalWidth =
 export function modal(createFn: (ctl: IModalControl, owner: MultiHolder) => DomElementArg,
                       options: IModalOptions = {}): void {
   function close() {
-    document.body.removeChild(modalDom);
-    // Ensure we run the disposers for the DOM contained in the modal.
-    dom.domDispose(modalDom);
+    if (modalDom.isConnected) {
+      document.body.removeChild(modalDom);
+      // Ensure we run the disposers for the DOM contained in the modal.
+      dom.domDispose(modalDom);
+    }
   }
 
   const modalDom = cssModalBacker(
diff --git a/app/client/widgets/AttachmentsEditor.ts b/app/client/widgets/AttachmentsEditor.ts
new file mode 100644
index 00000000..7ea16cf2
--- /dev/null
+++ b/app/client/widgets/AttachmentsEditor.ts
@@ -0,0 +1,447 @@
+// External dependencies
+import {computed, Computed, computedArray} from 'grainjs';
+import {MutableObsArray, obsArray, ObsArray, observable, Observable} from 'grainjs';
+import {dom, LiveIndex, makeLiveIndex, styled} from 'grainjs';
+
+// Grist client libs
+import {DocComm} from 'app/client/components/DocComm';
+import {selectFiles, uploadFiles} from 'app/client/lib/uploads';
+import {DocData} from 'app/client/models/DocData';
+import {TableData} from 'app/client/models/TableData';
+import {basicButton, basicButtonLink, cssButtonGroup} from 'app/client/ui2018/buttons';
+import {colors, testId, vars} from 'app/client/ui2018/cssVars';
+import {editableLabel} from 'app/client/ui2018/editableLabel';
+import {icon} from 'app/client/ui2018/icons';
+import {IModalControl, modal} from 'app/client/ui2018/modals';
+import {renderFileType} from 'app/client/widgets/AttachmentsWidget';
+import {NewBaseEditor, Options} from 'app/client/widgets/NewBaseEditor';
+import {CellValue} from 'app/common/DocActions';
+import {clamp, encodeQueryParams} from 'app/common/gutil';
+import {UploadResult} from 'app/common/uploads';
+import * as mimeTypes from 'mime-types';
+
+interface Attachment {
+  rowId: number;
+
+  // Checksum of the file content, with extension, which identifies the file data in the _gristsys_Files table.
+  fileIdent: string;
+
+  // MIME type of the data (looked up from fileIdent's extension).
+  fileType: string;
+
+  // User-defined filename of the attachment. An observable to support renaming.
+  filename: Observable<string>;
+
+  // Whether the attachment is an image, indicated by the presence of imageHeight in the record.
+  hasPreview: boolean;
+
+  // The download URL of the attachment; served with Content-Disposition of "attachment".
+  url: Observable<string>;
+
+  // The inline URL of the attachment; served with Content-Disposition of "inline".
+  inlineUrl: Observable<string>;
+}
+
+/**
+ * An AttachmentsEditor shows a full-screen modal with attachment previews, and options to rename,
+ * download, add or remove attachments in the edited cell.
+ */
+export class AttachmentsEditor extends NewBaseEditor {
+  private _attachmentsTable: TableData;
+  private _docComm: DocComm;
+
+  private _rowIds: MutableObsArray<number>;
+  private _attachments: ObsArray<Attachment>;
+  private _index: LiveIndex;
+  private _selected: Computed<Attachment|null>;
+
+  constructor(options: Options) {
+    super(options);
+
+    const docData: DocData = options.gristDoc.docData;
+    const cellValue: CellValue = options.cellValue;
+
+    // editValue is abused slightly to indicate a 1-based index of the attachment.
+    const initRowIndex: number|undefined = (options.editValue && parseInt(options.editValue, 0) - 1) || 0;
+
+    this._attachmentsTable = docData.getTable('_grist_Attachments')!;
+    this._docComm = docData.docComm;
+
+    this._rowIds = obsArray(Array.isArray(cellValue) ? cellValue.slice(1) as number[] : []);
+    this._attachments = computedArray(this._rowIds, (val: number): Attachment => {
+      const fileIdent: string = this._attachmentsTable.getValue(val, 'fileIdent') as string;
+      const fileType = mimeTypes.lookup(fileIdent) || 'application/octet-stream';
+      const filename: Observable<string> =
+        observable(this._attachmentsTable.getValue(val, 'fileName') as string);
+      return {
+        rowId: val,
+        fileIdent,
+        fileType,
+        filename,
+        hasPreview: Boolean(this._attachmentsTable.getValue(val, 'imageHeight')),
+        url: computed((use) => this._getUrl(fileIdent, use(filename))),
+        inlineUrl: computed((use) => this._getUrl(fileIdent, use(filename), true))
+      };
+    });
+    this._index = makeLiveIndex(this, this._attachments, initRowIndex);
+    this._selected = this.autoDispose(computed((use) => {
+      const index = use(this._index);
+      return index === null ? null : use(this._attachments)[index];
+    }));
+  }
+
+  // This "attach" is not about "attachments", but about attaching this widget to the page DOM.
+  public attach(cellRect: ClientRect|DOMRect) {
+    modal((ctl, owner) => {
+      // If FieldEditor is disposed externally (e.g. on navigation), be sure to close the modal.
+      this.onDispose(ctl.close);
+      return [
+        cssFullScreenModal.cls(''),
+        dom.onKeyDown({
+          Enter: (ev) => { ctl.close(); this.options.commands.fieldEditSaveHere(); },
+          Escape: (ev) => { ctl.close(); this.options.commands.fieldEditCancel(); },
+          ArrowLeft$: (ev) => !isInEditor(ev) && this._moveIndex(-1),
+          ArrowRight$: (ev) => !isInEditor(ev) && this._moveIndex(1),
+        }),
+        // Close if clicking into the background. (The default modal's behavior for this isn't
+        // triggered because our content covers the whole screen.)
+        dom.on('click', (ev, elem) => { if (ev.target === elem) { ctl.close(); }}),
+        ...this._buildDom(ctl)
+      ];
+    }, {noEscapeKey: true});
+  }
+
+  public getCellValue() {
+    return ["L", ...this._rowIds.get()] as CellValue;
+  }
+
+  public getCursorPos(): number {
+    return 0;
+  }
+
+  public getTextValue(): string {
+    return '';
+  }
+
+  // Builds the attachment preview modal.
+  private _buildDom(ctl: IModalControl) {
+    return [
+      cssHeader(
+        cssFlexExpand(dom.text(use => {
+            const len = use(this._attachments).length;
+            return len ? `${(use(this._index) || 0) + 1} of ${len}` : '';
+          }),
+          testId('pw-counter')
+        ),
+        dom.maybe(this._selected, selected =>
+          cssTitle(
+            cssEditableLabel(selected.filename, (val) => this._renameAttachment(selected, val),
+              testId('pw-name'))
+          )
+        ),
+        cssFlexExpand(
+          cssFileButtons(
+            dom.maybe(this._selected, selected =>
+              basicButtonLink(cssButton.cls(''), cssButtonIcon('Download'), 'Download',
+                dom.attr('href', selected.url),
+                dom.attr('target', '_blank'),
+                dom.attr('download', selected.filename),
+                testId('pw-download')
+              ),
+            ),
+            cssButton(cssButtonIcon('FieldAttachment'), 'Add',
+              dom.on('click', () => this._select()),
+              testId('pw-add')
+            ),
+            dom.maybe(this._selected, selected =>
+              cssButton(cssButtonIcon('Remove'), 'Delete',
+                dom.on('click', () => this._remove()),
+                testId('pw-remove')
+              ),
+            )
+          ),
+          cssCloseButton(cssBigIcon('CrossBig'), dom.on('click', () => ctl.close()),
+            testId('pw-close')),
+        )
+      ),
+      cssNextArrow(cssNextArrow.cls('-left'), cssBigIcon('Expand'), testId('pw-left'),
+        dom.hide(use => !use(this._attachments).length || use(this._index) === 0),
+        dom.on('click', () => this._moveIndex(-1))
+      ),
+      cssNextArrow(cssNextArrow.cls('-right'), cssBigIcon('Expand'), testId('pw-right'),
+        dom.hide(use => !use(this._attachments).length || use(this._index) === use(this._attachments).length - 1),
+        dom.on('click', () => this._moveIndex(1))
+      ),
+      dom.domComputed(this._selected, selected => renderContent(selected)),
+
+      // Drag-over logic
+      (elem: HTMLElement) => dragOverClass(elem, cssDropping.className),
+      cssDragArea(cssWarning('Drop files here to attach')),
+      dom.on('drop', ev => this._upload(ev.dataTransfer!.files)),
+      testId('pw-modal')
+    ];
+  }
+
+  private async _renameAttachment(att: Attachment, fileName: string): Promise<void> {
+    await this._attachmentsTable.sendTableAction(['UpdateRecord', att.rowId, {fileName}]);
+    // Update the observable, since it's not on its own observing changes.
+    att.filename.set(this._attachmentsTable.getValue(att.rowId, 'fileName') as string);
+  }
+
+  private _getUrl(fileIdent: string, filename: string, inline?: boolean): string {
+    return this._docComm.docUrl('attachment') + '?' + encodeQueryParams({
+      ...this._docComm.getUrlParams(),
+      ident: fileIdent,
+      name: filename,
+      ...(inline ? {inline: 1} : {})
+    });
+  }
+
+  private _moveIndex(dir: -1|1): void {
+    const next = this._index.get()! + dir;
+    this._index.set(clamp(next, 0, this._attachments.get().length));
+  }
+
+  // Removes the attachment being previewed from the cell (but not the document).
+  private _remove(): void {
+    this._rowIds.splice(this._index.get()!, 1);
+  }
+
+  private async _select(): Promise<void> {
+    const uploadResult = await selectFiles({docWorkerUrl: this._docComm.docWorkerUrl,
+                                            multiple: true, sizeLimit: 'attachment'});
+    return this._add(uploadResult);
+  }
+
+  private async _upload(files: FileList): Promise<void> {
+    const uploadResult = await uploadFiles(Array.from(files),
+                                           {docWorkerUrl: this._docComm.docWorkerUrl,
+                                            sizeLimit: 'attachment'});
+    return this._add(uploadResult);
+  }
+
+  private async _add(uploadResult: UploadResult|null): Promise<void> {
+    if (!uploadResult) { return; }
+    const rowIds = await this._docComm.addAttachments(uploadResult.uploadId);
+    const len = this._rowIds.get().length;
+    if (rowIds.length > 0) {
+      this._rowIds.push(...rowIds);
+      this._index.set(len);
+    }
+  }
+}
+
+function isInEditor(ev: KeyboardEvent): boolean {
+  return (ev.target as HTMLElement).tagName === 'INPUT';
+}
+
+function renderContent(att: Attachment|null): HTMLElement {
+  const commonArgs = [cssContent.cls(''), testId('pw-attachment-content')];
+  if (!att) {
+    return cssWarning('No attachments', cssDetails('Drop files here to attach.'), ...commonArgs);
+  } else if (att.hasPreview) {
+    return dom('img', dom.attr('src', att.url), ...commonArgs);
+  } else if (att.fileType.startsWith('video/')) {
+    return dom('video', dom.attr('src', att.inlineUrl), {autoplay: false, controls: true}, ...commonArgs);
+  } else if (att.fileType.startsWith('audio/')) {
+    return dom('audio', dom.attr('src', att.inlineUrl), {autoplay: false, controls: true}, ...commonArgs);
+  } else if (att.fileType.startsWith('text/') || att.fileType === 'application/json') {
+    // Rendering text/html is risky. Things like text/plain and text/csv we could render though,
+    // but probably not using object tag (which needs work to look acceptable).
+    return dom('div', ...commonArgs,
+      cssWarning(cssContent.cls(''), renderFileType(att.filename.get(), att.fileIdent),
+        cssDetails('Preview not available.')));
+  } else {
+    // Setting 'type' attribute is important to avoid a download prompt from Chrome.
+    return dom('object', {type: att.fileType}, dom.attr('data', att.inlineUrl), ...commonArgs,
+      cssWarning(cssContent.cls(''), renderFileType(att.filename.get(), att.fileIdent),
+        cssDetails('Preview not available.'))
+    );
+  }
+}
+
+function dragOverClass(target: HTMLElement, className: string): void {
+  let enterTarget: EventTarget|null = null;
+  function toggle(ev: DragEvent, onOff: boolean) {
+    enterTarget = onOff ? ev.target : null;
+    ev.stopPropagation();
+    ev.preventDefault();
+    target.classList.toggle(className, onOff);
+  }
+  dom.onElem(target, 'dragenter', (ev) => toggle(ev, true));
+  dom.onElem(target, 'dragleave', (ev) => (ev.target === enterTarget) && toggle(ev, false));
+  dom.onElem(target, 'drop', (ev) => toggle(ev, false));
+}
+
+const cssFullScreenModal = styled('div', `
+  background-color: initial;
+  width: 100%;
+  height: 100%;
+  border: none;
+  border-radius: 0px;
+  box-shadow: none;
+  padding: 0px;
+`);
+
+const cssHeader = styled('div', `
+  padding: 16px 24px;
+  position: fixed;
+  width: 100%;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  color: white;
+`);
+
+const cssCloseButton = styled('div', `
+  padding: 6px;
+  border-radius: 32px;
+  cursor: pointer;
+  background-color: ${colors.light};
+  --icon-color: ${colors.lightGreen};
+
+  &:hover {
+    background-color: ${colors.mediumGreyOpaque};
+    --icon-color: ${colors.darkGreen};
+  }
+`);
+
+const cssBigIcon = styled(icon, `
+  padding: 10px;
+`);
+
+const cssTitle = styled('div', `
+  display: inline-block;
+  padding: 8px 16px;
+  margin-right: 8px;
+  min-width: 0px;
+  overflow: hidden;
+
+  &:hover {
+    outline: 1px solid ${colors.slate};
+  }
+  &:focus-within {
+    outline: 1px solid ${colors.darkGreen};
+  }
+`);
+
+const cssEditableLabel = styled(editableLabel, `
+  font-size: ${vars.mediumFontSize};
+  font-weight: bold;
+  color: white;
+`);
+
+const cssFlexExpand = styled('div', `
+  flex: 1;
+  display: flex;
+`);
+
+const cssFileButtons = styled(cssButtonGroup, `
+  margin-left: auto;
+  margin-right: 16px;
+  height: 32px;
+  flex: none;
+`);
+
+const cssButton = styled(basicButton, `
+  background-color: ${colors.light};
+  font-weight: normal;
+  padding: 0 16px;
+  border-top: none;
+  border-right: none;
+  border-bottom: none;
+  border-left: 1px solid ${colors.darkGrey};
+  display: flex;
+  align-items: center;
+
+  &:first-child {
+    border: none;
+  }
+  &:hover {
+    background-color: ${colors.mediumGreyOpaque};
+    border-color: ${colors.darkGrey};
+  }
+`);
+
+const cssButtonIcon = styled(icon, `
+  --icon-color: ${colors.slate};
+  margin-right: 4px;
+`);
+
+const cssNextArrow = styled('div', `
+  position: fixed;
+  height: 32px;
+  margin: auto 24px;
+  top: 0px;
+  bottom: 0px;
+  z-index: 1;
+
+  padding: 6px;
+  border-radius: 32px;
+  cursor: pointer;
+  background-color: ${colors.lightGreen};
+  --icon-color: ${colors.light};
+
+  &:hover {
+    background-color: ${colors.darkGreen};
+  }
+  &-left {
+    transform: rotateY(180deg);
+    left: 0px;
+  }
+  &-right {
+    right: 0px;
+  }
+`);
+
+const cssDropping = styled('div', '');
+
+const cssContent = styled('div', `
+  display: block;
+  height: calc(100% - 72px);
+  width: calc(100% - 64px);
+  max-width: 800px;
+  margin-left: auto;
+  margin-right: auto;
+  margin-top: 64px;
+  margin-bottom: 8px;
+  outline: none;
+  img& {
+    width: max-content;
+    height: unset;
+  }
+  audio& {
+    padding-bottom: 64px;
+  }
+  .${cssDropping.className} > & {
+    display: none;
+  }
+`);
+
+const cssWarning = styled('div', `
+  display: flex;
+  flex-direction: column;
+  justify-content: center;
+  align-items: center;
+  font-size: ${vars.mediumFontSize};
+  font-weight: bold;
+  color: white;
+  padding: 0px;
+`);
+
+const cssDetails = styled('div', `
+  font-weight: normal;
+  margin-top: 24px;
+`);
+
+const cssDragArea = styled(cssContent, `
+  border: 2px dashed ${colors.mediumGreyOpaque};
+  height: calc(100% - 96px);
+  margin-top: 64px;
+  padding: 0px;
+  justify-content: center;
+  display: none;
+  .${cssDropping.className} > & {
+    display: flex;
+  }
+`);
diff --git a/app/client/widgets/PreviewsWidget.css b/app/client/widgets/AttachmentsWidget.css
similarity index 100%
rename from app/client/widgets/PreviewsWidget.css
rename to app/client/widgets/AttachmentsWidget.css
diff --git a/app/client/widgets/PreviewsWidget.ts b/app/client/widgets/AttachmentsWidget.ts
similarity index 71%
rename from app/client/widgets/PreviewsWidget.ts
rename to app/client/widgets/AttachmentsWidget.ts
index 488aab43..5feab2b8 100644
--- a/app/client/widgets/PreviewsWidget.ts
+++ b/app/client/widgets/AttachmentsWidget.ts
@@ -1,15 +1,15 @@
 import {Computed, dom, fromKo, input, makeTestId, onElem, styled, TestId} from 'grainjs';
 
+import * as commands from 'app/client/components/commands';
 import {dragOverClass} from 'app/client/lib/dom';
 import {selectFiles, uploadFiles} from 'app/client/lib/uploads';
 import {cssRow} from 'app/client/ui/RightPanel';
-import {colors} from 'app/client/ui2018/cssVars';
+import {colors, vars} from 'app/client/ui2018/cssVars';
 import {NewAbstractWidget} from 'app/client/widgets/NewAbstractWidget';
-import {NewBaseEditor} from 'app/client/widgets/NewBaseEditor';
-import {PreviewModal} from 'app/client/widgets/PreviewModal';
 import {encodeQueryParams} from 'app/common/gutil';
 import {TableData} from 'app/common/TableData';
 import {UploadResult} from 'app/common/uploads';
+import {extname} from 'path';
 
 const testId: TestId = makeTestId('test-pw-');
 
@@ -43,42 +43,15 @@ const attachmentPreview = styled('div', `
   border: 1px solid #bbb;
   margin: 0 2px 2px 0;
   position: relative;
-  vertical-align: top;
+  display: flex;
+  align-items: center;
+  justify-content: center;
   z-index: 0;
-
-  &:hover > .show_preview {
-    display: block;
-  }
-`);
-
-const showPreview = styled('div.glyphicon.glyphicon-eye-open.show_preview', `
-  position: absolute;
-  display: none;
-  right: -2px;
-  top: -2px;
-  width: 12px;
-  height: 12px;
-  border-radius: 2px;
-  background-color: #888;
-  color: white;
-  font-size: 6pt;
-  padding: 2px;
-  cursor: pointer;
-
   &:hover {
-    display: block;
+    border-color: ${colors.lightGreen};
   }
 `);
 
-const noPreviewIcon = styled('div.glyphicon.glyphicon-file', `
-  min-width: 100%;
-  color: #bbb;
-  text-align: center;
-  margin: calc(50% * 1.33 - 6px) 0;
-  font-size: 6pt;
-  vertical-align: top;
-`);
-
 const sizeLabel = styled('div', `
   color: ${colors.slate};
   margin-right: 9px;
@@ -89,9 +62,9 @@ export interface SavingObservable<T> extends ko.Observable<T> {
 }
 
 /**
- * PreviewsWidget - A widget for displaying attachments as image previews.
+ * AttachmentsWidget - A widget for displaying attachments as image previews.
  */
-export class PreviewsWidget extends NewAbstractWidget {
+export class AttachmentsWidget extends NewAbstractWidget {
 
   private _attachmentsTable: TableData;
   private _height: SavingObservable<string>;
@@ -126,7 +99,7 @@ export class PreviewsWidget extends NewAbstractWidget {
         dom.on('click', () => this._selectAndSave(cellValue))
       ),
       dom.forEach(values, (value: number) =>
-        isNaN(value) ? null : this._buildAttachment(value, cellValue)
+        isNaN(value) ? null : this._buildAttachment(value, values)
       ),
       dom.on('drop', ev => this._uploadAndSave(cellValue, ev.dataTransfer!.files))
     );
@@ -148,12 +121,13 @@ export class PreviewsWidget extends NewAbstractWidget {
     );
   }
 
-  protected _buildAttachment(value: number, cellValue: SavingObservable<number[]>): Element {
+  protected _buildAttachment(value: number, allValues: Computed<number[]>): Element {
     const filename: string = this._attachmentsTable.getValue(value, 'fileName') as string;
+    const fileIdent: string = this._attachmentsTable.getValue(value, 'fileIdent') as string;
     const height: number = this._attachmentsTable.getValue(value, 'imageHeight') as number;
     const width: number = this._attachmentsTable.getValue(value, 'imageWidth') as number;
     const hasPreview: boolean = Boolean(height);
-    const ratio: number = hasPreview ? (width / height) : .75;
+    const ratio: number = hasPreview ? (width / height) : 1;
 
     return attachmentPreview({title: filename}, // Add a filename tooltip to the previews.
       dom.style('height', (use) => `${use(this._height)}px`),
@@ -161,13 +135,12 @@ export class PreviewsWidget extends NewAbstractWidget {
       // TODO: Update to legitimately determine whether a file preview exists.
       hasPreview ? dom('img', {style: 'height: 100%; min-width: 100%; vertical-align: top;'},
         dom.attr('src', this._getUrl(value))
-      ) : noPreviewIcon(),
-      dom.cls('no_preview', () => !hasPreview),
-      showPreview(
-        dom.on('click', () => this._showPreview(value, cellValue)),
-        testId(`preview-${value}`)
-      ),
-      testId(String(value))
+      ) : renderFileType(filename, fileIdent, this._height),
+      // Open editor as if with input, using it to tell it which of the attachments to show. We
+      // pass in a 1-based index. Hitting a key opens the cell, and this approach allows an
+      // accidental feature of opening e.g. second attachment by hitting "2".
+      dom.on('dblclick', () => commands.allCommands.input.run(String(allValues.get().indexOf(value) + 1))),
+      testId('thumbnail'),
     );
   }
 
@@ -208,40 +181,35 @@ export class PreviewsWidget extends NewAbstractWidget {
     // Trigger a row height change in case the added attachment wraps to the next line.
     this.field.viewSection().events.trigger('rowHeightChange');
   }
-
-  // Show a preview for the attachment with the given rowId value in the attachments table.
-  private _showPreview(value: number, cellValue: SavingObservable<number[]>): void {
-    // Modal should be disposed on close.
-    const onClose = (_cellValue: number[]) => {
-      cellValue.setAndSave(_cellValue);
-      modal.dispose();
-    };
-    const modal = PreviewModal.create(this, this._getDocData(), cellValue.peek(), testId, value,
-      onClose);
-  }
 }
 
-/**
- * A PreviewsEditor is just the PreviewModal, which allows adding and removing attachments.
- */
-export class PreviewsEditor extends NewBaseEditor {
-  private _modal: any;
-
-  public attach(cellRect: ClientRect|DOMRect) {
-    const docData = this.options.gristDoc.docData;
-    // Disposal on close is handled by the FieldBuilder editor logic.
-    this._modal = PreviewModal.create(this, docData, this.options.cellValue as number[], testId);
-  }
-
-  public getCellValue(): any {
-    return this._modal.getCellValue();
-  }
-
-  public getCursorPos(): number {
-    return 0;
-  }
-
-  public getTextValue(): string {
-    return '';
-  }
+export function renderFileType(fileName: string, fileIdent: string, height?: ko.Observable<string>): HTMLElement {
+  // Prepend 'x' to ensure we return the extension even if the basename is empty (e.g. ".xls").
+  // Take slice(1) to strip off the leading period.
+  const extension = extname('x' + fileName).slice(1) || extname('x' + fileIdent).slice(1) || '?';
+  return cssFileType(extension.toUpperCase(),
+    height && cssFileType.cls((use) => {
+      const size = parseFloat(use(height));
+      return size < 28 ? '-small' : size < 60 ? '-medium' : '-large';
+    }),
+  );
 }
+
+const cssFileType = styled('div', `
+  height: 100%;
+  width: 100%;
+  max-height: 80px;
+  max-width: 80px;
+  background-color: ${colors.slate};
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  font-size: ${vars.mediumFontSize};
+  font-weight: bold;
+  color: white;
+  overflow: hidden;
+
+  &-small { font-size: ${vars.xxsmallFontSize}; }
+  &-medium { font-size: ${vars.smallFontSize}; }
+  &-large { font-size: ${vars.mediumFontSize}; }
+`);
diff --git a/app/client/widgets/FieldEditor.ts b/app/client/widgets/FieldEditor.ts
index ad5964a2..6c80e7e9 100644
--- a/app/client/widgets/FieldEditor.ts
+++ b/app/client/widgets/FieldEditor.ts
@@ -11,6 +11,7 @@ import {CellValue} from "app/common/DocActions";
 import {isRaisedException} from 'app/common/gristTypes';
 import * as gutil from 'app/common/gutil';
 import {Disposable, Holder, Observable} from 'grainjs';
+import isEqual = require('lodash/isEqual');
 
 type IEditorConstructor = typeof NewBaseEditor;
 interface ICommandGroup { [cmd: string]: () => void; }
@@ -38,7 +39,7 @@ export function saveWithoutEditor(
 // Set the given field of editRow to value, only if different from the current value of the cell.
 export async function setAndSave(editRow: DataRowModel, field: ViewFieldRec, value: CellValue): Promise<void> {
   const obs = editRow.cells[field.colId()];
-  if (value !== obs.peek()) {
+  if (!isEqual(value, obs.peek())) {
     return obs.setAndSave(value);
   }
 }
diff --git a/app/client/widgets/PreviewModal.ts b/app/client/widgets/PreviewModal.ts
deleted file mode 100644
index 54ee5dd9..00000000
--- a/app/client/widgets/PreviewModal.ts
+++ /dev/null
@@ -1,405 +0,0 @@
-// External dependencies
-import {computed, Computed, computedArray, Disposable} from 'grainjs';
-import {MutableObsArray, obsArray, ObsArray, observable, Observable} from 'grainjs';
-import {dom, input, LiveIndex, makeLiveIndex, noTestId, styled, TestId} from 'grainjs';
-import noop = require('lodash/noop');
-
-// Grist client libs
-import {DocComm} from 'app/client/components/DocComm';
-import {dragOverClass} from 'app/client/lib/dom';
-import {selectFiles, uploadFiles} from 'app/client/lib/uploads';
-import {DocData} from 'app/client/models/DocData';
-import {TableData} from 'app/client/models/TableData';
-import {button1Small, button1SmallBright} from 'app/client/ui/buttons';
-import {cssModalBody, cssModalTitle, IModalControl, modal} from 'app/client/ui2018/modals';
-import {encodeQueryParams, mod} from 'app/common/gutil';
-import {UploadResult} from 'app/common/uploads';
-
-
-const modalPreview = styled('div', `
-  position: relative;
-  max-width: 80%;
-  margin: 0 auto;
-  background-color: white;
-  border: 1px solid #bbb;
-`);
-
-const modalPreviewImage = styled('img', `
-  display: block;
-  max-width: 100%;
-  max-height: 400px;
-`);
-
-const noPreview = styled('div', `
-  margin: 40% 0;
-  text-align: center;
-  vertical-align: top;
-  color: #bbb;
-`);
-
-const thumbnail = styled('div', `
-  position: relative;
-  height: 100%;
-  margin: 0 5px;
-  cursor: pointer;
-`);
-
-const thumbnailOuterRow = styled('div', `
-  display: flex;
-  position: relative;
-  height: 60px;
-  margin: 0 10px;
-  justify-content: center;
-`);
-
-const thumbnailInnerRow = styled('div', `
-  display: inline-flex;
-  height: 100%;
-  padding: 10px 0;
-  overflow-x: auto;
-`);
-
-const addButton = styled('div.glyphicon.glyphicon-paperclip', `
-  position: relative;
-  flex: 0 0 40px;
-  height: 40px;
-  width: 40px;
-  margin: 9px 10px;
-  padding: 12px 6px;
-  text-align: center;
-  vertical-align: middle;
-  border: 1px dashed #bbbbbb;
-  cursor: pointer;
-  font-size: 12pt;
-`);
-
-const addButtonPlus = styled('div.glyphicon.glyphicon-plus', `
-  position: absolute;
-  left: 9px;
-  top: 9px;
-  font-size: 5pt;
-`);
-
-const selectedOverlay = styled('div', `
-  position: absolute;
-  top: 0;
-  width: 100%;
-  height: 100%;
-  background-color: #3390bf80;
-`);
-
-const noAttachments = styled('div', `
-  width: 100%;
-  height: 300px;
-  padding: 125px 0;
-  text-align: center;
-  border: 2px dashed #bbbbbb;
-  font-size: 12pt;
-  cursor: pointer;
-`);
-
-const menuBtnStyle = `
-  float: right;
-  margin: 0 5px;
-  cursor: pointer;
-  color: black;
-  text-decoration: none;
-`;
-
-const navArrowStyle = `
-  width: 10%;
-  height: 60px;
-  padding: 20px 0;
-  text-align: center;
-  cursor: pointer;
-  font-size: 14pt;
-`;
-
-interface Attachment {
-  rowId: number;
-  fileIdent: string;
-  filename: Observable<string>;
-  hasPreview: boolean;
-  url: Observable<string>;
-}
-
-// Used as a placeholder for the currently selected attachment if all attachments are removed.
-const nullAttachment: Attachment = {
-  rowId: 0,
-  fileIdent: '',
-  filename: observable(''),
-  hasPreview: false,
-  url: observable('')
-};
-
-
-/**
- * PreviewModal - Modal showing an attachment and options to rename, download or remove the
- * attachment from the cell.
- */
-export class PreviewModal extends Disposable {
-  private _attachmentsTable: TableData;
-  private _docComm: DocComm;
-
-  private _isEditingName: Observable<boolean> = observable(false);
-  private _newName: Observable<string> = observable('');
-  private _isRenameValid: Computed<boolean>;
-
-  private _rowIds: MutableObsArray<number>;
-  private _attachments: ObsArray<Attachment>;
-  private _index: LiveIndex;
-  private _selected: Computed<Attachment>;
-
-  constructor(
-    docData: DocData,
-    cellValue: number[],
-    testId: TestId = noTestId,
-    initRowId?: number,
-    onClose: (cellValue: any) => void = noop,
-  ) {
-    super();
-    this._attachmentsTable = docData.getTable('_grist_Attachments')!;
-    this._docComm = docData.docComm;
-
-    this._rowIds = obsArray(Array.isArray(cellValue) ? cellValue.slice(1) : []);
-    this._attachments = computedArray(this._rowIds, (val: number): Attachment => {
-      const fileIdent: string = this._attachmentsTable.getValue(val, 'fileIdent') as string;
-      const filename: Observable<string> =
-        observable(this._attachmentsTable.getValue(val, 'fileName') as string);
-      return {
-        rowId: val,
-        fileIdent,
-        filename,
-        hasPreview: Boolean(this._attachmentsTable.getValue(val, 'imageHeight')),
-        url: computed((use) => this._getUrl(fileIdent, use(filename)))
-      };
-    });
-    this._index = makeLiveIndex(this, this._attachments,
-      initRowId ? this._rowIds.get().indexOf(initRowId) : 0);
-    this._selected = this.autoDispose(computed((use) => {
-      const index = use(this._index);
-      return index === null ? nullAttachment : use(this._attachments)[index];
-    }));
-
-    this._isRenameValid = this.autoDispose(computed((use) =>
-      Boolean(use(this._newName) && (use(this._newName) !== use(use(this._selected).filename)))
-    ));
-
-    modal((ctl, owner) => {
-      owner.onDispose(() => { onClose(this.getCellValue()); });
-      return [
-        dom.style('padding', '16px'),   // To match the previous style more closely.
-        cssModalTitle(
-          dom('span',
-            dom.text((use) => use(use(this._selected).filename) || 'No attachments'),
-            testId('modal-title'),
-          ),
-          // This is a bootstrap-styled button, for now only to match previous style more closely.
-          dom('button', dom.cls('close'), '×', testId('modal-close-x'),
-            dom.on('click', () => ctl.close()),
-          )
-        ),
-        cssModalBody(this._buildDom(testId, ctl)),
-      ];
-    });
-
-    this.autoDispose(this._selected.addListener(att => { this._scrollToThumbnail(att.rowId); }));
-
-    // Initialize with the selected attachment's thumbnail in view.
-    if (initRowId) {
-      this._scrollToThumbnail(initRowId);
-    }
-  }
-
-  public getCellValue() {
-    const rowIds = this._rowIds.get() as any[];
-    return rowIds.length > 0 ? ["L"].concat(this._rowIds.get() as any[]) : '';
-  }
-
-  // Builds the attachment preview modal.
-  private _buildDom(testId: TestId, ctl: IModalControl): Element {
-    return dom('div',
-      // Prevent focus from switching away from the modal on mousedown.
-      dom.on('mousedown', (e) => e.preventDefault()),
-      dom.domComputed((use) =>
-        use(this._rowIds).length > 0 ? this._buildPreviewNav(testId, ctl) : this._buildEmptyMenu(testId)),
-      // Drag-over logic
-      dragOverClass('attachment_drag_over'),
-      dom.on('drop', ev => this._upload(ev.dataTransfer!.files)),
-      testId('modal')
-    );
-  }
-
-  private _buildPreviewNav(testId: TestId, ctl: IModalControl) {
-    const modalPrev = (selected: Attachment) => modalPreviewImage(
-      dom.attr('src', (use) => use(selected.url)),
-      testId('image')
-    );
-    const noPrev = noPreview({style: 'padding: 60px;'},
-      dom('div.glyphicon.glyphicon-file'),
-      dom('div', 'Preview not available')
-    );
-    return [
-      // Preview and left/right nav arrows
-      dom('div', {style: 'display: flex; align-items: center; height: 400px;'},
-        dom('div.glyphicon.glyphicon-chevron-left', {style: navArrowStyle},
-          dom.on('click', () => this._moveIndex(-1)),
-          testId('left')
-        ),
-        modalPreview(
-          dom.maybe(this._selected, (selected) =>
-            dom.domComputed((use) => selected.hasPreview ? modalPrev(selected) : noPrev)
-          ),
-          dom.attr('title', (use) => use(use(this._selected).filename)),
-        ),
-        dom('div.glyphicon.glyphicon-chevron-right', {style: navArrowStyle},
-          dom.on('click', () => this._moveIndex(1)),
-          testId('right')
-        )
-      ),
-      // Nav thumbnails
-      thumbnailOuterRow(
-        thumbnailInnerRow(
-          dom.forEach(this._attachments, (a: Attachment) => this._buildThumbnail(a)),
-          testId('thumbnails')
-        ),
-        addButton(
-          addButtonPlus(),
-          dom.on('click', () => { this._select(); }), // tslint:disable-line:no-floating-promises TODO
-          testId('add')
-        )
-      ),
-      // Menu buttons
-      dom('div', {style: 'height: 10px; margin: 10px;'},
-        dom('div.glyphicon.glyphicon-trash', {style: menuBtnStyle},
-          dom.on('click', () => this._remove()),
-          testId('remove')
-        ),
-        dom('a.glyphicon.glyphicon-download-alt', {style: menuBtnStyle},
-          dom.attr('href', (use) => use(use(this._selected).url)),
-          dom.attr('target', '_blank'),
-          dom.attr('download', (use) => use(use(this._selected).filename)),
-          testId('download')
-        ),
-        dom('div.glyphicon.glyphicon-pencil', {style: menuBtnStyle},
-          dom.on('click', () => this._isEditingName.set(!this._isEditingName.get())),
-          testId('rename')
-        )
-      ),
-      // Rename menu
-      dom.maybe(this._isEditingName, () => {
-        this._newName.set(this._selected.get().filename.get());
-        return dom('div', {style: 'display: flex; margin: 20px 0 0 0;'},
-          input(this._newName, {onInput: true},
-            {style: 'flex: 4 1 0; margin: 0 5px;', placeholder: 'Rename file...'},
-            // Allow the input element to gain focus.
-            dom.on('mousedown', (e) => e.stopPropagation()),
-            dom.onKeyPress({Enter: () => this._renameFile()}),
-            // Prevent the dialog from losing focus and disposing on input completion.
-            dom.on('blur', (ev) => ctl.focus()),
-            dom.onDispose(() => ctl.focus()),
-            testId('rename-input')
-          ),
-          button1Small('Cancel', {style: 'flex: 1 1 0; margin: 0 5px;'},
-            dom.on('click', () => this._isEditingName.set(false)),
-            testId('rename-cancel')
-          ),
-          button1SmallBright('Save', {style: 'flex: 1 1 0; margin: 0 5px;'},
-            dom.on('click', () => this._renameFile()),
-            dom.boolAttr('disabled', (use) => !use(this._isRenameValid)),
-            testId('rename-save')
-          )
-        );
-      })
-    ];
-  }
-
-  private _buildEmptyMenu(testId: TestId): Element {
-    return noAttachments('Click or drag to add attachments',
-      addButton({style: 'border: none; margin: 2px;'},
-        addButtonPlus(),
-      ),
-      dom.on('click', () => { this._select(); }), // tslint:disable-line:no-floating-promises TODO
-      testId('empty-add')
-    );
-  }
-
-  private _buildThumbnail(att: Attachment): Element {
-    const isSelected: Computed<boolean> = computed((use) =>
-      att.rowId === use(this._selected).rowId);
-    return thumbnail({id: `thumbnail-${att.rowId}`, style: att.hasPreview ? '' : 'width: 30px;'},
-      dom.autoDispose(isSelected),
-      // TODO: Update to legitimately determine whether a file preview exists.
-      att.hasPreview ? dom('img', {style: 'height: 100%; vertical-align: top;'},
-        dom.attr('src', (use) => this._getUrl(att.fileIdent, use(att.filename)))
-      ) : noPreview({style: 'width: 30px;'},
-        dom('div.glyphicon.glyphicon-file')
-      ),
-      dom.maybe(isSelected, () => selectedOverlay()),
-      // Add a filename tooltip to the thumbnails.
-      dom.attr('title', (use) => use(att.filename)),
-      dom.style('border', (use) => use(isSelected) ? '1px solid #317193' : '1px solid #bbb'),
-      dom.on('click', () => {
-        this._index.set(this._attachments.get().findIndex(a => a.rowId === att.rowId));
-      })
-    );
-  }
-
-  private _getUrl(fileIdent: string, filename: string): string {
-    return this._docComm.docUrl('attachment') + '?' + encodeQueryParams({
-      ...this._docComm.getUrlParams(),
-      ident: fileIdent,
-      name: filename
-    });
-  }
-
-  private _renameFile(): void {
-    const val = this._newName.get();
-    if (this._isRenameValid.get()) {
-      this._selected.get().filename.set(val);
-      const rowId = this._selected.get().rowId;
-      this._attachmentsTable.sendTableAction(['UpdateRecord', rowId, {fileName: val}]);
-      this._isEditingName.set(false);
-    }
-  }
-
-  private _moveIndex(dir: -1|1): void {
-    const len = this._attachments.get().length;
-    this._index.set(mod(this._index.get()! + dir, len));
-  }
-
-  private _scrollToThumbnail(rowId: number): void {
-    const tn = document.getElementById(`thumbnail-${rowId}`);
-    if (tn) {
-      tn.scrollIntoView();
-    }
-  }
-
-  // Removes the attachment being previewed from the cell (but not the document).
-  private _remove(): void {
-    this._rowIds.splice(this._index.get()!, 1);
-  }
-
-  private async _select(): Promise<void> {
-    const uploadResult = await selectFiles({docWorkerUrl: this._docComm.docWorkerUrl,
-                                            multiple: true, sizeLimit: 'attachment'});
-    return this._add(uploadResult);
-  }
-
-  private async _upload(files: FileList): Promise<void> {
-    const uploadResult = await uploadFiles(Array.from(files),
-                                           {docWorkerUrl: this._docComm.docWorkerUrl,
-                                            sizeLimit: 'attachment'});
-    return this._add(uploadResult);
-  }
-
-  private async _add(uploadResult: UploadResult|null): Promise<void> {
-    if (!uploadResult) { return; }
-    const rowIds = await this._docComm.addAttachments(uploadResult.uploadId);
-    const len = this._rowIds.get().length;
-    if (rowIds.length > 0) {
-      this._rowIds.push(...rowIds);
-      this._index.set(len);
-    }
-  }
-}
diff --git a/app/client/widgets/UserType.js b/app/client/widgets/UserType.js
index dfd0c3c7..d748ea80 100644
--- a/app/client/widgets/UserType.js
+++ b/app/client/widgets/UserType.js
@@ -221,16 +221,16 @@ var typeDefs = {
     label: 'Attachment',
     icon: 'FieldAttachment',
     widgets: {
-      Previews: {
-        cons: 'PreviewsWidget',
-        editCons: 'PreviewsEditor',
+      Attachments: {
+        cons: 'AttachmentsWidget',
+        editCons: 'AttachmentsEditor',
         icon: 'FieldAttachment',
         options: {
           height: '36'
         }
       }
     },
-    default: 'Previews'
+    default: 'Attachments'
   }
 };
 exports.typeDefs = typeDefs;
diff --git a/app/client/widgets/UserTypeImpl.js b/app/client/widgets/UserTypeImpl.js
index 39710c42..9732badc 100644
--- a/app/client/widgets/UserTypeImpl.js
+++ b/app/client/widgets/UserTypeImpl.js
@@ -1,7 +1,8 @@
 const {NTextBox} = require('./NTextBox');
 const {NumericTextBox} = require('./NumericTextBox');
 const {Spinner} = require('./Spinner');
-const {PreviewsWidget, PreviewsEditor} = require('./PreviewsWidget');
+const {AttachmentsWidget} = require('./AttachmentsWidget');
+const {AttachmentsEditor} = require('./AttachmentsEditor');
 const UserType = require('./UserType');
 const {HyperLinkEditor} = require('./HyperLinkEditor');
 const {NTextEditor} = require('./NTextEditor');
@@ -27,8 +28,8 @@ const nameToWidget = {
   'DateTimeTextBox': require('./DateTimeTextBox'),
   'DateTextBox': require('./DateTextBox'),
   'DateEditor': require('./DateEditor'),
-  'PreviewsWidget': PreviewsWidget,
-  'PreviewsEditor': PreviewsEditor,
+  'AttachmentsWidget': AttachmentsWidget,
+  'AttachmentsEditor': AttachmentsEditor,
   'DateTimeEditor': require('./DateTimeEditor'),
 };