imprv: Preview: Add loading placeholder

Fixes #11264

4 files changed, 308 insertions, 249 deletions

diff --git a/gajim/data/gui/preview.ui b/gajim/data/gui/preview.ui
index fb46b8c79..447f3e320 100644
--- a/gajim/data/gui/preview.ui
+++ b/gajim/data/gui/preview.ui
@@ -1,379 +1,436 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!-- Generated with glade 3.38.2 -->
+<!-- Generated with glade 3.40.0 -->
 <interface>
   <requires lib="gtk+" version="3.24"/>
-  <object class="GtkBox" id="preview_box">
+  <object class="GtkStack" id="preview_stack">
     <property name="visible">True</property>
     <property name="can-focus">False</property>
-    <property name="spacing">12</property>
+    <property name="hhomogeneous">False</property>
+    <property name="vhomogeneous">False</property>
+    <property name="transition-duration">50</property>
+    <property name="transition-type">crossfade</property>
     <child>
-      <object class="GtkEventBox" id="icon_event_box">
+      <object class="GtkBox">
+        <property name="width-request">300</property>
+        <property name="height-request">200</property>
         <property name="visible">True</property>
         <property name="can-focus">False</property>
-        <property name="no-show-all">True</property>
-        <property name="halign">start</property>
-        <signal name="realize" handler="_on_realize" swapped="no"/>
+        <property name="orientation">vertical</property>
+        <property name="spacing">12</property>
+        <property name="homogeneous">True</property>
         <child>
-          <object class="GtkButton" id="icon_button">
+          <object class="GtkSpinner">
             <property name="visible">True</property>
-            <property name="can-focus">True</property>
-            <property name="receives-default">False</property>
-            <property name="relief">none</property>
-            <signal name="button-press-event" handler="_on_button_press_event" swapped="no"/>
-            <signal name="clicked" handler="_on_content_button_clicked" swapped="no"/>
-            <child>
-              <placeholder/>
-            </child>
+            <property name="can-focus">False</property>
+            <property name="valign">end</property>
+            <property name="active">True</property>
+          </object>
+          <packing>
+            <property name="expand">False</property>
+            <property name="fill">True</property>
+            <property name="position">0</property>
+          </packing>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="visible">True</property>
+            <property name="can-focus">False</property>
+            <property name="valign">start</property>
+            <property name="label" translatable="yes">Loading Preview…</property>
             <style>
-              <class name="preview-image-button"/>
+              <class name="dim-label"/>
             </style>
           </object>
+          <packing>
+            <property name="expand">False</property>
+            <property name="fill">True</property>
+            <property name="position">1</property>
+          </packing>
         </child>
       </object>
       <packing>
-        <property name="expand">False</property>
-        <property name="fill">True</property>
-        <property name="position">0</property>
+        <property name="name">loading</property>
       </packing>
     </child>
     <child>
-      <object class="GtkBox" id="right_box">
+      <object class="GtkBox">
         <property name="visible">True</property>
         <property name="can-focus">False</property>
-        <property name="orientation">vertical</property>
-        <property name="spacing">3</property>
+        <property name="spacing">12</property>
         <child>
-          <object class="GtkBox" id="progress_box">
+          <object class="GtkEventBox" id="icon_event_box">
+            <property name="visible">True</property>
             <property name="can-focus">False</property>
             <property name="no-show-all">True</property>
-            <property name="spacing">12</property>
+            <property name="halign">start</property>
+            <signal name="realize" handler="_on_realize" swapped="no"/>
             <child>
-              <object class="GtkProgressBar" id="progressbar">
+              <object class="GtkButton" id="icon_button">
                 <property name="visible">True</property>
-                <property name="can-focus">False</property>
-                <property name="valign">center</property>
-              </object>
-              <packing>
-                <property name="expand">False</property>
-                <property name="fill">True</property>
-                <property name="position">0</property>
-              </packing>
-            </child>
-            <child>
-              <object class="GtkLabel" id="progress_text">
-                <property name="visible">True</property>
-                <property name="can-focus">False</property>
-                <property name="valign">center</property>
-                <property name="width-chars">4</property>
-                <property name="single-line-mode">True</property>
-                <style>
-                  <class name="dim-label"/>
-                  <class name="small-label"/>
-                </style>
-              </object>
-              <packing>
-                <property name="expand">False</property>
-                <property name="fill">True</property>
-                <property name="position">1</property>
-              </packing>
-            </child>
-            <child>
-              <object class="GtkEventBox">
-                <property name="visible">True</property>
-                <property name="can-focus">False</property>
-                <property name="valign">end</property>
-                <signal name="realize" handler="_on_realize" swapped="no"/>
+                <property name="can-focus">True</property>
+                <property name="receives-default">False</property>
+                <property name="relief">none</property>
+                <signal name="button-press-event" handler="_on_button_press_event" swapped="no"/>
+                <signal name="clicked" handler="_on_content_button_clicked" swapped="no"/>
                 <child>
-                  <object class="GtkButton" id="cancel_download_button">
-                    <property name="visible">True</property>
-                    <property name="can-focus">True</property>
-                    <property name="receives-default">False</property>
-                    <property name="tooltip-text" translatable="yes">Cancel Download</property>
-                    <property name="relief">none</property>
-                    <signal name="clicked" handler="_on_cancel_download_clicked" swapped="no"/>
-                    <child>
-                      <object class="GtkImage">
-                        <property name="visible">True</property>
-                        <property name="can-focus">False</property>
-                        <property name="icon-name">process-stop-symbolic</property>
-                      </object>
-                    </child>
-                    <style>
-                      <class name="border"/>
-                      <class name="flat"/>
-                    </style>
-                  </object>
+                  <placeholder/>
                 </child>
+                <style>
+                  <class name="preview-image-button"/>
+                </style>
               </object>
-              <packing>
-                <property name="expand">False</property>
-                <property name="fill">True</property>
-                <property name="pack-type">end</property>
-                <property name="position">2</property>
-              </packing>
             </child>
           </object>
           <packing>
             <property name="expand">False</property>
             <property name="fill">True</property>
-            <property name="pack-type">end</property>
             <property name="position">0</property>
           </packing>
         </child>
         <child>
-          <object class="GtkBox" id="content_box">
+          <object class="GtkBox" id="right_box">
             <property name="visible">True</property>
             <property name="can-focus">False</property>
             <property name="orientation">vertical</property>
-            <property name="spacing">6</property>
+            <property name="spacing">3</property>
             <child>
-              <object class="GtkEventBox">
-                <property name="visible">True</property>
+              <object class="GtkBox" id="progress_box">
                 <property name="can-focus">False</property>
-                <property name="halign">center</property>
-                <signal name="realize" handler="_on_realize" swapped="no"/>
+                <property name="no-show-all">True</property>
+                <property name="spacing">12</property>
                 <child>
-                  <object class="GtkButton" id="image_button">
+                  <object class="GtkProgressBar" id="progressbar">
                     <property name="visible">True</property>
-                    <property name="can-focus">True</property>
-                    <property name="receives-default">False</property>
-                    <property name="relief">none</property>
-                    <signal name="button-press-event" handler="_on_button_press_event" swapped="no"/>
-                    <signal name="clicked" handler="_on_content_button_clicked" swapped="no"/>
-                    <child>
-                      <placeholder/>
-                    </child>
+                    <property name="can-focus">False</property>
+                    <property name="valign">center</property>
+                  </object>
+                  <packing>
+                    <property name="expand">False</property>
+                    <property name="fill">True</property>
+                    <property name="position">0</property>
+                  </packing>
+                </child>
+                <child>
+                  <object class="GtkLabel" id="progress_text">
+                    <property name="visible">True</property>
+                    <property name="can-focus">False</property>
+                    <property name="valign">center</property>
+                    <property name="width-chars">4</property>
+                    <property name="single-line-mode">True</property>
                     <style>
-                      <class name="preview-image-button"/>
+                      <class name="dim-label"/>
+                      <class name="small-label"/>
                     </style>
                   </object>
+                  <packing>
+                    <property name="expand">False</property>
+                    <property name="fill">True</property>
+                    <property name="position">1</property>
+                  </packing>
                 </child>
-              </object>
-              <packing>
-                <property name="expand">False</property>
-                <property name="fill">True</property>
-                <property name="position">0</property>
-              </packing>
-            </child>
-            <child>
-              <object class="GtkLinkButton" id="link_button">
-                <property name="can-focus">True</property>
-                <property name="receives-default">False</property>
-                <property name="no-show-all">True</property>
-                <property name="halign">start</property>
-                <property name="relief">none</property>
-              </object>
-              <packing>
-                <property name="expand">False</property>
-                <property name="fill">True</property>
-                <property name="position">1</property>
-              </packing>
-            </child>
-          </object>
-          <packing>
-            <property name="expand">False</property>
-            <property name="fill">True</property>
-            <property name="position">1</property>
-          </packing>
-        </child>
-        <child>
-          <object class="GtkBox" id="button_box">
-            <property name="visible">True</property>
-            <property name="can-focus">False</property>
-            <property name="spacing">6</property>
-            <child>
-              <object class="GtkEventBox">
-                <property name="visible">True</property>
-                <property name="can-focus">False</property>
-                <property name="valign">end</property>
-                <signal name="realize" handler="_on_realize" swapped="no"/>
                 <child>
-                  <object class="GtkButton" id="download_button">
-                    <property name="can-focus">True</property>
-                    <property name="receives-default">False</property>
-                    <property name="no-show-all">True</property>
-                    <property name="tooltip-text" translatable="yes">Download</property>
-                    <property name="relief">none</property>
-                    <signal name="clicked" handler="_on_download" swapped="no"/>
+                  <object class="GtkEventBox">
+                    <property name="visible">True</property>
+                    <property name="can-focus">False</property>
+                    <property name="valign">end</property>
+                    <signal name="realize" handler="_on_realize" swapped="no"/>
                     <child>
-                      <object class="GtkImage">
+                      <object class="GtkButton" id="cancel_download_button">
                         <property name="visible">True</property>
-                        <property name="can-focus">False</property>
-                        <property name="icon-name">folder-download-symbolic</property>
+                        <property name="can-focus">True</property>
+                        <property name="receives-default">False</property>
+                        <property name="tooltip-text" translatable="yes">Cancel Download</property>
+                        <property name="relief">none</property>
+                        <signal name="clicked" handler="_on_cancel_download_clicked" swapped="no"/>
+                        <child>
+                          <object class="GtkImage">
+                            <property name="visible">True</property>
+                            <property name="can-focus">False</property>
+                            <property name="icon-name">process-stop-symbolic</property>
+                          </object>
+                        </child>
+                        <style>
+                          <class name="border"/>
+                          <class name="flat"/>
+                        </style>
                       </object>
                     </child>
-                    <style>
-                      <class name="border"/>
-                      <class name="flat"/>
-                    </style>
                   </object>
+                  <packing>
+                    <property name="expand">False</property>
+                    <property name="fill">True</property>
+                    <property name="pack-type">end</property>
+                    <property name="position">2</property>
+                  </packing>
                 </child>
               </object>
               <packing>
                 <property name="expand">False</property>
                 <property name="fill">True</property>
                 <property name="pack-type">end</property>
-                <property name="position">1</property>
+                <property name="position">0</property>
               </packing>
             </child>
             <child>
-              <object class="GtkEventBox">
+              <object class="GtkBox" id="content_box">
                 <property name="visible">True</property>
                 <property name="can-focus">False</property>
-                <property name="valign">end</property>
-                <signal name="realize" handler="_on_realize" swapped="no"/>
+                <property name="orientation">vertical</property>
+                <property name="spacing">6</property>
                 <child>
-                  <object class="GtkButton" id="save_as_button">
-                    <property name="can-focus">True</property>
-                    <property name="receives-default">False</property>
-                    <property name="no-show-all">True</property>
-                    <property name="tooltip-text" translatable="yes">Save as...</property>
-                    <signal name="clicked" handler="_on_save_as" swapped="no"/>
+                  <object class="GtkEventBox">
+                    <property name="visible">True</property>
+                    <property name="can-focus">False</property>
+                    <property name="halign">center</property>
+                    <signal name="realize" handler="_on_realize" swapped="no"/>
                     <child>
-                      <object class="GtkImage">
+                      <object class="GtkButton" id="image_button">
                         <property name="visible">True</property>
-                        <property name="can-focus">False</property>
-                        <property name="icon-name">document-save-as-symbolic</property>
+                        <property name="can-focus">True</property>
+                        <property name="receives-default">False</property>
+                        <property name="relief">none</property>
+                        <signal name="button-press-event" handler="_on_button_press_event" swapped="no"/>
+                        <signal name="clicked" handler="_on_content_button_clicked" swapped="no"/>
+                        <child>
+                          <placeholder/>
+                        </child>
+                        <style>
+                          <class name="preview-image-button"/>
+                        </style>
                       </object>
                     </child>
-                    <style>
-                      <class name="border"/>
-                      <class name="flat"/>
-                    </style>
                   </object>
+                  <packing>
+                    <property name="expand">False</property>
+                    <property name="fill">True</property>
+                    <property name="position">0</property>
+                  </packing>
                 </child>
-              </object>
-              <packing>
-                <property name="expand">False</property>
-                <property name="fill">True</property>
-                <property name="pack-type">end</property>
-                <property name="position">2</property>
-              </packing>
-            </child>
-            <child>
-              <object class="GtkEventBox">
-                <property name="visible">True</property>
-                <property name="can-focus">False</property>
-                <property name="valign">end</property>
-                <signal name="realize" handler="_on_realize" swapped="no"/>
                 <child>
-                  <object class="GtkButton" id="open_folder_button">
+                  <object class="GtkLinkButton" id="link_button">
                     <property name="can-focus">True</property>
                     <property name="receives-default">False</property>
                     <property name="no-show-all">True</property>
-                    <property name="tooltip-text" translatable="yes">Open folder</property>
-                    <signal name="clicked" handler="_on_open_folder" swapped="no"/>
-                    <child>
-                      <object class="GtkImage">
-                        <property name="visible">True</property>
-                        <property name="can-focus">False</property>
-                        <property name="icon-name">folder-symbolic</property>
-                      </object>
-                    </child>
-                    <style>
-                      <class name="border"/>
-                      <class name="flat"/>
-                    </style>
+                    <property name="halign">start</property>
+                    <property name="relief">none</property>
                   </object>
+                  <packing>
+                    <property name="expand">False</property>
+                    <property name="fill">True</property>
+                    <property name="position">1</property>
+                  </packing>
                 </child>
               </object>
               <packing>
                 <property name="expand">False</property>
                 <property name="fill">True</property>
-                <property name="pack-type">end</property>
-                <property name="position">3</property>
+                <property name="position">1</property>
               </packing>
             </child>
             <child>
-              <object class="GtkBox">
+              <object class="GtkBox" id="button_box">
                 <property name="visible">True</property>
                 <property name="can-focus">False</property>
-                <property name="halign">start</property>
-                <property name="orientation">vertical</property>
+                <property name="spacing">6</property>
                 <child>
-                  <object class="GtkLabel" id="file_name">
+                  <object class="GtkEventBox">
                     <property name="visible">True</property>
-                    <property name="can-focus">True</property>
-                    <property name="selectable">True</property>
-                    <property name="ellipsize">end</property>
-                    <property name="single-line-mode">True</property>
-                    <property name="max-width-chars">30</property>
-                    <property name="xalign">0</property>
-                    <style>
-                      <class name="dim-label"/>
-                      <class name="small-label"/>
-                    </style>
+                    <property name="can-focus">False</property>
+                    <property name="valign">end</property>
+                    <signal name="realize" handler="_on_realize" swapped="no"/>
+                    <child>
+                      <object class="GtkButton" id="download_button">
+                        <property name="can-focus">True</property>
+                        <property name="receives-default">False</property>
+                        <property name="no-show-all">True</property>
+                        <property name="tooltip-text" translatable="yes">Download</property>
+                        <property name="relief">none</property>
+                        <signal name="clicked" handler="_on_download" swapped="no"/>
+                        <child>
+                          <object class="GtkImage">
+                            <property name="visible">True</property>
+                            <property name="can-focus">False</property>
+                            <property name="icon-name">folder-download-symbolic</property>
+                          </object>
+                        </child>
+                        <style>
+                          <class name="border"/>
+                          <class name="flat"/>
+                        </style>
+                      </object>
+                    </child>
                   </object>
                   <packing>
                     <property name="expand">False</property>
                     <property name="fill">True</property>
-                    <property name="position">0</property>
+                    <property name="pack-type">end</property>
+                    <property name="position">1</property>
                   </packing>
                 </child>
                 <child>
-                  <object class="GtkLabel" id="file_size">
+                  <object class="GtkEventBox">
                     <property name="visible">True</property>
-                    <property name="can-focus">True</property>
-                    <property name="selectable">True</property>
-                    <property name="single-line-mode">True</property>
-                    <property name="max-width-chars">30</property>
-                    <property name="xalign">0</property>
-                    <style>
-                      <class name="dim-label"/>
-                      <class name="small-label"/>
-                    </style>
+                    <property name="can-focus">False</property>
+                    <property name="valign">end</property>
+                    <signal name="realize" handler="_on_realize" swapped="no"/>
+                    <child>
+                      <object class="GtkButton" id="save_as_button">
+                        <property name="can-focus">True</property>
+                        <property name="receives-default">False</property>
+                        <property name="no-show-all">True</property>
+                        <property name="tooltip-text" translatable="yes">Save as...</property>
+                        <signal name="clicked" handler="_on_save_as" swapped="no"/>
+                        <child>
+                          <object class="GtkImage">
+                            <property name="visible">True</property>
+                            <property name="can-focus">False</property>
+                            <property name="icon-name">document-save-as-symbolic</property>
+                          </object>
+                        </child>
+                        <style>
+                          <class name="border"/>
+                          <class name="flat"/>
+                        </style>
+                      </object>
+                    </child>
                   </object>
                   <packing>
                     <property name="expand">False</property>
                     <property name="fill">True</property>
-                    <property name="position">1</property>
+                    <property name="pack-type">end</property>
+                    <property name="position">2</property>
                   </packing>
                 </child>
                 <child>
-                  <object class="GtkLabel" id="info_message">
+                  <object class="GtkEventBox">
                     <property name="visible">True</property>
-                    <property name="can-focus">True</property>
-                    <property name="selectable">True</property>
-                    <property name="ellipsize">end</property>
-                    <property name="single-line-mode">True</property>
-                    <property name="max-width-chars">30</property>
-                    <property name="xalign">0</property>
-                    <style>
-                      <class name="dim-label"/>
-                      <class name="small-label"/>
-                    </style>
+                    <property name="can-focus">False</property>
+                    <property name="valign">end</property>
+                    <signal name="realize" handler="_on_realize" swapped="no"/>
+                    <child>
+                      <object class="GtkButton" id="open_folder_button">
+                        <property name="can-focus">True</property>
+                        <property name="receives-default">False</property>
+                        <property name="no-show-all">True</property>
+                        <property name="tooltip-text" translatable="yes">Open folder</property>
+                        <signal name="clicked" handler="_on_open_folder" swapped="no"/>
+                        <child>
+                          <object class="GtkImage">
+                            <property name="visible">True</property>
+                            <property name="can-focus">False</property>
+                            <property name="icon-name">folder-symbolic</property>
+                          </object>
+                        </child>
+                        <style>
+                          <class name="border"/>
+                          <class name="flat"/>
+                        </style>
+                      </object>
+                    </child>
                   </object>
                   <packing>
                     <property name="expand">False</property>
                     <property name="fill">True</property>
-                    <property name="position">2</property>
+                    <property name="pack-type">end</property>
+                    <property name="position">3</property>
+                  </packing>
+                </child>
+                <child>
+                  <object class="GtkBox">
+                    <property name="visible">True</property>
+                    <property name="can-focus">False</property>
+                    <property name="halign">start</property>
+                    <property name="orientation">vertical</property>
+                    <child>
+                      <object class="GtkLabel" id="file_name">
+                        <property name="visible">True</property>
+                        <property name="can-focus">True</property>
+                        <property name="selectable">True</property>
+                        <property name="ellipsize">end</property>
+                        <property name="single-line-mode">True</property>
+                        <property name="max-width-chars">30</property>
+                        <property name="xalign">0</property>
+                        <style>
+                          <class name="dim-label"/>
+                          <class name="small-label"/>
+                        </style>
+                      </object>
+                      <packing>
+                        <property name="expand">False</property>
+                        <property name="fill">True</property>
+                        <property name="position">0</property>
+                      </packing>
+                    </child>
+                    <child>
+                      <object class="GtkLabel" id="file_size">
+                        <property name="visible">True</property>
+                        <property name="can-focus">True</property>
+                        <property name="selectable">True</property>
+                        <property name="single-line-mode">True</property>
+                        <property name="max-width-chars">30</property>
+                        <property name="xalign">0</property>
+                        <style>
+                          <class name="dim-label"/>
+                          <class name="small-label"/>
+                        </style>
+                      </object>
+                      <packing>
+                        <property name="expand">False</property>
+                        <property name="fill">True</property>
+                        <property name="position">1</property>
+                      </packing>
+                    </child>
+                    <child>
+                      <object class="GtkLabel" id="info_message">
+                        <property name="visible">True</property>
+                        <property name="can-focus">True</property>
+                        <property name="selectable">True</property>
+                        <property name="ellipsize">end</property>
+                        <property name="single-line-mode">True</property>
+                        <property name="max-width-chars">30</property>
+                        <property name="xalign">0</property>
+                        <style>
+                          <class name="dim-label"/>
+                          <class name="small-label"/>
+                        </style>
+                      </object>
+                      <packing>
+                        <property name="expand">False</property>
+                        <property name="fill">True</property>
+                        <property name="position">2</property>
+                      </packing>
+                    </child>
+                  </object>
+                  <packing>
+                    <property name="expand">True</property>
+                    <property name="fill">True</property>
+                    <property name="pack-type">end</property>
+                    <property name="position">4</property>
                   </packing>
                 </child>
               </object>
               <packing>
-                <property name="expand">True</property>
+                <property name="expand">False</property>
                 <property name="fill">True</property>
                 <property name="pack-type">end</property>
-                <property name="position">4</property>
+                <property name="position">2</property>
               </packing>
             </child>
           </object>
           <packing>
             <property name="expand">False</property>
             <property name="fill">True</property>
-            <property name="pack-type">end</property>
-            <property name="position">2</property>
+            <property name="position">1</property>
           </packing>
         </child>
       </object>
       <packing>
-        <property name="expand">False</property>
-        <property name="fill">True</property>
+        <property name="name">preview</property>
         <property name="position">1</property>
       </packing>
     </child>
     <style>
-      <class name="preview-box"/>
+      <class name="preview-stack"/>
     </style>
   </object>
 </interface>
diff --git a/gajim/data/style/gajim.css b/gajim/data/style/gajim.css
index 48dc228a5..ad50008c5 100644
--- a/gajim/data/style/gajim.css
+++ b/gajim/data/style/gajim.css
@@ -644,7 +644,7 @@ infobar.error > revealer > box {
 }
 
 /* PreviewWidget */
-.preview-box {
+.preview-stack > box {
     border: 1px solid;
     border-color: @borders;
     border-radius: 4px;
diff --git a/gajim/gtk/builder.pyi b/gajim/gtk/builder.pyi
index 592cff32a..50430c8b0 100644
--- a/gajim/gtk/builder.pyi
+++ b/gajim/gtk/builder.pyi
@@ -701,7 +701,7 @@ class PreferencesBuilder(Builder):
 
 
 class PreviewBuilder(Builder):
-    preview_box: Gtk.Box
+    preview_stack: Gtk.Stack
     icon_event_box: Gtk.EventBox
     icon_button: Gtk.Button
     right_box: Gtk.Box
diff --git a/gajim/gtk/preview.py b/gajim/gtk/preview.py
index 27e39da81..87a34c883 100644
--- a/gajim/gtk/preview.py
+++ b/gajim/gtk/preview.py
@@ -67,7 +67,7 @@ class PreviewWidget(Gtk.Box):
 
         self._ui = get_builder('preview.ui')
         self._ui.connect_signals(self)
-        self.add(self._ui.preview_box)
+        self.add(self._ui.preview_stack)
 
         leftclick_action = app.settings.get('preview_leftclick_action')
         self._ui.icon_button.set_tooltip_text(
@@ -93,6 +93,7 @@ class PreviewWidget(Gtk.Box):
 
     @ensure_not_destroyed
     def update_progress(self, _preview: Preview, progress: float) -> None:
+        self._ui.preview_stack.set_visible_child_name('preview')
         self._ui.download_button.hide()
 
         self._ui.progress_box.show()
@@ -105,6 +106,7 @@ class PreviewWidget(Gtk.Box):
     def update(self, preview: Preview, data: GdkPixbufType | None) -> None:
         self._preview = preview
 
+        self._ui.preview_stack.set_visible_child_name('preview')
         self._ui.progress_box.hide()
         self._ui.info_message.hide()