Fixes #2050: Image preview for attachments

netbox/project-static/js/forms.js

@@ -398,4 +398,43 @@ $(document).ready(function() {
     // Account for the header height when hash-scrolling
     window.addEventListener('load', headerOffsetScroll);
     window.addEventListener('hashchange', headerOffsetScroll);
+
+    // Offset between the preview window and the window edges
+    const IMAGE_PREVIEW_OFFSET_X = 20
+    const IMAGE_PREVIEW_OFFSET_Y = 10
+
+    // Preview an image attachment when the link is hovered over
+    $('a.image-preview').on('mouseover', function(e) {
+        // Twice the offset to account for all sides of the picture
+        var maxWidth = window.innerWidth - (e.clientX + (IMAGE_PREVIEW_OFFSET_X * 2));
+        var maxHeight = window.innerHeight - (e.clientY + (IMAGE_PREVIEW_OFFSET_Y * 2));
+        var img = $('<img>').attr('id', 'image-preview-window').css({
+            display: 'none',
+            position: 'absolute',
+            maxWidth: maxWidth + 'px',
+            maxHeight: maxHeight + 'px',
+            left: e.pageX + IMAGE_PREVIEW_OFFSET_X + 'px',
+            top: e.pageY + IMAGE_PREVIEW_OFFSET_Y + 'px',
+            boxShadow: '0 0px 12px 3px rgba(0, 0, 0, 0.4)',
+        });
+
+        // Remove any existing preview windows and add the current one
+        $('#image-preview-window').remove();
+        $('body').append(img);
+
+        // Once loaded, show the preview if the image is indeed an image
+        img.on('load', function(e) {
+            if (e.target.complete && e.target.naturalWidth) {
+                $('#image-preview-window').fadeIn('fast');
+            }
+        });
+
+        // Begin loading
+        img.attr('src', e.target.href);
+    });
+
+    // Fade the image out; it will be deleted when another one is previewed
+    $('a.image-preview').on('mouseout', function() {
+        $('#image-preview-window').fadeOut('fast')
+    });
 });

netbox/templates/inc/image_attachments.html

@@ -10,7 +10,7 @@
             <tr{% if not attachment.size %} class="danger"{% endif %}>
                 <td>
                     <i class="fa fa-image"></i>
-                    <a href="{{ attachment.image.url }}" target="_blank">{{ attachment }}</a>
+                    <a class="image-preview" href="{{ attachment.image.url }}" target="_blank">{{ attachment }}</a>
                 </td>
                 <td>{{ attachment.size|filesizeformat }}</td>
                 <td>{{ attachment.created }}</td>