enh: Add option to disable FileDropper previews (#7944)

Author: hoxbro

examples/reference/widgets/FileDropper.ipynb

@@ -32,6 +32,9 @@
     "* **`max_files`** (int): Maximum number of files that can be uploaded if `multiple=True`.\n",
     "* **`max_total_file_size`** (str): Maximum size of all uploaded files, as a string with units given in KB or MB, e.g. 5MB or 750KB.\n",
     "* **`mime_type`** (dict[str, str]): A dictionary containing the mimetypes for each of the uploaded files indexed by their filename.\n",
+    "* **`previews`** (list[str]): List of previews to enable in the FileDropper. The following previews are available:\n",
+    "    * `image`: Adds support for image previews.\n",
+    "    * `pdf`: Adds support for PDF previews.\n",
     "* **`multiple`** (bool): Whether to allow uploading multiple files.\n",
     "* **`value`** (dict[str, str | bytes]): A dictionary containing the uploaded file(s) as bytes or string objects indexed by the filename. Files that have a `text/*` mimetype will automatically be decoded as `utf-8`.\n",
     "\n",

panel/models/file_dropper.py

@@ -44,6 +44,8 @@ class FileDropper(InputWidget):
 
     layout = Nullable(Enum("integrated", "compact", "circle", default="compact"))
 
+    previews = List(String)
+
     __javascript_raw__ = [
         f"{config.npm_cdn}/filepond-plugin-image-preview/dist/filepond-plugin-image-preview.js",
         f"{config.npm_cdn}/filepond-plugin-file-validate-size/dist/filepond-plugin-file-validate-size.js",

panel/models/file_dropper.ts

@@ -44,9 +44,14 @@ export class FileDropperView extends InputWidgetView {
   _transfer_in_process: string | null = null
 
   override initialize(): void {
-    super.initialize();
-    (window as any).FilePond.registerPlugin((window as any).FilePondPluginImagePreview);
-    (window as any).FilePond.registerPlugin((window as any).FilePondPluginPdfPreview);
+    super.initialize()
+    const {previews} = this.model
+    if (previews.includes("image")) {
+      (window as any).FilePond.registerPlugin((window as any).FilePondPluginImagePreview)
+    }
+    if (previews.includes("pdf")) {
+      (window as any).FilePond.registerPlugin((window as any).FilePondPluginPdfPreview)
+    }
     (window as any).FilePond.registerPlugin((window as any).FilePondPluginFileValidateType);
     (window as any).FilePond.registerPlugin((window as any).FilePondPluginFileValidateSize)
   }
@@ -165,6 +170,7 @@ export namespace FileDropper {
     max_total_file_size: p.Property<string | null>
     mime_type: p.Property<any>
     multiple: p.Property<boolean>
+    previews: p.Property<string[]>
   }
 }
 
@@ -190,6 +196,7 @@ export class FileDropper extends InputWidget {
       mime_type:           [ Any,                  {} ],
       multiple:            [ Bool,               true ],
       layout:              [ Nullable(DropperLayout), null ],
+      previews:            [ List(Str), [ "image", "pdf" ]],
     }))
   }
 }

panel/widgets/input.py

@@ -364,6 +364,13 @@ class FileDropper(Widget):
     multiple = param.Boolean(default=False, doc="""
         Whether to allow uploading multiple files.""")
 
+    previews = param.ListSelector(default=["image", "pdf"],
+        objects=["image", "pdf"], doc="""
+        List of previews to enable in the FileDropper.
+        The following previews are available:
+        - image: Adds support for image previews.
+        - pdf: Adds support for PDF previews.""")
+
     value = param.Dict(default={}, doc="""
         A dictionary containing the uploaded file(s) as bytes or string
         objects indexed by the filename. Files that have a text/* mimetype