1 files changed, 87 insertions, 0 deletions
diff --git a/toolkit/components/extensions/parent/ext-clipboard.js b/toolkit/components/extensions/parent/ext-clipboard.js
new file mode 100644
index 0000000000..9916b14be7
--- /dev/null
+++ b/toolkit/components/extensions/parent/ext-clipboard.js
@@ -0,0 +1,87 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+XPCOMUtils.defineLazyServiceGetter(
+  this,
+  "imgTools",
+  "@mozilla.org/image/tools;1",
+  "imgITools"
+);
+
+const Transferable = Components.Constructor(
+  "@mozilla.org/widget/transferable;1",
+  "nsITransferable"
+);
+
+this.clipboard = class extends ExtensionAPI {
+  getAPI(context) {
+    return {
+      clipboard: {
+        async setImageData(imageData, imageType) {
+          if (AppConstants.platform == "android") {
+            return Promise.reject({
+              message:
+                "Writing images to the clipboard is not supported on Android",
+            });
+          }
+          let img;
+          try {
+            img = imgTools.decodeImageFromArrayBuffer(
+              imageData,
+              `image/${imageType}`
+            );
+          } catch (e) {
+            return Promise.reject({
+              message: `Data is not a valid ${imageType} image`,
+            });
+          }
+
+          // Other applications can only access the copied image once the data
+          // is exported via the platform-specific clipboard APIs:
+          // nsClipboard::SelectionGetEvent (widget/gtk/nsClipboard.cpp)
+          // nsClipboard::PasteDictFromTransferable (widget/cocoa/nsClipboard.mm)
+          // nsDataObj::GetDib (widget/windows/nsDataObj.cpp)
+          //
+          // The common protocol for exporting a nsITransferable as an image is:
+          // - Use nsITransferable::GetTransferData to fetch the stored data.
+          // - QI imgIContainer on the pointer.
+          // - Convert the image to the native clipboard format.
+          //
+          // Below we create a nsITransferable in the above format.
+          let transferable = new Transferable();
+          transferable.init(null);
+          const kNativeImageMime = "application/x-moz-nativeimage";
+          transferable.addDataFlavor(kNativeImageMime);
+
+          // Internal consumers expect the image data to be stored as a
+          // nsIInputStream. On Linux and Windows, pasted data is directly
+          // retrieved from the system's native clipboard, and made available
+          // as a nsIInputStream.
+          //
+          // On macOS, nsClipboard::GetNativeClipboardData (nsClipboard.mm) uses
+          // a cached copy of nsITransferable if available, e.g. when the copy
+          // was initiated by the same browser instance. To make sure that a
+          // nsIInputStream is returned instead of the cached imgIContainer,
+          // the image is exported as as `kNativeImageMime`. Data associated
+          // with this type is converted to a platform-specific image format
+          // when written to the clipboard. The type is not used when images
+          // are read from the clipboard (on all platforms, not just macOS).
+          // This forces nsClipboard::GetNativeClipboardData to fall back to
+          // the native clipboard, and return the image as a nsITransferable.
+          transferable.setTransferData(kNativeImageMime, img);
+
+          Services.clipboard.setData(
+            transferable,
+            null,
+            Services.clipboard.kGlobalClipboard
+          );
+        },
+      },
+    };
+  }
+};