Add support for the download attribute on links for Cocoa/MacOS platf…

…orm (#1552) The download attribute wasn't forcing a download on mac, this makes it do that, and respects the suggested filename! Also add a test but skip it since it needs to be run manually and have user confirmation. Test fails before change and passes after.
r0x0r · Dec 27, 2024 · 0424777 · 0424777
1 parent 1ef7feb
commit 0424777
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diff --git a/tests/test_download.py b/tests/test_download.py
@@ -0,0 +1,70 @@
+import pytest
+
+import webview
+
+from .util import run_test, assert_js
+
+import time
+
+html = """
+<html>
+  <body>
+    <button id="start_download" onclick="click_handler()">Click me!</button>
+  </body>
+  <script>
+    function click_handler(){
+      const a = document.createElement('a'); // Create "a" element
+      const blob = new Blob(["Hello, World!"], { type: "text/plain" });
+      const url = URL.createObjectURL(blob); // Create an object URL from blob
+      a.setAttribute('href', url); // Set "a" element link
+      a.setAttribute('download', 'test_download.txt'); 
+      a.click(); // Start downloading
+      a.remove();
+    }
+
+    function verify_result(){
+        return confirm("Did the system prompt you for a download with name test_download.txt or download a file by that name? OK for yes, Cancel for no");
+    }
+
+    function checkFocus() {
+       return document.hasFocus();
+    }
+  </script>
+</html>
+"""
+
+@pytest.fixture
+def window():
+    return webview.create_window('Download test', html=html)
+
+# skip this test by default since it's a manual test that requires user interaction
+@pytest.mark.skip
+def test_download_attribute(window):
+    webview.settings['ALLOW_DOWNLOADS'] = True
+    run_test(webview, window, download_test)
+
+def get_result():
+    res = input("Did the system prompt you for a download with name test_download.txt or download a file by that name? Y/N").upper()
+    return (res == 'Y')
+
+def download_test(window):
+    # this should not cause the browser to navigate away but instead should trigger a download
+    # since the type is text the browser should support it and if it navigates to it it will display it instead
+    window.evaluate_js("document.getElementById('start_download').click();")
+    time.sleep(0.5)  # make sure it has executed
+
+    # if it loaded on the page and navigated away then it will fail this
+    elements = window.dom.get_elements('#start_download')
+    assert len(elements) == 1
+
+    # wait for download prompt to be dismissed and focus to come back to window
+    while not window.evaluate_js("checkFocus()"):
+        time.sleep(0.5)
+
+    # ask user if the test passed
+    assert window.evaluate_js("verify_result();")
+
+
+
+
+
diff --git a/webview/platforms/cocoa.py b/webview/platforms/cocoa.py
@@ -146,6 +146,23 @@ def userContentController_didReceiveScriptMessage_(self, controller, message):
                 body['params'] = None
             js_bridge_call(self.window, body['funcName'], body['params'], body['id'])
 
+    class DownloadDelegate(AppKit.NSObject):
+        # Download delegate to handle links with download attribute set
+        def download_decideDestinationUsingResponse_suggestedFilename_completionHandler_(self, download, decideDestinationUsingResponse, suggestedFilename, completionHandler):
+            save_dlg = AppKit.NSSavePanel.savePanel()
+            directory = Foundation.NSSearchPathForDirectoriesInDomains(
+                Foundation.NSDownloadsDirectory, 
+                Foundation.NSUserDomainMask, 
+                True)[0]
+            save_dlg.setDirectoryURL_(Foundation.NSURL.fileURLWithPath_(directory))
+            save_dlg.setNameFieldStringValue_(suggestedFilename)
+            if save_dlg.runModal() == AppKit.NSFileHandlingPanelOKButton:
+                filename = save_dlg.filename()
+                url = Foundation.NSURL.fileURLWithPath_(filename)
+                completionHandler(url)
+            else:
+                completionHandler(None)
+
     class BrowserDelegate(AppKit.NSObject):
 
         # Display a JavaScript alert panel containing the specified message
@@ -229,6 +246,11 @@ def webView_decidePolicyForNavigationAction_decisionHandler_(
             if not handler.__block_signature__:
                 handler.__block_signature__ = BrowserView.pyobjc_method_signature(b'v@i')
 
+            # Handle links with the download attribute set to recommend a file name
+            if action.shouldPerformDownload() and webview_settings['ALLOW_DOWNLOADS']:
+                handler(getattr(WebKit, 'WKNavigationActionPolicyDownload', 2))
+                return
+
             """ Disable back navigation on pressing the Delete key: """
             # Check if the requested navigation action is Back/Forward
             if action.navigationType() == getattr(WebKit, 'WKNavigationTypeBackForward', 2):
@@ -241,6 +263,9 @@ def webView_decidePolicyForNavigationAction_decisionHandler_(
             # Normal navigation, allow
             handler(getattr(WebKit, 'WKNavigationActionPolicyAllow', 1))
 
+        def webView_navigationAction_didBecomeDownload_(self, webview, navigationAction, download):
+            download.setDelegate_(BrowserView.DownloadDelegate.alloc().init().retain())
+
         def webView_decidePolicyForNavigationResponse_decisionHandler_(self, webview, navigationResponse, decisionHandler):
             if navigationResponse.canShowMIMEType():
                 decisionHandler(WebKit.WKNavigationResponsePolicyAllow)