iOS: accept files dragged in from other apps

ios/README.md

@@ -46,7 +46,9 @@ is removed. Settings live in Application Support; the working directory is
 Documents. Open starts the native document picker in Documents. Local documents
 open directly; external selections are read with security-scoped access and file
 coordination, then copied into Documents under a unique name. Native Save asks
-for a filename, applies the filter extension and confirms replacement. External directory picking, offscreen native
+for a filename, applies the filter extension and confirms replacement. Files dragged in
+from other apps are copied into Documents under a unique name and posted as
+`kEventDragDrop` at the drop point, one event per file. External directory picking, offscreen native
 windows and joystick discovery are not implemented; rejected requests log to
 stderr. Orion routes both Open and Save to these native dialogs.
 

ios/ios_local.h

@@ -20,6 +20,7 @@ extern EAGLContext *ios_context;
 extern CADisplayLink *ios_display_link;
 void ios_resize_surface(void);
 void ios_cancel_timers(void);
+void ios_install_drop(UIView *view);
 void ios_post_gesture(ax_gesture_t gesture);
 void ios_post_touch(uint32_t event, uint32_t wparam, void *lparam, ax_pointer_t pointer);
 #endif

ios/ios_system.m

@@ -32,6 +32,65 @@ void axJoystickShutdown(void) {}
   return url;
 }
 
+// "name", then "name 2", "name 3", ... starting at the given attempt.
+static NSURL *ios_unique_document(NSURL *documents, NSString *name, int attempt) {
+  NSURL *destination = nil;
+  for (int suffix = attempt; !destination || [NSFileManager.defaultManager fileExistsAtPath:destination.path]; suffix++) {
+    NSString *stem = name;
+    if (suffix > 1) {
+      stem = [NSString stringWithFormat:@"%@ %d", name.stringByDeletingPathExtension, suffix];
+      if (name.pathExtension.length) stem = [stem stringByAppendingPathExtension:name.pathExtension];
+    }
+    destination = [documents URLByAppendingPathComponent:stem];
+  }
+  return destination;
+}
+
+// Files dragged in from other apps are copied into Documents, then posted as
+// kEventDragDrop at the drop point, one event per file.
+@interface AXDropDelegate : NSObject <UIDropInteractionDelegate>
+@end
+@implementation AXDropDelegate
+- (BOOL)dropInteraction:(UIDropInteraction *)interaction canHandleSession:(id<UIDropSession>)session {
+  return [session hasItemsConformingToTypeIdentifiers:@[UTTypeData.identifier]];
+}
+- (UIDropProposal *)dropInteraction:(UIDropInteraction *)interaction sessionDidUpdate:(id<UIDropSession>)session {
+  return [[UIDropProposal alloc] initWithDropOperation:UIDropOperationCopy];
+}
+- (void)dropInteraction:(UIDropInteraction *)interaction performDrop:(id<UIDropSession>)session {
+  CGPoint at = [session locationInView:interaction.view];
+  NSURL *documents = ios_documents_url();
+  if (!documents) return;
+  for (UIDragItem *item in session.items) {
+    NSItemProvider *provider = item.itemProvider;
+    NSString *type = nil;
+    for (NSString *candidate in provider.registeredTypeIdentifiers)
+      if ([[UTType typeWithIdentifier:candidate] conformsToType:UTTypeData]) { type = candidate; break; }
+    if (!type) { IOS_TRACE("drop item has no file representation types=%s", provider.registeredTypeIdentifiers.description.UTF8String); continue; }
+    [provider loadFileRepresentationForTypeIdentifier:type completionHandler:^(NSURL *url, NSError *error) {
+      if (!url) { IOS_TRACE("drop load failed type=%s: %s", type.UTF8String, error.localizedDescription.UTF8String); return; }
+      // The provider's file is deleted when this handler returns; concurrent drops may race for a name.
+      NSError *copy_error = nil;
+      NSURL *destination = nil;
+      for (int attempt = 1; attempt < 100; attempt++) {
+        destination = ios_unique_document(documents, url.lastPathComponent, attempt);
+        copy_error = nil;
+        if ([NSFileManager.defaultManager copyItemAtURL:url toURL:destination error:&copy_error]) break;
+        if (copy_error.code != NSFileWriteFileExistsError) break;
+      }
+      if (copy_error) { IOS_TRACE("drop import failed name=%s: %s", url.lastPathComponent.UTF8String, copy_error.localizedDescription.UTF8String); return; }
+      axNotifyFileDropEvent(destination.fileSystemRepresentation, (float)at.x, (float)at.y);
+    }];
+  }
+}
+@end
+
+void ios_install_drop(UIView *view) {
+  static AXDropDelegate *delegate;   // UIDropInteraction holds its delegate weakly
+  if (!delegate) delegate = [AXDropDelegate new];
+  [view addInteraction:[[UIDropInteraction alloc] initWithDelegate:delegate]];
+}
+
 static void ios_wait_for_dismissal(void) {
   while (ios_window.rootViewController.presentedViewController) axWaitMessage(10);
 }
@@ -80,16 +139,8 @@ bool_t axGetOpenFileName(AXopenfilename const *ofn) {
   NSString *root = [documents.URLByResolvingSymlinksInPath.path stringByAppendingString:@"/"];
   BOOL local = [source.URLByResolvingSymlinksInPath.path hasPrefix:root];
   BOOL ok = YES;
-  if (!local) {
-    // Import external providers into permanent, app-owned storage without replacing another drawing.
-    NSString *name = source.lastPathComponent;
-    destination = [documents URLByAppendingPathComponent:name];
-    for (int suffix = 2; [NSFileManager.defaultManager fileExistsAtPath:destination.path]; suffix++) {
-      NSString *stem = [NSString stringWithFormat:@"%@ %d", name.stringByDeletingPathExtension, suffix];
-      if (name.pathExtension.length) stem = [stem stringByAppendingPathExtension:name.pathExtension];
-      destination = [documents URLByAppendingPathComponent:stem];
-    }
-  }
+  // Import external providers into permanent, app-owned storage without replacing another drawing.
+  if (!local) destination = ios_unique_document(documents, source.lastPathComponent, 1);
   if (strlen(destination.fileSystemRepresentation) >= ofn->nMaxFile) {
     ios_file_error(@"The selected filename is too long."); ok = NO;
   } else if (!local) {

ios/ios_window.m

@@ -207,6 +207,7 @@ - (void)viewDidLoad {
     [ios_view.trailingAnchor constraintEqualToAnchor:self.view.trailingAnchor],
     [ios_view.topAnchor constraintEqualToAnchor:self.view.topAnchor],
     [ios_view.bottomAnchor constraintEqualToAnchor:self.view.bottomAnchor]]];
+  ios_install_drop(ios_view);
   [ios_view addGestureRecognizer:[[UIHoverGestureRecognizer alloc] initWithTarget:ios_view action:@selector(hover:)]];
   UIPanGestureRecognizer *scroll = [[UIPanGestureRecognizer alloc] initWithTarget:ios_view action:@selector(scroll:)];
   scroll.minimumNumberOfTouches = 2;

platform.h

@@ -1219,6 +1219,7 @@ axMutexDestroy(axmutex_t mutex);
  * | `drag <x1> <y1> <x2> <y2>`   | Press at (x1,y1), drag to (x2,y2), release |
  * | `move <x> <y>`               | Mouse moved to (x, y) |
  * | `scroll <x> <y> <dx> <dy>`   | Scroll at (x, y) by the given wheel delta |
+ * | `drop <x> <y> <path>`        | Drop the file at path on (x, y), as a file dragged in |
  * | `key <code> [mods]`          | Key down + key up (virtual key code integer) |
  * | `keydown <code> [mods]`      | Key down only |
  * | `keyup <code> [mods]`        | Key up only |

rc_server_impl.c

@@ -121,6 +121,15 @@ rc_dispatch(int conn, const char *line)
                    (void *)(intptr_t)MAKEDWORD(dx, dy));
     rc_reply(conn, "ok\n");
 
+  } else if (strncmp(line, "drop ", 5) == 0) {
+    int consumed = 0;
+    if (sscanf(line + 5, "%d %d %n", &x, &y, &consumed) == 2 && line[5 + consumed]) {
+      axNotifyFileDropEvent(line + 5 + consumed, (float)x, (float)y);
+      rc_reply(conn, "ok\n");
+    } else {
+      rc_reply(conn, "err usage: drop <x> <y> <path>\n");
+    }
+
   /* --- Keyboard input --- */
 
   } else if (sscanf(line, "keydown %d %d", &code, &mods) == 2) {