Changeset 41793 in webkit

Timestamp:

Mar 17, 2009, 5:06:25 PM (16 years ago)

Author:

Darin Adler

Message:

2009-03-17 Darin Adler <Darin Adler>

Reviewed by Adele Peterson.

Bug 24477: REGRESSION (r41467): Page Down key scrolls two pages
​https://bugs.webkit.org/show_bug.cgi?id=24477
rdar://problem/6674184

• WebView/WebHTMLView.mm: (responderChainRespondsToSelector): Added. (-[WebHTMLView doCommandBySelector:]): Set eventWasHandled based on whether we can find a responder that responds to this selector rather than always assuming the selector will not be handled.

Location:

trunk/WebKit/mac

Files:

• ChangeLog (modified) (1 diff)
• WebView/WebHTMLView.mm (modified) (2 diffs)

trunk/WebKit/mac/ChangeLog

@@ +1 @@
+2009-03-17  Darin Adler  <darin@apple.com>
+
+        Reviewed by Adele Peterson.
+
+        Bug 24477: REGRESSION (r41467): Page Down key scrolls two pages
+        https://bugs.webkit.org/show_bug.cgi?id=24477
+        rdar://problem/6674184
+
+        * WebView/WebHTMLView.mm:
+        (responderChainRespondsToSelector): Added.
+        (-[WebHTMLView doCommandBySelector:]): Set eventWasHandled based on whether we
+        can find a responder that responds to this selector rather than always assuming
+        the selector will not be handled.
+
 2009-03-17  Mark Rowe  <mrowe@apple.com>
 

trunk/WebKit/mac/WebView/WebHTMLView.mm

@@ -5370 +5370 @@
 }
 
+static bool responderChainRespondsToSelector(NSResponder *firstResponder, SEL selector)
+{
+    for (NSResponder *responder = firstResponder; responder; responder = [responder nextResponder]) {
+        if ([responder respondsToSelector:selector])
+            return true;
+    }
+    return false;
+}
+
 - (void)doCommandBySelector:(SEL)selector
 {
@@ -5403 +5412 @@
                 eventWasHandled = command.execute(event);
             else {
+                // If WebKit does not support this command, we need to pass the selector to super.
                 _private->selectorForDoCommandBySelector = selector;
-                // If WebKit does not support this command, we need to pass the selector to super.
+                // We'll get the wrong value for eventWasHandled if respondsToSelector: doesn't
+                // exactly reflect what doCommandBySelector: does, for example an unusual class might
+                // not even pass the selector along to the next responder, or might handle a selector
+                // even though respondsToSelector: return NO. When that happens, there's a risk the
+                // event might end up handled twice. We know of no real-world examples of this.
+                eventWasHandled = responderChainRespondsToSelector(self, selector);
                 [super doCommandBySelector:selector];
                 _private->selectorForDoCommandBySelector = 0;
-                // In theory, [super doCommandBySelector:] can do some action that would cause WebKit 
-                // to need to consider the event handled.  But in practice, I've found no
-                // example of that happening and causing broken behavior.
-                eventWasHandled = false;
             }
         }