REGRESSION (Safari 17.2): Does not respect mousemove events in an ifr…

…ame when the mouse is clicked from outside of an iframe https://bugs.webkit.org/show_bug.cgi?id=269886 rdar://120540148 Reviewed by Wenson Hsieh. In 269246@main, we introduced a behavior change where initiating a drag gesture from a cancelled mousedown event causes all mousemove events to be routed to the originating frame till the drag gesture terminates with a corresponding mouseup event. This was a web compatibility regression since users expect to receive mouse events in the inner frame when we are dragging the pointer over it. Instead, this patch limits this mouse event target capturing behavior to subframes only, and not the outer frame. This patch makes mouse event targets independent of mousedown event cancellation when the pointer is dragged out of a subframe. This change in behavior aligns us with other major browser vendors' behavior. Finally, we update cancel-mousedown-and-drag-to-frame.html since the new behavior is essentially the opposite of what the test had been expecting. * LayoutTests/fast/events/cancel-mousedown-and-drag-from-frame-to-other-frame.html: * LayoutTests/fast/events/cancel-mousedown-and-drag-to-frame-expected.txt: * LayoutTests/fast/events/cancel-mousedown-and-drag-to-frame.html: * LayoutTests/fast/events/resources/mouse-drag-from-frame-target-subframe.html: * Source/WebCore/page/EventHandler.cpp: (WebCore::EventHandler::handleMousePressEvent): Canonical link: https://commits.webkit.org/275157@main
WebKit · Feb 22, 2024 · 50f43b7 · 50f43b7
1 parent 0ee25f1
commit 50f43b7
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Showing 5 changed files with 24 additions and 42 deletions.
diff --git a/LayoutTests/fast/events/cancel-mousedown-and-drag-from-frame-to-other-frame.html b/LayoutTests/fast/events/cancel-mousedown-and-drag-from-frame-to-other-frame.html
@@ -7,8 +7,8 @@
     testRunner.dumpAsText();
 }
 
-var unexpectedMouseMove = false;
-var unexpectedMouseUp = false;
+var mouseMoveInOtherFrame = false;
+var mouseUpInOtherFrame = false;
 
 function log(msg) {
     var msgNode = document.createTextNode(msg);
@@ -40,7 +40,7 @@
         eventSender.mouseMoveTo(endX, endY);
         eventSender.mouseUp();
     } finally {
-        if (unexpectedMouseUp || unexpectedMouseMove)
+        if (mouseUpInOtherFrame || mouseMoveInOtherFrame)
             log("FAIL! Received unexpected mouse event on other frame.");
         else
             log("PASS!");

diff --git a/LayoutTests/fast/events/cancel-mousedown-and-drag-to-frame-expected.txt b/LayoutTests/fast/events/cancel-mousedown-and-drag-to-frame-expected.txt
@@ -2,6 +2,6 @@ This tests that dragging from an element that returns false from its mousedown h
 Drag Me!
 
 Drag started
-Root frame received mouse move
-Root frame received mouseup event
+Subframe received mousemove event
+Subframe received mouseup event
 PASS!
diff --git a/LayoutTests/fast/events/cancel-mousedown-and-drag-to-frame.html b/LayoutTests/fast/events/cancel-mousedown-and-drag-to-frame.html
@@ -7,37 +7,22 @@
     testRunner.dumpAsText();
 }
 
+var mouseMoveInOtherFrame = false;
+var mouseUpInOtherFrame = false;
+
 function log(msg) {
     var msgNode = document.createTextNode(msg);
     var li = document.createElement("li");
     li.appendChild(msgNode);
     document.getElementById("log").appendChild(li);
 }
-var dragging = false;
-var waitingForUp = false;
+
 function dragStarted() {
-    if (dragging || waitingForUp) {
-        log("Unexpected drag start");
-        return;
-    }
     log("Drag started");
-    dragging = true;
-}
-
-window.onmousemove = function() {
-    if (!dragging || waitingForUp)
-        return;
-    log("Root frame received mouse move");
-    waitingForUp = true;
 }
 
 window.onmouseup = function() {
-    if (!waitingForUp) {
-        log("Unexpected mouseup");
-        return;
-    }
-    log("Root frame received mouseup event");
-    log("PASS!");
+    log("FAIL! Received unexpected mouseup on root frame");
 }
 
 window.onload = function() {
@@ -61,6 +46,11 @@
         eventSender.mouseMoveTo(endX, endY);
         eventSender.mouseUp();
     } finally {
+        if (mouseUpInOtherFrame && mouseMoveInOtherFrame)
+            log("PASS!");
+        else
+            log("FAIL! Drag was not reflected in subframe");
+
         if (window.testRunner)
             testRunner.notifyDone();
     }

diff --git a/LayoutTests/fast/events/resources/mouse-drag-from-frame-target-subframe.html b/LayoutTests/fast/events/resources/mouse-drag-from-frame-target-subframe.html
@@ -1,3 +1,3 @@
-<body onmousemove="parent.log('Received unexpected mousemove'); parent.unexpectedMouseMove = true;" onmouseup="parent.log('Received unexpected mouseup'); parent.unexpectedMouseUp = true;">
+<body onmousemove="parent.log('Subframe received mousemove event'); parent.mouseMoveInOtherFrame = true;" onmouseup="parent.log('Subframe received mouseup event'); parent.mouseUpInOtherFrame = true;">
 
 </body>
diff --git a/Source/WebCore/page/EventHandler.cpp b/Source/WebCore/page/EventHandler.cpp
@@ -1860,28 +1860,20 @@ HandleUserInputEventResult EventHandler::handleMousePressEvent(const PlatformMou
         if (auto remoteMouseEventData = userInputEventDataForRemoteFrame(dynamicDowncast<RemoteFrame>(subframe).get(), mouseEvent.hitTestResult().roundedPointInInnerNodeFrame()))
             return *remoteMouseEventData;
 
-        auto captureMouseEventsElementIfNeeded = [&](RefPtr<Element>&& element = nullptr) {
-            if (m_mousePressed && (m_capturesDragging || m_capturesDragging.inabilityReason() == CapturesDragging::InabilityReason::MousePressIsCancelled)) {
-                if (element)
-                    m_capturingMouseEventsElement = WTFMove(element);
-                else
-                    m_isCapturingRootElementForMouseEvents = true;
-                m_eventHandlerWillResetCapturingMouseEventsElement = true;
-            }
-        };
         RefPtr localSubframe = dynamicDowncast<LocalFrame>(subframe.get());
         if (localSubframe && passMousePressEventToSubframe(mouseEvent, *localSubframe)) {
             // Start capturing future events for this frame. We only do this if we didn't clear
             // the m_mousePressed flag, which may happen if an AppKit widget entered a modal event loop.
-            if (auto subframeCapturesDragging = localSubframe->eventHandler().capturesDragging())
-                m_capturesDragging = true;
-            else
-                m_capturesDragging = subframeCapturesDragging.inabilityReason();
-            captureMouseEventsElementIfNeeded(localSubframe->protectedOwnerElement().get());
+            m_capturesDragging = localSubframe->eventHandler().capturesDragging();
+            if (m_mousePressed) {
+                m_capturingMouseEventsElement = localSubframe->ownerElement();
+                m_eventHandlerWillResetCapturingMouseEventsElement = true;
+                if (!m_capturingMouseEventsElement)
+                    m_isCapturingRootElementForMouseEvents = true;
+            }
             invalidateClick();
             return true;
-        } else
-            captureMouseEventsElementIfNeeded();
+        }
     }
 
 #if ENABLE(PAN_SCROLLING)