Bug 1767165 - Fix dragend coordinates in child processes after bug 17…

…56241. r=tnikkel Bug 1756241 changed nsDragService::mDragEndPoint to be relative to the window. I didn't realize, but that point is passed as-is to child widgets. Changing the widget event to actually have a widget made the point be interpreted as widget-relative (which is correct in the parent process, but not in the child process). Account for this and fix the mDragEndPoint documentation while at it. Differential Revision: https://phabricator.services.mozilla.com/D145182
iaxat · May 2, 2022 · d28e76a · d28e76a
1 parent 24905d6
commit d28e76a
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Showing 6 changed files with 75 additions and 12 deletions.
diff --git a/dom/events/test/mochitest.ini b/dom/events/test/mochitest.ini
@@ -188,10 +188,12 @@ skip-if = toolkit == 'android' # wheel scroll isn't supported
 skip-if = toolkit == 'android' #CRASH_DUMP, RANDOM
 [test_dragstart.html]
 skip-if = toolkit == 'android' # not supported
+[test_drag_coords.html]
+skip-if = toolkit == 'android' # not supported
 [test_error_events.html]
 skip-if = toolkit == 'android' #TIMED_OUT
 [test_event_handler_cc.html]
-skip-if = 
+skip-if =
   os == "linux" && bits == 64 && !debug # Bug 1564622
   win10_2004 && bits == 64 && !debug # Bug 1564622
 [test_eventctors.html]

diff --git a/dom/events/test/test_drag_coords.html b/dom/events/test/test_drag_coords.html
@@ -0,0 +1,50 @@
+<!doctype html>
+<title>Test for drag event coordinates</title>
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script src="/tests/SimpleTest/EventUtils.js"></script>
+<link rel="stylesheet" href="/tests/SimpleTest/test.css"/>
+<style>
+  #draggable {
+    display: inline-block;
+    border: 1px solid;
+  }
+</style>
+<div draggable="true" id="draggable">Drag me</div>
+<script>
+add_task(async function test_drag_coords() {
+  let target = document.getElementById("draggable");
+  let coords = {};
+  let promises = [];
+  for (let type of ["dragstart", "dragend"]) {
+    promises.push(new Promise(function(resolve) {
+      target.addEventListener(type, function(e) {
+        info("Got " + e.type);
+        coords[e.type] = {
+          screen: {
+            x: e.screenX,
+            y: e.screenY,
+          },
+          client: {
+            x: e.clientX,
+            y: e.clientY,
+          },
+        };
+        resolve();
+      });
+    }));
+  }
+  synthesizePlainDragAndDrop({
+    srcElement: target,
+    srcX: 2,
+    srcY: 2,
+    stepX: 10,
+    stepY: 10,
+  });
+  await Promise.all(promises);
+  info(JSON.stringify(coords));
+  for (let coordType of ["screen", "client"]) {
+    is(coords.dragend[coordType].x, coords.dragstart[coordType].x + 12, `x ${coordType} is correct`);
+    is(coords.dragend[coordType].y, coords.dragstart[coordType].y + 12, `y ${coordType} is correct`);
+  }
+});
+</script>
diff --git a/widget/PuppetWidget.cpp b/widget/PuppetWidget.cpp
@@ -1023,11 +1023,7 @@ LayoutDeviceIntPoint PuppetWidget::GetChromeOffset() {
 }
 
 LayoutDeviceIntPoint PuppetWidget::WidgetToScreenOffset() {
-  auto positionRalativeToWindow =
-      WidgetToTopLevelWidgetTransform().TransformPoint(LayoutDevicePoint());
-
-  return GetWindowPosition() +
-         LayoutDeviceIntPoint::Round(positionRalativeToWindow);
+  return GetWindowPosition() + WidgetToTopLevelWidgetOffset();
 }
 
 LayoutDeviceIntPoint PuppetWidget::GetWindowPosition() {

diff --git a/widget/nsBaseDragService.cpp b/widget/nsBaseDragService.cpp
@@ -259,16 +259,22 @@ NS_IMETHODIMP nsBaseDragService::SetDragEndPointForTests(int32_t aScreenX,
   MOZ_ASSERT(mDoingDrag);
   MOZ_ASSERT(mSourceDocument);
   MOZ_ASSERT(mSessionIsSynthesizedForTests);
+
   if (!mDoingDrag || !mSourceDocument || !mSessionIsSynthesizedForTests) {
     return NS_ERROR_FAILURE;
   }
-  nsPresContext* presContext = mSourceDocument->GetPresContext();
-  if (NS_WARN_IF(!presContext)) {
+  nsPresContext* pc = mSourceDocument->GetPresContext();
+  if (NS_WARN_IF(!pc)) {
     return NS_ERROR_FAILURE;
   }
-  SetDragEndPoint(
-      LayoutDeviceIntPoint(presContext->CSSPixelsToDevPixels(aScreenX),
-                           presContext->CSSPixelsToDevPixels(aScreenY)));
+  auto p = LayoutDeviceIntPoint::Round(CSSIntPoint(aScreenX, aScreenY) *
+                                       pc->CSSToDevPixelScale());
+  // p is screen-relative, and we want them to be top-level-widget-relative.
+  if (nsCOMPtr<nsIWidget> widget = pc->GetRootWidget()) {
+    p -= widget->WidgetToScreenOffset();
+    p += widget->WidgetToTopLevelWidgetOffset();
+  }
+  SetDragEndPoint(p);
   return NS_OK;
 }
 
@@ -656,6 +662,9 @@ nsBaseDragService::FireDragEventAtSource(EventMessage aEventMessage,
   event.mInputSource = mInputSource;
   if (aEventMessage == eDragEnd) {
     event.mRefPoint = mEndDragPoint;
+    if (widget) {
+      event.mRefPoint -= widget->WidgetToTopLevelWidgetOffset();
+    }
     event.mUserCancelled = mUserCancelled;
   }
   event.mModifiers = aKeyModifiers;

diff --git a/widget/nsBaseDragService.h b/widget/nsBaseDragService.h
@@ -202,7 +202,7 @@ class nsBaseDragService : public nsIDragService, public nsIDragSession {
   // drag image.
   mozilla::CSSIntPoint mScreenPosition;
 
-  // the screen position where the drag ended
+  // The position relative to the top level widget where the drag ended.
   mozilla::LayoutDeviceIntPoint mEndDragPoint;
 
   uint32_t mSuppressLevel;

diff --git a/widget/nsIWidget.h b/widget/nsIWidget.h
@@ -1313,6 +1313,12 @@ class nsIWidget : public nsISupports {
     return mozilla::LayoutDeviceToLayoutDeviceMatrix4x4();
   }
 
+  mozilla::LayoutDeviceIntPoint WidgetToTopLevelWidgetOffset() {
+    return mozilla::LayoutDeviceIntPoint::Round(
+        WidgetToTopLevelWidgetTransform().TransformPoint(
+            mozilla::LayoutDevicePoint()));
+  }
+
   /**
    * Given the specified client size, return the corresponding window size,
    * which includes the area for the borders and titlebar. This method