Make QSimpleDrag work with highDPI scaling

Task-number: QTBUG-57863
Change-Id: I940179a694ce992245dabb77ef6e92e027427524
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

1 files changed, 29 insertions, 8 deletions

diff --git a/src/gui/kernel/qsimpledrag.cpp b/src/gui/kernel/qsimpledrag.cpp
index a6ce04dc34..fc62273325 100644
--- a/src/gui/kernel/qsimpledrag.cpp
+++ b/src/gui/kernel/qsimpledrag.cpp
@@ -53,6 +53,8 @@
 #include "qdir.h"
 #include "qimagereader.h"
 #include "qimagewriter.h"
+#include "qplatformscreen.h"
+#include "qplatformwindow.h"
 
 #include <QtCore/QEventLoop>
 #include <QtCore/QDebug>
@@ -316,6 +318,25 @@ void QBasicDrag::updateCursor(Qt::DropAction action)
     updateAction(action);
 }
 
+
+static inline QPoint fromNativeGlobalPixels(const QPoint &point)
+{
+#ifndef QT_NO_HIGHDPISCALING
+    QPoint res = point;
+    if (QHighDpiScaling::isActive()) {
+        for (const QScreen *s : qAsConst(QGuiApplicationPrivate::screen_list)) {
+            if (s->handle()->geometry().contains(point)) {
+                res = QHighDpi::fromNativePixels(point, s);
+                break;
+            }
+        }
+    }
+    return res;
+#else
+    return point;
+#endif
+}
+
 /*!
     \class QSimpleDrag
     \brief QSimpleDrag implements QBasicDrag for Drag and Drop operations within the Qt Application itself.
@@ -344,7 +365,7 @@ void QSimpleDrag::startDrag()
     QBasicDrag::startDrag();
     m_current_window = topLevelAt(QCursor::pos());
     if (m_current_window) {
-        QPlatformDragQtResponse response = QWindowSystemInterface::handleDrag(m_current_window, drag()->mimeData(), QCursor::pos(), drag()->supportedActions());
+        QPlatformDragQtResponse response = QWindowSystemInterface::handleDrag(m_current_window, drag()->mimeData(), QHighDpi::toNativePixels(QCursor::pos(), m_current_window), drag()->supportedActions());
         setCanDrop(response.isAccepted());
         updateCursor(response.acceptedAction());
     } else {
@@ -363,15 +384,15 @@ void QSimpleDrag::cancel()
     }
 }
 
-void QSimpleDrag::move(const QPoint &globalPos)
+void QSimpleDrag::move(const QPoint &nativeGlobalPos)
 {
-    //### not high-DPI aware
+    QPoint globalPos = fromNativeGlobalPixels(nativeGlobalPos);
     moveShapedPixmapWindow(globalPos);
     QWindow *window = topLevelAt(globalPos);
     if (!window)
         return;
 
-    const QPoint pos = globalPos - window->geometry().topLeft();
+    const QPoint pos = nativeGlobalPos - window->handle()->geometry().topLeft();
     const QPlatformDragQtResponse qt_response =
         QWindowSystemInterface::handleDrag(window, drag()->mimeData(), pos, drag()->supportedActions());
 
@@ -379,16 +400,16 @@ void QSimpleDrag::move(const QPoint &globalPos)
     setCanDrop(qt_response.isAccepted());
 }
 
-void QSimpleDrag::drop(const QPoint &globalPos)
+void QSimpleDrag::drop(const QPoint &nativeGlobalPos)
 {
-    //### not high-DPI aware
+    QPoint globalPos = fromNativeGlobalPixels(nativeGlobalPos);
 
-    QBasicDrag::drop(globalPos);
+    QBasicDrag::drop(nativeGlobalPos);
     QWindow *window = topLevelAt(globalPos);
     if (!window)
         return;
 
-    const QPoint pos = globalPos - window->geometry().topLeft();
+    const QPoint pos = nativeGlobalPos - window->handle()->geometry().topLeft();
     const QPlatformDropQtResponse response =
             QWindowSystemInterface::handleDrop(window, drag()->mimeData(),pos, drag()->supportedActions());
     if (response.isAccepted()) {