Cocoa: Delay QMimeData requests for DnD events.

We were delaying the conversion from Qt to OS X types,
but not the data request to the application.

Introduce "Eager" and "Lazy" pasteboard promises:

Eager promises request the application data immediately
and can continue to use the existing commit-promises-
on-app-exit logic. Eager promises are the default
type and will be used for copy/paste.

Lazy promises delay requesting the data from the application
for as long as possible, specifically until when 
promiseKeeper() is called. Lazy promises are used for
drag-and-drop and are not committed on application
exit.

This brings OS X DnD behavior in line with the 
Windows behavior.

[ChangeLog][OS X] Drag-and-drop QMimeData requests are
now delayed until drop time.

Task-number: QTBUG-31301
Change-Id: I8ddbba41593251f4c0c49c29492dce990066e20d
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@theqtcompany.com>

1 files changed, 14 insertions, 3 deletions

diff --git a/src/plugins/platforms/cocoa/qmacclipboard.h b/src/plugins/platforms/cocoa/qmacclipboard.h
index ba7a2e1aac..c5b6224545 100644
--- a/src/plugins/platforms/cocoa/qmacclipboard.h
+++ b/src/plugins/platforms/cocoa/qmacclipboard.h
@@ -43,15 +43,25 @@
 
 QT_BEGIN_NAMESPACE
 
+class QMacMimeData;
 class QMacPasteboard
 {
+public:
+    enum DataRequestType { EagerRequest, LazyRequest };
+private:
     struct Promise {
         Promise() : itemId(0), convertor(0) { }
-        Promise(int itemId, QMacInternalPasteboardMime *c, QString m, QVariant d, int o=0) : itemId(itemId), offset(o), convertor(c), mime(m), data(d) { }
+
+        static Promise eagerPromise(int itemId, QMacInternalPasteboardMime *c, QString m, QMacMimeData *d, int o = 0);
+        static Promise lazyPromise(int itemId, QMacInternalPasteboardMime *c, QString m, QMacMimeData *d, int o = 0);
+        Promise(int itemId, QMacInternalPasteboardMime *c, QString m, QMacMimeData *md, int o, DataRequestType drt);
+
         int itemId, offset;
         QMacInternalPasteboardMime *convertor;
         QString mime;
-        QVariant data;
+        QPointer<QMacMimeData> mimeData;
+        QVariant variantData;
+        DataRequestType dataRequestType;
     };
     QList<Promise> promises;
 
@@ -72,7 +82,8 @@ public:
 
     PasteboardRef pasteBoard() const;
     QMimeData *mimeData() const;
-    void setMimeData(QMimeData *mime);
+
+    void setMimeData(QMimeData *mime, DataRequestType dataRequestType = EagerRequest);
 
     QStringList formats() const;
     bool hasFormat(const QString &format) const;