dndwidgets: add DragDropFlowLayoutWidget

artiq/gui/dndwidgets.py

@@ -1,4 +1,6 @@
-from PyQt5 import QtCore, QtWidgets
+from PyQt5 import QtCore, QtWidgets, QtGui
+
+from artiq.gui.flowlayout import FlowLayout
 
 
 class VDragDropSplitter(QtWidgets.QSplitter):
@@ -98,3 +100,65 @@ class VDragScrollArea(QtWidgets.QScrollArea):
         dy = self._direction * self._speed
         new_val = min(max_, max(min_, val + dy))
         self.verticalScrollBar().setValue(new_val)
+
+
+# Widget with FlowLayout and drag and drop support between widgets
+class DragDropFlowLayoutWidget(QtWidgets.QWidget):
+    def __init__(self):
+        QtWidgets.QWidget.__init__(self)
+        self.layout = FlowLayout()
+        self.setLayout(self.layout)
+        self.setAcceptDrops(True)
+
+    def _get_index(self, pos):
+        for i in range(self.layout.count()):
+            if self.itemAt(i).geometry().contains(pos):
+                return i
+        return -1
+
+    def mousePressEvent(self, event):
+        if event.buttons() == QtCore.Qt.LeftButton \
+           and event.modifiers() == QtCore.Qt.ShiftModifier:
+            index = self._get_index(event.pos())
+            if index == -1:
+                return
+            drag = QtGui.QDrag(self)
+            mime = QtCore.QMimeData()
+            mime.setData("index", str(index).encode())
+            drag.setMimeData(mime)
+            pixmapi = QtWidgets.QApplication.style().standardIcon(
+                QtWidgets.QStyle.SP_FileIcon)
+            drag.setPixmap(pixmapi.pixmap(32))
+            drag.exec_(QtCore.Qt.MoveAction)
+        event.accept()
+
+    def dragEnterEvent(self, event):
+        event.accept()
+
+    def dropEvent(self, event):
+        index = self._get_index(event.pos())
+        source_layout = event.source()
+        source_index = int(bytes(event.mimeData().data("index")).decode())
+        if source_layout == self:
+            if index == source_index:
+                return
+            widget = self.layout.itemAt(source_index).widget()
+            self.layout.removeWidget(widget)
+            self.layout.addWidget(widget)
+            self.layout.itemList.insert(index, self.layout.itemList.pop())
+        else:
+            widget = source_layout.layout.itemAt(source_index).widget()
+            source_layout.layout.removeWidget(widget)
+            self.layout.addWidget(widget)
+            if index != -1:
+                self.layout.itemList.insert(index, self.layout.itemList.pop())
+        event.accept()
+
+    def addWidget(self, widget):
+        self.layout.addWidget(widget)
+
+    def count(self):
+        return self.layout.count()
+
+    def itemAt(self, i):
+        return self.layout.itemAt(i)