From aec0174c01f1e0c80fdd2ac51fa9a9be5d6516b9 Mon Sep 17 00:00:00 2001
From: Simon Renblad <srenblad@m-labs.hk>
Date: Mon, 8 Jan 2024 14:26:22 +0800
Subject: [PATCH] dndwidgets: add dnd widgets

---
 artiq/gui/dndwidgets.py | 100 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 artiq/gui/dndwidgets.py

diff --git a/artiq/gui/dndwidgets.py b/artiq/gui/dndwidgets.py
new file mode 100644
index 000000000..401981e78
--- /dev/null
+++ b/artiq/gui/dndwidgets.py
@@ -0,0 +1,100 @@
+from PyQt5 import QtCore, QtWidgets
+
+
+class DragDropSplitter(QtWidgets.QSplitter):
+    def __init__(self, parent):
+        QtWidgets.QSplitter.__init__(self, parent=parent)
+        self.setAcceptDrops(True)
+        self.setContentsMargins(0, 0, 0, 0)
+        self.setOrientation(QtCore.Qt.Vertical)
+        self.setChildrenCollapsible(False)
+
+    def resetSizes(self):
+        self.setSizes(self.count() * [1])
+
+    def dragEnterEvent(self, e):
+        e.accept()
+
+    def dragLeaveEvent(self, e):
+        self.setRubberBand(-1)
+        e.accept()
+
+    def dragMoveEvent(self, e):
+        pos = e.pos()
+        for n in range(self.count()):
+            w = self.widget(n)
+            if self.orientation() == QtCore.Qt.Vertical:
+                pos_p, w_p, w_s = pos.y(), w.y(), w.size().height()
+            else:
+                pos_p, w_p, w_s = pos.x(), w.x(), w.size().width()
+            if pos_p < w_p + w_s // 2:
+                self.setRubberBand(w_p)
+                break
+            elif n == self.count() - 1:
+                self.setRubberBand(w_p + w_s)
+        e.accept()
+
+    def dropEvent(self, e):
+        pos = e.pos()
+        widget = e.source()
+        index = self.indexOf(widget)
+        self.setRubberBand(-1)
+        for n in range(self.count()):
+            w = self.widget(n)
+            if n <= index:
+                k = n
+            else:
+                k = n - 1
+            if self.orientation() == QtCore.Qt.Vertical:
+                pos_p, w_p, w_s = pos.y(), w.y(), w.size().height()
+            else:
+                pos_p, w_p, w_s = pos.x(), w.x(), w.size().width()
+            if pos_p < w_p + w_s // 2:
+                self.insertWidget(k, widget)
+                break
+            elif n == self.count() - 1:
+                self.insertWidget(-1, widget)
+        e.accept()
+
+
+# Scroll area with auto-scroll on vertical drag
+class VDragScrollArea(QtWidgets.QScrollArea):
+    def __init__(self, parent):
+        QtWidgets.QScrollArea.__init__(self, parent)
+        self.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)
+        self.installEventFilter(self)
+        self._margin = 40
+        self._timer = QtCore.QTimer(self)
+        self._timer.setInterval(20)
+        self._timer.timeout.connect(self._on_auto_scroll)
+        self._direction = 0
+        self._speed = 10
+
+    def eventFilter(self, obj, e):
+        if e.type() == QtCore.QEvent.DragMove:
+            val = self.verticalScrollBar().value()
+            vp_height = self.viewport().height()
+            pos = e.pos()
+            if pos.y() < val + self._margin:
+                self._direction = -1
+            elif pos.y() > vp_height + val - self._margin:
+                self._direction = 1
+            else:
+                self._direction = 0
+            if not self._timer.isActive():
+                self._timer.start()
+        elif e.type() in (QtCore.QEvent.Drop, QtCore.QEvent.DragLeave):
+            self._timer.stop()
+        return False
+
+    def setAutoScrollMargin(self, margin):
+        self._margin = margin
+
+    def _on_auto_scroll(self):
+        val = self.verticalScrollBar().value()
+        mini = self.verticalScrollBar().minimum()
+        maxi = self.verticalScrollBar().maximum()
+        dx = self._direction * self._speed
+        new_val = min(maxi, max(mini, val + dx))
+        self.verticalScrollBar().setValue(new_val)
+