# Source code for pyqtgraph.parametertree.ParameterTree

    from ..Qt import QtCore, QtGui
    from ..widgets.TreeWidget import TreeWidget
    import os, weakref, re
    from .ParameterItem import ParameterItem
    #import functions as fn

    class ParameterTree(TreeWidget):
        """Widget used to display or control data from a hierarchy of Parameters"""

        def __init__(self, parent=None, showHeader=True):
            """
            ============== ========================================================
            **Arguments:**
            parent         (QWidget) An optional parent widget
            showHeader     (bool) If True, then the QTreeView header is displayed.
            ============== ========================================================
            """
            TreeWidget.__init__(self, parent)
            self.setVerticalScrollMode(self.ScrollPerPixel)
            self.setHorizontalScrollMode(self.ScrollPerPixel)
            self.setAnimated(False)
            self.setColumnCount(2)
            self.setHeaderLabels(["Parameter", "Value"])
            self.setAlternatingRowColors(True)
            self.paramSet = None
            self.header().setResizeMode(QtGui.QHeaderView.ResizeToContents)
            self.setHeaderHidden(not showHeader)
            self.itemChanged.connect(self.itemChangedEvent)
            self.lastSel = None
            self.setRootIsDecorated(False)

        def setParameters(self, param, showTop=True):
            """
            Set the top-level :class:`Parameter <pyqtgraph.parametertree.Parameter>`
            to be displayed in this ParameterTree.

            If *showTop* is False, then the top-level parameter is hidden and only
            its children will be visible. This is a convenience method equivalent
            to::

                tree.clear()
                tree.addParameters(param, showTop)
            """
            self.clear()
            self.addParameters(param, showTop=showTop)

        def addParameters(self, param, root=None, depth=0, showTop=True):
            """
            Adds one top-level :class:`Parameter <pyqtgraph.parametertree.Parameter>`
            to the view.

            ============== ==========================================================
            **Arguments:**
            param          The :class:`Parameter <pyqtgraph.parametertree.Parameter>`
                           to add.
            root           The item within the tree to which *param* should be added.
                           By default, *param* is added as a top-level item.
            showTop        If False, then *param* will be hidden, and only its
                           children will be visible in the tree.
            ============== ==========================================================
            """
            item = param.makeTreeItem(depth=depth)
            if root is None:
                root = self.invisibleRootItem()
                ## Hide top-level item
                if not showTop:
                    item.setText(0, '')
                    item.setSizeHint(0, QtCore.QSize(1,1))
                    item.setSizeHint(1, QtCore.QSize(1,1))
                    depth -= 1
            root.addChild(item)
            item.treeWidgetChanged()

            for ch in param:
                self.addParameters(ch, root=item, depth=depth+1)

        def clear(self):
            """
            Remove all parameters from the tree.
            """
            self.invisibleRootItem().takeChildren()

        def focusNext(self, item, forward=True):
            """Give input focus to the next (or previous) item after *item*
            """
            while True:
                parent = item.parent()
                if parent is None:
                    return
                nextItem = self.nextFocusableChild(parent, item, forward=forward)
                if nextItem is not None:
                    nextItem.setFocus()
                    self.setCurrentItem(nextItem)
                    return
                item = parent

        def focusPrevious(self, item):
            self.focusNext(item, forward=False)

        def nextFocusableChild(self, root, startItem=None, forward=True):
            if startItem is None:
                if forward:
                    index = 0
                else:
                    index = root.childCount()-1
            else:
                if forward:
                    index = root.indexOfChild(startItem) + 1
                else:
                    index = root.indexOfChild(startItem) - 1

            if forward:
                inds = list(range(index, root.childCount()))
            else:
                inds = list(range(index, -1, -1))

            for i in inds:
                item = root.child(i)
                if hasattr(item, 'isFocusable') and item.isFocusable():
                    return item
                else:
                    item = self.nextFocusableChild(item, forward=forward)
                    if item is not None:
                        return item
            return None

        def contextMenuEvent(self, ev):
            item = self.currentItem()
            if hasattr(item, 'contextMenuEvent'):
                item.contextMenuEvent(ev)

        def itemChangedEvent(self, item, col):
            if hasattr(item, 'columnChangedEvent'):
                item.columnChangedEvent(col)

        def selectionChanged(self, *args):
            sel = self.selectedItems()
            if len(sel) != 1:
                sel = None
            if self.lastSel is not None and isinstance(self.lastSel, ParameterItem):
                self.lastSel.selected(False)
            if sel is None:
                self.lastSel = None
                return
            self.lastSel = sel[0]
            if hasattr(sel[0], 'selected'):
                sel[0].selected(True)
            return TreeWidget.selectionChanged(self, *args)

        def wheelEvent(self, ev):
            self.clearSelection()
            return TreeWidget.wheelEvent(self, ev)