GraphItem.py

from .. import functions as fn
from .GraphicsObject import GraphicsObject
from .ScatterPlotItem import ScatterPlotItem
from ..Qt import QtGui, QtCore
import numpy as np
from .. import getConfigOption

__all__ = ['GraphItem']


class GraphItem(GraphicsObject):
    """A GraphItem displays graph information as
    a set of nodes connected by lines (as in 'graph theory', not 'graphics'). 
    Useful for drawing networks, trees, etc.
    """

    def __init__(self, **kwds):
        GraphicsObject.__init__(self)
        self.scatter = ScatterPlotItem()
        self.scatter.setParentItem(self)
        self.adjacency = None
        self.pos = None
        self.picture = None
        self.pen = 'default'
        self.setData(**kwds)
        
    def setData(self, **kwds):
        """
        Change the data displayed by the graph. 
        
        ============ =========================================================
        Arguments
        pos          (N,2) array of the positions of each node in the graph.
        adj          (M,2) array of connection data. Each row contains indexes 
                     of two nodes that are connected.
        pen          The pen to use when drawing lines between connected 
                     nodes. May be one of: 
                     
                     * QPen
                     * a single argument to pass to pg.mkPen
                     * a record array of length M
                       with fields (red, green, blue, alpha, width). Note
                       that using this option may have a significant performance
                       cost.
                     * None (to disable connection drawing)
                     * 'default' to use the default foreground color.
                     
        symbolPen    The pen used for drawing nodes.
        ``**opts``   All other keyword arguments are given to 
                     :func:`ScatterPlotItem.setData() <pyqtgraph.ScatterPlotItem.setData>`
                     to affect the appearance of nodes (symbol, size, brush, 
                     etc.)
        ============ =========================================================
        """
        if 'adj' in kwds:
            self.adjacency = kwds.pop('adj')
            assert self.adjacency.dtype.kind in 'iu'
            self.picture = None
        if 'pos' in kwds:
            self.pos = kwds['pos']
            self.picture = None
        if 'pen' in kwds:
            self.setPen(kwds.pop('pen'))
            self.picture = None
        if 'symbolPen' in kwds:    
            kwds['pen'] = kwds.pop('symbolPen')
        self.scatter.setData(**kwds)
        self.informViewBoundsChanged()

    def setPen(self, pen):
        self.pen = pen
        self.picture = None

    def generatePicture(self):
        self.picture = QtGui.QPicture()
        if self.pen is None or self.pos is None or self.adjacency is None:
            return
        
        p = QtGui.QPainter(self.picture)
        try:
            pts = self.pos[self.adjacency]
            pen = self.pen
            if isinstance(pen, np.ndarray):
                lastPen = None
                for i in range(pts.shape[0]):
                    pen = self.pen[i]
                    if np.any(pen != lastPen):
                        lastPen = pen
                        if pen.dtype.fields is None:
                            p.setPen(fn.mkPen(color=(pen[0], pen[1], pen[2], pen[3]), width=1))                            
                        else:
                            p.setPen(fn.mkPen(color=(pen['red'], pen['green'], pen['blue'], pen['alpha']), width=pen['width']))
                    p.drawLine(QtCore.QPointF(*pts[i][0]), QtCore.QPointF(*pts[i][1]))
            else:
                if pen == 'default':
                    pen = getConfigOption('foreground')
                p.setPen(fn.mkPen(pen))
                pts = pts.reshape((pts.shape[0]*pts.shape[1], pts.shape[2]))
                path = fn.arrayToQPath(x=pts[:,0], y=pts[:,1], connect='pairs')
                p.drawPath(path)
        finally:
            p.end()

    def paint(self, p, *args):
        if self.picture == None:
            self.generatePicture()
        if getConfigOption('antialias') is True:
            p.setRenderHint(p.Antialiasing)
        self.picture.play(p)
        
    def boundingRect(self):
        return self.scatter.boundingRect()
        
    def dataBounds(self, *args, **kwds):
        return self.scatter.dataBounds(*args, **kwds)
    
    def pixelPadding(self):
        return self.scatter.pixelPadding()