pyqtgraph/pyqtgraph/exporters/SVGExporter.py

from .Exporter import Exporter
from pyqtgraph.parametertree import Parameter
from pyqtgraph.Qt import QtGui, QtCore, QtSvg
import pyqtgraph as pg
import re
import xml.dom.minidom as xml
import numpy as np


__all__ = ['SVGExporter']

class SVGExporter(Exporter):
    Name = "Scalable Vector Graphics (SVG)"
    def __init__(self, item):
        Exporter.__init__(self, item)
        #tr = self.getTargetRect()
        self.params = Parameter(name='params', type='group', children=[
            #{'name': 'width', 'type': 'float', 'value': tr.width(), 'limits': (0, None)},
            #{'name': 'height', 'type': 'float', 'value': tr.height(), 'limits': (0, None)},
        ])
        #self.params.param('width').sigValueChanged.connect(self.widthChanged)
        #self.params.param('height').sigValueChanged.connect(self.heightChanged)

    def widthChanged(self):
        sr = self.getSourceRect()
        ar = sr.height() / sr.width()
        self.params.param('height').setValue(self.params['width'] * ar, blockSignal=self.heightChanged)
        
    def heightChanged(self):
        sr = self.getSourceRect()
        ar = sr.width() / sr.height()
        self.params.param('width').setValue(self.params['height'] * ar, blockSignal=self.widthChanged)
        
    def parameters(self):
        return self.params
    
    def export(self, fileName=None, toBytes=False):
        if toBytes is False and fileName is None:
            self.fileSaveDialog(filter="Scalable Vector Graphics (*.svg)")
            return
        #self.svg = QtSvg.QSvgGenerator()
        #self.svg.setFileName(fileName)
        #dpi = QtGui.QDesktopWidget().physicalDpiX()
        ### not really sure why this works, but it seems to be important:
        #self.svg.setSize(QtCore.QSize(self.params['width']*dpi/90., self.params['height']*dpi/90.))
        #self.svg.setResolution(dpi)
        ##self.svg.setViewBox()
        #targetRect = QtCore.QRect(0, 0, self.params['width'], self.params['height'])
        #sourceRect = self.getSourceRect()
        
        #painter = QtGui.QPainter(self.svg)
        #try:
            #self.setExportMode(True)
            #self.render(painter, QtCore.QRectF(targetRect), sourceRect)
        #finally:
            #self.setExportMode(False)
        #painter.end()

        ## Workaround to set pen widths correctly
        #data = open(fileName).readlines()
        #for i in range(len(data)):
            #line = data[i]
            #m = re.match(r'(<g .*)stroke-width="1"(.*transform="matrix\(([^\)]+)\)".*)', line)
            #if m is not None:
                ##print "Matched group:", line
                #g = m.groups()
                #matrix = list(map(float, g[2].split(',')))
                ##print "matrix:", matrix
                #scale = max(abs(matrix[0]), abs(matrix[3]))
                #if scale == 0 or scale == 1.0:
                    #continue
                #data[i] = g[0] + ' stroke-width="%0.2g" ' % (1.0/scale) + g[1] + '\n'
                ##print "old line:", line
                ##print "new line:", data[i]
        #open(fileName, 'w').write(''.join(data))
        
        ## Qt's SVG generator is not complete. (notably, it lacks clipping)
        ## Instead, we will use Qt to generate SVG for each item independently,
        ## then manually reconstruct the entire document.
        xml = generateSvg(self.item)
        
        if toBytes:
            return bytes(xml)
        else:
            with open(fileName, 'w') as fh:
                fh.write(xml)

xmlHeader = """\
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"  version="1.2" baseProfile="tiny">
<title>pyqtgraph SVG export</title>
<desc>Generated with Qt and pyqtgraph</desc>
<defs>
</defs>
"""

def generateSvg(item):
    global xmlHeader
    try:
        node = _generateItemSvg(item)
    finally:
        ## reset export mode for all items in the tree
        if isinstance(item, QtGui.QGraphicsScene):
            items = item.items()
        else:
            items = [item]
            for i in items:
                items.extend(i.childItems())
        for i in items:
            if hasattr(i, 'setExportMode'):
                i.setExportMode(False)
    
    cleanXml(node)
    
    return xmlHeader + node.toprettyxml(indent='    ') + "\n</svg>\n"


def _generateItemSvg(item, nodes=None, root=None):
    ## This function is intended to work around some issues with Qt's SVG generator
    ## and SVG in general.
    ## 1) Qt SVG does not implement clipping paths. This is absurd.
    ##    The solution is to let Qt generate SVG for each item independently,
    ##    then glue them together manually with clipping.
    ##    
    ##    The format Qt generates for all items looks like this:
    ##    
    ##    <g>
    ##        <g transform="matrix(...)">
    ##            one or more of: <path/> or <polyline/> or <text/>
    ##        </g>
    ##        <g transform="matrix(...)">
    ##            one or more of: <path/> or <polyline/> or <text/>
    ##        </g>
    ##        . . .
    ##    </g>
    ##    
    ## 2) There seems to be wide disagreement over whether path strokes
    ##    should be scaled anisotropically. 
    ##      see: http://web.mit.edu/jonas/www/anisotropy/
    ##    Given that both inkscape and illustrator seem to prefer isotropic
    ##    scaling, we will optimize for those cases.  
    ##    
    ## 3) Qt generates paths using non-scaling-stroke from SVG 1.2, but 
    ##    inkscape only supports 1.1. 
    ##    
    ##    Both 2 and 3 can be addressed by drawing all items in world coordinates.
    
    
    
    if nodes is None:  ## nodes maps all node IDs to their XML element. 
                       ## this allows us to ensure all elements receive unique names.
        nodes = {}
        
    if root is None:
        root = item
                
    ## Skip hidden items
    if hasattr(item, 'isVisible') and not item.isVisible():
        return None
        
    ## If this item defines its own SVG generator, use that.
    if hasattr(item, 'generateSvg'):
        return item.generateSvg(nodes)
    

    ## Generate SVG text for just this item (exclude its children; we'll handle them later)
    tr = QtGui.QTransform()
    if isinstance(item, QtGui.QGraphicsScene):
        xmlStr = "<g>\n</g>\n"
        childs = [i for i in item.items() if i.parentItem() is None]
        doc = xml.parseString(xmlStr)
    else:
        childs = item.childItems()
        tr = itemTransform(item, root)
        
        #print item, pg.SRTTransform(tr)

        #tr.translate(item.pos().x(), item.pos().y())
        #tr = tr * item.transform()
        arr = QtCore.QByteArray()
        buf = QtCore.QBuffer(arr)
        svg = QtSvg.QSvgGenerator()
        svg.setOutputDevice(buf)
        dpi = QtGui.QDesktopWidget().physicalDpiX()
        ### not really sure why this works, but it seems to be important:
        #self.svg.setSize(QtCore.QSize(self.params['width']*dpi/90., self.params['height']*dpi/90.))
        svg.setResolution(dpi)

        p = QtGui.QPainter()
        p.begin(svg)
        if hasattr(item, 'setExportMode'):
            item.setExportMode(True, {'painter': p})
        try:
            p.setTransform(tr)
            item.paint(p, QtGui.QStyleOptionGraphicsItem(), None)
        finally:
            p.end()
            ## Can't do this here--we need to wait until all children have painted as well.
            ## this is taken care of in generateSvg instead.
            #if hasattr(item, 'setExportMode'):
                #item.setExportMode(False)
            
        xmlStr = str(arr)
        doc = xml.parseString(xmlStr)
        
    try:
        ## Get top-level group for this item
        g1 = doc.getElementsByTagName('g')[0]
        ## get list of sub-groups
        g2 = [n for n in g1.childNodes if isinstance(n, xml.Element) and n.tagName == 'g']
    except:
        print doc.toxml()
        raise


    ## Get rid of group transformation matrices by applying
    ## transformation to inner coordinates
    correctCoordinates(g1, item)
    
    ## make sure g1 has the transformation matrix
    #m = (tr.m11(), tr.m12(), tr.m21(), tr.m22(), tr.m31(), tr.m32())
    #g1.setAttribute('transform', "matrix(%f,%f,%f,%f,%f,%f)" % m)
    
    #print "=================",item,"====================="
    #print g1.toprettyxml(indent="  ", newl='')
    
    ## Inkscape does not support non-scaling-stroke (this is SVG 1.2, inkscape supports 1.1)
    ## So we need to correct anything attempting to use this.
    #correctStroke(g1, item, root)
    
    ## decide on a name for this item
    baseName = item.__class__.__name__
    i = 1
    while True:
        name = baseName + "_%d" % i
        if name not in nodes:
            break
        i += 1
    nodes[name] = g1
    g1.setAttribute('id', name)
    
    ## If this item clips its children, we need to take car of that.
    childGroup = g1  ## add children directly to this node unless we are clipping
    if not isinstance(item, QtGui.QGraphicsScene):
        ## See if this item clips its children
        if int(item.flags() & item.ItemClipsChildrenToShape) > 0:
            ## Generate svg for just the path
            if isinstance(root, QtGui.QGraphicsScene):
                path = QtGui.QGraphicsPathItem(item.mapToScene(item.shape()))
            else:
                path = QtGui.QGraphicsPathItem(root.mapToParent(item.mapToItem(root, item.shape())))
            pathNode = _generateItemSvg(path, root=root).getElementsByTagName('path')[0]
            ## and for the clipPath element
            clip = name + '_clip'
            clipNode = g1.ownerDocument.createElement('clipPath')
            clipNode.setAttribute('id', clip)
            clipNode.appendChild(pathNode)
            g1.appendChild(clipNode)
            
            childGroup = g1.ownerDocument.createElement('g')
            childGroup.setAttribute('clip-path', 'url(#%s)' % clip)
            g1.appendChild(childGroup)
    ## Add all child items as sub-elements.
    childs.sort(key=lambda c: c.zValue())
    for ch in childs:
        cg = _generateItemSvg(ch, nodes, root)
        if cg is None:
            continue
        childGroup.appendChild(cg)  ### this isn't quite right--some items draw below their parent (good enough for now)
    
    return g1

def correctCoordinates(node, item):
    ## Remove transformation matrices from <g> tags by applying matrix to coordinates inside.
    groups = node.getElementsByTagName('g')
    for grp in groups:
        matrix = grp.getAttribute('transform')
        match = re.match(r'matrix\((.*)\)', matrix)
        if match is None:
            vals = [1,0,0,1,0,0]
        else:
            vals = map(float, match.groups()[0].split(','))
        tr = np.array([[vals[0], vals[2], vals[4]], [vals[1], vals[3], vals[5]]])
        
        removeTransform = False
        for ch in grp.childNodes:
            if not isinstance(ch, xml.Element):
                continue
            if ch.tagName == 'polyline':
                removeTransform = True
                coords = np.array([map(float, c.split(',')) for c in ch.getAttribute('points').strip().split(' ')])
                coords = pg.transformCoordinates(tr, coords, transpose=True)
                ch.setAttribute('points', ' '.join([','.join(map(str, c)) for c in coords]))
            elif ch.tagName == 'path':
                removeTransform = True
                newCoords = ''
                for c in ch.getAttribute('d').strip().split(' '):
                    x,y = c.split(',')
                    if x[0].isalpha():
                        t = x[0]
                        x = x[1:]
                    else:
                        t = ''
                    nc = pg.transformCoordinates(tr, np.array([[float(x),float(y)]]), transpose=True)
                    newCoords += t+str(nc[0,0])+','+str(nc[0,1])+' '
                ch.setAttribute('d', newCoords)
            elif ch.tagName == 'text':
                removeTransform = False
                ## leave text alone for now. Might need this later to correctly render text with outline.
                #c = np.array([
                    #[float(ch.getAttribute('x')), float(ch.getAttribute('y'))], 
                    #[float(ch.getAttribute('font-size')), 0], 
                    #[0,0]])
                #c = pg.transformCoordinates(tr, c, transpose=True)
                #ch.setAttribute('x', str(c[0,0]))
                #ch.setAttribute('y', str(c[0,1]))
                #fs = c[1]-c[2]
                #fs = (fs**2).sum()**0.5
                #ch.setAttribute('font-size', str(fs))
            else:
                print('warning: export not implemented for SVG tag %s (from item %s)' % (ch.tagName, item))
                
            ## correct line widths if needed
            if removeTransform and ch.getAttribute('vector-effect') != 'non-scaling-stroke':
                w = float(grp.getAttribute('stroke-width'))
                s = pg.transformCoordinates(tr, np.array([[w,0], [0,0]]), transpose=True)
                w = ((s[0]-s[1])**2).sum()**0.5
                ch.setAttribute('stroke-width', str(w))
            
        if removeTransform:
            grp.removeAttribute('transform')
        

def itemTransform(item, root):
    ## Return the transformation mapping item to root
    ## (actually to parent coordinate system of root)
    
    if item is root:
        tr = QtGui.QTransform()
        tr.translate(*item.pos())
        tr = tr * item.transform()
        return tr
        
    
    if int(item.flags() & item.ItemIgnoresTransformations) > 0:
        pos = item.pos()
        parent = item.parentItem()
        if parent is not None:
            pos = itemTransform(parent, root).map(pos)
        tr = QtGui.QTransform()
        tr.translate(pos.x(), pos.y())
        tr = item.transform() * tr
    else:
        ## find next parent that is either the root item or 
        ## an item that ignores its transformation
        nextRoot = item
        while True:
            nextRoot = nextRoot.parentItem()
            if nextRoot is None:
                nextRoot = root
                break
            if nextRoot is root or int(nextRoot.flags() & nextRoot.ItemIgnoresTransformations) > 0:
                break
        
        if isinstance(nextRoot, QtGui.QGraphicsScene):
            tr = item.sceneTransform()
        else:
            tr = itemTransform(nextRoot, root) * item.itemTransform(nextRoot)[0]
            #pos = QtGui.QTransform()
            #pos.translate(root.pos().x(), root.pos().y())
            #tr = pos * root.transform() * item.itemTransform(root)[0]
        
    
    return tr


#def correctStroke(node, item, root, width=1):
    ##print "==============", item, node
    #if node.hasAttribute('stroke-width'):
        #width = float(node.getAttribute('stroke-width'))
    #if node.getAttribute('vector-effect') == 'non-scaling-stroke':
        #node.removeAttribute('vector-effect')
        #if isinstance(root, QtGui.QGraphicsScene):
            #w = item.mapFromScene(pg.Point(width,0))
            #o = item.mapFromScene(pg.Point(0,0))
        #else:
            #w = item.mapFromItem(root, pg.Point(width,0))
            #o = item.mapFromItem(root, pg.Point(0,0))
        #w = w-o
        ##print "   ", w, o, w-o
        #w = (w.x()**2 + w.y()**2) ** 0.5
        ##print "   ", w
        #node.setAttribute('stroke-width', str(w))
    
    #for ch in node.childNodes:
        #if isinstance(ch, xml.Element):
            #correctStroke(ch, item, root, width)
            
def cleanXml(node):
    ## remove extraneous text; let the xml library do the formatting.
    hasElement = False
    nonElement = []
    for ch in node.childNodes:
        if isinstance(ch, xml.Element):
            hasElement = True
            cleanXml(ch)
        else:
            nonElement.append(ch)
    
    if hasElement:
        for ch in nonElement:
            node.removeChild(ch)
    elif node.tagName == 'g':  ## remove childless groups
        node.parentNode.removeChild(node)