Question

How do I render glyphs in pyqt using the svggraphicsItem?

Answer 1

Recently I found that svg files generated by Cairo do not plot properly in pyqt. The error comes from the use of glyphs which seem not to be shown in pyqt (this might be wrong but I couldn’t find any way of getting glyphs to render).

I ended up writing a set of functions that will convert the glyphs to svg paths so the file will render normally.

These could still use some improvements for rendering color and other style elements (which are locked in the functions that I wrote).

These functions will need to be embedded in a class or have self removed to be used elsewhere.

I just wanted people to have these so they wouldn’t have to search high and low like I did to find a way to render glyphs in pyqt.

Hope for the best,
Kyle

def convertSVG(self, file): 
    dom = self._getsvgdom(file) 
    print dom 
    self._switchGlyphsForPaths(dom) 
    self._commitSVG(file, dom) 
def _commitSVG(self, file, dom): 
    f = open(file, 'w') 
    dom.writexml(f) 
    f.close() 
def _getsvgdom(self, file): 
    print 'getting DOM model' 
    import xml.dom 
    import xml.dom.minidom as mini 
    f = open(file, 'r') 
    svg = f.read() 
    f.close() 
    dom = mini.parseString(svg) 
    return dom 
def _getGlyphPaths(self, dom): 
    symbols = dom.getElementsByTagName('symbol') 
    glyphPaths = {} 
    for s in symbols: 
        pathNode = [p for p in s.childNodes if 'tagName' in dir(p) and p.tagName == 'path'] 
        glyphPaths[s.getAttribute('id')] = pathNode[0].getAttribute('d') 
    return glyphPaths 
def _switchGlyphsForPaths(self, dom): 
    glyphs = self._getGlyphPaths(dom) 
    use = self._getUseTags(dom) 
    for glyph in glyphs.keys(): 
        print glyph 
        nl = self.makeNewList(glyphs[glyph].split(' ')) 
        u = self._matchUseGlyphs(use, glyph) 
        for u2 in u: 
            print u2, 'brefore' 
            self._convertUseToPath(u2, nl) 
            print u2, 'after' 

def _getUseTags(self, dom): 
    return dom.getElementsByTagName('use') 
def _matchUseGlyphs(self, use, glyph): 
    matches = [] 
    for i in use: 
        print i.getAttribute('xlink:href') 
        if i.getAttribute('xlink:href') == '#'+glyph: 
            matches.append(i) 
    print matches 
    return matches 
def _convertUseToPath(self, use, strokeD): 
    ## strokeD is a list of lists of strokes to make the glyph 
    newD = self.nltostring(self.resetStrokeD(strokeD, use.getAttribute('x'), use.getAttribute('y'))) 
    use.tagName = 'path' 
    use.removeAttribute('xlink:href') 
    use.removeAttribute('x') 
    use.removeAttribute('y') 
    use.setAttribute('style', 'fill: rgb(0%,0%,0%); stroke-width: 0.5; stroke-linecap: round; stroke-linejoin: round; stroke: rgb(0%,0%,0%); stroke-opacity: 1;stroke-miterlimit: 10; ') 
    use.setAttribute('d', newD) 
def makeNewList(self, inList): 
    i = 0 
    nt = [] 
    while i < len(inList): 
        start = i + self.listFind(inList[i:], ['M', 'L', 'C', 'Z']) 
        end = start + self.listFind(inList[start+1:], ['M', 'L', 'C', 'Z', '', ' ']) 
        nt.append(inList[start:end+1]) 
        i = end + 1 
    return nt 
def listFind(self, x, query): 
    for i in range(len(x)): 
        if x[i] in query: 
            return i 
    return len(x) 
def resetStrokeD(self, strokeD, x, y): 
    nsd = [] 
    for i in strokeD: 
        nsd.append(self.resetXY(i, x, y)) 
    return nsd 
def resetXY(self, nl, x, y): # convert a list of strokes to xy coords 
    nl2 = [] 
    for i in range(len(nl)): 
        if i == 0: 
            nl2.append(nl[i]) 
        elif i%2: # it's odd 
            nl2.append(float(nl[i]) + float(x)) 
        elif not i%2: # it's even 
            nl2.append(float(nl[i]) + float(y)) 
        else: 
            print i, nl[i], 'error' 
    return nl2 
def nltostring(self, nl): # convert a colection of nl's to a string 
    col = [] 
    for l in nl: 
        templ = [] 
        for c in l: 
            templ.append(str(c)) 
        templ = ' '.join(templ) 
        col.append(templ) 
    return ' '.join(col)