Hello. I'm back on this list after quite some time. I'm working on some stuff involving bezier curves and wanted to write my own bezier display applet to keep in handy, so that I can adjust the nodes and handles and it would show me real-time what the resultant curve looks like.
However even a minimal Bezier drawing (bezierview-0) throws errors on my main 64 bit system with PyQt 4.9.1 with Qt 4.8.1 on Kubuntu Precise. So I tested on a 32 bit Kubuntu Oneiric (older) VM installation I have which has PyQt 4.8.5 and Qt 4.7.4 and it worked OK enough. But once I got around to programming the important points (i.e. tweaking the points, see bezierview-1) it once more segfaulted even on that older system and I'm back to square one. Help please! (FWIW the code is GPLed.) The minimal stuff if written in C++ doesn't segfault on my latest Qt 4.8.1. (I was hoping to do everything in PyQt so I only wrote the minimal thing in C++ so far.) Thanks! -- Shriramana Sharma
#! /usr/bin/env python from PyQt4 . QtCore import * from PyQt4 . QtGui import * class BezierWidget ( QWidget ) : def __init__ ( self, parent = None ) : super ( BezierWidget, self ) . __init__ ( parent ) self . setFixedSize ( 400, 400 ) self . p1 = QPointF ( 100, 150 ) self . c1 = QPointF ( 166, 250 ) self . c2 = QPointF ( 234, 250 ) self . p2 = QPointF ( 300, 150 ) def paintEvent ( self, event ) : self . painter = QPainter ( self ) self . painter . setRenderHint ( QPainter . Antialiasing ) self . painter . translate ( 0, 400 ) self . painter . scale ( 1, -1 ) self . bezier = QPainterPath () self . bezier . moveTo ( self . p1 ) self . bezier . cubicTo ( self . c1, self . c2, self . p2 ) self . painter . strokePath ( self . bezier, self . painter . pen () ) app = QApplication ( [] ) bezierWidget = BezierWidget () bezierWidget . show () app . exec_ ()
#! /usr/bin/env python from PyQt4 . QtCore import * from PyQt4 . QtGui import * class BezierWidget ( QWidget ) : def __init__ ( self, parent = None ) : super ( BezierWidget, self ) . __init__ ( parent ) self . setFixedSize ( 400, 400 ) self . p1 = QPointF ( 100, 150 ) self . c1 = QPointF ( 166, 250 ) self . c2 = QPointF ( 234, 250 ) self . p2 = QPointF ( 300, 150 ) self . tweaking = False def paintEvent ( self, event ) : self . painter = QPainter ( self ) self . painter . setRenderHint ( QPainter . Antialiasing ) self . painter . translate ( 0, 400 ) self . painter . scale ( 1, -1 ) self . palette = QApplication . palette () self . bezierPen = QPen ( self . palette . text (), 1 ) self . handlePen = QPen ( self . palette . highlight (), 2, Qt . DashLine ) self . bezier = QPainterPath () self . bezier . moveTo ( self . p1 ) self . bezier . cubicTo ( self . c1, self . c2, self . p2 ) self . painter . strokePath ( self . bezier, self . bezierPen ) self . diamond = QPainterPath () self . diamond . moveTo ( 2, 0 ) self . diamond . lineTo ( 0, 2 ) self . diamond . lineTo ( -2, 0 ) self . diamond . lineTo ( 0, -2 ) self . diamond . closeSubpath () self . handle1 = QPainterPath () self . handle1 . moveTo ( self . p1 ) self . handle1 . lineTo ( self . c1 ) self . painter . strokePath ( self . handle1, self . handlePen ) self . handle2 = QPainterPath () self . handle2 . moveTo ( self . p2 ) self . handle2 . lineTo ( self . c2 ) self . painter . strokePath ( self . handle2, self . handlePen ) for x in ( self . p1, self . c1, self . c2, self . p2 ) : self . painter . save () self . painter . translate ( x ) self . painter . scale ( 2, 2 ) self . painter . fillPath ( self . diamond, self . palette . highlightedText () ) self . painter . restore () def mousePressEvent ( self, event ) : pt = event . posF () pt . setY ( 400 - pt . y () ) print ( pt ) offset = 5 hotspot = QRectF ( - offset, - offset, offset * 2, offset * 2 ) for x in ( self . p1, self . c1, self . c2, self . p2 ) : print ( hotspot . translated ( x ) ) if hotspot . translated ( x ) . contains ( pt ) : print ( hotspot . translated ( x ), "contains", x ) self . tweaking = True if x is self . p1 : self . tweakedPoint = "p1" elif x is self . c1 : self . tweakedPoint = "c1" elif x is self . c2 : self . tweakedPoint = "c2" elif x is self . p2 : self . tweakedPoint = "p2" return def mouseMoveEvent ( self, event ) : if self . tweaking : pt = event . posF () pt . setY ( 400 - pt . y () ) print ( "moving " + self . tweakedPoint + " to", pt ) if self . tweakedPoint == "p1" : self . p1 = pt elif self . tweakedPoint == "c1" : self . c1 = pt elif self . tweakedPoint == "c2" : self . c2 = pt elif self . tweakedPoint == "p2" : self . p2 = pt self . update () def mouseReleaseEvent ( self, event ) : self . tweaking = False #class MainWindow ( QtGui . QWidget ) : #def __init__ ( self ) : #QWidget . __init__ ( self ) #self . bezierWidget = BezierWidget () app = QApplication ( [] ) bezierWidget = BezierWidget () bezierWidget . show () app . exec_ ()
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