Drawing shapes using GraphicsView, GraphicsScene and GraphicsItem(s)

[HelderC]

Hi.

If I want to create a kind of "Ms Paint" using GraphicsView, GraphicsScene and Items, which class I have to reimplement to get mousepress and mousemove events? GraphicsView or Scene?

I tried to use Scene, but even with it in 600x500 WidthxHeight ever place that I click the coordinates are the same 0,0 and the follow code dont draw any thing, in this case, a line.

from PyQt4.QtGui import *
from PyQt4.QtCore import *
 
class GraphicsScene(QGraphicsScene):
    def __init__(self, parent = None):
        super(GraphicsScene, self).__init__(parent)
 
        self.setSceneRect(0, 0, 600, 500)
        self.setBackgroundBrush(QColor(242, 251, 235))
 
 
    def mousePressEvent(self, e):
        self.pointBegin = self.pointEnd = e.pos()
 
        self.line = QGraphicsLineItem(QLineF(self.pointBegin, self.pointEnd))
        self.line.setFlags(QGraphicsItem.ItemIsMovable)
 
        self.addItem(self.line)
 
    def mouseMoveEvent(self, e):
        self.pointEnd = e.pos()
 
        self.line.setLine(QLineF(self.pointBegin, self.pointEnd))
 
 
    def mouseReleaseEvent(self, e):
        self.line.setLine(QLineF(self.pointBegin, self.pointEnd))

from PyQt4.QtGui import *
from PyQt4.QtCore import *

class GraphicsScene(QGraphicsScene):
    def __init__(self, parent = None):
        super(GraphicsScene, self).__init__(parent)
        
        self.setSceneRect(0, 0, 600, 500)
        self.setBackgroundBrush(QColor(242, 251, 235))
        
    
    def mousePressEvent(self, e):
        self.pointBegin = self.pointEnd = e.pos()
        
        self.line = QGraphicsLineItem(QLineF(self.pointBegin, self.pointEnd))
        self.line.setFlags(QGraphicsItem.ItemIsMovable)
        
        self.addItem(self.line)
        
    def mouseMoveEvent(self, e):
        self.pointEnd = e.pos()
        
        self.line.setLine(QLineF(self.pointBegin, self.pointEnd))
        
        
    def mouseReleaseEvent(self, e):
        self.line.setLine(QLineF(self.pointBegin, self.pointEnd))

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[norobro]

Have you looked in the docs?

[HelderC]

Yes, I did. The "e" param at mouseXEvent is all of that type.

My question is: "...which class I have to reimplement to get mousepress and mousemove events?"

Thank you anyway.

[norobro]

My answer is, as described in the docs: change e.pos() to e.scenePos()

And you're welcome.

[HelderC]

Sorry man, but I'm a little confuse.

You want to say I have to reimplement the GraphicsView, instead GraphicsScene and use e.scenePos() instead e.pos() ??

Is that correct?

[wysota]

My question is: "...which class I have to reimplement to get mousepress and mousemove events?"

It can be either QGraphicsView, QGraphicsScene or one of QGraphicsItem subclasses, depending on what you want to do with the event.

You are getting 0 because calling pos() doesn't make sense in context of the scene. use scenePos() as already advised.

[HelderC]

Ah, ok... finally I think I got it.

Thank you guys.