Painting lines

[jacek]

foreach (ShapeItem shapeItem, shapeItems) 
{
   //...
}

foreach (ShapeItem shapeItem, shapeItems) 
{
   //...
}

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What are these ShapeItems?

for(int j=0;j<looplength;j++)
    	/*{
			if(list.nodeID[j]>0 && list.nodeID[j]<100)
			{
	   	painter.drawLine( list.position[list.nodeID[j]]+offset, list.position[list.nodeID[j+1]]+offset );
	   	}
 
 
	  }*/
 
	   painter.drawLine( list.position[n1]+offset, list.position[n2]+offset );
		painter.drawText(QRect(midpoint,textbox),0,tr("%1").arg(topology[n1][n2]));
 
    }

for(int j=0;j<looplength;j++)
    	/*{
			if(list.nodeID[j]>0 && list.nodeID[j]<100)
			{
	   	painter.drawLine( list.position[list.nodeID[j]]+offset, list.position[list.nodeID[j+1]]+offset );
	   	}
		
		
	  }*/
	 
	   painter.drawLine( list.position[n1]+offset, list.position[n2]+offset );
		painter.drawText(QRect(midpoint,textbox),0,tr("%1").arg(topology[n1][n2]));
	 
    }

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Where do you change n1 and n2?

Your paintEvent() should be something like this:

for each edge in Edges:
   draw line from edge.startNode.point to edge.endNode.point
   draw text edge.label at midPoint( edge.startNode.point, edge.endNode.point )

for each edge in Edges:
   draw line from edge.startNode.point to edge.endNode.point
   draw text edge.label at midPoint( edge.startNode.point, edge.endNode.point )

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[therealjag]

Quote:
Qt Code:
foreach (ShapeItem shapeItem, shapeItems) { //...}

What are these ShapeItems?

the shapeItems are just my nodes that i have created. they arent linked in any programmable way like in a linked list or anything they have just been created individually.
n1 and n2 get changed when the user enters their value so the first user input gets set to n1 and the second user input gets set to n2. the capacity for the link then gets asked for after that.

[jacek]

n1 and n2 get changed when the user enters their value so the first user input gets set to n1 and the second user input gets set to n2. the capacity for the link then gets asked for after that.

So in fact your paintEvent() draws only one edge?

[therealjag]

yeah it only draws 1 edge at a time but is there a way to keep the older ones drawn on the screen?

[jacek]

yeah it only draws 1 edge at a time but is there a way to keep the older ones drawn on the screen?

You can't, you must draw all of them every time paintEvent() is invoked. The only thing you could do is to paint them on a pixmap and then paint that pixmap in paintEvent().

[therealjag]

how would i generate a pixmap for my code?

[jacek]

Just create it and paint on it using QPainter, but IMO it would be easier just to paint all edges every time (unless you have a really big graph). You can try Qanava

[therealjag]

i looked at Qavana but it seems to be unavailable for windows. i guess theres no other way of doing it is there?

[therealjag]

how would i paint all edges everytime? would i haveto ask the user for all inputs each time?

[jacek]

how would i paint all edges everytime? would i haveto ask the user for all inputs each time?

No, just ask once and save the data in proper data structure.

[therealjag]

ru talking about an array or an array of structs of some sort? i was thinking about using linked lists but im not very sure about using them in qt...

[jacek]

ru talking about an array or an array of structs of some sort? i was thinking about using linked lists but im not very sure about using them in qt...

There are many options. You can keep a list of nodes and each node can contain a list of edges. You can also keep a list of nodes and a list of edges.

First think what data you need to store and how would you like to access it, then choose a data structure that fits the best.

[jacek]

i looked at Qavana but it seems to be unavailable for windows.

Then why all screenshots were taken on windows?

i guess theres no other way of doing it is there?

If you can draw one line, then just add a loop and you're done.