Position in a QPixMap created from a QGraphicsScene

[wysota]

Thanks for the reply. I don't think that you did understand my requirement correctly. I already have the two scene stuff working quite well, and it is exactly what I need.

I'm not sure of that. I'd go for a single scene as well.

The intent of the smaller scene is just to be a way to edit the QPixMap on the QGraphicsPixMapItem on the larger scene.

According to me the "pixmap" should never have been a pixmap. It should be a composition of items, espcially if you want to treat it as something composed from items.

A pixmap is a bitmap, it's composed from pixels not from objects. If your picture is to be a composition of objects then treat it as so.

[stevel]

No, you guys are not seeing the bigger picture. The way I am doing this makes sense, and really fits my project. Does anyone have a suggestion about my question?

I will try again to explain what I am doing, which as I said, is working well, and doing exactly what I want.

On the main QGraphicsScene, there are many types of Items. One of them is something called a block, which has an icon. The icon is represented by a QGraphicsPixMap. When you double click on a block, you can open up a window which allows you to edit it's icon. This window is also a QGraphicsScene. I cannot, and do not want to represent this as anything other then a QGraphicsPixMapItem, as there can potentially be thousands of blocks on the main window.

For the most part, I don't care about the details of the Scene that was used to build the block, however, there are a couple of items on that scene that I do care about, and I need to save information about where those items are on the QPixMap when it is created. All I want to know is how to get the location (pos) of those items in the coordinates of the QPixMap, not the coordinates of the scene that made the QPixMap. Here is my latest try, which is not working yet.

This code is in the GrapphicsItem whose position I care about, and I am trying to create a position point that is offset by the location of the created QPixMap, but I don't have the logic right obviously.

QPointF   point1, point2;
 
	// JSL - Calculate the location of the position of the item on the icon
	point1 = mapToScene(pos());
	point2 = scene()->itemsBoundingRect().center();
	drawData.iconPos = point2 - point1;

QPointF   point1, point2;

	// JSL - Calculate the location of the position of the item on the icon
	point1 = mapToScene(pos());
	point2 = scene()->itemsBoundingRect().center();
	drawData.iconPos = point2 - point1;

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[wysota]

Make the coordinates of the "pixmap scene" reflect those of the scene containing the pixmap. The easiest way to do it is to use QGraphicsItem::sceneBoundingRect(). Then pass the returned rect to QGraphicsScene::setSceneRect() of the newly created scene.

Then all your calculations will be done in the same coordinate space.

[stevel]

wysota,

Thanks for your help. I don't think I have fully managed to communicate what I am doing, because part of what you were saying really didn't apply, but your mention of the sceneBoundingRect function helped, because this code:

QRectF	  rect;
	QPointF   point1, point2;
 
	// JSL - Calculate the location of the position of the item on the icon
	rect			= sceneBoundingRect();
	point1			= rect.topLeft();
	point2			= scene()->itemsBoundingRect().topLeft();
	drawData.iconPos= point1 - point2;

QRectF	  rect;
	QPointF   point1, point2;

	// JSL - Calculate the location of the position of the item on the icon
	rect			= sceneBoundingRect();
	point1			= rect.topLeft();
	point2			= scene()->itemsBoundingRect().topLeft();
	drawData.iconPos= point1 - point2;

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seems to be doing the trick. Thanks again. I think I can move on from here.