CODEWITHSUNDEEP
c++qt
Simon
Simon

Reputation: 2246

QT QGraphicsScene set origin to bottom left

I am writing a scene editor to edit levels for an iphone game. The point of origin within the iphone/ipad environment is the bottom left of the display.

How can I correctly move the origin within the QGraphicsScene object ? I have tried with

// iWidth and iHeight are maximum scene dimension values
pScene->setSceneRect(0, iHeight, iWidth, iHeight);

but this doesn't work.

Without going to a complicated (at least for me) transformation matrix, how should I be moving the origin point ?

EDIT :

As requested, here is a resume of how I am creating the scene and adding images to it :

// Creation of the Scene within a QMainWindow derived class
QGraphicsScene* m_pScene = new QGraphicsScene(this);
ui->levelScene->setScene(m_pScene);

// insertion of the background png image
QPixmap* pm = new QPixmap(strFileName, 0);
QGraphicsPixmapItem* pi = new QGraphicsPixmapItem();
pi->setPixmap(*pm);
m_pScene->addItem(pi);

// adjustment of the layout
m_pScene->setSceneRect(0, iHeight, iWidth, iHeight);

// add a movable png image to the scene above the background
pm = new QPixmap(*g_pChoData->m_pcDirImages + "/" + pChoElem->m_Image, 0);
pi = new QGraphicsPixmapItem();
pi->setPixmap(*pm);
pi->setPos(iPosX, iPosY);
pi->setZValue(iPosZ);
pi->setFlags(QGraphicsItem::ItemIsMovable | QGraphicsItem::ItemIsSelectable);
m_pScene->addItem(pi);

Upvotes: 2

Views: 3482

Answers (1)

Simon
Simon

Reputation: 2246

Here is the solution, at least in my case.

To put 0,0 at the bottom left -

m_pScene->setSceneRect(0, -iHeight, iWidth, iHeight);

Then, all images inserted into the scene need to have their Y position adjusted :

pi->setPos(iPosX, -iPosY);

Last little trick which caused me problems was that the clients reference point for an image is the center of the image and not a corner.

Thank you to all who helped here.

Upvotes: 1

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