QImageReader::SetClipRect limitation on size(Large Image)

naughtykid

The limitation on rect varies on systems, which I don't know why.
I want to display a very large image 20000 x 30000 of image on graphicView.
anyone encounter the limitation on this?

@
SetClipRect
{
System:
Dell Vostro 1510
Intel Core 2 Duo T8100 2.09 GHz
3 GB of RAM
Window XP 32 bit service pack 3
QImageReader::setClipRect() support up to 13824 x 13824(vice versa) only

System:
AMD QuadCore phenom 3 GHz
8 GB of RAM
Window XP 64 bit
QImageReader::setClipRect() support up to 14234 x 14235(vice versa) only

System:
Dell Vostro 1400
Intel Core 2 Duo T7250 2.0 GHz
2 GB of RAM
Window XP 32 bit service pack 3
QImageReader::setClipRect() support up to 15000 x 15894(vice versa) only

System:
Dell Vostro 3700
Intel Core i5 2.27 GHz
4 GB of Ram
Window 7 64 bit
QImageReader::setClipRect() support up to 18880 x 18881(vice versa) only
}
@

EDIT: please use code highlighting by @-tags. thanks. Gerolf

? Offline

there are known issues of loading such large images .. you might want to break it to chunks and load and stitch them while displaying

dangelog

[quote author="naughtykid" date="1299743480"]The limitation on rect varies on systems, which I don't know why.
I want to display a very large image 20000 x 30000 of image on graphicView.
anyone encounter the limitation on this?[/quote]

Are you aware that a 20k x 30k / 32bpp image requires 234E8 byte = 2,4 GByte of contiguous memory for being loaded? Yes, QImage isn't that smart. Split the image in chunks and load them on demand or so.

naughtykid

Thank you for the reply.

Here's what I did:

@
{
QImageReader reader1(file);
reader1.setClipRect(QRect(halfWidth, 0, halfWidth, halfHeight));
QPixmap img01 = QPixmap::fromImage(reader1.read());
QGraphicsItem* itemHolder = reinterpret_cast<QGraphicsItem*>(_scene.addPixmap(img01));
}

{
QImageReader reader2(file);
reader2.setClipRect(QRect(0, 0, halfWidth, halfHeight));
QPixmap img02 = QPixmap::fromImage(reader2.read());
QGraphicsItem* itemHolder = reinterpret_cast<QGraphicsItem*>(_scene.addPixmap(img02));
}

{
QImageReader reader3(file);
reader3.setClipRect(QRect(halfWidth, halfHeight, halfWidth, halfHeight));
QPixmap img03 = QPixmap::fromImage(reader3.read());
QGraphicsItem* itemHolder = reinterpret_cast<QGraphicsItem*>(_scene.addPixmap(img03));
}

{
QImageReader reader4(file);
reader4.setClipRect(QRect(0, halfHeight, halfWidth, halfHeight));
QPixmap img04 = QPixmap::fromImage(reader4.read());
QGraphicsItem* itemHolder = reinterpret_cast<QGraphicsItem*>(_scene.addPixmap(img04));
}

ui.graphicsView->show();@

Just to confirm is this the correct way to split the image in chunks. I'm still pretty new to Qt :)