[Qt-interest] memory control in QImage bits() function

[Mehmet Kaplan]

Hi to all,
I'm trying to copy the image data in QImage image class to another
pointer like given below:


uchar* newData = qImage->bits();


in definition of bits() function it is written that:
"Note that QImage uses implicit data sharing. This function performs a
deep copy of the shared pixel data, thus ensuring that this QImage is
the only one using the current return value."

For example when i use a big image like 300 mb, in the lines above
memory usage is increased by totally 600 mb, which proves the
definiton of bits() function.
But after a statement like this
for(int i=0;i<100000;i++)
	newData [i]=0;

original QImage is also changes (first few lines become black because
of zero value).

To solve this problem i changed the code like this:
uchar * newData = new uchar[qImage->numBytes];
uchar* uc = qImage->bits();
memcpy ( newData, uc, qImage->numBytes );

But with these lines memory usage increases 600 mb (300 mb each for
first and second line).
Isn't there any solution for creating new data (new pointer) and spend
300 mb for this operation.