Construct QPixmap or QImage from raw data.

[The Storm]

Hi all,

I am writing a plugin for an application. This application have a callback interface that I inherit and when an image arrive the following method is called:

void IListener::onImage(int height, int width, int *data);

void IListener::onImage(int height, int width, int *data);

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In that method I have to create a valid QPixmap or QImage from those height, weight and integer data pointer. If someone know how to do that, please share with me.

Regards,
The Storm

[drhex]

Is that "data" raw pixels with no header?

QImage has a constructor for width and height where you can supply a format argument indicating how many bits per pixel you have and how they are arranged.
Then you can copy the data into the QImage line by line using the pointer provided by
QImage::scanLine (which needs to be properly casted first).

[The Storm]

So basicly you mean that I have to do something like this:

QImage image( width, height, format );

QImage image( width, height, format );

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But then how to copy the data ? Could you please be more specific. Is QImage::Format_RGB32 good format, the image have transparent parts btw.

[The Storm]

Anyone, please. I forgot to mentoin that the data are raw pixels.

[pgorszkowski]

Tha main problem is what format of data is inside in this integer data pointer. Is it rgba (0xAARRGGBB) or rgb( (0xffRRGGBB) or what. In case of rgba you can do something like this:

void onImage(int height, int width, int* data)
{
QImage image(width, height, QImage::Format_ARGB32);
for(int y(0);y < height;++y)
	for(int x(0);x < width;++x)
        {
                int index(y*width + x);
		image.setPixel(x, y, data[index]);
         }
}

void onImage(int height, int width, int* data)
{
QImage image(width, height, QImage::Format_ARGB32);
for(int y(0);y < height;++y)
	for(int x(0);x < width;++x)
        {
                int index(y*width + x);
		image.setPixel(x, y, data[index]);
         }
}

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Here you have the link to available format of image:
http://doc.trolltech.com/4.4/qimage.html#Format-enum

[The Storm]

Thanks a lot. The image is PNG and the format QImage::Format_ARGB32 have done the work. My end realisation actually is a bit differend and I hope more fast:

void	onImage(int height, int width, int* data)
{	
	QImage image = QImage( width, height, QImage::Format_ARGB32 );
 
	for (int i = 0; i < height; ++i)
		memcpy(image.scanLine(i), data + i * width, width * 4);
}

void	onImage(int height, int width, int* data)
{	
	QImage image = QImage( width, height, QImage::Format_ARGB32 );
	   
	for (int i = 0; i < height; ++i)
		memcpy(image.scanLine(i), data + i * width, width * 4);
}

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I hope that this will be useful for others that have my issue.