porting my virtua girl player to qt

[JeanC]

Hello,

After my 2 initial projects with Qt have been succesfull it's time to wet my feet a little with graphics programming.

In windows I succeeded in making my own virtuagirl player, it plays animations of stripping girls in the corner above the tray.

I like to port this to linux, I miss it
The data for the animations is in some kind of run length encoding. But in stead of a normal bitmap, each frame is build using the windows mechanismes CreateRectRgn(), CombineRgn() in order to have a transparant image on the desktop.

I like to have some advice on how to go about this.

Thank you. Jean.

[elcuco]

Dud, when you finish it, please give me a download link

[pherthyl]

Hmm.. This might be quite difficult, if the file format is composed of basically commands to the Windows graphics system. I suppose it depends on the complexity of the commands. If there are only a few commands that are used, I would reimplement them using QPainter equivalents, but if they run the full gamut of GDI commands then I would look into using Wine to port your existing application to Linux, or even run it outright.

[JeanC]

The Create/Add Rgn stuff in windows is basically a way to have a *window* which is not a pure rectangle, but an irregular shape, like a girl for instance. Because of it being a window in itself, it is automatically transparent from the underlying background, the desktop. If the girl moves her arm, the background under the previous armshape is restored because the window shape changes. That painting is done automatically by the os. This is about what I'm looking for. Can qpainter do (something like) this?

[spud]

Not QPainter, but QWidget.
QWidget::setMask ( const QBitmap & bitmap )

[JeanC]

setMask() looks promising. I'm gonna invest, thanks.
I'll let you guys know when there's a download link, may take a while though.

[JeanC]

Well, the graphics system is something which is not learned in a day, overwhelming.

My questions:

In the shaped clock example the actual drawing is done in the paint event by using QPainter. But I would like to use a QImage and setPixel() because in that way I hope I can set a mask from the pixelmap I have build on that QImage

How do I do that?

Note, I don't use the paintevent like in that example, I use a frame() function triggered by a timer. The window has FramelessWindowHint attribute so a paintevent is not needed.

Also, I don't think scanLine() will be faster because the pixel data comes in vertical rows, am I correct?

Thanks.

[spud]

I'm not completely sure I understood most of your post, so I'll just tell you how I would go about this problem. It really shouldn't be to complicated.

First prepare the data:
For each frame you should have a QPixmap of the girl and a QBitmap of the mask. I don't now in which format you have the images, but once you've loaded the data into a QImage or QPixmap QPixmap::createMaskFromColor() should help you create the mask.

Make your QWidget subclass a frameless window and connect a timer to a slot(which you seem to have done)

You do need paintEvent(), painting outside paintEvent is not allowed! All you need to do in frame() is to select which new QPixmap/QBitmap pair to use and call setMask().

paintEvent will be called automatically when needed and all you have to do is paint the QPixmap at (0,0)

Don't complicate things more than necessary! You won't need scanLine() unless you are reading binary data into a QImage.

[wysota]

Have a look at this:

http://zrusin.blogspot.com/2006/10/argb-windows.html

[JeanC]

Thank you both.

I'm trying to go the way spud describes.

in constructor (I need to construct it on the stack, else cannot set width / height):

image = new QPixmap(400, 400);

image = new QPixmap(400, 400);

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in frame()

void Girl::frame()
{
image->fill(Qt::red);
setMask(image->createMaskFromColor(Qt::black, Qt::MaskOutColor));
}

void Girl::frame()
{
image->fill(Qt::red);
setMask(image->createMaskFromColor(Qt::black, Qt::MaskOutColor));
}

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in paintEvent()

void Girl::paintEvent(QPaintEvent *)
{
QPainter painter(this);
painter.drawPixmap(QPoint(0, 0), *image);
}

void Girl::paintEvent(QPaintEvent *)
{
QPainter painter(this);
painter.drawPixmap(QPoint(0, 0), *image);
}

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Program crashes with segmentation fault. Not a smooth ride yet.
p.s. the pixeldata comes from a run length encoded file and is presented in vertical lines of 1 pixel width each which than can be put on the pixmap with drawLine().

[wysota]

You meant something like this?

[JeanC]

Grin, what have you got there?
Can it zoom?
My eyes are bad, that's a reason I wanted to write a player myself in the first place so I could add 2 , 3 and 4 times zoom.

[wysota]

Zooming is not a problem, but the resolution of the animations I have is hmm... bad It's 160x120, so zooming will make it look terrible. If you have larger anims, they shouldn't pose a problem.

By the way - I implemented both approaches - using setMask and using ARGB display and the latter works much much better.