[SOLVED] Widget I can draw on.

Santosh Reddy

jaskmar

Could I? How? QImage does not inherits from QWidget...

Santosh Reddy

You can set the background image using stylesheets

jaskmar

And if I want to create an animation by showing QImage's one-by-one?

Sam

For animations you can have a look at "QPropertyAnimation Class":http://qt-project.org/doc/qt-5.0/qtcore/qpropertyanimation.html

jaskmar

:/
I can not imagine how should it work. I can't even display simple image loaded from file. So which property would I animate. On which widget?

Ohh, I am afraid I will have to write my own widget indeed. But that's strange for me as I have noticed that Qt liblary is well-equipped compared to wxWidgets, where wxStaticBitmap exists.

PS: Sorry for my English again. Is it hard to understand what I write? :D

Chris Kawa

For static images you can use simple QLabel and QLabel::setPixmap. For animation there's a QLabel::setMovie. You could play around with a custom QIODevice for the QMovie.

Sam

There is an example available in Qt creator "Basic Drawing Example":http://doc.qt.digia.com/stable/painting-basicdrawing.html and also for basic reference you can have a look at this "tutorial":http://www.voidrealms.com/viewtutorial.aspx?id=35. In order to set a background image you can use "Qt StyleSheets":http://qt-project.org/doc/qt-4.8/stylesheet-examples.html

There are many tutorials available at "wwww.voidrealms.com":http://www.voidrealms.com/tutorials.aspx?filter=qt based on Qt 4 which are helpful for a start.

Regards
Soumitra

jaskmar

I have already seen the example. It is based on writing own widget, but I am asking about different way (I have written the reason earlier). Maybe Krzysztof's way is satisfactory, I will try.

In the midtime I found a solution using QGraphicsView, which unfortunately doesn't work. My code:
@
QImage Image("/path/to/image.png");
QPixmap Pixmap;
Pixmap.convertFromImage(Image);
QGraphicsPixmapItem Item(Pixmap);
QGraphicsScene *Scene = ui->GraphicsView->scene();
Scene->addItem(&Item);
@
The code compiles, but I receive an error during execution. In english it would be "Unexpected program termination" or sth. like that.

EDIT:
Ok, Krzysztof's way is what I was looking for. About QMovie, I briefly checked this class documentation and I didn't notice the way to make an animation using several QImage's or QPixmap's. I will be thinking about it deeper tommorow. Is it better way than simple replacing images in a thread? Maybe simpler?

Santosh Reddy

QGraphicsPixmapItem is created on stack, are you sure that it will remain in scope for all the time during scene is in scope. Instead you could create it on heap (using new)

jaskmar

No, the problem is different. I have already tried this way:
@
QImage *Image = new QImage("/path/a.png");
QPixmap *Pixmap = new QPixmap;
Pixmap->convertFromImage(*Image);
QGraphicsPixmapItem *Item = new QGraphicsPixmapItem(*Pixmap);
QGraphicsScene *Scene = ui->GraphicsView->scene();
Scene->addItem(Item);
@
And the result is the same.
The error-generating line is the last one.

Santosh Reddy

Then I have say that the view does not have scene set, what deos ui->GraphicsView->scene(); return?

jaskmar

Of course.
So there are two ways:

using QGraphicsView:
@
QImage *Image = new QImage("/home/foo/a.png");
QPixmap *Pixmap = new QPixmap;
Pixmap->convertFromImage(*Image);
QGraphicsPixmapItem *Item = new QGraphicsPixmapItem(*Pixmap);
QGraphicsScene *Scene = new QGraphicsScene;
ui->GraphicsView->setScene(Scene);
Scene->addItem(Item);
@

or using QLabel
@
QImage Image("/home/foo/a.png");
QPixmap Pixmap;
Pixmap.convertFromImage(Image);
ui->label->setPixmap(Pixmap);
@

And this thread is SOLVED.
Thanks a lot and deep Greathings.