Set orientation on embedded device

bkamps

I have a C++ application that uses QML for user interface on an embedded device. The embedded device has a 320x240 screen but it's rotated (so it's in portrait mode). I developer and run the application on a normal pc. All the images I made in portrait mode.

I have defined my main qml as follows:

@
Item {
width: 240
height: 320

BorderImage {
   source: "someimage.png"
}

}
@

When I run this on a pc, no problem. When I run this on my embedded device the picture is shown rotated on the up right side of my display.

To get the picture shown correctly on my embedded device I use the transform option:

@
transform: Rotation { id: windowOri; origin.x: 100; origin.y: 140; angle: 270}
@

This works for the main page but other (non-fullscreen) windows that are shown on top of the main window are not shown correctly and I need to set the positions "manually":

@
PropertyChanges { target: messageWindow; x: 15; y: 70 }
@

I am not convinced this is the correct way to set the orientation. I have found many examples but all of them are symbian / meegoo related. I am also not sure if the Rotation option is causing a performance issue...

Anyone have some suggestions?

Chuck Gao

you can try Page element to set orientation lock if you are developing the app on Harmattan or Symbian device.
Which platform are you target in ?

bkamps

I use a custom embedded device, no nokia device... Is using transform : Rotation the way to go?

mbrasser

The flickr and calculator demos in Qt 4.7 give an example of handling rotation purely from QML; if you haven't seen them already they might be worth a look.

Rotating the entire QML scene will generally have some performance impact. If possible, you may want to look at handling the rotation lower in the stack (e.g. so Qt sees a 240x320 screen geometry).

Regards,
Michael

bkamps

Thanks mbrasser. I have looked at the calculator example and I see that they also use the transform option. The difference is that they "draw" all there qml user interface components while I use images (png files) to show my components. I am not sure if the transform option is efficient for rotating pictures.

Can you please explain what you mean by this:

If possible, you may want to look at handling the rotation lower in the stack (e.g. so Qt sees a 240×320 screen geometry).

Chuck Gao

hi bkamps,
Can you get it's(the device) orientation?

I think mbrasser means you can try to handle the rotation in a lower API, which may not the Qt staff. But meanwhile, if you can get the orientation, you can try rotate QML scene to see it's performance.

Br,
Chuck

bkamps

You mean rotate the pictures myself (using a imageeditor) instead of using Rotation? I notice that when I don't rotate on the target the drawing of windows is a lot quicker. Ofcourse I only see a part of the window (because the display is landscape and all my windows/pictures are portrait).

mbrasser

[quote author="bkamps" date="1340865823"]Can you please explain what you mean by this:

If possible, you may want to look at handling the rotation lower in the stack (e.g. so Qt sees a 240×320 screen geometry).
[/quote]

Sure, I was thinking of, for example, the transformed display driver available for QWS ( http://doc.qt.nokia.com/4.7-snapshot/qt-embedded-displaymanagement.html ).

In terms of your QML scene, are you saying the entire UI is a single Image? Or just that it is composed of many Images (rather than Rectangles, Text, etc)?

Regards,
Michael

bkamps

[quote author="mbrasser" date="1340930133"][quote author="bkamps" date="1340865823"]Can you please explain what you mean by this: > If possible, you may want to look at handling the rotation lower in the stack (e.g. so Qt sees a 240×320 screen geometry). [/quote] Sure, I was thinking of, for example, the transformed display driver available for QWS ( http://doc.qt.nokia.com/4.7-snapshot/qt-embedded-displaymanagement.html ). In terms of your QML scene, are you saying the entire UI is a single Image? Or just that it is composed of many Images (rather than Rectangles, Text, etc)? Regards, Michael [/quote]

The applications consists of multiple images, but also Rectangles and Text..

mbrasser

[quote author="bkamps" date="1340947047"]The applications consists of multiple images, but also Rectangles and Text..[/quote]

I would expect the QML transform to have a performance impact -- from memory QPainter has a number of optimizations that can't be applied when more complex transforms are present. You could try running with the QML_SHOW_FRAMERATE environment variable set to see what sort of performance you get for rotated vs. non-rotated.

Regards,
Michael