ubuntu-phone team mailing list archive

[Sam Segers <sam.sgrs@xxxxxxxxx>]

Hi,

I have a problem with this QML/JS approach. You can make objects from C++
and bind to those signals and values to the UI. I tried to do something
similar with JavaScript but don't know how. Having all the logic, values
etc in an external JavaScript file and only the UI in QML.

I can't seem to find how to bind QML properties to values defined in
JavaScript, or how to update my UI from JavaScript transparently. All the
examples you find online let the js file set the values of qml objects and
read from them. I solved this by making my js file a library, let QML set a
js variable to a QML object and only set the values of this QML object and
bind the UI with these. So my js file sets these values instead of its own.
I end up with a QML object that has a lot of properties and signals. Do you
have a better way?

Sam


2013/7/29 Michael Zanetti <michael.zanetti@xxxxxxxxxxxxx>

> Hi
>
> On Monday 29 July 2013 15:53:52 Andreas Poulsen wrote:
> > I just wondered, if there is any plan to have a more general QML UI
> > toolkit. For now, there is Ubuntu.Components, Sailfish OS has some
> > components, and QtQuick is going to have some QtQuick.components. Could
> > you guys talk together about some standard components? It would be much
> > more easy, to develop one app for 2 or 3 platforms, than creating it for
> > 3 platforms using the same technology, but different toolkits. Just a
> > wish from an app developer :)
>
> Yes, this is really one of the bad things of the current state with QML in
> general.
>
> There are talks in progress to align APIs as close as possible. However, I
> think it won't be possible (at least not in the foreseeable future) to have
> the same components everywhere. The reason is that different platform look
> and
> behave differently. Even if most of the components could probably aligned,
> there will always be differences for some of them. For example if a
> platform
> doesn't have some UI pattern or a platform invents a new one. One example
> is
> the hiding Toolbar on Ubuntu. MeeGo's toolbar didn't do that so there is
> the
> need of a difference in the API.
>
> Also a different look of the same UI patterns introduces problems here. For
> example if one platform uses big round buttons with spaces in between while
> another one uses small square buttons without a space. That would allow
> you to
> place a different amount of items into one row. While the API might be
> compatible, your application would look quite bad one one of the platforms.
>
> The original idea for QML was to write the common stuff in Qt/C++ and then
> create a very thin UI layer with QML on top of it. That thin UI layer is
> easy
> and fast to write (just puttin some Buttons and Images into a layout and
> hook
> functionality up to the C++ business logic which is really cross platform).
> This works quite well for me having a bunch of apps running on Maemo,
> MeeGo,
> Symbian, KDE and Ubuntu Touch.
>
> Of course, if you write an app only in QML and smash your javaScript
> somewhere
> between the painting code, your app's portability will go towards 0. You
> can
> of course stick to JavaScript for the platform independent code too, but
> make
> sure to have JavaScript in separate files, and with a clean API, never
> accessing properties/elements from the QML code from within JavaScript.
> Then I
> guess you can create something somewhat portable without C++ too.
>
> Br,
> Michael
>
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