Integrating Qt Quick components in Ministro

Wed Feb 1 20:59:40 UTC 2012

Some quick look comments:

On Wed, Feb 1, 2012 at 9:20 PM, BogDan <bog_dan_ro at yahoo.com> wrote:
> Hello everyone,
>
>   I have good news on this topic, I manage to check (a little bit) Android's source code and to extract, the exact, android's look and style informations for a few widgets (buttonStyle, editTextStyle, radioButtonStyle, checkboxStyle, etc.) and store them into a .json file (check the attachment). Because qt 4.x doesn't come with json support, IMHO we have two options:
>   1 - to use this [1] qt json implementation.
>   2 - or to backport Qt 5.x json implementation (my favorite option, because it seems more complex and complete than the first one).
>
>   I need more time to finish the extraction class (which will be part of the next Ministro release), so, if someone wants to step in and begin the Qt implementation it will be very appreciated !
>
>   To understand how android paints the widgets you have to check a simple widget how it's painted. So let's check Button class [2], which extends TextView class [3] which extends the View class [4].
>
> How it works:
>   - Button class only pass to its super class (TextView)  the style attribute (com.android.internal.R.attr.buttonStyle)
>   - TextView class pass the same information to its super class (View) then in its constructor (check "public TextView(Context context, AttributeSet attrs, int defStyle)" ) extracts text informations (e.g.TextAppearance_textColor,TextAppearance_textSize, TextAppearance_typeface, etc.) which are used to draw the text (check onDraw (...)).
>   - View class in its constructor (check "public View(Context context, AttributeSet attrs, int defStyle)") extracts a few informations e.g. View_background, View_paddingLeft, etc. which are used to paint the basic parts of the widget (e.g. the background).
>
>   If you check the json file, you'll see that there are more than one .png files used to paint the background, one for every view state (enabled, disabled, pressed, etc.). Android split every .png file into nine pieces (it uses nine patch technique [5], [6]) which are used to seamlessly resize the widget. AFAIK there is no support for such a thing into Qt, so IMHO this is the first thing which must be implemented.
>

The nime patch looks exactly same than Qt BorderImage (
http://developer.qt.nokia.com/doc/qt-4.8/qml-borderimage.html )

Also, system that uses different images for different states is
exactly same that is used on components
meegotouch-button-background-pressed.png
meegotouch-button-background.png
meegotouch-button-background-selected.png
....
and this for all combinations, inverted, disabled ...

The problem then comes more than could we do some mapping of Android
and MeeGotouch states like
meegotouch-button-background -> buttonStyle_View-background_Enabled.png

MeeGocomponents uses mthemedaemon plugin that fetch images, so, if we
could make just mapping names
and json query, we could in theory get theme engine.

Symbian components uses svg images , meegocomponents borderimages .
There is very little
difference in component API's. Least what I have used, porting on apps
were mostly changing import statements
and change of some colors.

Kate

> This weekend I hope to have enough time to create a wiki page which will describe the content of the json file.
>
> Cheers,
> BogDan.
>
>
> [1] https://github.com/ereilin/qt-json
> [2] http://www.java2s.com/Open-Source/Android/android-core/platform-frameworks-base/android/widget/Button.java.htm
> [3] http://www.java2s.com/Open-Source/Android/android-core/platform-frameworks-base/android/widget/TextView.java.htm
> [4] http://www.java2s.com/Open-Source/Android/android-core/platform-frameworks-base/android/view/View.java.htm
> [5] http://developer.android.com/reference/android/graphics/NinePatch.html
>
> [6] http://developer.android.com/guide/topics/graphics/2d-graphics.html#nine-patch
>
>
>>
>> Hi,
>>
>>    Yes, sadly we have to get our hands  very dirty.
>>    First step is to identify all Qt components then we have to find
>> Android's corresponding components, then we must extract the style &
>> look information to a central location (IMHO Ministro should do this job), then
>> any application which starts will peek this infos from that location and use
>> them to paint all controls.
>>    Second step is to check how Android paints the controls, here the things will
>> become dirty, we have to check
>> "frameworks/base/core/java/android/widget/TextView.java" from Android
>> source code and it seems we have to use a lot of private data, I hope the
>> Android versions are not so different.
>>   Third step is to change Ministro in order to extract all the infos we need to
>> paint our controls.
>>    Fourth step is to create a QStyle plugin (which will be used by QML as well)
>> which loads the data extracted by Ministro and use it to paint the controls. If
>> the extract procedure is very fast (less than 10ms), I doubt it will be that
>> fast :),  we can skip the third step and extract the data directly in  QStyle.
>>    Fifth step, if everything works, we must get drunk !
>>
>>
>> Cheers,
>> BogDan.
>>
>>
>>>
>>>
>>> While I don't agree on "almost all applications have the same
>> look" (as far as I can see, the only fully common UI element is the
>> menu/toolbar combo), I respect your choice.
>>>
>>> The first step would be to define what is the "Android style". Is
>> there some Google guidelines you plan to follow?
>>>
>>> Regards
>>> - Chris -
>>>
>>>
>>> On Tue, Jan 3, 2012 at 17:45, BogDan <bog_dan_ro at yahoo.com> wrote:
>>>
>>> Hi,
>>>>
>>>>
>>>>   I think none of your examples are good to follow :) The reason why
>> meego doesn't use QtStyle to draw the widgets is because meego doesn't
>> have a "native" style. Symbian is even worst, open any two
>> applications on symbian and you'll see that none of them have the same look
>> & style :) On Android is a different story, almost all applications have the
>> same look & style, so if we want to have a first class citizen port, all Qt
>> applications *MUST* look the same as any android application. I'm choosing
>> to make QStyle plugin because this way all Qt applications will benefit from it,
>> either they are made using old-fashion widgets or QML components.
>>>> For me a good android style is a top priority, I don't believe
>> I'll have enough time to finish it till beta 1 but who knows ...:) maybe if
>> other people will join me we can split the work and we can have this feature in
>> time for beta1.
>>>>
>>>>
>>>> Cheers,
>>>> BogDan.
>>>>
>>>>
>>>>
>>>>>
>>>>> and please note that the Qt quick components (either symbian or
>> meego) don't use Qt widget styles. All the components are drawn in qml so
>> the componenets would unfortunately not benefit from your work on a widget
>> style.
>>>>>> - Chris -
>>>>
>>>>>
>>>>>
>>>>> On Thu, Dec 22, 2011 at 21:53, BogDan <bog_dan_ro at yahoo.com>
>> wrote:
>>>>>
>>>>>
>>>>>>
>>>>>> Hi Chris,
>>>>>>
>>>>>> Please accept my apologize for the slow reply.
>>>>>> I think before we'll integrate the components into Ministro,
>> we must do a few things:
>>>>>>  - the components MUST use Android's style, next year
>> I'm planning to create a style plugin for
>>>>>>
>>>>>> widgets which should be used by Qt Quick Components for Android.
>>>>>>  - wait until Nokia finishes to define the API for Qt Quick
>> components [1]. We can't afford to break the API after we release it :)
>>>>>>
>>>>>>
>>>>>> Cheers,
>>>>>> BogDan.
>>>>>>
>>>>>>
>>>>>> [1] https://bugreports.qt.nokia.com/browse/QTCOMPONENTS-200
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> Hi guys,
>>>>>>>
>>>>>>> What would the steps be to integrate the Qt quick components
>> for Android to Ministro as a package?
>>>>>>>
>>>>>>> - Chris -
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>>
>>>
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