Dmitry Kazakov dimula73 at
Tue May 15 07:47:16 UTC 2012

On Tue, May 15, 2012 at 2:45 AM, Sven Langkamp <sven.langkamp at>wrote:

>> How it can be achieved in the constraints of the strokes [0]:
>> 1) The caller asks KisStrokeStrategyFactoryRegistry for the factory of
>> "ScaleLayer" stroke.
>> 2) The factory does the following: i) calls image->barrierLock() to fetch
>> right size information about the image; ii) calls image->unlock(); iii)
>> fires up the configuration dialog.
>> 3) The factory creates the stroke strategy for the "ScaleLayer" stroke
>> (usual undo command based stroke)
>> 4) The factory uploads the XML data about the stroke into the strategy
>> 4) The factory starts a new stroke and populates it with commands
>> 5) The strokes system calls the stroke strategy's method toXML, which
>> saves the data
>> Comment:
>> For each action we create one (!) class only: KisStrokeStrategyFactory.
>> The factory creates a simple undo-command-based stroke, forms XML, passes
>> it to the stroke strategy, then populates the strategy with the commands.
>> Later, when the stroke is finished, the framework asks the strategy for the
>> XML and it returns the value formed by the factory.
>> The advantage of this approach is that we shouldn't change anything and
>> only need to add one class per action. More than that this approach will
>> not demand us to add toXML/fromXML to the undo commands: you are right,
>> commands are too lowlevel for that.
>> Btw, take into account, that the strokes framework is capable of
>> canceling the tasks! It works right now (and is tested in unittests), but
>> it isn't connected anywhere to the UI because of the problems with
>> shortcuts in our tools.
>> If you agree that we implement it this way we can discuss it further and
>> assign the tasks ;). I can do the work of adding gathering the XML into the
>> stroke system (it shouldn't be much of work) and create base classes for
>> the factories.
>> [0] -
> I'm not sure why you want to do step 1. The stroke would be empty at that
> point and only be used much later.

Yes, there is no stroke at the step 1 yet, but I'd prefer to encapsulate
the dialog, formation of the XML data and the creation of the stroke in a
separate object for the following reasons:

1) In several cases we must to barrierLock the image before showing the
dialog, in others we needn't. It means we need to have a general code for
this locking in the base class.
2) The second reason is even more important. The user should be able to see
the dialog for the recorded actions. He can use it either for editing the
recorded action or for modifying the action on-the-go. Both the usecases
are implemented in PS.

The XML data you mention could be much easier be done with the
> KisPropertiesConfiguration. There is no way around it as we have to save
> the input values at some point. This should also be used by scripts and
> macros I think.

Yes, I agree. The highlevel code in factories can surely use it. What I'm
not sure about is whether properties can work good for usual strokes, which
might contain very long array of short values (points). Is it possible to
do without working it around with a set of preperties pt1,pt2,...,ptN?

> I'm not sold on the undo command based stroke. These tend to really make
> the code more complicated and I would prefer if we could make this more
> simple. Might be better to base it on KisStrokeJob. Btw we really need more
> documentation for the Strokes system, without it's pretty hard to grasp
> what the classes do or what sequentiality and exclusivity do.

There is a documentation on undo-command based strokes in
If you need some more information on a particular topic, please ask and
I'll add it.

The system will not become more complicated, because the factories would
use the same KisProcessingApplicator, which would get one more method
(something like attachXMLData()). So the code of, e.g. "ScaleImage" will
not change much. It will just be moved to a separate class and be coupled
with function for generating XML.

> One class for each action sounds very heavy. We have probably over a
> hundred action that are possible and I think we should keep the needed code
> to a minimum. Maybe we need to pick some simple action and then think it
> through and check which changes would be needed. We really need to get it
> right before the big porting starts.

Yes, sure. We can start with, e.g. "ScaleImage" method of KisImage. It is
already ported to the strokes, so it is easier to port it =)

Dmitry Kazakov
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