[ bloc ] I do not understand why some behavior is not in the right place

I saw in bleedingEdge it is different and looks better.
Now I was wondering why shape did not do the rendering and I thought that this is may be because a shape can be used for doing something else
than rendering. For example clipping or as igor mentioned defining the shape of the interaction



drawOnSpartaCanvas: aCanvas
    "Actually render receiver on aCanvas in local bounds.
    Override to customize.
    aCanvas is an instance of AthensCanvas
    aCanvas must not be nil"

    self assert: self shape path context isNotNil.

    aCanvas
        clipPreserveBy: self shape during: [
            aCanvas paintGroup: [
                aCanvas setPaint: self shape fillPaint.
                aCanvas fillPreserve.
                aCanvas paintMode source.
                aCanvas setStrokePaint: self shape strokePaint.
                aCanvas stroke ] ] 

unprotectedFullDrawOnSpartaCanvas: aCanvas
    "Draw the full structure on the given Canvas withing drawing bounds
    without caring about any errors and visibility. I am responsible for
    clipping and transforming canvas's path to local coordinates
    to allow simpler actual drawing in drawOnAthensCanvas:
    Additional checks should be implemented in fullDrawOnAthensCanvas:
    aCanvas is an instance of AthensCanvas.
    aCanvas must not be nil.
    @see BlElement>>#fullDrawOnAthensCanvas:
    @see BlElement>>#drawOnAthensCanvas:"
    self shape adaptTo: self.
    self shape path context: aCanvas.

    aCanvas
        transform: self transformation
        during: [
            self clippingStrategy
                clip: self
                on: aCanvas
                during: [ self drawOnSpartaCanvas: aCanvas ]
                childrenDuring: [ self drawChildrenOnSpartaCanvas: aCanvas ] ]

Hi igor

I like your feedback.
Could you summarize it based on the latest alpha version and now that you saw the code?

In the bloc version you discussed with alain (in the house I was renovating) an element had a view that were responsibe of the rendering
but it was not good.

Stef

Le 4/4/16 20:51, Igor Stasenko a écrit :

Some more bashing today.. (don't take it personal, i may be wrong)

BlPath hierarchy.. and BlShape.

Why you redefining what is shape and what is path?

Of course, you are free to do it in Bloc..

But in terms of Athens, all of BlPath are actually - shapes..

And BlShape is some kind of encapsulation of shape, paints and transform.

It is a dumb state holder without any extra logic. 

My rule of thumb: do not produce dumb state holders. They has to be smart,

else it makes no sense in creating separate entity and designating it as something else than any other bunch of data thrown into single clump, 

sitting there deaf, blind, dead and silent until someone else will grab it somewhere 

and start using it for own purpose.

Sure, i could understand, why you potentially may want such object(s) around,

but it is not shape anymore and i wouldn't call it like that. Because shape

are shape, and has nothing to do with paints and transform,

it don't knows and don't cares whether it will be filled or stroked or both,

 and how many times, and if there will be single paint or thousand.

Such kind of properties is simply orthogonal to what shape existing for,

because it exists only to define geometry.

I think all of that came from not understanding the roles of objects and how they interact in Athens.

Shapes define geometry.

Paints define how that geometry will be filled/altered. 

The shapes and paints are related in a way that paints are used to fill shapes. But there's nothing tells that single shape can be  filled only once with prescribed paint, and only then stroked.. or vise versa.

The order and amount of operations, combinations and effects are up to the user. And they have to stay like so, if you don't intend to shrink feature set and hardwire, what users can do and what they cannot.

I really hoping that you had no such intent.

Be on your place, if you want to have a number of commonly used shapes, just make a

factory class, so i can tell:

CommonShapes rectangle: a@b to: c@d

except, that Rectangle is a shape already.. and wrapping it with own class

just adds more complexity, creating one extra beloved dumb state holder and nothing else.

But i would imagine i could have:

CommonShapes circle: 100@100

or

CommonShapes roundedRectangle: 100@100 radius: 5

in any case, since there could be infinite number of 'possibly useful objects'

when we talking about geometry.. your BlPath hierarchy will tend to grow and grow over time, ad infinity.

Well, people love when there's order, like in that comic where guy painted 'cat' label on his cat, 'car' label on his car.. and all around in same way. 

Can't blame for that.. So, maybe. Whatever.. 

But your examples demonstating insane amount of bloat..

For example:

exampleLine

self new

layoutStrategy: BlLinearLayout horizontal;

layoutParamsDo: [ :lp |

lp horizontal wrapContent.

lp vertical wrapContent ];

addChild:(self new

layoutParams: BlLinearLayoutParams new;

shape:

(BlShape new

fillPaint: (BlColorPaint new color: (Color blue alpha: 0.5));

strokePaint:

(BlStrokePaint new

paint: (BlColorPaint new color: (Color green alpha: 1));

lineStyle: BlStrokeLineStyle new;

width: 5);

path: (BlLinePath new));

extent: 400 @ 200);

openInWorld

Guys, are you serious, you will find happy users, that is forced to produce so much

code in order to draw a single, simple line on the screen?

You must be kidding.

I see that it is indeed comes from the requirement that BlElement can hot-swap its shape on the fly.. And so, you are forced to define all the properties

and construct all the things in place.

But there should be some sanity limit, where you should stop asking user for 

so much details.

But if you want to go to such extreme, then all your examples would look like that:

BlElement new 

content: (MyFancyPony new);

openInWorld.

Where MyFancyPony, is a content - an object that defines shape, and knows how to render itself and so on. A smart object, that knows how to behave and draw itself. Not just holding state.

 And number of properties and/or behavior

is then up to the user. And he is free to use anything fancy or not to deliver content on the screen.

That would be much better. But then it will duplicate the features of BlElement (or at least a significant subset of it) - being able to render itself.

But still.

P.S. Now i see BlElement.. why nobody said that it is replacement for Morph?

I was thinking that in addition to BlMorph, you have BlElement :)

Sure, you don't need two compositions. As long as there one thing that represent UI elements, that can form hierarchy its ok.
So, i retract my comments about Elements.. And apologize.

--

Best regards,
Igor Stasenko.

Doru

I have the impression that
clipping and interaction can be defined by a "shape"
then the drawing can be either drawn in a canvas or delegate to something else (for example for the cursor if there is an hardware rendering).

I like this discussion and the feedback of igor because he is kicking our asses much better than me in fact
because he has real argument while I just got feelings :)

Stef

Le 4/4/16 19:10, Tudor Girba a écrit :

Hi,

Indeed, this was not clear. The original idea of the shape was to be primarily responsible for the clipping, but in the meantime the stroke and fill filtered in the implementation. Alex, Andrei and I will now change the “shape” to only be responsible for clipping and leave the drawing to the element. We will also propose a solution for dealing with drawing and interaction.

Please stay tuned and thanks for this discussion.

Cheers,
Doru

On Apr 4, 2016, at 9:00 AM, stepharo <[hidden email]> wrote:

I saw in bleedingEdge it is different and looks better.
Now I was wondering why shape did not do the rendering and I thought that this is may be because a shape can be used for doing something else
than rendering. For example clipping or as igor mentioned defining the shape of the interaction



drawOnSpartaCanvas: aCanvas
    "Actually render receiver on aCanvas in local bounds.
    Override to customize.
    aCanvas is an instance of AthensCanvas
    aCanvas must not be nil"

    self assert: self shape path context isNotNil.

    aCanvas
        clipPreserveBy: self shape during: [
            aCanvas paintGroup: [
                aCanvas setPaint: self shape fillPaint.
                aCanvas fillPreserve.
                aCanvas paintMode source.
                aCanvas setStrokePaint: self shape strokePaint.
                aCanvas stroke ] ]



unprotectedFullDrawOnSpartaCanvas: aCanvas
    "Draw the full structure on the given Canvas withing drawing bounds
    without caring about any errors and visibility. I am responsible for
    clipping and transforming canvas's path to local coordinates
    to allow simpler actual drawing in drawOnAthensCanvas:
    Additional checks should be implemented in fullDrawOnAthensCanvas:
    aCanvas is an instance of AthensCanvas.
    aCanvas must not be nil.
    @see BlElement>>#fullDrawOnAthensCanvas:
    @see BlElement>>#drawOnAthensCanvas:"
    self shape adaptTo: self.
    self shape path context: aCanvas.

    aCanvas
        transform: self transformation
        during: [
            self clippingStrategy
                clip: self
                on: aCanvas
                during: [ self drawOnSpartaCanvas: aCanvas ]
                childrenDuring: [ self drawChildrenOnSpartaCanvas: aCanvas ] ]

--
www.tudorgirba.com
www.feenk.com

"To utilize feedback, you first have to acquire it."

On 4 April 2016 at 23:17, stepharo <[hidden email]> wrote:

Doru

I have the impression that
clipping and interaction can be defined by a "shape"
then the drawing can be either drawn in a canvas or delegate to something else (for example for the cursor if there is an hardware rendering).

I like this discussion and the feedback of igor because he is kicking our asses much better than me in fact
because he has real argument while I just got feelings :)

It is easy to kick asses.. much easier than doing things.

And please, explain to guys, that i am not some kind of trolly crazy angry idiot, who sits in the corner making giggles and throwing paperballs into student(s), because its fun.

It is because i also made similar mistakes, or have to fix other's mistakes at own time, and really don't want people repeating them over and over again, like ShadowCanvas, now its ShadowPaint. 

 

Stef

Le 4/4/16 19:10, Tudor Girba a écrit :

Hi,

Indeed, this was not clear. The original idea of the shape was to be primarily responsible for the clipping, but in the meantime the stroke and fill filtered in the implementation. Alex, Andrei and I will now change the “shape” to only be responsible for clipping and leave the drawing to the element. We will also propose a solution for dealing with drawing and interaction.

Please stay tuned and thanks for this discussion.

Cheers,
Doru

On Apr 4, 2016, at 9:00 AM, stepharo <[hidden email]> wrote:

I saw in bleedingEdge it is different and looks better.
Now I was wondering why shape did not do the rendering and I thought that this is may be because a shape can be used for doing something else
than rendering. For example clipping or as igor mentioned defining the shape of the interaction



drawOnSpartaCanvas: aCanvas
    "Actually render receiver on aCanvas in local bounds.
    Override to customize.
    aCanvas is an instance of AthensCanvas
    aCanvas must not be nil"

    self assert: self shape path context isNotNil.

    aCanvas
        clipPreserveBy: self shape during: [
            aCanvas paintGroup: [
                aCanvas setPaint: self shape fillPaint.
                aCanvas fillPreserve.
                aCanvas paintMode source.
                aCanvas setStrokePaint: self shape strokePaint.
                aCanvas stroke ] ]



unprotectedFullDrawOnSpartaCanvas: aCanvas
    "Draw the full structure on the given Canvas withing drawing bounds
    without caring about any errors and visibility. I am responsible for
    clipping and transforming canvas's path to local coordinates
    to allow simpler actual drawing in drawOnAthensCanvas:
    Additional checks should be implemented in fullDrawOnAthensCanvas:
    aCanvas is an instance of AthensCanvas.
    aCanvas must not be nil.
    @see BlElement>>#fullDrawOnAthensCanvas:
    @see BlElement>>#drawOnAthensCanvas:"
    self shape adaptTo: self.
    self shape path context: aCanvas.

    aCanvas
        transform: self transformation
        during: [
            self clippingStrategy
                clip: self
                on: aCanvas
                during: [ self drawOnSpartaCanvas: aCanvas ]
                childrenDuring: [ self drawChildrenOnSpartaCanvas: aCanvas ] ]

--
www.tudorgirba.com
www.feenk.com

"To utilize feedback, you first have to acquire it."

--

Best regards,
Igor Stasenko.

On 5 April 2016 at 00:51, Andrei Chis <[hidden email]> wrote:

btw, Andrei , if you looking how you can test if point contains shape or not, take a look at AthensCurveFlattener.

It converts curved path, that containing Bezier curves (or not) into simple polygonal shape that consists only from a simple lines.

Then there AthensPolygonTester, that has the piece you missing:

- a small algorithm that can test if given point inside or outside that polygon.

Please note that it is simpler even-odd rule algorithm. It not works correctly for all possible cases.

There's another algorithm- winding number algorithm, that is much better,

but i had to switch to other stuff before were able to get my hands to it.

It is more reliable, since it can work for self-intersecting shapes.

https://en.wikipedia.org/wiki/Point_in_polygon

  

So, what you need is to wire these things down to Bloc.Then whenever you need to test whether point within shape or not, you can convert any path into polygon and perform the test. And of course, you can cache the results of conversion in order to avoid expensive computations every time you need to perform such tests. Once path is converted, the test is relatively cheap and costs something like O(n), where n is number of line segments.

Or maybe, to simplify things, you could extend the shape protocol and introduce #containsPoint: 

or as variant #containsPoint:ifNotAvailable: 

so that if shape implements such feature - it can answer true or false, and if not - evaluating a block. So, you don't have to implement all tests for all kinds of shapes that invented or not yet invented in universe.

--

Best regards,
Igor Stasenko.

As far as I know bloc already has perfect hit detection. In BlPath. What a
dumb state holder!

--
View this message in context: http://forum.world.st/bloc-I-do-not-understand-why-some-behavior-is-not-in-the-right-place-tp4888273p4888315.html
Sent from the Pharo Smalltalk Developers mailing list archive at Nabble.com.