Tobias

You write that NullEncoder and subclasses could be summarized as

    "Put objects onto another thing with encoding inbetween".

which I think is helpful for understanding.

Maybe we consider for the class comment of NullEncoder

    "Put objects onto another thing with encoding/transformation inbetween".


But also note that this is not only related to PostscriptCanvas as we have


NullEncoder
    FlattenEncoder
         Canvas
             FormCanvas

FormCanvas has some nice usage examples.

#test1 is

test1
	"FormCanvas test1"

	| canvas |
	canvas := FormCanvas extent: 200 at 200.
	canvas fillColor: (Color black).
	canvas line: 10 at 10 to: 50 at 30 width: 1 color: (Color red).
	canvas frameRectangle: ((20 at 20) corner: (120 at 120)) width: 4 color:
(Color green).
	canvas point: 100 at 100 color: (Color black).
	canvas drawString: 'Hello, World!' at: 40 at 40 font: nil color: (Color cyan).
	canvas fillRectangle: ((10 at 80) corner: (31 at 121)) color: (Color magenta).
	canvas fillOval: ((10 at 80) corner: (31 at 121)) color: (Color cyan).
	canvas frameOval: ((40 at 80) corner: (61 at 121)) color: (Color blue).
	canvas frameOval: ((70 at 80) corner: (91 at 121)) width: 3 color: (Color
red alpha: 0.2).
	canvas fillRectangle: ((130 at 30) corner: (170 at 80)) color: (Color lightYellow).
	canvas showAt: 0 at 0.


This works fine in an MVC project

--Hannes

On 9/29/17, Tobias Pape <Das.Linux at gmx.de> wrote:
> Hi Hannes
>
>> On 29.09.2017, at 15:21, H. Hirzel <hannes.hirzel at gmail.com> wrote:
>>
>> And there is no 'FlattenEncoder' in Pharo 6
>
>>
>>
>> On 9/29/17, H. Hirzel <hannes.hirzel at gmail.com> wrote:
>>> We have
>>>
>>> NullEncoder
>>>    FlattenEncoder
>>>        Canvas
>
> So here's the Thing: I looked in 3.8, and there's:
>
> Object
>  NullEncoder 		- Morphic-Postscript Filters
>   FlattenEncoder	- Morphic-Postscript Filters
>    Canvas		- Morphic-Support
>     PostscriptCanvas	- Morphic-Postscript Canvases
>
> But also note that they all have a callback via class>>filterSelector:
>
> NullEncoder>>filterSelector		^ #writeOnFilterStream:
> FlattenEncoder>>filterSelector		^ #flattenOnStream:
> Canvas>>filterSelector			^ #drawOnCanvas:
> PostscriptCanvas>>filterSelector	^ #fullDrawPostscriptOn:
>
> I think part of that happened because this all shared common functionallity,
> In the sense that all those things "Put objects onto another thing with
> encoding inbetween".
> Thinking of things like a n-dimensonal stream or so…
>
> I checked and It is like that even in Squeak 3.6, 3.0, 2.8.
> Squeak 1.13 does not have any of those, and it has no Morphic.
>
> Self Morphic does not have such Encoders, tho.
>
> In the end it all seems to be related to the PostScript Canvas, which,
> understandably, has to have access to certain objects and actually has to
> "encode" them into a file.
>
> Best regards
> 	-Tobias
>
>
>
>>>
>>> there are no direct users of NullEncoder and FlattenEncoder.
>>>
>>> FlattenEncoder class comment is just
>>>
>>>    'The simplest possible encoding:  leave the objects as is.'
>>>
>>> a bit terse. Does not really say what the issue is about.
>>>
>>>
>>>
>>> On 9/29/17, H. Hirzel <hannes.hirzel at gmail.com> wrote:
>>>> P.S.
>>>>
>>>> There is no NullEncoder in Pharo.
>>>>
>>>> The class Canvas is not in a package 'Morphic-Support' but in a
>>>> package 'Graphics-Canvas'.
>>>>
>>>> There is no 'Graphics-Canvas' package in Squeak. [2]
>>>>
>>>> Seems like a good idea to move Canvas and subclasses to a package
>>>> 'Graphics-Canvas' as well.
>>>>
>>>>
>>>> [2] Graphics package in Squeak 6.0a-17405
>>>>
>>>> Graphics-Display Objects
>>>> Graphics-External-Ffenestri
>>>> Graphics-Files
>>>> Graphics-Fonts
>>>> Graphics-Primitives
>>>> Graphics-Text
>>>> Graphics-Transformations
>>>> GraphicsTests-Files
>>>> GraphicsTests-Primitives
>>>> GraphicsTests-Text
>>>>
>>>> On 9/29/17, H. Hirzel <hannes.hirzel at gmail.com> wrote:
>>>>> Hello
>>>>>
>>>>> NullEncoder is subclass of object ([1] for full hierachy). It is a
>>>>> superclass of Canvas.
>>>>>
>>>>> What is the function of NullEncoder. No class comment so far?
>>>>>
>>>>> Regards
>>>>> Hannes
>>>>>
>>>>>
>>>>> -------------------------------------------------------------------------------------------------------------------------------
>>>>>
>>>>> [1] NullEncoder printHierarchy '
>>>>> ProtoObject #()
>>>>> 	Object #()
>>>>> 		NullEncoder #(''target'' ''filterSelector'')
>>>>> 			FlattenEncoder #()
>>>>> 				ByteEncoder #()
>>>>> 					PrintableEncoder #()
>>>>> 						PostscriptEncoder #()
>>>>> 							PostscriptEncoderToDisk #()
>>>>> 						PropertyListEncoder #()
>>>>> 				Canvas #()
>>>>> 					ColorMappingCanvas #(''myCanvas'')
>>>>> 						AlphaBlendingCanvas #(''alpha'')
>>>>> 						ShadowDrawingCanvas #(''shadowColor'')
>>>>> 					FormCanvas #(''origin'' ''clipRect'' ''form'' ''port''
>>>>> ''shadowColor'')
>>>>> 						BalloonCanvas #(''transform'' ''colorTransform'' ''engine''
>>>>> ''aaLevel'' ''deferred'')
>>>>> 						BlueFormCanvas #()
>>>>> 						ColorPatchCanvas #(''stopMorph'' ''foundMorph'' ''doStop'')
>>>>> 						MultiResolutionCanvas #(''deferredMorphs'')
>>>>> 					PluggableCanvas #()
>>>>> 						BufferedCanvas #(''remote'' ''previousVersion'' ''lastTick''
>>>>> ''dirtyRect'' ''mirrorOfScreen'')
>>>>> 						CachingCanvas #(''cacheCanvas'' ''mainCanvas'')
>>>>> 						ClippingCanvas #(''canvas'' ''clipRect'')
>>>>> 						MultiCanvas #(''canvases'' ''extent'' ''depth'')
>>>>> 						NullCanvas #()
>>>>> 					PostscriptCanvas #(''origin'' ''clipRect'' ''currentColor''
>>>>> ''shadowColor'' ''currentFont'' ''morphLevel'' ''gstateStack''
>>>>> ''fontMap'' ''usedFonts'' ''psBounds'' ''topLevelMorph''
>>>>> ''initialScale'' ''savedMorphExtent'' ''currentTransformation''
>>>>> ''printSpecs'' ''pages'')
>>>>> 						DSCPostscriptCanvas #()
>>>>> 							DSCPostscriptCanvasToDisk #()
>>>>> 						EPSCanvas #()
>>>>> 					RemoteCanvas #(''innerClipRect'' ''outerClipRect'' ''transform''
>>>>> ''connection'' ''shadowColor'')'
>>>>>
>>>>
>>>
>>
>
>
>