> On 29.09.2017, at 17:50, H. Hirzel <hannes.hirzel at gmail.com> wrote:
> 
> And also note that we have
> 
>    Canvas subclass: #PostscriptCanvas
> 
> which is in another category 'MorphicExtras-Postscript Canvases'.
> 
> Not in the category 'Morphic-Support' in which NullEncoder and Canvas is.
> 

Yea, but it used to be different, only Canvas in Morphic-Support.

Object
NullEncoder 		- Morphic-Postscript Filters
 FlattenEncoder		- Morphic-Postscript Filters
  Canvas		- Morphic-Support
   PostscriptCanvas	- Morphic-Postscript Canvases


We would probably have to ask Dan or so on the whys and wherefores…


> And PostscriptCanvas is for the use in Morphic as it has an instance
> variable 'topLevelMorph'.
> 
> 
> 
> On 9/29/17, H. Hirzel <hannes.hirzel at gmail.com> wrote:
>> 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'')'
>>>>>>> 
>>>>>> 
>>>>> 
>>>> 
>>> 
>>> 
>>> 
>> 
>