Milan Zimmermann wrote:

>On May 1, 2005 05:33 pm, Bert Freudenberg wrote:
>  
>
>>Am 01.05.2005 um 19:54 schrieb Milan Zimmermann:
>>    
>>
>>>Hi,
>>>
>>>I am trying to paint (draw lines) on Canvas from workspace. I use:
>>>
>>>aDrawingForm := Form extent: 400 at 600 depth: Display depth.
>>>aCanvas := aDrawingForm getCanvas.
>>>aCanvas fillColor: (Color yellow).
>>>aDrawingForm asMorph openInWorld.
>>><Alt-d>
>>>
>>>This shows yeallow canvas. Then I do
>>>
>>>aCanvas line: 10 at 10 to: 50 at 30 width: 3 color: (Color black).
>>>aCanvas flush.
>>><Alt-d>
>>>      
>>>
><<snip>>
>  
>
>>What your code does is draw into the form of an ImageMorph. Of
>>course, the Morph does not know that you modified the form. So it
>>does not repaint itself (that is, copy its form to the Display). It
>>does redisplay when you move it, however.
>>
>>I'm not sure what you're actually trying to achieve. If you want to
>>draw directly to the display, then use
>>
>>     aCanvas := Display getCanvas.
>>    
>>
>
>
>Thanks, I tried this, but do not really want to draw on the "basic display" 
>(not sure about the correct name) as it draws on the whole world. Obviously I 
>do not know about the way Squeak graphic works, this is one part of my small 
>project which I use to learn Smalltalk. I should have explained what I am 
>trying to achieve: 
>
>I am trying to draw (lines, rectangles etc) onto some object that I could 
>manipulate in world as a window or a morph (which would provide clipping as 
>well). The only way I found to do this is to draw on a Canvas inside a form, 
>but obviously failing to make the Canvas changes to tell the container how to 
>refresh (I am sure my terminology is wrong too)
>
>I tried to search the Swiki for code examples to do this, but did not get far 
>enough ... so far,
>
Try sending a 'changed' message to the morph after drawing on it.
Karl