Am 20.09.2013 um 12:24 schrieb Igor Stasenko <siguctua@gmail.com>:




On 20 September 2013 12:15, Norbert Hartl <norbert@hartl.name> wrote:
Next try. I may do something stupid but it appears that all morphs draw on the same coordinate system. Meaning that every Morph that will draw something at 0@0 will put it in the top left corner of the image displayed. I would expect that a morph that is positioned somewhere provides a canvas where 0@0 is relative to the position of the morph. If coordinates are absoulte how can I delegate work to sub components and having them calculate the offsets properly?

Welcome to club.

To ease the pain, take a look at TransformMorph.

Thanks. I'm trying to understand TransformMorph but I don't really get it. I cannot see _how_ it is transforming stuff. For testing I have three morphs

MasterMorph
   TransformMorph
      TestMorph

In TransformMorph I use

MorphicTransform offset: 0 angle: 0 scale: 10.0.

When I implement #drawOn: in TestMorph and do 

   aCanvas 
fillRectangle: (Rectangle origin: 10@10 extent: 10@10)
color: Color red.

the result looks good although I don't understand where the coordinates are translated. To me it appears that the way it goes is from Canvas to GrafPort and I didn't find the location where TransformMorph comes into play. I'm trying to figure that out because I cannot use Float coordinates in my transform morph. Doing in TestMorph>>#drawOn something like

   aCanvas fillRectangle: (Rectangle origin: 0.9@0.9 extent: 1@1)
color: Color green. 

I get two problems. Basically the Rectangle is truncated to Ints before the transform. Additionally in this particular case the rectangle is not displayed at all. For 0.89@.089 I can see it truncated at origin 0@0 but at 0.9@0.9 it just disappears. Same goes for 0.63 and other values. 

And I don't know how to debug morphic because using breakpoints is too dangerous while it is in stepping mode.

thanks,

Norbert