2015-02-05 6:29 GMT+01:00 Sean P. DeNigris <sean@clipperadams.com>:

The following works as I expect:

�� morph := Morph new
�� topLeft: 200@400;
�� openInWorld.

�� outputRect := morph fullBounds.
�� canvas := Display defaultCanvasClass extent: outputRect extent depth:
Display depth.
�� scale := 1.
�� t := MorphicTransform offset: outputRect topLeft angle: 0 scale: scale.
�� clipRect := outputRect translateBy: outputRect topLeft negated.
�� canvas transformBy: t clippingTo: clipRect during: [ :aCanvas |
�� aCanvas fullDrawMorph: morph ].
�� canvas form asMorph openInWindow.

�� "morph delete."

but if I change scale even a little bit (e.g. 0.95), things quickly go
south.
Check out scale = 1 vs scale = 0.95 below:
<http://forum.world.st/file/n4803830/Screenshot_2015-02-05_00.png>
Obviously they differ by more than I expected. If I change scale to 0.5, the
morph disappears from view in the canvas completely.

I had both translation and scale working in a spike by translating with
FormCanvas>>#translateBy:during: and then magifying with "canvas form
magnifyBy: 0.5", but I want to do this in my morph's drawing method, so I
want to do both with the canvas.

Where am I going wrong here?

The scaling factor changes the effective coordinates of the morph

Morph topLeft 200@400

scale 0.5

Morph draws itself at 100@200

Therefore your MorphicTransform translates to far away (or not far enough?)

�� morph := EllipseMorph new
�� topLeft: 200@400;
�� openInWorld.

�� outputRect := morph fullBounds.
�� canvas := Display defaultCanvasClass extent: outputRect extent depth: Display depth.
�� scale := 0.5.

�� "scale the offset of the translation too"

�� t := MorphicTransform offset: outputRect topLeft * scale angle: 0 scale: scale.
�� clipRect := outputRect translateBy: outputRect topLeft negated.
�� canvas transformBy: t clippingTo: clipRect during: [ :aCanvas |
�� aCanvas fullDrawMorph: morph ].
�� canvas form asMorph openInWindow.
�� morph delete.

What do you want to achieve?

Both
magnifyBy: and
transformBy:clippingTo:during:�� (with non-pure-translation)

actually do the same, they warp-blitting a form.

��

-----
Cheers,
Sean
--
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