2015-02-05 6:29 GMT+01:00 Sean P. DeNigris <s...@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
> --
> View this message in context:
> http://forum.world.st/Canvas-Transform-Goes-Haywire-if-Scaled-tp4803830.html
> Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
>
>
