El 14-04-2014, a las 8:21, Juraj Kubelka <juraj.kubelka@gmail.com> escribió:
Thank you Stef,
the example helped me a lot to understand how to play with Athens.
The solution is not what I am looking for. If someone starts to play with alpha canal, s/he will get unexpected results.
I have finally found an example in C language. It look like this: -=-=-=-=- cairo_set_line_width (cr, 0.1); cairo_save (cr); cairo_scale (cr, 1, 0.2); cairo_arc (cr, 1.5, 1.5, 1, 0, 2 * M_PI); cairo_restore (cr); cairo_set_source_rgba (cr, 0, 1, 0, 0.50); cairo_stroke (cr); -=-=-=-=- <tips-ellipse.png>
I do not know how to write the same instructions with Athens.
First, they draw one arc (cairo_arc (cr, 1.5, 1.5, 1, 0, 2 * M_PI);), I draw 4 arcs: -=-=-=-=- canvas createPath: [ :builder | builder absolute; moveTo: 0 @ 0.5; ccwArcTo: 0.5 @ 0.0 angle: 90 degreesToRadians; ccwArcTo: 0.0 @ -0.5 angle: 90 degreesToRadians; ccwArcTo: -0.5 @ 0.0 angle: 90 degreesToRadians; ccwArcTo: 0 @ 0.5 angle: 90 degreesToRadians ]. -=-=-=-=-
OK, now I can draw ellipse with just one arc: -=-=-=- canvas createPath: [ :builder | builder absolute; moveTo: 0.5 @ 0; arcCenterX: 0 centerY: 0 radius: 0.5 startAngle: 0 endAngle: Float twoPi -=-=-=- Why is this method in private protocol? Why I should not use it? Why I have to use âmoveTo:â? In C-example they do not use it. But I have to, otherwise there is an extra line on the canvas: Well, I see in AthensCairoPathBuilder>>createPath:, there is call of "self moveToX: 0 Y: 0.â. If I remove it, I do not have to write âmoveTo: 0.5@0â. So, I understand why I have to write it in my code. The question is what is the purpose of "self moveToX: 0 Y: 0.â? I guess it simplify some situations, am I right? Which one? There is actual Athens example: -=-=-=- AthensSceneView new scene: [ :can | | path | path := can createPath: [ :builder | builder absolute; moveTo: 0.5 @ 0; arcCenterX: 0 centerY: 0 radius: 0.5 startAngle: 0 endAngle: Float twoPi ]. can pathTransform restoreAfter: [ can pathTransform scaleBy: 200 @ 50. (can setStrokePaint: Color red) width: 0.1. can drawShape: path. ]. ] ; openInWindow -=-=-=- Thank you, Juraj
Second, they set line width, before any other action (like cairo_save). I do: -=-=-=-=- canvas pathTransform scaleBy: 200 @ 50. (can setStrokePaint: Color red) width: 0.1. can drawShape: path. -=-=-=-=-
So, my result in Athens is like this: <Captura de pantalla 2014-04-14 a la(s) 8.18.38.png>
Any idea? The example is explained here, C source code is here (by clicking on the image in the page).
Thank you, Jura
El 12-04-2014, a las 4:01, Pharo4Stef <pharo4Stef@free.fr> escribió:
AthensSceneView new scene: [ :can | | path | path := can createPath: [ :builder | builder absolute; moveTo: 0 @ 0.5; ccwArcTo: 0.5 @ 0.0 angle: 90 degreesToRadians; ccwArcTo: 0.0 @ -0.5 angle: 90 degreesToRadians; ccwArcTo: -0.5 @ 0.0 angle: 90 degreesToRadians; ccwArcTo: 0 @ 0.5 angle: 90 degreesToRadians ].
can pathTransform restoreAfter: [ can pathTransform scaleBy: 200 . can setPaint: Color red ; drawShape: path. "(athensCanvas setStrokePaint: strokePaint) width: (self strokeWidth / self scale) asFloat." can drawShape: path.]. can pathTransform restoreAfter: [ can pathTransform scaleBy: 190 . can setPaint: Color blue ; drawShape: path. "(athensCanvas setStrokePaint: strokePaint) width: (self strokeWidth / self scale) asFloat." can drawShape: path
] ] ; openInWindow
<Screen Shot 2014-04-12 at 09.01.09.pdf>
