June 2014 - Pharo-users - lists.pharo.org

Re: [Pharo-users] Athens and ellipse drawing

by Nicolai Hess

in (pure) cairo it is possible to stroke a path, after restoring the current state/transformation: cairo_set_line_width (cr, 0.1); cairo_save (cr); cairo_scale (cr, 0.5, 1); cairo_arc (cr, 0.5, 0.5, 0.40, 0, 2 * M_PI); cairo_restore (cr); cairo_stroke (cr); So we can scale the circle arc to an elliptic one, without scaling the stroke width. >From my observation, this is not possible with the current athens rendering scheme: steps in AthensCanvas draw-> setPathTransform loadpath stroke/fill Igor, did I miss something, is it possible with the Athens API ? nicolai 2014-04-23 14:54 GMT+02:00 Henrik Johansen <henrik.s.johansen(a)veloxit.no>: > > On 23 Apr 2014, at 2:31 , Igor Stasenko <siguctua(a)gmail.com> wrote: > > > > > On 23 April 2014 13:17, Henrik Johansen <henrik.s.johansen(a)veloxit.no> > wrote: > >> >> On 22 Apr 2014, at 2:23 , Igor Stasenko <siguctua(a)gmail.com> wrote: >> >> > as for why there's 4 arc segments instead of one, its because >> > of bad approximation, when drawing more that 90 degree arcs. >> > >> > also, in athens, arc segment is defined with following inputs: >> > - end point of previous segment (implicit) >> > - angle >> > - direction (clockwise/counterclockwise) >> > - end point >> > >> > the radius, therefore calculated automatically, because with given set >> of parameters there's only one way to draw an arc connecting given points. >> > >> > Now if you put angle of 360 degrees, you cannot draw arc without >> specifying radius, >> > because your end points will coincide, which means there's infinite >> number of ways to draw full circle passing through a single point, with any >> radius. >> > >> > cairo using different inputs for specifying arc segments.. >> > - center, radius, start angle, end angle >> > >> > the problem with such parametrization is that it is completely separate >> from rest of commands (line/move/bezier etc).. and you will be very lucky >> if your arc will be connected with rest of your path.. because arc's >> starting point depends on start angle, instead of last point of previous >> path segment. >> > >> > this was the main reason to use more appropriate parametrization to get >> rid of inconsistency.. while losing ability to draw full circle with single >> command.. >> >> AFAICT, still doesnât explain how to draw an ellipse with constant stroke >> path width, which was the original question :) >> >> > Right, what is missing is elliptical arc segment type. And there's no > direct support for it in Cairo.. so it can be only approximated by other > segment types, like lines or bezier curves. > There's a work started on calculating path geometry using approximation > with line segments.. it can be used to represent any kind of curves defined > parametrically. > But it is not yet plugged into the API. > > > One way is to not use a transformed circle path altogether, but draw the >> actual ellipsis path using cubic beziers: >> >> http://www.charlespetzold.com/blog/2012/12/Bezier-Circles-and-Bezier-Ellips… >> >> ellipsisOfExtent := [:builder :anExtent | | halfX halfY | >> halfX := anExtent x / 2. >> halfY := anExtent y / 2. >> âWe expect relative builder, and start the ellipsis at >> anExtent x / 2 @ 0" >> builder >> curveVia: 0@(halfY negated * 0.55) and: (0.45 * >> halfX)@halfY negated to: halfX@ halfY negated; >> curveVia: halfX* 0.55 @ 0 and: halfX@ (0.45 * >> halfY) to: halfX @ halfY; >> curveVia: 0 @ (halfY * 0.55 ) and: (0.45 * halfX >> negated @ halfY) to: halfX negated @ halfY; >> curveVia: (halfX negated * 0.55) @ 0 and: halfX >> negated @ (halfY negated * 0.45) to: halfX negated @ halfY negated; >> close]. >> >> AthensSceneView new >> scene: [ :can | >> | path | >> >> path := can >> createPath: [ :builder | >> builder moveTo: 10@60. >> ellipsisOfExtent value: builder >> value: 200@100 ]. >> (can >> >> setStrokePaint: Color red) >> width: 8 asFloat. >> can drawShape: path ] ; >> openInWindow >> >> > quite nice approximation. What is an error measure comparing to true > ellipse? > > > From the abstract of the paper cited in the linked site: > > *We provide a surprisingly simple cubic BÃ©zier curve which gives a very > accurate approximation to a segment of a circle. Joining the BÃ©zier > segments we obtain an approximation to the circle with continuous tangent > and curvature. For 45Â° segments the error is approximately 2Â·10-6, and in > general the approximation is sixth order accurate.* > > Considering the code simply stretches a bezier circleâs control points, > Iâd say quite. In fact, Iâd be surprised if the arc primitive in cairo is > implemented using a different method. > > (Of course, even less error using the actual value of the formula for 90 > degrees, instead of approximate values .55 / 1- 0.55.) > > Cheers, > Henry >

June 22, 2014

Re: [Pharo-users] Fwd: [ANN] FIFA World Cup 2014

by Arturo Zambrano

Great!!! :) On Fri, Jun 20, 2014 at 6:54 PM, Sean P. DeNigris <sean(a)clipperadams.com> wrote: > HernÃ¡n Morales Durand wrote > > http://80738163270632.blogspot.com/2014/06/fifa-world-cup-2014-app.html > > Cool! I love fun little apps like this. And the blog entry and screencast > made it easy to experience without having to even dl :) > > > > ----- > Cheers, > Sean > -- > View this message in context: > http://forum.world.st/Fwd-ANN-FIFA-World-Cup-2014-tp4763759p4764025.html > Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com. > >

June 22, 2014

Re: [Pharo-users] Pharo Video Tutorial

by Hilaire Fernandes

Great! I just learn about Window group with your vidorials Thanks Hilaire Le 22/06/2014 00:00, kilon alios a Ã©crit : > I have uploaded 5 new video tutorials to my playlist that can be found here > -- Dr. Geo http://drgeo.eu iStoa - https://launchpad.net/istoa

June 22, 2014

Re: [Pharo-users] Pharo Video Tutorial

by kilon alios

Thank you Tudor and Esteban . I have uploaded 5 new video tutorials to my playlist that can be found here https://www.youtube.com/watch?v=Ol5ivaEATLQ&list=PLqbtQ7OkSta0ULYAd7Qdxof85… 1) Why Pharo 2) Install Pharo 3) Create a Class 4) Workspace Variables 5) Instance Variables 6) Temporary Variables 7) Inheritance 8) Binary Messages 9) Class Variables and Methods 10) Class and Method Comments 11) Browser Icons 12) Conditions 14) Arrays 15) OrderedCollection and useful methods for collections *16) Dark Theme* *17) Interval* *18) Dictionary and our first GUI with Pharo* *19) Inspector* *20) Deep Into System Browser* these five new tutorials are around 1 hour in total, the total of the Playlist is now 3 hours 26 minutes and growing. I decided to do System Browser 30 minutes long instead of break it down to 5-10 minutes parts cause I think that System browser is better explained in a whole, but I have added music I have created to make the video easier to watch . Hope you find them useful and easy to follow :) On Thu, May 15, 2014 at 7:46 PM, Esteban Lorenzano <estebanlm(a)gmail.com> wrote: > supercool kilon, thank you very much! > > Esteban > > On 15 May 2014, at 18:36, kilon alios <kilon.alios(a)gmail.com> wrote: > > As you may or may not be aware of I have started a series of Video > Tutorials that I upload to YouTube. I also add these tutorials to my "Pharo > Video Tutorial" playlist. Since the last time I posted I have added 9 new > tutorials. The playlist is now 2 hours and 22 minutes long and of course > there is a lot more to come. > > The playlist is here : > > > https://www.youtube.com/watch?v=Ol5ivaEATLQ&list=PLqbtQ7OkSta0ULYAd7Qdxof85… > > This is the list of the video tutorials the new ones are marked with bold : > > 1) Why Pharo > 2) Install Pharo > 3) Create a Class > 4) Workspace Variables > 5) Instance Variables > 6) Temporary Variables > *7) Inheritance* > *8) Binary Messages* > *9) Class Variables and Methods* > *10) Class and Method Comments* > *11) Browser Icons* > *12) Conditions * > *14) Arrays* > *15) OrderedCollection and useful methods for collections* > > > >

June 21, 2014

Re: [Pharo-users] Pharo3.0 + Swap Ctrl and Alt keys

by stepharo

We started to clean the character conversions because the logic was not good. Now we hope that with the new handling of events it will get better because the vm does not emit certain characters and this is difficult to do something about it. Now I would have prefered that the changes do not impact you guys. Stef On 13/6/14 13:30, Thushar G R wrote: > Hi all, > > In Pharo 2.0 i find that "Ctrl+d" would do the doIt in workspace. In > Pharo3.0 for doIt, i need to do "Alt+d". > > 1) Is this change intentional? > 2) if so am i advised to practice all the shortcuts using Alt keys > instead of Ctrl key for pahro 3? > 3) Any way to bring back the Ctrl/Alt swap settings (I have asked this > before in stackoverflow) > 4) Any one knows a hack or workaround for this? > > Actually i was trying to figure out point 4) but no luck till now. I > changed it in keymappings builders in AbstractNautilusUI and similar > places but it simply dont work. > > Any help is appreciated and TIA. > > G R Thushar

June 21, 2014

Re: [Pharo-users] Fwd: [ANN] FIFA World Cup 2014

by Sean P. DeNigris

HernÃ¡n Morales Durand wrote > http://80738163270632.blogspot.com/2014/06/fifa-world-cup-2014-app.html Cool! I love fun little apps like this. And the blog entry and screencast made it easy to experience without having to even dl :) ----- Cheers, Sean -- View this message in context: http://forum.world.st/Fwd-ANN-FIFA-World-Cup-2014-tp4763759p4764025.html Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.

June 20, 2014

Re: [Pharo-users] [ANN] DrGeo 14.07 "Athens landing"

by Hilaire Fernandes

Thanks Martin, I really need people to look at using DrGeo and report me broken stuff. Hilaire Le 20/06/2014 18:16, MartinW a Ã©crit : > And also on OS X there is a dialog after startup that says: âGot startup > errors, proceed to open debuggersâ. The error is "MessageNotUnderstood: > UndefinedObject class>>useHTTPProxy:â I attach the debug log. -- Dr. Geo http://drgeo.eu iStoa - https://launchpad.net/istoa

June 20, 2014

Re: [Pharo-users] [ANN] DrGeo 14.07 "Athens landing"

by Hilaire Fernandes

Igor, do you have any idea? This is strange bug, nevertheless a killing one as drawing circle partially off screen is very common. Thanks Hilaire Le 18/06/2014 22:20, Nicolai Hess a Ã©crit : > Windows users, I test the application with Wine it works! But I have > this strange bugs: https://bugs.launchpad.net/drgeo/+bug/1331559 > Do you have it? > > > Yes, I can confirm this bug on Windows 7. It does not occure on linux. > And I was able to reproduce this bug on a plain pharo 4 image. > So, I don't think this is related to pharo or drgeo at all. Maybe a bug > in cairo? > -- Dr. Geo http://drgeo.eu iStoa - https://launchpad.net/istoa

June 20, 2014

Re: [Pharo-users] [ANN] DrGeo 14.07 "Athens landing"

by MartinW

Hilaire Fernandes-6 wrote > Windows users, I test the application with Wine it works! But I have > this strange bugs: https://bugs.launchpad.net/drgeo/+bug/1331559 > Do you have it? It occurs on OS X 10.9.3 too. And also on OS X there is a dialog after startup that says: âGot startup errors, proceed to open debuggersâ. The error is "MessageNotUnderstood: UndefinedObject class>>useHTTPProxy:â I attach the debug log. But apart from that it looks very good! Iâm a big fan. Perhaps one day you could publish a part of it as a Pharo-Desktop-Application-Framework :) I aleardy used Dr.Geo twice as inspiration for how to deploy Pharo desktop applications. M. PharoDebug.log <http://forum.world.st/file/n4763997/PharoDebug.log> -- View this message in context: http://forum.world.st/ANN-DrGeo-14-07-Athens-landing-tp4763710p4763997.html Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.

June 20, 2014

Re: [Pharo-users] Fwd: [ANN] FIFA World Cup 2014

by HernÃ¡n Morales Durand

The blog entry with a screenshot: http://80738163270632.blogspot.com/2014/06/fifa-world-cup-2014-app.html Cheers, HernÃ¡n 2014-06-19 11:27 GMT-03:00 HernÃ¡n Morales Durand <hernan.morales(a)gmail.com>: > Hi Kilon. > If you want to experiment with another JSON mapping and Spec there are > more endpoints here > > http://worldcup.sfg.io/group_results > http://worldcup.sfg.io/matches/country?fifa_code=USA > http://worldcup.sfg.io/teams > > - Another thing could be to sort by clicking the TreeModel header. > - Adding country flags would be cool. > - A refresh button. > > Is a nice change to show your (anyone) fast coding skills given that > WC ends in a couple of weeks ;) > Cheers, > > HernÃ¡n > > > > 2014-06-19 5:13 GMT-03:00 kilon alios <kilon.alios(a)gmail.com>: >> Wow very nice indeed. What you intend on improving ? looks quite complete to >> me . >> >> >> On Thu, Jun 19, 2014 at 11:04 AM, HernÃ¡n Morales Durand >> <hernan.morales(a)gmail.com> wrote: >>> >>> I did a small application to retrieve on-line data from the FIFA World >>> Cup 2014. You can installl it and open in Pharo 3 by doing: >>> >>> Gofer it >>> smalltalkhubUser: 'hernan' project: 'FIFAWorldCup2014'; >>> configurationOf: 'FIFAWorldCup2014'; >>> loadDevelopment. >>> >>> FIFAWorldCupApp open. >>> >>> Let me know if you want to contribute. >>> Enjoy >>> >>> HernÃ¡n >>> >>

June 19, 2014