# Drawing with a Cairo context outside an expose signal **URL:** \ **Category:** Ruby-Gnome 2\ **Created:** [June 16, 2008, 10:38am UTC](https://www.ruby-forum.com/t/drawing-with-a-cairo-context-outside-an-expose-signal/140566 "2008-06-16T10:38:24Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![genericguy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/5daacb/32.png) [@genericguy](https://www.ruby-forum.com/u/genericguy)\ **Post date:** [June 16, 2008, 10:38am UTC](https://www.ruby-forum.com/t/drawing-with-a-cairo-context-outside-an-expose-signal/140566/1 "2008-06-16T10:38:24Z")
Hi, I’m trying to allow a user to draw to a DrawingArea with Cairo. The only problem is that I cannot figure out how to draw without using create\_cairo\_context in the expose event. I realize that I need to draw then if I want anything to be displayed, but I’d like to be able to draw to a ‘buffer’ in other parts of the script and then draw the buffer in the expose event. There are two ways that I can think of doing this. The first would be to create my own Cairo::Context. Since I don’t know how create\_cairo\_context links a context to the DrawingArea, is stuck for that. The other way would be to draw to a surface and call context.set\_source\_surface. For some reason, though, this function doesn’t seem to be present in the ruby binding. Thanks! ---
**Author:** ![genericguy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/5daacb/32.png) [@genericguy](https://www.ruby-forum.com/u/genericguy)\ **Post date:** [June 16, 2008, 1:44pm UTC](https://www.ruby-forum.com/t/drawing-with-a-cairo-context-outside-an-expose-signal/140566/2 "2008-06-16T13:44:10Z")
Hi, In [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) “[ruby-gnome2-devel-en] Drawing with a Cairo context outside an expose signal” on Mon, 16 Jun 2008 10:38:24 +0200, “Lucas L.” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > The other way would be to draw to a surface and call > context.set\_source\_surface. For some reason, though, this function > doesn’t seem to be present in the ruby binding. Use Cairo::Context#set\_source. It’s general method. It accepts (r, g, b), (r, g, b, a), ([r, g, b]), ([r, g, b, a]), (pattern) or (surface, x, y). ## Thanks, kou ---
**Author:** ![genericguy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/5daacb/32.png) [@genericguy](https://www.ruby-forum.com/u/genericguy)\ **Post date:** [June 16, 2008, 2:17pm UTC](https://www.ruby-forum.com/t/drawing-with-a-cairo-context-outside-an-expose-signal/140566/3 "2008-06-16T14:17:43Z")
Ah, I was searching the docs for surface\_source. rcairo really needs English documentation. Thanks! Kouhei S. wrote: > Hi, > > In [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > “[ruby-gnome2-devel-en] Drawing with a Cairo context outside an expose > signal” on Mon, 16 Jun 2008 10:38:24 +0200, > “Lucas L.” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > The other way would be to draw to a surface and call > > context.set\_source\_surface. For some reason, though, this function > > doesn’t seem to be present in the ruby binding. > > Use Cairo::Context#set\_source. It’s general method. It > accepts (r, g, b), (r, g, b, a), ([r, g, b]), ([r, g, b, > a]), (pattern) or (surface, x, y). > > ## Thanks, > > kou ---
**Author:** ![genericguy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/5daacb/32.png) [@genericguy](https://www.ruby-forum.com/u/genericguy)\ **Post date:** [June 16, 2008, 2:22pm UTC](https://www.ruby-forum.com/t/drawing-with-a-cairo-context-outside-an-expose-signal/140566/4 "2008-06-16T14:22:02Z")
Hi, In [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) “Re: [ruby-gnome2-devel-en] Drawing with a Cairo context outside an expose signal” on Mon, 16 Jun 2008 14:17:43 +0200, “Lucas L.” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Ah, I was searching the docs for surface\_source. > rcairo really needs English documentation. I need your help. ## Thanks, kou ---
**Author:** ![genericguy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/5daacb/32.png) [@genericguy](https://www.ruby-forum.com/u/genericguy)\ **Post date:** [June 16, 2008, 2:30pm UTC](https://www.ruby-forum.com/t/drawing-with-a-cairo-context-outside-an-expose-signal/140566/5 "2008-06-16T14:30:16Z")
Kouhei S. wrote: > Hi, > > In [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > “Re: [ruby-gnome2-devel-en] Drawing with a Cairo context outside an > expose signal” on Mon, 16 Jun 2008 14:17:43 +0200, > “Lucas L.” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > Ah, I was searching the docs for surface\_source. > > rcairo really needs English documentation. > > I need your help. > > ## Thanks, > > kou Is there a wiki or something? I’d gladly help. Right now I just try to make sense of Google’s translation of the Japanese docs:D ---
**Author:** ![genericguy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/5daacb/32.png) [@genericguy](https://www.ruby-forum.com/u/genericguy)\ **Post date:** [June 16, 2008, 2:38pm UTC](https://www.ruby-forum.com/t/drawing-with-a-cairo-context-outside-an-expose-signal/140566/6 "2008-06-16T14:38:48Z")
Hi, In [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) “Re: [ruby-gnome2-devel-en] Drawing with a Cairo context outside an expose signal” on Mon, 16 Jun 2008 14:30:16 +0200, “Lucas L.” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > Ah, I was searching the docs for surface\_source. > > > rcairo really needs English documentation. > > > > I need your help. > > Is there a wiki or something? I’d gladly help. Thanks! There is a Subversion repository: [https://www.cozmixng.org/repos/rcairo-doc/](https://www.cozmixng.org/repos/rcairo-doc/) Could you mail your prefer account name and salted password (you may use htpasswd) to me? > Right now I just try to make sense of Google’s translation of the > Japanese docs:D The Japanese documentations are based on cairo’s documents: [http://www.cairographics.org/manual/](http://www.cairographics.org/manual/) Most of them will help you. ## Thanks, kou