Comments on: Custom widgets with Cairo.

By: Bruno Boaventura (brunobol) » Blog Archive » Yet about custom widgets with Cairo

Tue, 11 Mar 2008 00:24:28 +0000

[...] Bruno Boaventura (brunobol) « Custom widgets with Cairo. [...]

By: carlosg

carlosg — Mon, 10 Mar 2008 13:43:09 +0000

another possibility for rounded shapes is checking that x^2 + y^2 < 1

By: Karl Lattimer

Karl Lattimer — Mon, 10 Mar 2008 08:47:21 +0000

Oops, I should have noticed, you only want the input shaped… /halfasleep

By: Karl Lattimer

Karl Lattimer — Mon, 10 Mar 2008 08:45:32 +0000

Have you looked at the gsm_color_button.c/h code in gnome-system-monitor

That does it

By: jonner

jonner — Mon, 10 Mar 2008 00:53:30 +0000

alternately, use something like goocanvas.

By: Davyd

Davyd — Mon, 10 Mar 2008 00:20:07 +0000

As people have said, you can easily calculate whether or not you’re inside the area, either using Cairo or by doing your own geometry calculations. You could overload the vcall for the signal and eat the event in the case where you don’t want to send it out (probably shouldn’t do this).

Alternatively, if you were using GooCanvas, you could connect button-press-event directly to the clock object. It makes a lot of this stuff much simpler to do.

By: greg

greg — Sun, 09 Mar 2008 23:29:12 +0000

On receiving a click event create a dummy surface, draw the clock, then use cairo_in_fill for hit testing.

By: otte

otte — Sun, 09 Mar 2008 23:27:13 +0000

You can use cairo_in_fill() to check if you’re in a given path you constructed in cairo or cairo_in_stroke() for strokes. And then you have to check that for every mouse move. It’s how I do it in Swfdec.

So it is possible, but it’s not a drop-in one-line function that does that for you.

By: writser

writser — Sun, 09 Mar 2008 23:14:53 +0000

see:

http://library.gnome.org/devel/gdk/stable/gdk-Windows.html#gdk-window-input-shape-combine-mask

I don’t know whether it already works on windows. You could also manually construct a bitmask (you can use almost the same cairo code) and check whether the input falls in the mask manually.

By: desrt

desrt — Sun, 09 Mar 2008 22:39:30 +0000

you can’t have X only give you events for this area without using a separate window and xshape. this is not what you want to do.

what you want to do, instead, is capture all events but then use cairo_in_fill or cairo_in_stroke to check if the point that was clicked on is within the area that you’re interested in.