Re: problem handling "mouse button press"

[Simon Hookway <lord_seoman hotmail com>]

On Tue, 2002-03-19 at 14:37, Havoc Pennington wrote:
> Simon Hookway <lord_seoman hotmail com> writes:
> > Actually, i found that the eventbox has the button_press and
> > button_release masks set as default.
>
> Good, convenient.
>
> > The next problem is this will catch the button press anywhere on the
> > pixmap.
>
> Hmm. Would be easier if you were using GdkPixbuf/GtkImage from GTK 2.
> Then you could just check the value of the alpha channel at the
> clicked pixel.
>
> With GTK 1.2, you will need to gdk_image_get_from_drawable() the mask
> for the pixmap, then gdk_image_get_pixel() the pixel at the place
> where the user clicked.

hmm, i'm now using gtk2, i have a pixmap that i rendered into an
eventbox as a GtkImage. I then render each button from a pixbuf onto
certain portions of the GtkImage to create the buttons. ATM, when i get
a click or release event i use gdk_window_get_pointer and test to see if
the pointer is in the button area. This creates a problem if the button
is irregular in shape.

But because my buttons are still in a pixbuf, i could test the alpha
channel of the original using the pointer location returned from the
gdk_window_get_pointer call (accounting for the offset of course). 

Is there a better way to do this?

> You only need to get_from_drawable() a 1x1 area where the user
> clicked, so should be pretty fast. Don't get the whole bitmap.
>
> Havoc
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Simon