R help - May 2009 - Draw a rectangle on top of an image using RGtk2?

Dear all,

I use gtkImageFromFile to display an image. Then I want to do some
gsignal to handle mouse event. I click the mouse and move a another
position and release. I can get the position of the firs click and the
release position,  then I would to draw a rectangle to display the
region I have selected. I need some hints on what functions should I
look for. I tried to google but don't know how.

Thanks.

-- 
HUANG Ronggui, Wincent
PhD Candidate
Dept of Public and Social Administration
City University of Hong Kong
Home page: http://asrr.r-forge.r-project.org/rghuang.html

On Fri, May 22, 2009 at 11:27 PM, Ronggui Huang
<ronggui.huang@gmail.com>wrote:
> Dear all,
>
> I use gtkImageFromFile to display an image. Then I want to do some
> gsignal to handle mouse event. I click the mouse and move a another
> position and release. I can get the position of the firs click and the
> release position,  then I would to draw a rectangle to display the
> region I have selected. I need some hints on what functions should I
> look for. I tried to google but don't know how.
>
The GtkImage widget is just for showing images. If you want to start doing
interactive graphics, I'd suggest moving to the more general GtkDrawingArea
widget and connecting to the expose-event signal. You can then use GdkPixbuf
for loading and drawing the image onto the drawing area. And then draw a
rectangle on top with gdkDrawRectangle().

See demos drawingArea and images.

Michael

>
> Thanks.
>
> --
> HUANG Ronggui, Wincent
> PhD Candidate
> Dept of Public and Social Administration
> City University of Hong Kong
> Home page: http://asrr.r-forge.r-project.org/rghuang.html
>
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