Re: Get position of cursor in widget?
Le lundi 16 juillet 2007 12:50, charlesvpacker a écrit : I'm a GTK newbie who has successfully taken the very first steps toward building a custom image processing application. I've figured out how to read and display an image using a GtkImage and GtkPixbuf. I've also modified a block of pixels in the existing pixbuf and updated the displayed image via gtk_image_set_from_pixbuf. Now I want to get the pixel position of the mouse cursor resting on the image. I don't recall seeing a GTK tutorial on capturing pointer position or motion. Could somebody, um, point me to one? If you want this from within a mouse event handler, you can use the (x,y) and (x_root,y_root) members provided by all the mouse event types. The first pair gives the position of the mouse relative to the event window and the second the position relative to the screen origin. If you're not in a handler, you still have gdk_window_get_pointer() and gdk_display_get_pointer(). See the Gdk reference manual for more infos (sections 'Event structures', 'Windows' and 'Display'). -- Cédric Lucantis ___ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
Re: Image process in gdk
Le dimanche 20 mai 2007 17:45, Luis Ramirez a écrit : Hello I am just a beginner in gtk and after working with the excellent samples available I wanted to begin with a simple program that loads an image and applies different processes on it (brightness, BW, rotate, ...). If I load and process the image before gtk_main() everything goes right but if I link the call_back of a Button to a function, the image does not change. I have tried to use the widget expose_event but it works with a widget created with gtk_drawing_area_new(), but not with a widget created with gdk_pixbuf_new_from_file(). It looks like you are confusing GdkPixbuf and GtkPixbuf. A GdkPixbuf is not a widget but only an object storing a bitmap, while a GtkPixbuf is a widget displaying a GdkPixbuf. Anyway, GtkPixbuf is deprecated so you should use GtkImage instead. If it's not enough for your needs, you'll have to create your own widget extending GtkDrawingArea, see the Gtk tutorial (section 'Writing your own widgets') for more infos about that. Do you have any simple example about it?. It is simpler to show images with cairo? There's also a complete example in the tutorial (scribble). Cairo is a vector graphics lib, which is very different from bitmap graphics. I never used it, so I don't know if it's easier, it's just another world and the choice depends on what you want to do. -- Cédric Lucantis ___ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
Re: Gtk+ and multithreating
Le lundi 14 mai 2007 20:20, Michael Ekstrand a écrit : On Mon, 2007-05-14 at 19:53 +0200, Michelle Konzack wrote: So, can anyone provide me with a Tutorial HOW TO MULTITHREAD those functions some_code_to_update_the_dialog ? And maybe some other tips... Can you do everything asynchronously? Initiate your connections, and set up some GIOChannels to watch for data availability? That will let you set up callbacks so the GLib main loop will notify your program as bits of data are available from each server. You don't block on communication, your GUI stays responsive, and you don't have to worry about the complexities of multithreading. - Michael Michael is probably right, but to answer your question there's a good documentation about that in the GLib manual. See the sections 'Threads', 'Thread Pools' and 'Asynchronous Queues' under 'Glib Core Application Support'. If you want to know more, there's a tutorial here (about pthread but with a general introduction) : http://www.llnl.gov/computing/tutorials/pthreads -- Cédric Lucantis ___ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
Re: Simple draw question
You should never draw anything in an enter/leave callback, but only in an expose event. Also note that creating/destroying a GC each time you draw it is very slow, so you should do something like this instead: Ok, I have questions here and they are because I really want to know why and not start anything. 1. Why is drawing in the enter in leave callback not something you should do? Is it because if you do to much it can cause a backlog of events? Merely a 'good design' question, but also because some prepare/release stuff is required before and after drawing on a GdkWindow (basicaly to set the clipping region and to setup the double buffer and copy its contents after the drawing operations). This is done by gdk_window_begin_paint_rect() and gdk_window_end_paint() which are automatically called by gtk when an expose event is processed. I think you can also call these yourself if you really want to keep your drawing within the leave/enter events, but a more 'conventional' way is to invalidate the window and then call gdk_window_process_updates() to process the expose event immediately. You'll find a lot of interesting things about that in the GdkWindow doc. 2. Actually while creating and destroying a GC may be slow (and I don't think it is actually that slow) it seems that in this case I should have just looked them up off the widget (which I didn't know there were several GCs off of the widget style). Not sure it is that slow, but using an existing one is obviously faster than creating it. It's also better (but of course not mandatory) to use the ones provided by the widget style, first because that's why they are here, and because it'll keep your app consistent if the user modify some style/resource settings (but I don't know much about that). For info, manys GCs are created by the style, see gtkstyle.h for a list of them. 3. I did try what you recommended and basically I found this. The expose event was not fired enough. I _think_ what happens is that GTK optimizes calls to event handlers and so if you send it 5 requests to expose on the same object and they stack up in the dispatcher, you only get one expose event called (this is actually the right thing to do) and so when I was testing this, I would get only one call to expose and so the box would never be drawn. (my guess could be totally wrong here). I don't understand what you mean here. It's true that gtk optimizes the invalidate calls, not by stacking them but by keeping an 'update_area' for each window and thus only redrawing the dirty part of it when nothing else has to be done (this is managed by an idle event). But even if you get only one call to expose, shouldn't it be enough to redraw it ? Finally, note that I'm definitely not a gtk wizard, so maybe am I only saying stupid things here ;) -- Cédric Lucantis ___ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
Re: Simple draw question
Le samedi 5 mai 2007 00:48, Kevin DeKorte a écrit :
Hi,
I have a situation where I need to highlight an eventbox when a user
enters it and unhighlight it when the users leaves. I'm using this code
but the color I'm drawing in the leave_button_callback is always wrong
and varies from run to run with the program. Any ideas what I am doing
wrong. I was looking for a XOR option or something but I don't see it.
gboolean enter_button_callback (GtkWidget *widget, GdkEventCrossing
*event, gpointer data)
{
GdkGC *gc;
gc = gdk_gc_new(widget-window);
gdk_draw_rectangle(widget-window, gc, FALSE, 0, 0,
widget-allocation.width-1,
widget-allocation.height-1);
gdk_gc_unref(gc);
return FALSE;
}
gboolean leave_button_callback (GtkWidget *widget, GdkEventCrossing
*event, gpointer data)
{
GdkGC *gc;
GdkGCValues v;
GdkColor color;
GdkColormap *map;
gc = gdk_gc_new(widget-window);
map = gdk_gc_get_colormap(gc);
gdk_gc_get_values(gc,v);
gdk_colormap_query_color(map,v.background.pixel,color);
gdk_gc_set_foreground(gc,color);
gdk_draw_rectangle(widget-window, gc, FALSE, 0, 0,
widget-allocation.width-1,
widget-allocation.height-1);
gdk_gc_unref(gc);
return FALSE;
}
You should never draw anything in an enter/leave callback, but only in an
expose event. Also note that creating/destroying a GC each time you draw it
is very slow, so you should do something like this instead:
enter_button_callback()
{
gtk_widget_set_state(widget, GTK_STATE_PRELIGHT);
/* not sure this is required, as it's maybe called by set_state? */
/* you may use gdk_window_invalidate_* instead for better performances,
* see the docs for more infos */
gtk_widget_queue_draw(widget);
}
leave_button_callback()
{
/* same with GTK_STATE_NORMAL */
}
expose_button_callback()
{
gdk_draw_rectangle(widget-window, widget-state-fg_gc[widget-state],
...)
}
--
Cédric Lucantis
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Re: Radio button
My application has a number of radio buttons stored in a horizontal button box. The radio buttons were created with gtk_radio_button_new_with_label and gtk_radio_button_new_with_label_from_widget. Each button and its label is left-justified (aligned?) within its allocation rectangle. I want the button and the label to be centered in the allocation rectangle. The machines on which my application will be deployed are running Gtk version 2.0. Thanks in advance for any help. You need a GtkAlignment widget, documented in the manual. -- Cédric Lucantis ___ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
Re: Cross compilation for windows
Hi, I thought of running my application on windows, so i searched in google and i got the script to setup cross compilation environment for window.And I succeded in setting up the environment for cross-compilation using the sources binutils-2.11.2.tar.bz2 gcc-2.95.3.tar.gz mingw-runtime-1.0.1-20010726-src.tar.gz w32api-1.0.1-20010726-src.tar.gz Now my problem is how to cross compile? I dont have any idea to cross compile, There's a 'cross compiling the glib package' in glib user's manual. It worked fine for me, but I'm only using glib, not gtk so I can't help for it. Anyway you'll probably prefer to use the prebuild packages available on gtk.org (follow the Projects/GTK+ for Win32 link) -- Cédric Lucantis ___ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
Re: Need your help on the widget's width and height
Le Vendredi 17 Mars 2006 13:17, yeajchao a écrit :
Hello everyone
I am writing my own gtk widget
and i want my own widget's height and width ratio is 0.8, like this:
widget-allocation.height / widget-allocation.width == 0.8
and my gtk_mywidget_size_allocate() function like this:
Start of my code
---
static void
gtk_mywidget_size_allocate(GtkWidget *widget,
GtkAllocation *allocation)
{
??
if (allocation-height = allocation-width * 0.8)
allocation-height = allocation-width;
else
allocation-width = allocation-height/0.8;
widget-allocation = *allocation;
??
}
End of my code -
But ,i found ,in my test application,my own widget's size didn't change
Who can tell my what's wrroy ?
And who can tell my how to maintain my widget's height, width ratio to a
constant value ?
Any help would be much appreciated !
The GtkAspectFrame widget seems to be what you are looking for. You
can probably use it or at least have a look at its source code. It
looks like you already read it, but just in case there is a chapter
'Creating your own widget' in the Gtk tutorial which explains the size
negotiation process.
Bye,
--
Cédric Lucantis
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