I'm currently making a project in my IT School and I work with SDL (The project is image processing and stuff like that), and currently I just display the image with SDL without interface (buttons etc...). I know a little bit about GTK so I want to know if I can display an image (here a SDL_Surface) into a GTK window
I made some research but nothing was very clear...
Thank you !
Drawing widgets using SDL
Drawing widgets(menu, buttons etc) using SDL drawing functions and handling actions by tracking the cursor position during the occurrence of event(on which item the cursor was while the event was performed).
This becomes very complicated and would be better to use an existing GUI library with some simple hacks. You can find code example for drawing a button here.
Copying SDL surface into target GUI widget
This involves copying pixel by pixel(predefined functions might be available to do the same, gdk_draw_rgb_image in case of gtk) of the sdl surface into target gui widget(can be a drawingArea in case of GTK).
Merging SDL window into a GUI widget
In X11 and win32 systems each windows are given with a window id and by default sdl and gtk would have separate window id resulting two different windows, we can exploit SDL_CreateWindowFrom function to use single window for sdl and gtk in which we will force both the libraries to use a single window id.
You can find similar question here.
GTK Plug and Socket
Plug and Socket enables embeeding widget from one process to another. GTK will create a socket and pass the socket id to SDL and SDL would create window from that socket ID.
Event loop handling:
After merging SDL with GTK you might find gtk and sdl have their own event loops hence handling events might not be as expected. To solve that issue you can handle
events in GTK and propagate the event to SDL using SDL_PushEvent function and vice versa in case you are using user defined events.
.
.
static SDL_Event SDLevent;
switch(event->keyval)
{
case GDK_KEY_m:
SDLevent.type = SDL_KEYUP;
SDLevent.key.keysym.sym = SDLK_m;
SDL_PushEvent(&SDLevent);
break;
.
.
.
This link has a nice explanation for above methods.
Related
I would like to embed a simple X11 window in a gtk widget.
I have found this gist https://gist.github.com/pastapojken/69f1e223fd926425f7ae770a95ec79a2 which does almost but not quite what I am looking for: It allows to add gtk widgets inside an X window, not the contrary.
I don't know if I am being clear as I am quite a newbie in both X11 and gtk. So here is a quick schema:
So is this even possible, any advice on how to make this work ? I feel like all I need to do is inherit from GtkWidget and set its GdkWindow to a wrapper of the XID like this:
win = gdk_x11_window_foreign_new_for_display(display, xid);
gtk_widget_set_window(myWidget, win);
But I was not sucessful this way, all I get is two top level windows as shown below.
I am running Fedora 32 on X11, NOT wayland
thanks!
I created two windows using GLFW. The first window has an OpenGL context and the second one doesn't. What I want to do is render the same scene to both windows using a single OpenGL context. Something like this.
glBindVertexArray(vaoId);
// ... tell OpenGL to draw on first window
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(...);
// ... swap first window buffers
// ... tell OpenGL to draw on second window
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(...);
// ... swap second window buffers
glBindVertexArray(0);
The problem is I don't know how to tell OpenGL to draw on a specific window. And I also don't know how to swap buffers for a specific window. If it's necessary, I can use Win32 API.
As far as I'm aware, GLFW does not directly support that in it's API. It generally considers a Window and a GL context as a unit. However, with the native APIs, you can do what you want. For windows 32 in partiuclar, have a look at wglMakeCurrent(). In GLFW, you can get the required context and window handles via GLFW's native access API. Note that you will only get a HWND that way, you will have to manually use GetDC() to get the device context of the window.
Be aware that switching contexts will imply flushing the GL command queue, which can have negative effects on the performance. See GL_KHR_context_flush_control for more details.
I've derived my own widget type from GtkWidget in order to use it as a drawing surface for OpenGL. To give OpenGL control over the underlying X11 Window, I need to disable the widget's double buffering - else the whole rendering result will be drawn over by GTK's buffer swap.
However, gtk_widget_set_double_buffered and the "double-buffered" property have been deprecated in the current version of GTK+3 for being too platform-dependent.
Is there a way to disable double buffering on the GDK or X11 level instead?
This is a rather old question, but I'll give it a shot.
In any even slightly more recent context (i.e. with GTK+ >= 3.16, which is over 6 years old by now), I guess the best solution would be to avoid rolling your own OpenGL widget and just use Gtk.GLArea instead: https://docs.gtk.org/gtk3/class.GLArea.html
Alternatively, if you happen to be stuck with an ancient GTK+ version, maybe on an embedded device, then there aren't many options besides gtk_widget_set_double_buffered (see also https://people.gnome.org/~shaunm/girdoc/C/Gtk.Widget.set_double_buffered.html): this does not set any X11/Xorg window flags or similar, but just changes the internal event handling of GTK+ to either send draw calls to an offscreen buffer, or directly to the visible surface.
Note that this offscreen buffer is completely separate from anything involving X or OpenGL.
The Gtk+ 3 migration guide shows how the GdkEventExpose.region field can be used to provide a fine-grained area for re-rendering widgets. We already do something like this in Inkscape to avoid rendering excessive amounts of complicated stuff on our drawing canvas.
However, the example in the guide shows how to do this for the old Gtk+ 2 expose_event handler.
How do I do the equivalent in a new Gtk+ 3 draw handler, which receives a "ready-clipped" Cairo context as a parameter, rather than a GdkEventExpose?
I guess one possibility is to use cairo_copy_clip_rectangle_list on the "ready-clipped" cairo context to obtain a list of rectangles that make up the region to draw. Does anyone have any experience of using this? Does it seem like a sensible approach?
Yes, you should use cairo_copy_clip_rectangle_list() on the cairo_t that you get in your widget's ::draw() signal handler. See this commit for an example:
http://git.gnome.org/browse/vte/commit/?id=21a064ac8b5925108b0ab9bd6516664c8cd3e268
Since I have not much clue, I decided to check the source code. GDK emits a GDK_EXPOSE event on a window and creates the GdkEventExpose instance for this.
This event is then handled in gtk/gtkmain.c via gtk_widget_send_expose():
http://git.gnome.org/browse/gtk+/tree/gtk/gtkwidget.c?id=eecb9607a5c0ee38eadb446545beccd0922cb0b8#n6104
This function clips the cairo_t to GdkEventExpose.region, as you already learned in the docs.
This then calls _gtk_widget_draw_internal() which emits the actual draw signal:
http://git.gnome.org/browse/gtk+/tree/gtk/gtkwidget.c?id=eecb9607a5c0ee38eadb446545beccd0922cb0b8#n5726
As far as I can see, nothing here let's you access the clip region directly. In gtk_widget_send_expose() the GdkEvent is added as userdata to the cairo context. However, this is not accessible, because all the involved functions and variables are static. So you'll have to use cairo_copy_clip_rectangle_list().
However, this sounds quite inefficent. First gdk_cairo_region transforms the region into a number of calls to cairo_rectangle and then cairo transforms this from its internal representation into a cairo_rectangle_list_t (which may fail if the clip is, for some reason, not a region). If you see this being slow, it might make sense to have some shortcut for this added to gtk directly.
This has been my problem since I started using openGL.
What code am I going to use to show text and get value. I could not use printf and scanf and my only header file is glut.h.
This has been my problem since I started using openGL.
What code am I going to use to show text
Difficult subject, because OpenGL itself doesn't deal with text output. You can:
render text to an image and display that
create a texture atlas from the glyphs of a font, then render from that font texture
draw the font glyph outlines as geometry
If you Google "OpenGL font rendering" you'll get a large number of results of papers on the topic. Recent and old ones alike.
and get value.
Not with OpenGL. OpenGL is a drawing API. You send it points, lines and triangles, and it draws nice pictures for you. User input is outside the scope of OpenGL. That's on part of the GUI system. Most likely one of
Windows GDI
MacOS Cocoa
X11
Standard user input event processing applies. Usually one uses a toolkit like Qt, GTK or similar. Those toolkits deal with user input processing through their event mechanism.
http://linux.die.net/man/3/glutstrokestring
How about this?
#include <openglut.h>
glutStrokeString(GLUT_STROKE_ROMAN, "I will draw this string at the origin of the model");