testprogram.c
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| /* | |
| ____ _____ | |
| /\__ \ /\ ___\ | |
| \/__/\ \ \ \ \__/_ | |
| \ \ \ \ \____ \ | |
| _\_\ \ \/__/_\ \ | |
| /\ _____\ /\ _____\ | |
| \/______/ \/______/ | |
| Copyright (C) 2011 Joerg Seebohn | |
| This program is free software; you can redistribute it and/or modify | |
| it under the terms of the GNU General Public License as published by | |
| the Free Software Foundation; either version 2 of the License, or | |
| (at your option) any later version. | |
| This program demonstrates how an X11 window with OpenGL support | |
| can be drawn transparent. | |
| The title bar and window border drawn by the window manager are | |
| drawn opaque. | |
| Only the background of the window which is drawn with OpenGL | |
| glClearColor( 0.7, 0.7, 0.7, 0.7) ; | |
| glClear(GL_COLOR_BUFFER_BIT) ; | |
| is 30% transparent. | |
| Compile it with: | |
| gcc -std=gnu99 -o test testprogram.c -lX11 -lGL | |
| */ | |
| #include<X11/Xlib.h> | |
| #include<X11/Xatom.h> | |
| #include<X11/keysym.h> | |
| #include<GL/gl.h> | |
| #include<GL/glx.h> | |
| #include<stdio.h> | |
| #include<stdlib.h> | |
| intmain(intargc, char*argv[]) | |
| { | |
| Display*display=XOpenDisplay( 0 ) ; | |
| constchar*xserver=getenv( "DISPLAY" ) ; | |
| if (display==0) | |
| { | |
| printf("Could not establish a connection to X-server '%s'\n", xserver ) ; | |
| exit(1) ; | |
| } | |
| // query Visual for "TrueColor" and 32 bits depth (RGBA) | |
| XVisualInfovisualinfo ; | |
| XMatchVisualInfo(display, DefaultScreen(display), 32, TrueColor, &visualinfo); | |
| // create window | |
| Windowwin ; | |
| GCgc ; | |
| XSetWindowAttributesattr ; | |
| attr.colormap=XCreateColormap( display, DefaultRootWindow(display), visualinfo.visual, AllocNone) ; | |
| attr.event_mask=ExposureMask | KeyPressMask ; | |
| attr.background_pixmap=None ; | |
| attr.border_pixel=0 ; | |
| win=XCreateWindow( display, DefaultRootWindow(display), | |
| 50, 300, 400, 100, // x,y,width,height : are possibly opverwriteen by window manager | |
| 0, | |
| visualinfo.depth, | |
| InputOutput, | |
| visualinfo.visual, | |
| CWColormap|CWEventMask|CWBackPixmap|CWBorderPixel, | |
| &attr | |
| ) ; | |
| gc=XCreateGC( display, win, 0, 0) ; | |
| // set title bar name of window | |
| XStoreName( display, win, "Transparent Window with OpenGL Support" ) ; | |
| // say window manager which position we would prefer | |
| XSizeHintssizehints ; | |
| sizehints.flags=PPosition | PSize ; | |
| sizehints.x=50 ; sizehints.y=300 ; | |
| sizehints.width=400 ; sizehints.height=100 ; | |
| XSetWMNormalHints( display, win, &sizehints ) ; | |
| // Switch On >> If user pressed close key let window manager only send notification >> | |
| Atomwm_delete_window=XInternAtom( display, "WM_DELETE_WINDOW", 0) ; | |
| XSetWMProtocols( display, win, &wm_delete_window, 1) ; | |
| { | |
| // change foreground color to brown | |
| XColorxcol ; | |
| xcol.red=153*256 ; // X11 uses 16 bit colors ! | |
| xcol.green=116*256 ; | |
| xcol.blue=65*256 ; | |
| XAllocColor( display, attr.colormap, &xcol) ; | |
| XGCValuesgcvalues ; | |
| gcvalues.foreground=xcol.pixel ; | |
| XChangeGC( display, gc, GCForeground, &gcvalues) ; | |
| } | |
| // create OpenGL context | |
| GLXContextglcontext=glXCreateContext( display, &visualinfo, 0, True ) ; | |
| if (!glcontext) | |
| { | |
| printf("X11 server '%s' does not support OpenGL\n", xserver ) ; | |
| exit(1) ; | |
| } | |
| glXMakeCurrent( display, win, glcontext ) ; | |
| // now let the window appear to the user | |
| XMapWindow( display, win) ; | |
| intisUserWantsWindowToClose=0 ; | |
| while( !isUserWantsWindowToClose ) | |
| { | |
| intisRedraw=0 ; | |
| /* XPending returns number of already queued events. | |
| * If no events are queued XPending sends all queued requests to the X-server | |
| * and tries to read new incoming events. */ | |
| while( XPending(display) >0 ) | |
| { | |
| // process event | |
| XEventevent ; | |
| XNextEvent( display, &event) ; | |
| switch(event.type) | |
| { // see 'man XAnyEvent' for a list of available events | |
| caseClientMessage: | |
| // check if the client message was send by window manager to indicate user wants to close the window | |
| if ( event.xclient.message_type==XInternAtom( display, "WM_PROTOCOLS", 1) | |
| &&event.xclient.data.l[0] ==XInternAtom( display, "WM_DELETE_WINDOW", 1) | |
| ) | |
| { | |
| isUserWantsWindowToClose=1 ; | |
| } | |
| break; | |
| caseKeyPress: | |
| if (XLookupKeysym(&event.xkey, 0) ==XK_Escape) | |
| { | |
| isUserWantsWindowToClose=1 ; | |
| } | |
| break ; | |
| caseExpose: | |
| isRedraw=1 ; | |
| break ; | |
| default: | |
| // do nothing | |
| break ; | |
| } | |
| } | |
| // ... all events processed, now do other stuff ... | |
| if (isRedraw) | |
| { // needs redraw | |
| // use opengl to clear background in (transparent) light grey | |
| glClearColor( 0.7, 0.7, 0.7, 0.7) ; | |
| glClear(GL_COLOR_BUFFER_BIT) ; | |
| glXSwapBuffers( display, win) ; | |
| glXWaitGL() ; | |
| // draw string with X11 | |
| XDrawString( display, win, gc, 10, 20, "Hello ! ", 7) ; | |
| } | |
| // ... do something else ... | |
| } | |
| XDestroyWindow( display, win ) ; | |
| win=0 ; | |
| XCloseDisplay( display ) ; | |
| display=0 ; | |
| return0 ; | |
| } |