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Diffstat (limited to 'reference/C/X_EXAMPLES/root_colour.c')
| -rw-r--r-- | reference/C/X_EXAMPLES/root_colour.c | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/reference/C/X_EXAMPLES/root_colour.c b/reference/C/X_EXAMPLES/root_colour.c new file mode 100644 index 0000000..430baa8 --- /dev/null +++ b/reference/C/X_EXAMPLES/root_colour.c @@ -0,0 +1,235 @@ +/************************************************************************ + * + * Purpose: Program to randomly change the root window colour on X Displays. + * + * Description. + * The program randomly selects a target colour and then + * performs a basic interpolation to move from the current + * colour to the target colour. When the target has been + * reached, a new target is selected and the process is + * repeated. + * + * Notes: 1) No attempt is made to see if the client supports colour. + * 2) Other applications may cause problems if they have allocated + * all the available colour cells in the colour map. + * 3) Use the following command to compile. + * + * gcc root_col.c -lX11 + * 4) Tested on Linux running XFree386 and FVWM + * and SunOS 4.1.3 running X11R5 and Motif. + * + * Author: M.J. Leslie + * + * Date: 26-Mar-95 + * + ************************************************************************/ +/****************** Includes ********************************************/ + +#include <X11/Xlib.h> +#include <X11/Xutil.h> +#include <X11/Xos.h> + +#include <stdio.h> +#include <stdlib.h> + +/************************************************************************/ + +#define INC 512 /* Increments between colours. */ +#define MAX_COL 65536 /* Max number of colours. */ +#define SECONDS 2 /* # of seconds between updates */ + +/****************** Functions *******************************************/ + +void help(char * proganme); /* Give some help on syntax. */ + + /* Used to see if a colour gun has + * reached its required intensity + */ +int reached_target( unsigned short colour, unsigned short target_colour); + +void root_colour(int seconds); /* Where the real work starts. */ + + /* Change the colour of the + * root window */ +void change_colour(Display * display, + Window root, + Colormap colormap, + XColor colour); + +/************************************************************************/ + +main(int argc, char * argv[]) + { + int seconds=SECONDS; + /* Have we got cmd line parms? */ + if (argc > 1 ) + { + /* Yes. Is Help Required? */ + if ( !strcmp(argv[1], "-h")) + { + help(argv[0]); /* Yes. */ + exit(0); + } + /* Do we have an integer. */ + if (!sscanf(argv[1], "%u", &seconds)) + { + help(argv[0]); /* No. */ + exit(0); + } + + } + + root_colour(seconds); /* Start colouring the + * root window. + * 'seconds' is the # of seconds + * between updates. */ + } + +/************************************************************************/ + +void root_colour(int seconds) + { + Display * display; + int screen; + char * display_name=NULL; + Window root; + Colormap colormap; + XColor colour, target_colour; + + /**************************************** + * + * Initalise the X environment. + * + ****************************************/ + + /* Connect to X display server. */ + display=XOpenDisplay(display_name); + + /* Get screen ID */ + screen=DefaultScreen(display); + + root=RootWindow(display, screen); + + /* Load the default colour map */ + colormap = DefaultColormap(display, screen); + + /* Starting colour - Grey */ + colour.red=MAX_COL/2; colour.green=MAX_COL/2; colour.blue=MAX_COL/2; + + colour.flags = DoRed|DoGreen|DoBlue; + + /**************************************** + * + * Loop forever. + * + ****************************************/ + + while(1) + { + /* Increments used to go from the current + * colour to the target colour. */ + + int red_inc, green_inc, blue_inc; + + /* Flags used to show when the target + * colour has been reached. + * + * 0 = Arrived at the target colour. + * 1 = Not arrived at the target colour. + * */ + int red=1, green=1, blue=1; + + /* Random selection of a new target + * colour */ + + target_colour.red=rand()%MAX_COL; + target_colour.green=rand()%MAX_COL; + target_colour.blue=rand()%MAX_COL; + + /* Calculate the direction to go in + * to reach the new target colour. */ + + red_inc = ( target_colour.red > colour.red ) ? INC : INC * -1; + green_inc = ( target_colour.green > colour.green) ? INC : INC * -1; + blue_inc = ( target_colour.blue > colour.blue ) ? INC : INC * -1; + + + /* Loop until all three colours have + * reached their required value. */ + + while(red || green || blue) + { + /* Change the colour of the root window */ + + change_colour(display, root, colormap, colour); + + /* Increment onto the next colour. */ + + if ( red=reached_target(colour.red, target_colour.red)) + colour.red += red_inc; + if (green=reached_target(colour.green, target_colour.green)) + colour.green += green_inc; + if ( blue=reached_target(colour.blue, target_colour.blue)) + colour.blue += blue_inc; + + sleep(seconds); /* Pause...... */ + + } + + } + + XCloseDisplay(display); + } + +/************************************************************************/ + +int reached_target( unsigned short colour, unsigned short target_colour) + { + return (( colour >= target_colour-INC && colour <= target_colour+INC) ?0:1); + } + +/************************************************************************/ + +void change_colour(Display * display, + Window root, + Colormap colormap, + XColor colour) + { + /* Reserve a cell in the colour map */ + + XAllocColorCells(display, colormap, False, NULL, 0, &colour.pixel, 1); + + /* Place the required colour in the map.*/ + + XStoreColor(display, colormap, &colour); + + /* Free the cell so it can be reused. */ + + XFreeColors(display, colormap, &colour.pixel, 1, 0); + + /* Set the root window colour. */ + + XSetWindowBackground(display, root, colour.pixel); + + /* Refresh the root window (with the new + * colour). */ + + XClearWindow(display, root); + + } + +/************************************************************************/ + +void help(char * progname) + { + + printf("\n%s information\n\n", progname); + + puts(" This program randomly changes the color of the screen background."); + puts("\n Syntax:\n"); + + printf("\t%s \tRun the program with with a default update time\n", progname); + printf("\t\t \tof %d seconds.\n", SECONDS); + printf("\t%s 3\tRun the program specifing the delay between updates.\n", progname); + printf("\t%s -h\tHelp. you are reading it.\n\n", progname); + } |