/*

 x blender by shudder <shudder@gbg.bg>
 gcc -Wall -O2 -L/usr/X11R6/lib -I/usr/X11R6/include -o xblend xblend.c -lX11 -lXpm 

*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/xpm.h>

#define MAXCOLORS sizeof(colors)/sizeof(char *)
#define OUTPUT_FILE "xblender.xpm"

char *colors[]={"#000000", "#ffffff", "#ff0000",
		"#00ff00", "#0000ff", "#ffff00",
		"#ff00ff", "#00ffff", "#ffaa00"};

int w = 200;
int h = 100;
int screen;
Display *display;
Colormap colormap;
Window win;

struct {
  Window w;
  XColor c;
} cw[MAXCOLORS];

Pixmap blend(XColor c1, XColor c2) {
  int i;
  int red, green, blue;
  XColor color;
  Pixmap pixmap;
  GC gc;

  pixmap = XCreatePixmap(display, win, w, h, DefaultDepth(display, screen));
  gc = XCreateGC(display, pixmap, 0, 0);

  color.red = red = c1.red;
  color.green = green = c1.green;
  color.blue = blue = c1.blue;

  for(i=0; i<w+1; i++) {
    XAllocColor(display, colormap, &color);
    XSetForeground(display, gc, color.pixel);
    XDrawLine(display, pixmap, gc, i, 0, i, h);

    color.red = red += (c2.red-c1.red)/w;
    color.green = green += (c2.green-c1.green)/w;
    color.blue = blue += (c2.blue-c1.blue)/w;
  }

  XSetWindowBackgroundPixmap(display, win, pixmap);
  XClearWindow(display, win);

  return pixmap;
}

long setcolor(int r, int g, int b, XColor *color) {
  color->red = r;
  color->green = g;
  color->blue = b;

  XAllocColor(display, colormap, color);

  return color->pixel;
}

long setnamedcolor(char *name, XColor *color) {
  XAllocNamedColor(display, colormap, name, color, color);
  return color->pixel;
}

int main(int argc, char *argv[]) {
  int i, p;
  int black, white;
  int quit;
  char *title = "x blender";
  XColor color1, color2;
  XEvent event;
  XFontStruct *font;
  Window root;
  Window c1, c2;
  Window blend_b, save_b;
  GC gc;
  Atom watom;
  XTextProperty t;
  XpmAttributes xa;

  if (argc < 3) {
    fprintf(stderr, "usage: %s color1 color2\n", argv[0]); exit(1); }
  if (!(display = XOpenDisplay(getenv("DISPLAY")))) {
    fprintf(stderr, "%s: unable to open display: %s\n", argv[0], getenv("DISPLAY")); exit(1); }

  screen = DefaultScreen(display);
  root = RootWindow(display, screen);
  font = XLoadQueryFont(display, "*helvetica*medium*-r*12*");
  black = BlackPixel(display, screen);
  white = WhitePixel(display, screen);
  colormap = DefaultColormap(display, screen);
  quit = 0;
  memset(&xa, 0, sizeof(XpmAttributes));

  win = XCreateSimpleWindow(display, root, 200, 200, w, h+100, 0, 0, white);
  XSelectInput(display, win, StructureNotifyMask);

  watom = XInternAtom(display, "WM_DELETE_WINDOW", False);
  XSetWMProtocols(display, win, &watom, 1);
  XStringListToTextProperty(&title, 1, &t);
  XSetWMName(display, win, &t);

  /* create 20x20 color boxes */
  for (i=0, p=2; i<MAXCOLORS; i++, p+=21) {
    cw[i].w = XCreateSimpleWindow(display, win, p, 102, 20, 20, 1, black, 
	setnamedcolor(colors[i], &cw[i].c));
    XSelectInput(display, cw[i].w, ButtonPressMask);
    XMapWindow(display, cw[i].w);
  }

  XAllocNamedColor(display, colormap, argv[1], &color1, &color1);
  XAllocNamedColor(display, colormap, argv[2], &color2, &color2);

  c1 = XCreateSimpleWindow(display, win, 40, 130, 50, 20, 1, black, color1.pixel);
  XMapWindow(display, c1);
  c2 = XCreateSimpleWindow(display, win, 95, 130, 50, 20, 1, black, color2.pixel);
  XMapWindow(display, c2);

  blend_b = XCreateSimpleWindow(display, win, 40, 155, 50, 20, 1, black, white);
  XSelectInput(display, blend_b, ExposureMask | ButtonPressMask);
  XMapWindow(display, blend_b);

  save_b = XCreateSimpleWindow(display, win, 95, 155, 50, 20, 1, black, white);
  XSelectInput(display, save_b, ExposureMask | ButtonPressMask);
  XMapWindow(display, save_b);

  gc = XCreateGC(display, blend_b, 0, 0);
  XSetForeground(display, gc, black);

  XMapWindow(display, win);

  while(!quit) {
    XNextEvent(display, &event);

    switch(event.type) {
      case Expose:
	if (event.xany.window == blend_b)
	  XDrawString(display, blend_b, gc, 10, 13, "Blend", 5);
	else if (event.xany.window == save_b)
	  XDrawString(display, save_b, gc, 13, 13, "Save", 4);
	break;
      case ButtonPress:
	if (event.xany.window == blend_b) blend(color1, color2);
	else if (event.xany.window == save_b)
	  XpmWriteFileFromPixmap(display, OUTPUT_FILE,
		blend(color1, color2), 0, &xa);
	else {
	  for (i=0; i<MAXCOLORS; i++) if (cw[i].w == event.xany.window) {

	    XSetWindowBackground(display,
		(event.xbutton.button == Button1) ? c1 : c2,
		setcolor(cw[i].c.red, cw[i].c.green, cw[i].c.blue,
		(event.xbutton.button == Button1) ? &color1 : &color2));
	    XClearWindow(display, (event.xbutton.button == Button1) ? c1 : c2);
	    break;
	  }
	}
	break;
      case ConfigureNotify:
	/* handle redrawing when main window is resized */
	if (event.xconfigure.width == w && event.xconfigure.height == h) break;
	w = event.xconfigure.width;
	h = event.xconfigure.height;
	blend(color1, color2);
	break;
      case ClientMessage: quit = 1;
    }
  }

  XCloseDisplay(display);

  return 0;
}