/*
Scaling Pixmap.

Ryzen 5 5600x + VMware Player + Ubuntu Linux 20.04 LTS.
1920 x 1080.
slow result : 0.510753 sec
fast result : 0.000045 sec
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <X11/Xlib.h>
#include <X11/xpm.h>
#include <math.h>
#include <time.h>

/* include xpm binary */
#include "bg01.xpm"
#define XPM_W 640
#define XPM_H 360
#define XPM_NAME bg01_xpm

/*
#include "bg02.xpm"
#define XPM_W 320
#define XPM_H 180
#define XPM_NAME bg02_xpm
*/

/* kind. 0: slow, 1: fast */
#define SCALING_KIND 1

#define WIN_X 0
#define WIN_Y 64
#define BORDER 0

#ifndef M_PI
#define M_PI 3.14159265358979
#endif

#define deg2rad(x) (x * M_PI / 180.0)

/* get a color value from a color name */
static unsigned long
get_color(Display *dpy, char *colorname)
{
    Colormap cmap;
    XColor near_color, true_color;

    cmap = DefaultColormap(dpy, DefaultScreen(dpy));
    XAllocNamedColor(dpy, cmap, colorname, &near_color, &true_color);
    return near_color.pixel;
}

/* scale Pixmap */
static void
scale_pixmap(Display *dpy, Drawable win,
             Pixmap *src, Pixmap *dst,
             int src_w, int src_h, int dst_w, int dst_h)
{
    GC gc;
    float xscale, yscale;
    int x, y;
    struct timespec start, end;
    double diff;

    xscale = (float)src_w / dst_w;
    yscale = (float)src_h / dst_h;

    gc = XCreateGC(dpy, win, 0, 0);
    XSetGraphicsExposures(dpy, gc, False);

    timespec_get(&start, TIME_UTC);

    switch (SCALING_KIND)
    {
    case 0:
        /* slow */
        for (y = 0; y < dst_h; y++)
        {
            int sy = (int)(y * yscale);
            for (x = 0; x < dst_w; x++)
                XCopyArea(dpy, *src, *dst, gc, (int)(x * xscale), sy, 1, 1, x, y);
        }
        break;
    case 1:
        /* fast */
        for (x = dst_w - 1; x >= 0; x--)
            XCopyArea(dpy, *src, *dst, gc, (int)(x * xscale), 0, 1, src_h, x, 0);
        for (y = dst_h - 1; y >= 0; y--)
            XCopyArea(dpy, *dst, *dst, gc, 0, (int)(y * yscale), dst_w, 1, 0, y);
        break;
    default:
        break;
    }

    XFreeGC(dpy, gc);

    timespec_get(&end, TIME_UTC);
    diff = (end.tv_sec + (double)end.tv_nsec / 1000000000) - (start.tv_sec + (double)start.tv_nsec / 1000000000);
    printf("%lf sec\n", diff);
}

/* update and draw */
static void
update(Display *dpy, Drawable win, GC gc, double ang, Pixmap pix, Pixmap buf)
{
    XWindowAttributes xgwa;
    int r, x, y;
    int buf_w, buf_h;

    /* get window attributes */
    XGetWindowAttributes(dpy, win, &xgwa);
    buf_w = xgwa.width;  /* window width */
    buf_h = xgwa.height; /* window height */

    scale_pixmap(dpy, win, &pix, &buf, XPM_W, XPM_H, buf_w, buf_h);

    r = 64;
    x = 0;
    /* x = r * cos(deg2rad(ang)); */
    y = r * sin(deg2rad(ang));

    /* clear window */
    XClearWindow(dpy, win);

    /* draw image (Pixmap) */
    XSetGraphicsExposures(dpy, gc, False);
    XCopyArea(dpy, buf, win, gc, 0, 0, buf_w, buf_h, x, y); /* copy Pixmap */
}

int main(void)
{
    Display *dpy;
    Window root;
    Window win;
    int screen;
    int display_w, display_h;
    XEvent evt;
    unsigned long black, white;
    XWindowAttributes xgwa;
    GC gc;
    Pixmap pix;
    Pixmap buf;
    int busy_loop;
    double ang;

    /* open display */
    dpy = XOpenDisplay(NULL);
    root = DefaultRootWindow(dpy);
    screen = DefaultScreen(dpy);

    /* get display size */
    display_w = DisplayWidth(dpy, screen);
    display_h = DisplayHeight(dpy, screen);
    printf("Screen: %d x %d\n", display_w, display_h);

    /* get color black and white */
    white = WhitePixel(dpy, screen);
    black = BlackPixel(dpy, screen);

    /* create window */
    win = XCreateSimpleWindow(dpy, root,
                              WIN_X, WIN_Y, display_w, display_h, BORDER,
                              white, black);

    XSelectInput(dpy, win, KeyPressMask | ExposureMask);

    XMapWindow(dpy, win);

    /* wait display window */
    do
    {
        XNextEvent(dpy, &evt);
    } while (evt.type != Expose);

    XMoveWindow(dpy, win, WIN_X, WIN_Y);

    /* create graphics context */
    gc = XCreateGC(dpy, win, 0, 0);
    XSetGraphicsExposures(dpy, gc, False);

    /* load image */
    if (XpmCreatePixmapFromData(dpy, win, XPM_NAME, &pix, NULL, NULL))
    {
        fprintf(stderr, "Error not load xpm.");
        return 1;
    }

    XGetWindowAttributes(dpy, win, &xgwa);
    buf = XCreatePixmap(dpy, win, display_w, display_h, xgwa.depth);
    XSetForeground(dpy, gc, get_color(dpy, "green"));
    XFillRectangle(dpy, buf, gc, 0, 0, display_w, display_h);

    ang = 0;

    busy_loop = 1;
    while (busy_loop)
    {
        /* event */
        while (XPending(dpy))
        {
            XNextEvent(dpy, &evt);
            switch (evt.type)
            {
                /*
            case Expose:
                if (evt.xexpose.count == 0)
                {
                }
                break;
                */
            case KeyPress:
                busy_loop = 0;
                break;
            default:
                break;
            }
        }

        update(dpy, win, gc, ang, pix, buf);
        ang += 4.0;
        if (ang >= 360)
            ang -= 360;

        XFlush(dpy);
        usleep(16 * 1000); /* wait */
    }

    XFreePixmap(dpy, pix);
    XFreePixmap(dpy, buf);
    XFreeGC(dpy, gc);

    XDestroyWindow(dpy, win);
    XCloseDisplay(dpy);
    return 0;
}