xrectdraw Draw geometry of a rectangular screen region
	git clone https://noxz.tech/git/xrectdraw.git
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commit: 1e2cfd2b86b828ac0f8b64ad6262ff25ebe069a8
parent: 
author: Chris Noxz <chris@noxz.tech>
date:   Thu, 31 Oct 2019 16:00:31 +0100

Initial commit

diff --git a/xrectdraw.c b/xrectdraw.c
@@ -0,0 +1,146 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
+Display *dpy;
+int screen;
+Window root;
+Window win;
+Drawable drw;
+XColor color;
+
+void
+draw(int x, int y, int width, int height)
+{
+    int i;
+    XWindowAttributes wa;
+    XSetWindowAttributes swa;
+    XClassHint ch = {"xdrwrct", "xdrwrct"};
+    XIM xim;
+    XIC xic;
+
+    int ix = x - 2,
+        iy = y - 2,
+        iw = 2,
+        ih = height + 5;
+
+    swa.border_pixel = 0;
+    swa.background_pixel = color.pixel;
+    swa.override_redirect = 1;
+    swa.event_mask = ExposureMask | KeyPressMask | ButtonPressMask;
+
+    XGetWindowAttributes(dpy, root, &wa);
+
+    for (i = 0; i < 4; i++) {
+        win = XCreateWindow(dpy, root, ix, iy, iw, ih, 0,
+            CopyFromParent, CopyFromParent, CopyFromParent,
+            CWOverrideRedirect | CWBackPixel | CWEventMask, &swa);
+
+        XSetClassHint(dpy, win, &ch);
+
+        xim = XOpenIM(dpy, NULL, NULL, NULL);
+        xic = XCreateIC(xim, XNInputStyle, XIMPreeditNothing | XIMStatusNothing,
+            XNClientWindow, win, XNFocusWindow, win, NULL);
+
+        XMapRaised(dpy, win);
+        XSetInputFocus(dpy, win, RevertToParent, CurrentTime);
+
+        switch (i) {
+        case 0:
+            ix += (width + 3);
+            break;
+        case 1:
+            ix -= (width + 3);
+            iw = (width + 5);
+            ih = 2;
+            break;
+        case 2:
+            ih = 5;
+            iy += (height + 3);
+            break;
+        }
+    }
+}
+
+int
+hex(const char c)
+{
+    if (c >= 0x30 && c <= 0x39)
+        return c - 0x30;
+    else if (c >= 0x41 && c <= 0x46)
+        return c - 0x41 + 10;
+    else if (c >= 0x61 && c <= 0x66)
+        return c - 0x61 + 10;
+    else
+        puts("error: cannot set color");
+}
+
+void
+setcolor(const char *clr)
+{
+    int i, r;
+    const char *ptr;
+
+    color.flags = DoRed | DoGreen | DoBlue;
+    for (i = 0; i < 3; i++) {
+        ptr = clr + (1 + i * 2);
+        r = (hex(ptr[0]) * 16 + hex(ptr[1])) * 256;
+
+        switch (i) {
+        case 0:
+            color.red = r;
+            break;
+        case 1:
+            color.green = r;
+            break;
+        case 2:
+            color.blue = r;
+            break;
+        }
+    }
+    XAllocColor(dpy, DefaultColormap(dpy, screen), &color);
+}
+
+int
+main(int argc, char *argv[])
+{
+    int width, height,
+        x, y;
+
+    if (argc != 6
+        || strcmp(argv[1], "-h") == 0
+        || strcmp(argv[1], "--help") == 0) {
+        printf("usage: %s x y width height #RRGGBB\n", argv[0]);
+        return 1;
+    }
+
+    if (!(dpy = XOpenDisplay(NULL)))
+        puts("error: cannot open display");
+    screen = DefaultScreen(dpy);
+    root = RootWindow(dpy, screen);
+
+    x = atoi(argv[1]);
+    y = atoi(argv[2]);
+    width = atoi(argv[3]);
+    height = atoi(argv[4]);
+    setcolor(argv[5]);
+
+    draw(x, y, width, height);
+
+    XEvent ev;
+    for (;;) {
+        XNextEvent(dpy, &ev);
+        if (ev.type == Expose)
+            continue;
+        else if (ev.type == KeyPress && ev.xkey.keycode == 0x09)
+            break;
+        else if (ev.type == ButtonPress)
+            XSetInputFocus(dpy, win, RevertToParent, CurrentTime);
+    }
+
+    XCloseDisplay(dpy);
+    return 0;
+}