Fix behaviour when TrueColor / 24 bit depth is not available (#114)

* Fix regression introduced in c7ca547 which made nsxiv not start in
  non-TrueColor X server.
* Introduce a new fix for embedding into tabbed-alpha. 
* Fixes a visual glitch from original sxiv when drawing transparent images in 8
  bit depth. In 8 bit PseudoColor, `.pixel` is just an index into the 256
  defined colors and thus trying to extract rgb bits from it would result in
  visual glitch. The values `.color.red` on the other hand and so on are always
  integers between 0 and 0xFFFF representing the color as expected.
* Use XColor for win_bg/fg and mrk_fg

Co-authored-by: NRK <nrk@disroot.org>

image.c

@@ -577,7 +577,7 @@ void img_render(img_t *img)
 	int sx, sy, sw, sh;
 	int dx, dy, dw, dh;
 	Imlib_Image bg;
-	unsigned long c;
+	XColor c;
 
 	win = img->win;
 	img_fit(img);
@@ -646,7 +646,7 @@ void img_render(img_t *img)
 			imlib_image_put_back_data(data);
 		} else {
 			c = win->win_bg;
-			imlib_context_set_color(c >> 16 & 0xFF, c >> 8 & 0xFF, c & 0xFF, 0xFF);
+			imlib_context_set_color(c.red >> 8, c.green >> 8, c.blue >> 8, 0xFF);
 			imlib_image_fill_rectangle(0, 0, dw, dh);
 		}
 		imlib_blend_image_onto_image(img->im, 0, sx, sy, sw, sh, 0, 0, dw, dh);

nsxiv.h

@@ -416,9 +416,9 @@ struct win {
 	Window xwin;
 	win_env_t env;
 
-	unsigned long win_bg;
-	unsigned long win_fg;
-	unsigned long mrk_fg;
+	XColor win_bg;
+	XColor win_fg;
+	XColor mrk_fg;
 #if HAVE_LIBFONTS
 	XftColor bar_bg;
 	XftColor bar_fg;

thumbs.c

@@ -44,7 +44,7 @@ char* tns_cache_filepath(const char *filepath)
 
 	if (*filepath != '/')
 		return NULL;
-	
+
 	if (strncmp(filepath, cache_dir, strlen(cache_dir)) != 0) {
 		/* don't cache images inside the cache directory! */
 		len = strlen(cache_dir) + strlen(filepath) + 2;
@@ -469,14 +469,14 @@ void tns_mark(tns_t *tns, int n, bool mark)
 	if (n >= 0 && n < *tns->cnt && tns->thumbs[n].im != NULL) {
 		win_t *win = tns->win;
 		thumb_t *t = &tns->thumbs[n];
-		unsigned long col = win->win_bg;
+		unsigned long col = win->win_bg.pixel;
 		int x = t->x + t->w, y = t->y + t->h;
 
 		win_draw_rect(win, x - 1, y + 1, 1, tns->bw, true, 1, col);
 		win_draw_rect(win, x + 1, y - 1, tns->bw, 1, true, 1, col);
 
 		if (mark)
-			col = win->mrk_fg;
+			col = win->mrk_fg.pixel;
 
 		win_draw_rect(win, x, y, tns->bw + 2, tns->bw + 2, true, 1, col);
 
@@ -490,7 +490,7 @@ void tns_highlight(tns_t *tns, int n, bool hl)
 	if (n >= 0 && n < *tns->cnt && tns->thumbs[n].im != NULL) {
 		win_t *win = tns->win;
 		thumb_t *t = &tns->thumbs[n];
-		unsigned long col = hl ? win->win_fg : win->win_bg;
+		unsigned long col = hl ? win->win_fg.pixel : win->win_bg.pixel;
 		int oxy = (tns->bw + 1) / 2 + 1, owh = tns->bw + 2;
 
 		win_draw_rect(win, t->x - oxy, t->y - oxy, t->w + owh, t->h + owh,

window.c

@@ -80,12 +80,11 @@ void xft_alloc_color(const win_env_t *e, const char *name, XftColor *col)
 }
 #endif /* HAVE_LIBFONTS */
 
-void win_alloc_color(const win_env_t *e, const char *name, unsigned long *pixel)
+void win_alloc_color(const win_env_t *e, const char *name, XColor *col)
 {
-	XColor screen, exact;
-	if (!XAllocNamedColor(e->dpy, e->cmap, name, &screen, &exact))
+	XColor screen;
+	if (!XAllocNamedColor(e->dpy, e->cmap, name, &screen, col))
 		error(EXIT_FAILURE, 0, "Error allocating color '%s'", name);
-	*pixel = exact.pixel;
 }
 
 const char* win_res(XrmDatabase db, const char *name, const char *def)
@@ -112,9 +111,6 @@ void win_init(win_t *win)
 #endif
 	char *res_man;
 	XrmDatabase db;
-	XVisualInfo vis;
-	XWindowAttributes attr;
-	Window parent;
 
 	memset(win, 0, sizeof(win_t));
 
@@ -125,19 +121,9 @@ void win_init(win_t *win)
 	e->scr = DefaultScreen(e->dpy);
 	e->scrw = DisplayWidth(e->dpy, e->scr);
 	e->scrh = DisplayHeight(e->dpy, e->scr);
-
-	parent = options->embed != 0 ? options->embed : RootWindow(e->dpy, e->scr);
-
-	if (options->embed == 0) {
-		e->depth = DefaultDepth(e->dpy, e->scr);
-	} else {
-		XGetWindowAttributes(e->dpy, parent, &attr);
-		e->depth = attr.depth;
-	}
-
-	XMatchVisualInfo(e->dpy, e->scr, e->depth, TrueColor, &vis);
-	e->vis = vis.visual;
-	e->cmap = XCreateColormap(e->dpy, parent, e->vis, None);
+	e->depth = DefaultDepth(e->dpy, e->scr);
+	e->vis = DefaultVisual(e->dpy, e->scr);
+	e->cmap = DefaultColormap(e->dpy, e->scr);
 
 	if (setlocale(LC_CTYPE, "") == NULL || XSupportsLocale() == 0)
 		error(0, 0, "No locale support");
@@ -197,6 +183,7 @@ void win_open(win_t *win)
 	XWMHints hints;
 	pid_t pid;
 	char hostname[256];
+	XSetWindowAttributes attrs;
 
 	e = &win->env;
 	parent = options->embed != 0 ? options->embed : RootWindow(e->dpy, e->scr);
@@ -238,8 +225,12 @@ void win_open(win_t *win)
 		win->y = 0;
 	}
 
+	attrs.colormap = e->cmap;
+	attrs.border_pixel = 0;
+
 	win->xwin = XCreateWindow(e->dpy, parent, win->x, win->y, win->w, win->h, 0,
-	                          e->depth, InputOutput, e->vis, 0, NULL);
+	                          e->depth, InputOutput, e->vis,
+	                          CWColormap | CWBorderPixel, &attrs);
 	if (win->xwin == None)
 		error(EXIT_FAILURE, 0, "Error creating X window");
 
@@ -317,7 +308,7 @@ void win_open(win_t *win)
 	win->buf.h = e->scrh;
 	win->buf.pm = XCreatePixmap(e->dpy, win->xwin, win->buf.w, win->buf.h, e->depth);
 
-	XSetForeground(e->dpy, gc, win->win_bg);
+	XSetForeground(e->dpy, gc, win->win_bg.pixel);
 	XFillRectangle(e->dpy, win->buf.pm, gc, 0, 0, win->buf.w, win->buf.h);
 	XSetWindowBackgroundPixmap(e->dpy, win->xwin, win->buf.pm);
 	XMapWindow(e->dpy, win->xwin);
@@ -398,7 +389,7 @@ void win_clear(win_t *win)
 		win->buf.pm = XCreatePixmap(e->dpy, win->xwin,
 		                            win->buf.w, win->buf.h, e->depth);
 	}
-	XSetForeground(e->dpy, gc, win->win_bg);
+	XSetForeground(e->dpy, gc, win->win_bg.pixel);
 	XFillRectangle(e->dpy, win->buf.pm, gc, 0, 0, win->buf.w, win->buf.h);
 }
 
@@ -455,7 +446,7 @@ void win_draw_bar(win_t *win)
 	XSetForeground(e->dpy, gc, win->bar_bg.pixel);
 	XFillRectangle(e->dpy, win->buf.pm, gc, 0, win->h, win->w, win->bar.h);
 
-	XSetForeground(e->dpy, gc, win->win_bg);
+	XSetForeground(e->dpy, gc, win->win_bg.pixel);
 	XSetBackground(e->dpy, gc, win->bar_bg.pixel);
 
 	if ((len = strlen(r->buf)) > 0) {