patch: alpha

This patch allows users to change the opacity of the background.  Note
that you need an X composite manager (e.g. compton, xcompmgr) to make
this patch effective.

The alpha value affects the default background only.  The color
designated by 'defaultbg' should not be used elsewhere.  Embedding might
fail after applying this patch.

2 files changed, 38 insertions, 9 deletions

diff --git a/config.def.h b/config.def.h
index b962afb..adfcb77 100644
--- a/config.def.h
+++ b/config.def.h
@@ -93,6 +93,9 @@ char *termname = "st-256color";
  */
 unsigned int tabspaces = 8;
 
+/* bg opacity */
+float alpha = 0.8;
+
 /* Terminal colors (16 first used in escape sequence) */
 static const char *colorname[] = {
 	/* 8 normal colors */
diff --git a/x.c b/x.c
index d73152b..f32fd6c 100644
--- a/x.c
+++ b/x.c
@@ -105,6 +105,7 @@ typedef struct {
 	XSetWindowAttributes attrs;
 	int scr;
 	int isfixed; /* is fixed geometry? */
+	int depth; /* bit depth */
 	int l, t; /* left and top offset */
 	int gm; /* geometry mask */
 } XWindow;
@@ -752,7 +753,7 @@ xresize(int col, int row)
 
 	XFreePixmap(xw.dpy, xw.buf);
 	xw.buf = XCreatePixmap(xw.dpy, xw.win, win.w, win.h,
-			DefaultDepth(xw.dpy, xw.scr));
+			xw.depth);
 	XftDrawChange(xw.draw, xw.buf);
 	xclear(0, 0, win.w, win.h);
 
@@ -812,6 +813,10 @@ xloadcols(void)
 			else
 				die("could not allocate color %d\n", i);
 		}
+
+	dc.col[defaultbg].color.alpha = (unsigned short)(0xffff * alpha);
+	dc.col[defaultbg].pixel &= 0x00FFFFFF;
+	dc.col[defaultbg].pixel |= (unsigned char)(0xff * alpha) << 24;
 	loaded = 1;
 }
 
@@ -842,6 +847,12 @@ xsetcolorname(int x, const char *name)
 	XftColorFree(xw.dpy, xw.vis, xw.cmap, &dc.col[x]);
 	dc.col[x] = ncolor;
 
+	if (x == defaultbg) {
+		dc.col[defaultbg].color.alpha = (unsigned short)(0xffff * alpha);
+		dc.col[defaultbg].pixel &= 0x00FFFFFF;
+		dc.col[defaultbg].pixel |= (unsigned char)(0xff * alpha) << 24;
+	}
+
 	return 0;
 }
 
@@ -1134,11 +1145,25 @@ xinit(int cols, int rows)
 	Window parent, root;
 	pid_t thispid = getpid();
 	XColor xmousefg, xmousebg;
+	XWindowAttributes attr;
+	XVisualInfo vis;
 
 	if (!(xw.dpy = XOpenDisplay(NULL)))
 		die("can't open display\n");
 	xw.scr = XDefaultScreen(xw.dpy);
-	xw.vis = XDefaultVisual(xw.dpy, xw.scr);
+
+	root = XRootWindow(xw.dpy, xw.scr);
+	if (!(opt_embed && (parent = strtol(opt_embed, NULL, 0))))
+		parent = root;
+
+	if (XMatchVisualInfo(xw.dpy, xw.scr, 32, TrueColor, &vis) != 0) {
+		xw.vis = vis.visual;
+		xw.depth = vis.depth;
+	} else {
+		XGetWindowAttributes(xw.dpy, parent, &attr);
+		xw.vis = attr.visual;
+		xw.depth = attr.depth;
+	}
 
 	/* font */
 	if (!FcInit())
@@ -1148,7 +1173,7 @@ xinit(int cols, int rows)
 	xloadfonts(usedfont, 0);
 
 	/* colors */
-	xw.cmap = XDefaultColormap(xw.dpy, xw.scr);
+	xw.cmap = XCreateColormap(xw.dpy, parent, xw.vis, None);
 	xloadcols();
 
 	/* adjust fixed window geometry */
@@ -1168,11 +1193,8 @@ xinit(int cols, int rows)
 		| ButtonMotionMask | ButtonPressMask | ButtonReleaseMask;
 	xw.attrs.colormap = xw.cmap;
 
-	root = XRootWindow(xw.dpy, xw.scr);
-	if (!(opt_embed && (parent = strtol(opt_embed, NULL, 0))))
-		parent = root;
-	xw.win = XCreateWindow(xw.dpy, root, xw.l, xw.t,
-			win.w, win.h, 0, XDefaultDepth(xw.dpy, xw.scr), InputOutput,
+	xw.win = XCreateWindow(xw.dpy, parent, xw.l, xw.t,
+			win.w, win.h, 0, xw.depth, InputOutput,
 			xw.vis, CWBackPixel | CWBorderPixel | CWBitGravity
 			| CWEventMask | CWColormap, &xw.attrs);
 	if (parent != root)
@@ -1183,7 +1205,7 @@ xinit(int cols, int rows)
 	dc.gc = XCreateGC(xw.dpy, xw.win, GCGraphicsExposures,
 			&gcvalues);
 	xw.buf = XCreatePixmap(xw.dpy, xw.win, win.w, win.h,
-			DefaultDepth(xw.dpy, xw.scr));
+			xw.depth);
 	XSetForeground(xw.dpy, dc.gc, dc.col[defaultbg].pixel);
 	XFillRectangle(xw.dpy, xw.buf, dc.gc, 0, 0, win.w, win.h);
 
@@ -2047,6 +2069,10 @@ main(int argc, char *argv[])
 	case 'a':
 		allowaltscreen = 0;
 		break;
+	case 'A':
+		alpha = strtof(EARGF(usage()), NULL);
+		LIMIT(alpha, 0.0, 1.0);
+		break;
 	case 'c':
 		opt_class = EARGF(usage());
 		break;