Adding alpha patch

README.md

@@ -15,7 +15,7 @@ Refer to [https://tools.suckless.org/slock/](https://tools.suckless.org/slock/)
 
 ### Changelog:
 
-2020-08-03 - Added keypress_feedback and blur_pixelated_screen patches
+2020-08-03 - Added alpha, keypress_feedback and blur_pixelated_screen patches
 
 2019-11-27 - Added xresources patch
 
@@ -25,6 +25,10 @@ Refer to [https://tools.suckless.org/slock/](https://tools.suckless.org/slock/)
 
 ### Patches included:
 
+   - [alpha](https://github.com/khuedoan/slock)
+      - enables transparency for slock
+      - intended to be combined with a compositor that can blur the transparent background
+
    - [blur_pixelated_screen](https://tools.suckless.org/slock/patches/blur-pixelated-screen/)
       - sets the lockscreen picture to a blured or pixelated screenshot
 

config.def.h

@@ -1,6 +1,6 @@
 /* user and group to drop privileges to */
 static const char *user  = "nobody";
-static const char *group = "nogroup";
+static const char *group = "nogroup"; // use "nobody" for arch
 
 static const char *colorname[NUMCOLS] = {
 	[INIT] =   "black",     /* after initialization */
@@ -34,6 +34,11 @@ ResourcePref resources[] = {
 };
 #endif // XRESOURCES_PATCH
 
+#if ALPHA_PATCH
+/* lock screen opacity */
+static const float alpha = 0.9;
+#endif // ALPHA_PATCH
+
 /* treat a cleared input like a wrong password (color) */
 static const int failonclear = 1;
 

patches.def.h

@@ -9,6 +9,12 @@
 
 /* Patches */
 
+/* This patch enables transparency for slock. This is intended to be combined
+ * with a compositor that can blur the transparent background.
+ * Extrapolated from https://github.com/khuedoan/slock
+ */
+#define ALPHA_PATCH 0
+
 /* This patch sets the lockscreen picture to a blured or pixelated screenshot.
  * This patch depends on the Imlib2 library, uncomment the relevant line in
  * config.mk when enabling this patch.

slock.c

@@ -20,6 +20,9 @@
 #include <X11/Xutil.h>
 
 #include "patches.h"
+#if ALPHA_PATCH
+#include <X11/Xatom.h>
+#endif // ALPHA_PATCH
 #if KEYPRESS_FEEDBACK_PATCH
 #include <time.h>
 #endif // KEYPRESS_FEEDBACK_PATCH
@@ -439,6 +442,11 @@ lockscreen(Display *dpy, struct xrandr *rr, int screen)
 			#if QUICKCANCEL_PATCH
 			locktime = time(NULL);
 			#endif // QUICKCANCEL_PATCH
+			#if ALPHA_PATCH
+			unsigned int opacity = (unsigned int)(alpha * 0xffffffff);
+			XChangeProperty(dpy, lock->win, XInternAtom(dpy, "_NET_WM_WINDOW_OPACITY", False), XA_CARDINAL, 32, PropModeReplace, (unsigned char *)&opacity, 1L);
+			XSync(dpy, False);
+			#endif // ALPHA_PATCH
 			return lock;
 		}