Add click events to i3bar

If the statusline generator (i.e. i3status) specifies click_events:true
in the protocol header, i3bar will write a JSON array on it's stdin
notifying it if the user clicks on a block.

The exact protocol is documented in docs/i3bar-protocol.

docs/i3bar-protocol

@@ -51,7 +51,7 @@ consists of a single JSON hash:
 
 *All features example*:
 ------------------------------
-{ "version": 1, "stop_signal": 10, "cont_signal": 12 }
+{ "version": 1, "stop_signal": 10, "cont_signal": 12, "click_events": true }
 ------------------------------
 
 (Note that before i3 v4.3 the precise format had to be +{"version":1}+,
@@ -110,6 +110,9 @@ cont_signal::
 	Specify to i3bar the signal (as an integer)to send to continue your
 	processing.
 	The default value (if none is specified) is SIGCONT.
+click_events::
+	If specified and true i3bar will write a infinite array (same as above)
+	to your stdin.
 
 === Blocks in detail
 
@@ -210,3 +213,28 @@ An example of a block which uses all possible entries follows:
  "separator_block_width": 9
 }
 ------------------------------------------
+
+=== Click events
+
+If enabled i3bar will send you notifications if the user clicks on a block and
+looks like this:
+
+name::
+	Name of the block, if set
+instance::
+	Instance of the block, if set
+x, y::
+	X11 root window coordinates where the click occured
+button:
+	X11 button ID (for example 1 to 3 for left/middle/right mouse button)
+
+*Example*:
+------------------------------------------
+{
+ "name": "ethernet",
+ "instance": "eth0",
+ "button": 1,
+ "x": 1320,
+ "y": 1400
+}
+------------------------------------------

i3bar/include/child.h

@@ -33,6 +33,12 @@ typedef struct {
      * The signal requested by the client to inform it of theun hidden state of i3bar
      */
     int cont_signal;
+
+    /**
+     * Enable click events
+     */
+    bool click_events;
+    bool click_events_init;
 } i3bar_child;
 
 /*
@@ -68,4 +74,10 @@ void stop_child(void);
  */
 void cont_child(void);
 
+/*
+ * Generates a click event, if enabled.
+ *
+ */
+void send_block_clicked(int button, const char *name, const char *instance, int x, int y);
+
 #endif

i3bar/include/common.h

@@ -54,6 +54,10 @@ struct status_block {
     uint32_t x_offset;
     uint32_t x_append;
 
+    /* Optional */
+    char *name;
+    char *instance;
+
     TAILQ_ENTRY(status_block) blocks;
 };
 

i3bar/src/child.c

@@ -21,6 +21,7 @@
 #include <yajl/yajl_common.h>
 #include <yajl/yajl_parse.h>
 #include <yajl/yajl_version.h>
+#include <yajl/yajl_gen.h>
 
 #include "common.h"
 
@@ -35,6 +36,9 @@ ev_child *child_sig;
 yajl_callbacks callbacks;
 yajl_handle parser;
 
+/* JSON generator for stdout */
+yajl_gen gen;
+
 typedef struct parser_ctx {
     /* True if one of the parsed blocks was urgent */
     bool has_urgent;
@@ -85,6 +89,8 @@ static int stdin_start_array(void *context) {
         first = TAILQ_FIRST(&statusline_head);
         I3STRING_FREE(first->full_text);
         FREE(first->color);
+        FREE(first->name);
+        FREE(first->instance);
         TAILQ_REMOVE(&statusline_head, first, blocks);
         free(first);
     }
@@ -152,6 +158,18 @@ static int stdin_string(void *context, const unsigned char *val, unsigned int le
         ctx->block.min_width = (uint32_t)predict_text_width(text);
         i3string_free(text);
     }
+    if (strcasecmp(ctx->last_map_key, "name") == 0) {
+        char *copy = (char*)malloc(len+1);
+        strncpy(copy, (const char *)val, len);
+        copy[len] = 0;
+        ctx->block.name = copy;
+    }
+    if (strcasecmp(ctx->last_map_key, "instance") == 0) {
+        char *copy = (char*)malloc(len+1);
+        strncpy(copy, (const char *)val, len);
+        copy[len] = 0;
+        ctx->block.instance = copy;
+    }
     return 1;
 }
 
@@ -336,6 +354,18 @@ void child_sig_cb(struct ev_loop *loop, ev_child *watcher, int revents) {
     cleanup();
 }
 
+void child_write_output(void) {
+    if (child.click_events) {
+        const unsigned char *output;
+        size_t size;
+        yajl_gen_get_buf(gen, &output, &size);
+        fwrite(output, 1, size, stdout);
+        fwrite("\n", 1, 1, stdout);
+        fflush(stdout);
+        yajl_gen_clear(gen);
+    }
+}
+
 /*
  * Start a child-process with the specified command and reroute stdin.
  * We actually start a $SHELL to execute the command so we don't have to care
@@ -361,10 +391,16 @@ void start_child(char *command) {
     parser = yajl_alloc(&callbacks, NULL, &parser_context);
 #endif
 
+    gen = yajl_gen_alloc(NULL);
+
     if (command != NULL) {
-        int fd[2];
+        int pipe_in[2]; /* pipe we read from */
-        if (pipe(fd) == -1)
+        int pipe_out[2]; /* pipe we write to */
-            err(EXIT_FAILURE, "pipe(fd)");
+
+        if (pipe(pipe_in) == -1)
+            err(EXIT_FAILURE, "pipe(pipe_in)");
+        if (pipe(pipe_out) == -1)
+            err(EXIT_FAILURE, "pipe(pipe_out)");
 
         child.pid = fork();
         switch (child.pid) {
@@ -372,10 +408,13 @@ void start_child(char *command) {
                 ELOG("Couldn't fork(): %s\n", strerror(errno));
                 exit(EXIT_FAILURE);
             case 0:
-                /* Child-process. Reroute stdout and start shell */
+                /* Child-process. Reroute streams and start shell */
-                close(fd[0]);
 
-                dup2(fd[1], STDOUT_FILENO);
+                close(pipe_in[0]);
+                close(pipe_out[1]);
+
+                dup2(pipe_in[1], STDOUT_FILENO);
+                dup2(pipe_out[0], STDIN_FILENO);
 
                 static const char *shell = NULL;
 
@@ -385,10 +424,13 @@ void start_child(char *command) {
                 execl(shell, shell, "-c", command, (char*) NULL);
                 return;
             default:
-                /* Parent-process. Rerout stdin */
+                /* Parent-process. Reroute streams */
-                close(fd[1]);
 
-                dup2(fd[0], STDIN_FILENO);
+                close(pipe_in[1]);
+                close(pipe_out[0]);
+
+                dup2(pipe_in[0], STDIN_FILENO);
+                dup2(pipe_out[1], STDOUT_FILENO);
 
                 break;
         }
@@ -409,6 +451,52 @@ void start_child(char *command) {
     atexit(kill_child_at_exit);
 }
 
+void child_click_events_initialize(void) {
+    if (!child.click_events_init) {
+        yajl_gen_array_open(gen);
+        child_write_output();
+        child.click_events_init = true;
+    }
+}
+
+void child_click_events_key(const char *key) {
+    yajl_gen_string(gen, (const unsigned char *)key, strlen(key));
+}
+
+/*
+ * Generates a click event, if enabled.
+ *
+ */
+void send_block_clicked(int button, const char *name, const char *instance, int x, int y) {
+    if (child.click_events) {
+        child_click_events_initialize();
+
+        yajl_gen_map_open(gen);
+
+        if (name) {
+            child_click_events_key("name");
+            yajl_gen_string(gen, (const unsigned char *)name, strlen(name));
+        }
+
+        if (instance) {
+            child_click_events_key("instance");
+            yajl_gen_string(gen, (const unsigned char *)instance, strlen(instance));
+        }
+
+        child_click_events_key("button");
+        yajl_gen_integer(gen, button);
+
+        child_click_events_key("x");
+        yajl_gen_integer(gen, x);
+
+        child_click_events_key("y");
+        yajl_gen_integer(gen, y);
+
+        yajl_gen_map_close(gen);
+        child_write_output();
+    }
+}
+
 /*
  * kill()s the child-process (if any). Called when exit()ing.
  *

i3bar/src/parse_json_header.c

@@ -31,6 +31,7 @@ static enum {
     KEY_VERSION,
     KEY_STOP_SIGNAL,
     KEY_CONT_SIGNAL,
+    KEY_CLICK_EVENTS,
     NO_KEY
 } current_key;
 
@@ -54,6 +55,21 @@ static int header_integer(void *ctx, long val) {
         default:
             break;
     }
+
+    return 1;
+}
+
+static int header_boolean(void *ctx, int val) {
+    i3bar_child *child = ctx;
+
+    switch (current_key) {
+        case KEY_CLICK_EVENTS:
+            child->click_events = val;
+            break;
+        default:
+            break;
+    }
+
     return 1;
 }
 
@@ -71,13 +87,15 @@ static int header_map_key(void *ctx, const unsigned char *stringval, unsigned in
         current_key = KEY_STOP_SIGNAL;
     } else if (CHECK_KEY("cont_signal")) {
         current_key = KEY_CONT_SIGNAL;
+    } else if (CHECK_KEY("click_events")) {
+        current_key = KEY_CLICK_EVENTS;
     }
     return 1;
 }
 
 static yajl_callbacks version_callbacks = {
     NULL, /* null */
-    NULL, /* boolean */
+    &header_boolean, /* boolean */
     &header_integer,
     NULL, /* double */
     NULL, /* number */

i3bar/src/xcb.c

@@ -320,24 +320,11 @@ void handle_button(xcb_button_press_event_t *event) {
     }
 
     int32_t x = event->event_x >= 0 ? event->event_x : 0;
+    int32_t original_x = x;
 
     DLOG("Got Button %d\n", event->detail);
 
     switch (event->detail) {
-        case 1:
-            /* Left Mousbutton. We determine, which button was clicked
-             * and set cur_ws accordingly */
-            TAILQ_FOREACH(cur_ws, walk->workspaces, tailq) {
-                DLOG("x = %d\n", x);
-                if (x >= 0 && x < cur_ws->name_width + 10) {
-                    break;
-                }
-                x -= cur_ws->name_width + 11;
-            }
-            if (cur_ws == NULL) {
-                return;
-            }
-            break;
         case 4:
             /* Mouse wheel up. We select the previous ws, if any.
              * If there is no more workspace, don’t even send the workspace
@@ -358,6 +345,52 @@ void handle_button(xcb_button_press_event_t *event) {
 
             cur_ws = TAILQ_NEXT(cur_ws, tailq);
             break;
+        default:
+            /* Check if this event regards a workspace button */
+            TAILQ_FOREACH(cur_ws, walk->workspaces, tailq) {
+                DLOG("x = %d\n", x);
+                if (x >= 0 && x < cur_ws->name_width + 10) {
+                    break;
+                }
+                x -= cur_ws->name_width + 11;
+            }
+            if (cur_ws == NULL) {
+                /* No workspace button was pressed.
+                 * Check if a status block has been clicked.
+                 * This of course only has an effect,
+                 * if the child reported bidirectional protocol usage. */
+
+                /* First calculate width of tray area */
+                trayclient *trayclient;
+                int tray_width = 0;
+                TAILQ_FOREACH_REVERSE(trayclient, walk->trayclients, tc_head, tailq) {
+                    if (!trayclient->mapped)
+                        continue;
+                    tray_width += (font.height + 2);
+                }
+
+                int block_x = 0, last_block_x;
+                int offset = (walk->rect.w - (statusline_width + tray_width)) - 10;
+
+                x = original_x - offset;
+                if (x < 0)
+                    return;
+
+                struct status_block *block;
+
+                TAILQ_FOREACH(block, &statusline_head, blocks) {
+                    last_block_x = block_x;
+                    block_x += block->width + block->x_offset + block->x_append;
+
+                    if (x <= block_x && x >= last_block_x) {
+                        send_block_clicked(event->detail, block->name, block->instance, event->root_x, event->root_y);
+                        return;
+                    }
+                }
+                return;
+            }
+            if (event->detail != 1)
+                return;
     }
 
     /* To properly handle workspace names with double quotes in them, we need