Implement title_format

This implements the title_format command, with a new placeholder %shell
which gets substituted with the view type (xwayland, xdg_shell_v6 or
wl_shell).

Example config:

    for_window [title=".*"] title_format %title (class=%class instance=%instance shell=%shell)

10 files changed, 201 insertions, 42 deletions

diff --git a/include/sway/commands.h b/include/sway/commands.h
index 0732a90a..d39ac56c 100644
--- a/include/sway/commands.h
+++ b/include/sway/commands.h
@@ -144,6 +144,7 @@ sway_cmd cmd_splitt;
 sway_cmd cmd_splitv;
 sway_cmd cmd_sticky;
 sway_cmd cmd_swaybg_command;
+sway_cmd cmd_title_format;
 sway_cmd cmd_unmark;
 sway_cmd cmd_workspace;
 sway_cmd cmd_ws_auto_back_and_forth;
diff --git a/include/sway/tree/container.h b/include/sway/tree/container.h
index b07af72c..61ab7ca1 100644
--- a/include/sway/tree/container.h
+++ b/include/sway/tree/container.h
@@ -63,7 +63,8 @@ struct sway_container {
          */
         size_t id;
 
-        char *name;
+        char *name;            // The view's title (unformatted)
+        char *formatted_title; // The title displayed in the title bar
 
         enum sway_container_type type;
         enum sway_container_layout layout;
@@ -204,7 +205,6 @@ void container_update_title_textures(struct sway_container *container);
  */
 void container_calculate_title_height(struct sway_container *container);
 
-void container_update_title(struct sway_container *container,
-                const char *new_title);
+void container_notify_child_title_changed(struct sway_container *container);
 
 #endif
diff --git a/include/sway/tree/view.h b/include/sway/tree/view.h
index 21127ab1..9d4256f7 100644
--- a/include/sway/tree/view.h
+++ b/include/sway/tree/view.h
@@ -48,6 +48,7 @@ struct sway_view {
 
         bool is_fullscreen;
 
+        char *title_format;
         enum sway_container_border border;
         int border_thickness;
 
@@ -164,6 +165,8 @@ const char *view_get_class(struct sway_view *view);
 
 const char *view_get_instance(struct sway_view *view);
 
+const char *view_get_type(struct sway_view *view);
+
 void view_configure(struct sway_view *view, double ox, double oy, int width,
         int height);
 
@@ -207,4 +210,11 @@ void view_child_init(struct sway_view_child *child,
 
 void view_child_destroy(struct sway_view_child *child);
 
+/**
+ * Re-read the view's title property and update any relevant title bars.
+ * The force argument makes it recreate the title bars even if the title hasn't
+ * changed.
+ */
+void view_update_title(struct sway_view *view, bool force);
+
 #endif
diff --git a/sway/commands.c b/sway/commands.c
index efed7ddf..2e1cdc2c 100644
--- a/sway/commands.c
+++ b/sway/commands.c
@@ -182,6 +182,7 @@ static struct cmd_handler command_handlers[] = {
         { "splith", cmd_splith },
         { "splitt", cmd_splitt },
         { "splitv", cmd_splitv },
+        { "title_format", cmd_title_format },
 };
 
 static int handler_compare(const void *_a, const void *_b) {
diff --git a/sway/commands/title_format.c b/sway/commands/title_format.c
new file mode 100644
index 00000000..a2f6e6ff
--- /dev/null
+++ b/sway/commands/title_format.c
@@ -0,0 +1,31 @@
+#define _POSIX_C_SOURCE 200809L
+#include <string.h>
+#include "sway/commands.h"
+#include "sway/config.h"
+#include "sway/tree/arrange.h"
+#include "sway/tree/view.h"
+#include "log.h"
+#include "stringop.h"
+
+struct cmd_results *cmd_title_format(int argc, char **argv) {
+        struct cmd_results *error = NULL;
+        if ((error = checkarg(argc, "title_format", EXPECTED_AT_LEAST, 1))) {
+                return error;
+        }
+        struct sway_container *container =
+                config->handler_context.current_container;
+        if (container->type != C_VIEW) {
+                return cmd_results_new(CMD_INVALID, "title_format",
+                                "Only views can have a title_format");
+        }
+        struct sway_view *view = container->sway_view;
+        char *format = join_args(argv, argc);
+        if (view->title_format) {
+                free(view->title_format);
+        }
+        view->title_format = strdup(format);
+        view_update_title(view, true);
+        config_find_font_height(true);
+        arrange_root();
+        return cmd_results_new(CMD_SUCCESS, NULL, NULL);
+}
diff --git a/sway/desktop/xdg_shell_v6.c b/sway/desktop/xdg_shell_v6.c
index 5880e9a9..fcee8ce9 100644
--- a/sway/desktop/xdg_shell_v6.c
+++ b/sway/desktop/xdg_shell_v6.c
@@ -176,8 +176,7 @@ static void handle_commit(struct wl_listener *listener, void *data) {
         // TODO: Let floating views do whatever
         view_update_size(view, xdg_shell_v6_view->pending_width,
                 xdg_shell_v6_view->pending_height);
-        container_update_title(view->swayc,
-                        view->wlr_xdg_surface_v6->toplevel->title);
+        view_update_title(view, false);
         view_damage(view, false);
 }
 
diff --git a/sway/desktop/xwayland.c b/sway/desktop/xwayland.c
index a1e672ce..b4eda71f 100644
--- a/sway/desktop/xwayland.c
+++ b/sway/desktop/xwayland.c
@@ -223,7 +223,7 @@ static void handle_commit(struct wl_listener *listener, void *data) {
         view_update_size(view, xwayland_view->pending_width,
                 xwayland_view->pending_height);
         view_damage(view, false);
-        container_update_title(view->swayc, view->wlr_xwayland_surface->title);
+        view_update_title(view, false);
 }
 
 static void handle_unmap(struct wl_listener *listener, void *data) {
diff --git a/sway/meson.build b/sway/meson.build
index 7c93b5c4..f70a8e44 100644
--- a/sway/meson.build
+++ b/sway/meson.build
@@ -60,6 +60,7 @@ sway_sources = files(
         'commands/set.c',
         'commands/split.c',
         'commands/swaybg_command.c',
+        'commands/title_format.c',
         'commands/workspace.c',
         'commands/ws_auto_back_and_forth.c',
 
diff --git a/sway/tree/container.c b/sway/tree/container.c
index 9fb47020..e1be32d1 100644
--- a/sway/tree/container.c
+++ b/sway/tree/container.c
@@ -348,7 +348,6 @@ struct sway_container *container_view_create(struct sway_container *sibling,
                 swayc, title, sibling, sibling ? sibling->type : 0, sibling->name);
         // Setup values
         swayc->sway_view = sway_view;
-        container_update_title(swayc, title);
         swayc->width = 0;
         swayc->height = 0;
 
@@ -572,7 +571,7 @@ static void update_title_texture(struct sway_container *con,
         if (*texture) {
                 wlr_texture_destroy(*texture);
         }
-        if (!con->name) {
+        if (!con->formatted_title) {
                 return;
         }
 
@@ -581,7 +580,8 @@ static void update_title_texture(struct sway_container *con,
         int height = config->font_height * scale;
 
         cairo_t *c = cairo_create(NULL);
-        get_text_size(c, config->font, &width, NULL, scale, false, "%s", con->name);
+        get_text_size(c, config->font, &width, NULL, scale, false,
+                        "%s", con->formatted_title);
         cairo_destroy(c);
 
         cairo_surface_t *surface = cairo_image_surface_create(
@@ -596,7 +596,7 @@ static void update_title_texture(struct sway_container *con,
                         class->text[2], class->text[3]);
         cairo_move_to(cairo, 0, 0);
 
-        pango_printf(cairo, config->font, scale, false, "%s", con->name);
+        pango_printf(cairo, config->font, scale, false, "%s", con->formatted_title);
 
         cairo_surface_flush(surface);
         unsigned char *data = cairo_image_surface_get_data(surface);
@@ -622,57 +622,31 @@ void container_update_title_textures(struct sway_container *container) {
 }
 
 void container_calculate_title_height(struct sway_container *container) {
-        if (!container->name) {
+        if (!container->formatted_title) {
                 container->title_height = 0;
                 return;
         }
         cairo_t *cairo = cairo_create(NULL);
         int height;
         get_text_size(cairo, config->font, NULL, &height, 1, false,
-                        "%s", container->name);
+                        "%s", container->formatted_title);
         cairo_destroy(cairo);
         container->title_height = height;
 }
 
-static void container_notify_child_title_changed(
-                struct sway_container *container) {
+void container_notify_child_title_changed(struct sway_container *container) {
         if (!container || container->type != C_CONTAINER) {
                 return;
         }
         if (container->layout != L_TABBED && container->layout != L_STACKED) {
                 return;
         }
-        if (container->name) {
-                free(container->name);
+        if (container->formatted_title) {
+                free(container->formatted_title);
         }
         // TODO: iterate children and concatenate their titles
-        container->name = strdup("");
+        container->formatted_title = strdup("");
         container_calculate_title_height(container);
         container_update_title_textures(container);
         container_notify_child_title_changed(container->parent);
 }
-
-void container_update_title(struct sway_container *container,
-                const char *new_title) {
-        if (!new_title) {
-                new_title = "";
-        }
-
-        if (container->name && strcmp(container->name, new_title) == 0) {
-                return;
-        }
-
-        if (container->name) {
-                free(container->name);
-        }
-        container->name = strdup(new_title);
-        container_calculate_title_height(container);
-        container_update_title_textures(container);
-        container_notify_child_title_changed(container->parent);
-
-        size_t prev_max_height = config->font_height;
-        config_find_font_height(false);
-        if (config->font_height != prev_max_height) {
-                arrange_root();
-        }
-}
diff --git a/sway/tree/view.c b/sway/tree/view.c
index 84962306..4a01f096 100644
--- a/sway/tree/view.c
+++ b/sway/tree/view.c
@@ -1,3 +1,4 @@
+#define _POSIX_C_SOURCE 200809L
 #include <stdlib.h>
 #include <wayland-server.h>
 #include <wlr/render/wlr_renderer.h>
@@ -67,6 +68,18 @@ const char *view_get_instance(struct sway_view *view) {
         return NULL;
 }
 
+const char *view_get_type(struct sway_view *view) {
+        switch(view->type) {
+        case SWAY_VIEW_WL_SHELL:
+                return "wl_shell";
+        case SWAY_VIEW_XDG_SHELL_V6:
+                return "xdg_shell_v6";
+        case SWAY_VIEW_XWAYLAND:
+                return "xwayland";
+        }
+        return "unknown";
+}
+
 void view_configure(struct sway_view *view, double ox, double oy, int width,
                 int height) {
         if (view->impl->configure) {
@@ -348,6 +361,11 @@ void view_unmap(struct sway_view *view) {
         view->swayc = NULL;
         view->surface = NULL;
 
+        if (view->title_format) {
+                free(view->title_format);
+                view->title_format = NULL;
+        }
+
         if (parent->type == C_OUTPUT) {
                 arrange_output(parent);
         } else {
@@ -475,3 +493,127 @@ void view_child_destroy(struct sway_view_child *child) {
                 free(child);
         }
 }
+
+static char *parse_title_format(struct sway_view *view) {
+        if (!view->title_format || strcmp(view->title_format, "%title") == 0) {
+                return strdup(view_get_title(view));
+        }
+        const char *title = view_get_title(view);
+        const char *class = view_get_class(view);
+        const char *instance = view_get_instance(view);
+        const char *shell = view_get_type(view);
+        size_t title_len = title ? strlen(title) : 0;
+        size_t class_len = class ? strlen(class) : 0;
+        size_t instance_len = instance ? strlen(instance) : 0;
+        size_t shell_len = shell ? strlen(shell) : 0;
+
+        // First, determine the length
+        size_t len = 0;
+        char *format = view->title_format;
+        char *next = strchr(format, '%');
+        while (next) {
+                len += next - format;
+                format = next;
+
+                if (strncmp(next, "%title", 6) == 0) {
+                        len += title_len;
+                        format += 6;
+                } else if (strncmp(next, "%class", 6) == 0) {
+                        len += class_len;
+                        format += 6;
+                } else if (strncmp(next, "%instance", 9) == 0) {
+                        len += instance_len;
+                        format += 9;
+                } else if (strncmp(next, "%shell", 6) == 0) {
+                        len += shell_len;
+                        format += 6;
+                } else {
+                        ++format;
+                        ++len;
+                }
+                next = strchr(format, '%');
+        }
+        len += strlen(format);
+
+        char *buffer = calloc(len + 1, 1);
+        if (!sway_assert(buffer, "Unable to allocate title string")) {
+                return NULL;
+        }
+
+        // Now build the title
+        format = view->title_format;
+        next = strchr(format, '%');
+        while (next) {
+                // Copy everything up to the %
+                strncat(buffer, format, next - format);
+                format = next;
+
+                if (strncmp(next, "%title", 6) == 0) {
+                        if (title) {
+                                strcat(buffer, title);
+                        }
+                        format += 6;
+                } else if (strncmp(next, "%class", 6) == 0) {
+                        if (class) {
+                                strcat(buffer, class);
+                        }
+                        format += 6;
+                } else if (strncmp(next, "%instance", 9) == 0) {
+                        if (instance) {
+                                strcat(buffer, instance);
+                        }
+                        format += 9;
+                } else if (strncmp(next, "%shell", 6) == 0) {
+                        strcat(buffer, shell);
+                        format += 6;
+                } else {
+                        strcat(buffer, "%");
+                        ++format;
+                }
+                next = strchr(format, '%');
+        }
+        strcat(buffer, format);
+
+        return buffer;
+}
+
+void view_update_title(struct sway_view *view, bool force) {
+        if (!view->swayc) {
+                return;
+        }
+        const char *title = view_get_title(view);
+
+        if (!force) {
+                if (title && view->swayc->name && strcmp(title, view->swayc->name) == 0) {
+                        return;
+                }
+                if (!title && !view->swayc->name) {
+                        return;
+                }
+        }
+
+        if (title) {
+                if (view->swayc->name) {
+                        free(view->swayc->name);
+                }
+                if (view->swayc->formatted_title) {
+                        free(view->swayc->formatted_title);
+                }
+                view->swayc->name = strdup(title);
+                view->swayc->formatted_title = parse_title_format(view);
+        } else {
+                free(view->swayc->name);
+                free(view->swayc->formatted_title);
+                view->swayc->name = NULL;
+                view->swayc->formatted_title = NULL;
+        }
+        container_calculate_title_height(view->swayc);
+        container_update_title_textures(view->swayc);
+        container_notify_child_title_changed(view->swayc->parent);
+
+        size_t prev_max_height = config->font_height;
+        config_find_font_height(false);
+        if (config->font_height != prev_max_height) {
+                arrange_root();
+        }
+}