Implement floating_modifier and mouse operations for floating views

This implements the following:

* `floating_modifier` configuration directive
* Drag a floating window by its title bar
* Hold mod + drag a floating window from anywhere
* Resize a floating view by dragging the border
* Resize a floating view by holding mod and right clicking anywhere on
the view
* Resize a floating view and keep aspect ratio by holding shift while
resizing using either method
* Mouse cursor turns into resize when hovering floating border or corner

7 files changed, 361 insertions, 12 deletions

diff --git a/sway/commands.c b/sway/commands.c
index f1f03574..f40f0e9d 100644
--- a/sway/commands.c
+++ b/sway/commands.c
@@ -103,6 +103,7 @@ static struct cmd_handler handlers[] = {
         { "exec_always", cmd_exec_always },
         { "floating_maximum_size", cmd_floating_maximum_size },
         { "floating_minimum_size", cmd_floating_minimum_size },
+        { "floating_modifier", cmd_floating_modifier },
         { "focus", cmd_focus },
         { "focus_follows_mouse", cmd_focus_follows_mouse },
         { "focus_wrapping", cmd_focus_wrapping },
diff --git a/sway/commands/floating_modifier.c b/sway/commands/floating_modifier.c
new file mode 100644
index 00000000..1ced50af
--- /dev/null
+++ b/sway/commands/floating_modifier.c
@@ -0,0 +1,30 @@
+#ifdef __linux__
+#include <linux/input-event-codes.h>
+#elif __FreeBSD__
+#include <dev/evdev/input-event-codes.h>
+#endif
+#include <xkbcommon/xkbcommon.h>
+#include <xkbcommon/xkbcommon-names.h>
+#include <strings.h>
+#include "sway/commands.h"
+#include "sway/config.h"
+#include "list.h"
+#include "log.h"
+#include "util.h"
+
+struct cmd_results *cmd_floating_modifier(int argc, char **argv) {
+        struct cmd_results *error = NULL;
+        if ((error = checkarg(argc, "floating_modifier", EXPECTED_EQUAL_TO, 1))) {
+                return error;
+        }
+
+        uint32_t mod = get_modifier_mask_by_name(argv[0]);
+        if (!mod) {
+                return cmd_results_new(CMD_INVALID, "floating_modifier",
+                                "Invalid modifier");
+        }
+
+        config->floating_mod = mod;
+
+        return cmd_results_new(CMD_SUCCESS, NULL, NULL);
+}
diff --git a/sway/input/cursor.c b/sway/input/cursor.c
index c76c20b3..6ad214b5 100644
--- a/sway/input/cursor.c
+++ b/sway/input/cursor.c
@@ -5,15 +5,19 @@
 #elif __FreeBSD__
 #include <dev/evdev/input-event-codes.h>
 #endif
+#include <limits.h>
 #include <wlr/types/wlr_cursor.h>
 #include <wlr/types/wlr_xcursor_manager.h>
 #include <wlr/types/wlr_idle.h>
 #include "list.h"
 #include "log.h"
+#include "sway/desktop.h"
 #include "sway/desktop/transaction.h"
 #include "sway/input/cursor.h"
+#include "sway/input/keyboard.h"
 #include "sway/layers.h"
 #include "sway/output.h"
+#include "sway/tree/arrange.h"
 #include "sway/tree/view.h"
 #include "sway/tree/workspace.h"
 #include "wlr-layer-shell-unstable-v1-protocol.h"
@@ -127,7 +131,7 @@ static struct sway_container *container_at_coords(
                 return ws;
         }
 
-        c = seat_get_focus_inactive(seat, output->swayc);
+        c = seat_get_active_child(seat, output->swayc);
         if (c) {
                 return c;
         }
@@ -139,6 +143,173 @@ static struct sway_container *container_at_coords(
         return output->swayc;
 }
 
+static enum resize_edge find_resize_edge(struct sway_container *cont,
+                struct sway_cursor *cursor) {
+        if (cont->type != C_VIEW) {
+                return RESIZE_EDGE_NONE;
+        }
+        struct sway_view *view = cont->sway_view;
+        if (view->border == B_NONE || !view->border_thickness || view->using_csd) {
+                return RESIZE_EDGE_NONE;
+        }
+
+        enum resize_edge edge = 0;
+        if (cursor->cursor->x < cont->x + view->border_thickness) {
+                edge |= RESIZE_EDGE_LEFT;
+        }
+        if (cursor->cursor->y < cont->y + view->border_thickness) {
+                edge |= RESIZE_EDGE_TOP;
+        }
+        if (cursor->cursor->x >= cont->x + cont->width - view->border_thickness) {
+                edge |= RESIZE_EDGE_RIGHT;
+        }
+        if (cursor->cursor->y >= cont->y + cont->height - view->border_thickness) {
+                edge |= RESIZE_EDGE_BOTTOM;
+        }
+        return edge;
+}
+
+static void handle_drag_motion(struct sway_seat *seat,
+                struct sway_cursor *cursor) {
+        struct sway_container *con = seat->op_container;
+        desktop_damage_whole_container(con);
+        container_floating_translate(con,
+                        cursor->cursor->x - cursor->previous.x,
+                        cursor->cursor->y - cursor->previous.y);
+        desktop_damage_whole_container(con);
+}
+
+static void calculate_floating_constraints(struct sway_container *con,
+                int *min_width, int *max_width, int *min_height, int *max_height) {
+        if (config->floating_minimum_width == -1) { // no minimum
+                *min_width = 0;
+        } else if (config->floating_minimum_width == 0) { // automatic
+                *min_width = 75;
+        } else {
+                *min_width = config->floating_minimum_width;
+        }
+
+        if (config->floating_minimum_height == -1) { // no minimum
+                *min_height = 0;
+        } else if (config->floating_minimum_height == 0) { // automatic
+                *min_height = 50;
+        } else {
+                *min_height = config->floating_minimum_height;
+        }
+
+        if (config->floating_maximum_width == -1) { // no maximum
+                *max_width = INT_MAX;
+        } else if (config->floating_maximum_width == 0) { // automatic
+                struct sway_container *ws = container_parent(con, C_WORKSPACE);
+                *max_width = ws->width;
+        } else {
+                *max_width = config->floating_maximum_width;
+        }
+
+        if (config->floating_maximum_height == -1) { // no maximum
+                *max_height = INT_MAX;
+        } else if (config->floating_maximum_height == 0) { // automatic
+                struct sway_container *ws = container_parent(con, C_WORKSPACE);
+                *max_height = ws->height;
+        } else {
+                *max_height = config->floating_maximum_height;
+        }
+}
+static void handle_resize_motion(struct sway_seat *seat,
+                struct sway_cursor *cursor) {
+        struct sway_container *con = seat->op_container;
+        double center_lx = con->x + con->width / 2;
+        double center_ly = con->y + con->height / 2;
+        enum resize_edge edge = seat->op_resize_edge;
+
+        // The amount the mouse has moved since the start of the resize operation
+        // Positive is down/right
+        double mouse_move_x = cursor->cursor->x - seat->op_ref_lx;
+        double mouse_move_y = cursor->cursor->y - seat->op_ref_ly;
+
+        if (edge == RESIZE_EDGE_TOP || edge == RESIZE_EDGE_BOTTOM) {
+                mouse_move_x = 0;
+        }
+        if (edge == RESIZE_EDGE_LEFT || edge == RESIZE_EDGE_RIGHT) {
+                mouse_move_y = 0;
+        }
+
+        double grow_width = seat->op_ref_lx > center_lx ?
+                mouse_move_x : -mouse_move_x;
+        double grow_height = seat->op_ref_ly > center_ly ?
+                mouse_move_y : -mouse_move_y;
+
+        if (seat->op_resize_preserve_ratio) {
+                double x_multiplier = grow_width / seat->op_ref_width;
+                double y_multiplier = grow_height / seat->op_ref_height;
+                double avg_multiplier = (x_multiplier + y_multiplier) / 2;
+                grow_width = seat->op_ref_width * avg_multiplier;
+                grow_height = seat->op_ref_height * avg_multiplier;
+        }
+
+        // If we're resizing from the center (mod + right click), we need to double
+        // the amount we're growing because we're doing it in both directions.
+        if (edge == RESIZE_EDGE_NONE) {
+                grow_width *= 2;
+                grow_height *= 2;
+        }
+
+        // Determine new width/height, and accommodate for min/max values
+        double width = seat->op_ref_width + grow_width;
+        double height = seat->op_ref_height + grow_height;
+        int min_width, max_width, min_height, max_height;
+        calculate_floating_constraints(con, &min_width, &max_width,
+                        &min_height, &max_height);
+        width = fmax(min_width, fmin(width, max_width));
+        height = fmax(min_height, fmin(height, max_height));
+
+        // Recalculate these, in case we hit a min/max limit
+        grow_width = width - seat->op_ref_width;
+        grow_height = height - seat->op_ref_height;
+
+        // Determine grow x/y values - these are relative to the container's x/y at
+        // the start of the resize operation.
+        double grow_x = 0, grow_y = 0;
+        if (edge & RESIZE_EDGE_LEFT) {
+                grow_x = -grow_width;
+        } else if (edge & RESIZE_EDGE_RIGHT) {
+                grow_x = 0;
+        } else {
+                grow_x = -grow_width / 2;
+        }
+        if (edge & RESIZE_EDGE_TOP) {
+                grow_y = -grow_height;
+        } else if (edge & RESIZE_EDGE_BOTTOM) {
+                grow_y = 0;
+        } else {
+                grow_y = -grow_height / 2;
+        }
+
+        // Determine the amounts we need to bump everything relative to the current
+        // size.
+        int relative_grow_width = width - con->width;
+        int relative_grow_height = height - con->height;
+        int relative_grow_x = (seat->op_ref_con_lx + grow_x) - con->x;
+        int relative_grow_y = (seat->op_ref_con_ly + grow_y) - con->y;
+
+        // Actually resize stuff
+        con->x += relative_grow_x;
+        con->y += relative_grow_y;
+        con->width += relative_grow_width;
+        con->height += relative_grow_height;
+
+        if (con->type == C_VIEW) {
+                struct sway_view *view = con->sway_view;
+                view->x += relative_grow_x;
+                view->y += relative_grow_y;
+                view->width += relative_grow_width;
+                view->height += relative_grow_height;
+        }
+
+        arrange_windows(con);
+        transaction_commit_dirty();
+}
+
 void cursor_send_pointer_motion(struct sway_cursor *cursor, uint32_t time_msec,
                 bool allow_refocusing) {
         if (time_msec == 0) {
@@ -146,6 +317,18 @@ void cursor_send_pointer_motion(struct sway_cursor *cursor, uint32_t time_msec,
         }
 
         struct sway_seat *seat = cursor->seat;
+
+        if (seat->operation != OP_NONE) {
+                if (seat->operation == OP_DRAG) {
+                        handle_drag_motion(seat, cursor);
+                } else {
+                        handle_resize_motion(seat, cursor);
+                }
+                cursor->previous.x = cursor->cursor->x;
+                cursor->previous.y = cursor->cursor->y;
+                return;
+        }
+
         struct wlr_seat *wlr_seat = seat->wlr_seat;
         struct wlr_surface *surface = NULL;
         double sx, sy;
@@ -194,15 +377,54 @@ void cursor_send_pointer_motion(struct sway_cursor *cursor, uint32_t time_msec,
                 }
         }
 
-        // reset cursor if switching between clients
-        struct wl_client *client = NULL;
-        if (surface != NULL) {
-                client = wl_resource_get_client(surface->resource);
-        }
-        if (client != cursor->image_client) {
+        // Handle cursor image
+        if (surface) {
+                // Reset cursor if switching between clients
+                struct wl_client *client = wl_resource_get_client(surface->resource);
+                if (client != cursor->image_client) {
+                        wlr_xcursor_manager_set_cursor_image(cursor->xcursor_manager,
+                                        "left_ptr", cursor->cursor);
+                        cursor->image_client = client;
+                }
+        } else if (c && container_is_floating(c)) {
+                // Try a floating container's resize edge
+                enum resize_edge edge = find_resize_edge(c, cursor);
+                if (edge == RESIZE_EDGE_NONE) {
+                        wlr_xcursor_manager_set_cursor_image(cursor->xcursor_manager,
+                                        "left_ptr", cursor->cursor);
+                } else if (edge == RESIZE_EDGE_TOP) {
+                        wlr_xcursor_manager_set_cursor_image(cursor->xcursor_manager,
+                                        "top_side", cursor->cursor);
+                } else if (edge == RESIZE_EDGE_RIGHT) {
+                        wlr_xcursor_manager_set_cursor_image(cursor->xcursor_manager,
+                                        "right_side", cursor->cursor);
+                } else if (edge == RESIZE_EDGE_BOTTOM) {
+                        wlr_xcursor_manager_set_cursor_image(cursor->xcursor_manager,
+                                        "bottom_side", cursor->cursor);
+                } else if (edge == RESIZE_EDGE_LEFT) {
+                        wlr_xcursor_manager_set_cursor_image(cursor->xcursor_manager,
+                                        "left_side", cursor->cursor);
+                } else if (edge == (RESIZE_EDGE_TOP | RESIZE_EDGE_LEFT)) {
+                        wlr_xcursor_manager_set_cursor_image(cursor->xcursor_manager,
+                                        "top_left_corner", cursor->cursor);
+                } else if (edge == (RESIZE_EDGE_TOP | RESIZE_EDGE_RIGHT)) {
+                        wlr_xcursor_manager_set_cursor_image(cursor->xcursor_manager,
+                                        "top_right_corner", cursor->cursor);
+                } else if (edge == (RESIZE_EDGE_BOTTOM | RESIZE_EDGE_LEFT)) {
+                        wlr_xcursor_manager_set_cursor_image(cursor->xcursor_manager,
+                                        "bottom_left_corner", cursor->cursor);
+                } else if (edge == (RESIZE_EDGE_BOTTOM | RESIZE_EDGE_RIGHT)) {
+                        wlr_xcursor_manager_set_cursor_image(cursor->xcursor_manager,
+                                        "bottom_right_corner", cursor->cursor);
+                } else {
+                        wlr_xcursor_manager_set_cursor_image(cursor->xcursor_manager,
+                                        "left_ptr", cursor->cursor);
+                }
+                cursor->image_client = NULL;
+        } else {
                 wlr_xcursor_manager_set_cursor_image(cursor->xcursor_manager,
-                        "left_ptr", cursor->cursor);
-                cursor->image_client = client;
+                                "left_ptr", cursor->cursor);
+                cursor->image_client = NULL;
         }
 
         // send pointer enter/leave
@@ -243,8 +465,79 @@ static void handle_cursor_motion_absolute(
         transaction_commit_dirty();
 }
 
+static void handle_end_operation(struct sway_seat *seat) {
+        if (seat->operation == OP_DRAG) {
+                // We "move" the container to its own location so it discovers its
+                // output again.
+                struct sway_container *con = seat->op_container;
+                container_floating_move_to(con, con->x, con->y);
+                seat->operation = OP_NONE;
+                seat->op_container = NULL;
+        } else {
+                // OP_RESIZE
+                seat->operation = OP_NONE;
+                seat->op_container = NULL;
+        }
+}
+
+static void dispatch_cursor_button_floating(struct sway_cursor *cursor,
+                uint32_t time_msec, uint32_t button, enum wlr_button_state state,
+                struct wlr_surface *surface, double sx, double sy,
+                struct sway_container *cont) {
+        struct sway_seat *seat = cursor->seat;
+
+        // Deny dragging or resizing a fullscreen view
+        if (cont->type == C_VIEW && cont->sway_view->is_fullscreen) {
+                wlr_seat_pointer_notify_button(seat->wlr_seat, time_msec, button, state);
+                return;
+        }
+
+        struct wlr_keyboard *keyboard = wlr_seat_get_keyboard(seat->wlr_seat);
+        bool mod_pressed = keyboard &&
+                (keyboard->modifiers.depressed & config->floating_mod);
+        enum resize_edge edge = find_resize_edge(cont, cursor);
+        bool over_title = edge == RESIZE_EDGE_NONE && !surface;
+
+        // Check for beginning drag
+        if (button == BTN_LEFT && state == WLR_BUTTON_PRESSED &&
+                        (mod_pressed || over_title)) {
+                seat->operation = OP_DRAG;
+                seat->op_container = cont;
+                seat->op_button = button;
+                return;
+        }
+
+        // Check for beginning resize
+        bool resizing_via_border = button == BTN_LEFT && edge;
+        bool resizing_via_mod = button == BTN_RIGHT && mod_pressed;
+        if ((resizing_via_border || resizing_via_mod) &&
+                        state == WLR_BUTTON_PRESSED) {
+                seat->operation = OP_RESIZE;
+                seat->op_container = cont;
+                seat->op_resize_preserve_ratio = keyboard &&
+                        (keyboard->modifiers.depressed & 1); // Shift
+                seat->op_resize_edge = edge;
+                seat->op_button = button;
+                seat->op_ref_lx = cursor->cursor->x;
+                seat->op_ref_ly = cursor->cursor->y;
+                seat->op_ref_con_lx = cont->x;
+                seat->op_ref_con_ly = cont->y;
+                seat->op_ref_width = cont->width;
+                seat->op_ref_height = cont->height;
+                return;
+        }
+
+        // Send event to surface
+        wlr_seat_pointer_notify_button(seat->wlr_seat, time_msec, button, state);
+}
+
 void dispatch_cursor_button(struct sway_cursor *cursor,
                 uint32_t time_msec, uint32_t button, enum wlr_button_state state) {
+        if (cursor->seat->operation != OP_NONE &&
+                        button == cursor->seat->op_button && state == WLR_BUTTON_RELEASED) {
+                handle_end_operation(cursor->seat);
+                return;
+        }
         if (time_msec == 0) {
                 time_msec = get_current_time_msec();
         }
@@ -259,6 +552,11 @@ void dispatch_cursor_button(struct sway_cursor *cursor,
                 if (layer->current.keyboard_interactive) {
                         seat_set_focus_layer(cursor->seat, layer);
                 }
+                wlr_seat_pointer_notify_button(cursor->seat->wlr_seat,
+                                time_msec, button, state);
+        } else if (cont && container_is_floating(cont)) {
+                dispatch_cursor_button_floating(cursor, time_msec, button, state,
+                                surface, sx, sy, cont);
         } else if (surface && cont && cont->type != C_VIEW) {
                 // Avoid moving keyboard focus from a surface that accepts it to one
                 // that does not unless the change would move us to a new workspace.
@@ -275,12 +573,14 @@ void dispatch_cursor_button(struct sway_cursor *cursor,
                 if (new_ws != old_ws) {
                         seat_set_focus(cursor->seat, cont);
                 }
+                wlr_seat_pointer_notify_button(cursor->seat->wlr_seat,
+                                time_msec, button, state);
         } else if (cont) {
                 seat_set_focus(cursor->seat, cont);
+                wlr_seat_pointer_notify_button(cursor->seat->wlr_seat,
+                                time_msec, button, state);
         }
 
-        wlr_seat_pointer_notify_button(cursor->seat->wlr_seat,
-                        time_msec, button, state);
         transaction_commit_dirty();
 }
 
diff --git a/sway/meson.build b/sway/meson.build
index 09bc40b8..f4fdc8ea 100644
--- a/sway/meson.build
+++ b/sway/meson.build
@@ -42,6 +42,7 @@ sway_sources = files(
         'commands/exec_always.c',
         'commands/floating.c',
         'commands/floating_minmax_size.c',
+        'commands/floating_modifier.c',
         'commands/focus.c',
         'commands/focus_follows_mouse.c',
         'commands/focus_wrapping.c',
diff --git a/sway/tree/container.c b/sway/tree/container.c
index 4dbfbb29..ba4af352 100644
--- a/sway/tree/container.c
+++ b/sway/tree/container.c
@@ -323,6 +323,8 @@ static struct sway_container *container_destroy_noreaping(
                 }
         }
 
+        container_end_mouse_operation(con);
+
         con->destroying = true;
         container_set_dirty(con);
 
@@ -964,6 +966,8 @@ void container_set_floating(struct sway_container *container, bool enable) {
                 container_reap_empty_recursive(workspace->sway_workspace->floating);
         }
 
+        container_end_mouse_operation(container);
+
         ipc_event_window(container, "floating");
 }
 
@@ -1009,7 +1013,7 @@ void container_get_box(struct sway_container *container, struct wlr_box *box) {
 /**
  * Translate the container's position as well as all children.
  */
-static void container_floating_translate(struct sway_container *con,
+void container_floating_translate(struct sway_container *con,
                 double x_amount, double y_amount) {
         con->x += x_amount;
         con->y += y_amount;
@@ -1105,3 +1109,13 @@ static bool find_urgent_iterator(struct sway_container *con,
 bool container_has_urgent_child(struct sway_container *container) {
         return container_find(container, find_urgent_iterator, NULL);
 }
+
+void container_end_mouse_operation(struct sway_container *container) {
+        struct sway_seat *seat;
+        wl_list_for_each(seat, &input_manager->seats, link) {
+                if (seat->op_container == container) {
+                        seat->op_container = NULL;
+                        seat->operation = OP_NONE;
+                }
+        }
+}
diff --git a/sway/tree/layout.c b/sway/tree/layout.c
index 1f898f8a..533906fa 100644
--- a/sway/tree/layout.c
+++ b/sway/tree/layout.c
@@ -562,6 +562,7 @@ void container_move(struct sway_container *container,
                 workspace_detect_urgent(last_ws);
                 workspace_detect_urgent(next_ws);
         }
+        container_end_mouse_operation(container);
 }
 
 enum sway_container_layout container_get_default_layout(
diff --git a/sway/tree/view.c b/sway/tree/view.c
index 7881e6d7..24594950 100644
--- a/sway/tree/view.c
+++ b/sway/tree/view.c
@@ -387,6 +387,8 @@ void view_set_fullscreen(struct sway_view *view, bool fullscreen) {
                 }
         }
 
+        container_end_mouse_operation(view->swayc);
+
         ipc_event_window(view->swayc, "fullscreen_mode");
 }