output: Support multiple adjacent outputs.

When querying for an adjacent output we now need an absolute position in
order to know which adjacent output that matches. (The position is
either the current mouse position or the center of the currently focused
container, depending on context.)

If two outputs have one edge each that at least partially align with
each other they now count as adjacent.

Seamless mouse is affected by this and now properly moves and positions
itself between outputs with "uneven" placement (as long as they have at
least some part of the edge adjacent to each other).

When focusing or moving a container in a specified direction the center
of the current focused container decides where to look for an adjacent
output. So if e.g. an output has two adjacent outputs to the right and a
"focus right" command is issued then it's the placement of the currently
focused container that decides which output actually gets focused.

Also, if an output has at least one output adjacent in some direction
but the entire edge is not covered (ie. it has "holes" with no outputs),
then the algorithm will choose the output that is closest to the
currently focused container (this does not apply to seamless mouse, the
pointer will just stop at the edge in that case).

4 files changed, 155 insertions, 46 deletions

diff --git a/sway/commands.c b/sway/commands.c
index f194681e..dfb3c12d 100644
--- a/sway/commands.c
+++ b/sway/commands.c
@@ -377,11 +377,13 @@ static struct cmd_results *cmd_focus(int argc, char **argv) {
         struct cmd_results *error = NULL;
         if (argc > 0 && strcasecmp(argv[0], "output") == 0) {
                 swayc_t *output = NULL;
+                struct wlc_point abs_pos;
+                get_absolute_center_position(get_focused_container(&root_container), &abs_pos);
                 if ((error = checkarg(argc, "focus", EXPECTED_EQUAL_TO, 2))) {
                         return error;
-                } else if (!(output = output_by_name(argv[1]))) {
+                } else if (!(output = output_by_name(argv[1], &abs_pos))) {
                         return cmd_results_new(CMD_FAILURE, "focus output",
-                                "Can't find output with name/at direction %s", argv[1]);
+                                "Can't find output with name/at direction '%s' @ (%i,%i)", argv[1], abs_pos.x, abs_pos.y);
                 } else if (!workspace_switch(swayc_active_workspace_for(output))) {
                         return cmd_results_new(CMD_FAILURE, "focus output",
                                 "Switching to workspace on output '%s' was blocked", argv[1]);
@@ -591,11 +593,13 @@ static struct cmd_results *cmd_move(int argc, char **argv) {
                 } else if (strcasecmp(argv[1], "to") == 0 && strcasecmp(argv[2], "output") == 0) {
                         // move container to output x
                         swayc_t *output = NULL;
+                        struct wlc_point abs_pos;
+                        get_absolute_center_position(view, &abs_pos);
                         if (view->type != C_CONTAINER && view->type != C_VIEW) {
                                 return cmd_results_new(CMD_FAILURE, "move", "Can only move containers and views.");
-                        } else if (!(output = output_by_name(argv[3]))) {
+                        } else if (!(output = output_by_name(argv[3], &abs_pos))) {
                                 return cmd_results_new(CMD_FAILURE, "move",
-                                        "Can't find output with name/direction '%s'", argv[3]);
+                                        "Can't find output with name/direction '%s' @ (%i,%i)", argv[3], abs_pos.x, abs_pos.y);
                         } else {
                                 swayc_t *container = get_focused_container(output);
                                 if (container->is_floating) {
@@ -610,13 +614,15 @@ static struct cmd_results *cmd_move(int argc, char **argv) {
         } else if (strcasecmp(argv[0], "workspace") == 0) {
                 // move workspace (to output x)
                 swayc_t *output = NULL;
+                struct wlc_point abs_pos;
+                get_absolute_center_position(view, &abs_pos);
                 if ((error = checkarg(argc, "move workspace", EXPECTED_EQUAL_TO, 4))) {
                         return error;
                 } else if (strcasecmp(argv[1], "to") != 0 || strcasecmp(argv[2], "output") != 0) {
                         return cmd_results_new(CMD_INVALID, "move", expected_syntax);
-                } else if (!(output = output_by_name(argv[3]))) {
+                } else if (!(output = output_by_name(argv[3], &abs_pos))) {
                         return cmd_results_new(CMD_FAILURE, "move workspace",
-                                "Can't find output with name/at direction '%s'", argv[3]);
+                                "Can't find output with name/direction '%s' @ (%i,%i)", argv[3], abs_pos.x, abs_pos.y);
                 }
                 if (view->type == C_WORKSPACE) {
                         // This probably means we're moving an empty workspace, but
diff --git a/sway/handlers.c b/sway/handlers.c
index cadfce5c..3f3c1bdd 100644
--- a/sway/handlers.c
+++ b/sway/handlers.c
@@ -305,28 +305,39 @@ static bool handle_pointer_motion(wlc_handle handle, uint32_t time, const struct
                         !pointer_state.left.held && !pointer_state.right.held && !pointer_state.scroll.held) {
 
                 swayc_t *output = swayc_active_output(), *adjacent = NULL;
+                struct wlc_point abs_pos = *origin;
+                abs_pos.x += output->x;
+                abs_pos.y += output->y;
                 if (origin->x == 0) { // Left edge
-                        if ((adjacent = swayc_adjacent_output(output, MOVE_LEFT))) {
+                        if ((adjacent = swayc_adjacent_output(output, MOVE_LEFT, &abs_pos, false))) {
                                 if (workspace_switch(swayc_active_workspace_for(adjacent))) {
                                         new_origin.x = adjacent->width;
+                                        // adjust for differently aligned outputs (well, this is
+                                        // only correct when the two outputs have the same
+                                        // resolution or the same dpi I guess, it should take
+                                        // physical attributes into account)
+                                        new_origin.y += (output->y - adjacent->y);
                                 }
                         }
                 } else if ((double)origin->x == output->width) { // Right edge
-                        if ((adjacent = swayc_adjacent_output(output, MOVE_RIGHT))) {
+                        if ((adjacent = swayc_adjacent_output(output, MOVE_RIGHT, &abs_pos, false))) {
                                 if (workspace_switch(swayc_active_workspace_for(adjacent))) {
                                         new_origin.x = 0;
+                                        new_origin.y += (output->y - adjacent->y);
                                 }
                         }
                 } else if (origin->y == 0) { // Top edge
-                        if ((adjacent = swayc_adjacent_output(output, MOVE_UP))) {
+                        if ((adjacent = swayc_adjacent_output(output, MOVE_UP, &abs_pos, false))) {
                                 if (workspace_switch(swayc_active_workspace_for(adjacent))) {
                                         new_origin.y = adjacent->height;
+                                        new_origin.x += (output->x - adjacent->x);
                                 }
                         }
                 } else if ((double)origin->y == output->height) { // Bottom edge
-                        if ((adjacent = swayc_adjacent_output(output, MOVE_DOWN))) {
+                        if ((adjacent = swayc_adjacent_output(output, MOVE_DOWN, &abs_pos, false))) {
                                 if (workspace_switch(swayc_active_workspace_for(adjacent))) {
                                         new_origin.y = 0;
+                                        new_origin.x += (output->x - adjacent->x);
                                 }
                         }
                 }
diff --git a/sway/layout.c b/sway/layout.c
index fe7d820a..741addf1 100644
--- a/sway/layout.c
+++ b/sway/layout.c
@@ -533,13 +533,17 @@ swayc_t *get_swayc_in_direction_under(swayc_t *container, enum movement_directio
                         return parent;
                 }
         }
+        // If moving to an adjacent output we need a starting position (since this
+        // output might border to multiple outputs).
+        struct wlc_point abs_pos;
+        get_absolute_center_position(container, &abs_pos);
         while (true) {
                 // Test if we can even make a difference here
                 bool can_move = false;
                 int diff = 0;
                 if (parent->type == C_ROOT) {
                         sway_log(L_DEBUG, "Moving between outputs");
-                        return swayc_adjacent_output(container, dir);
+                        return swayc_adjacent_output(container, dir, &abs_pos, true);
                 } else {
                         if (dir == MOVE_LEFT || dir == MOVE_RIGHT) {
                                 if (parent->layout == L_HORIZ) {
diff --git a/sway/output.c b/sway/output.c
index 5044b7aa..cf8ed9a5 100644
--- a/sway/output.c
+++ b/sway/output.c
@@ -2,15 +2,15 @@
 #include "output.h"
 #include "log.h"
 
-swayc_t *output_by_name(const char* name) {
+swayc_t *output_by_name(const char* name, const struct wlc_point *abs_pos) {
         if (strcasecmp(name, "left") == 0) {
-                return swayc_adjacent_output(NULL, MOVE_LEFT);
+                return swayc_adjacent_output(NULL, MOVE_LEFT, abs_pos, true);
         } else if (strcasecmp(name, "right") == 0) {
-                return swayc_adjacent_output(NULL, MOVE_RIGHT);
+                return swayc_adjacent_output(NULL, MOVE_RIGHT, abs_pos, true);
         } else if (strcasecmp(name, "up") == 0) {
-                return swayc_adjacent_output(NULL, MOVE_UP);
+                return swayc_adjacent_output(NULL, MOVE_UP, abs_pos, true);
         } else if (strcasecmp(name, "down") == 0) {
-                return swayc_adjacent_output(NULL, MOVE_DOWN);
+                return swayc_adjacent_output(NULL, MOVE_DOWN, abs_pos, true);
         } else {
                 for(int i = 0; i < root_container.children->length; ++i) {
                         swayc_t *c = root_container.children->items[i];
@@ -22,66 +22,126 @@ swayc_t *output_by_name(const char* name) {
         return NULL;
 }
 
-swayc_t *swayc_adjacent_output(swayc_t *output, enum movement_direction dir) {
-        // TODO: This implementation is naïve: We assume all outputs are
-        // perfectly aligned (ie. only a single output per edge which covers
-        // the whole edge).
+// Position is where on the edge (as absolute position) the adjacent output should be searched for.
+swayc_t *swayc_adjacent_output(swayc_t *output, enum movement_direction dir,
+                const struct wlc_point *abs_pos, bool pick_closest) {
+
         if (!output) {
                 output = swayc_active_output();
         }
+        // In order to find adjacent outputs we need to test that the outputs are
+        // aligned on one axis (decided by the direction given) and that the given
+        // position is within the edge of the adjacent output. If no such output
+        // exists we pick the adjacent output within the edge that is closest to
+        // the given position, if any.
         swayc_t *adjacent = NULL;
+        char *dir_text = NULL;
         switch(dir) {
                 case MOVE_LEFT:
+                case MOVE_RIGHT: ;
+                        double delta_y = 0;
                         for(int i = 0; i < root_container.children->length; ++i) {
                                 swayc_t *c = root_container.children->items[i];
                                 if (c == output || c->type != C_OUTPUT) {
                                         continue;
                                 }
-                                if (c->y == output->y && c->x + c->width == output->x) {
-                                        sway_log(L_DEBUG, "%s is left of current output %s", c->name, output->name);
-                                        adjacent = c;
-                                        break;
-                                }
-                        }
-                        break;
-                case MOVE_RIGHT:
-                        for(int i = 0; i < root_container.children->length; ++i) {
-                                swayc_t *c = root_container.children->items[i];
-                                if (c == output || c->type != C_OUTPUT) {
+                                bool x_aligned = dir == MOVE_LEFT ?
+                                        c->x + c->width == output->x :
+                                        c->x == output->x + output->width;
+                                if (!x_aligned) {
                                         continue;
                                 }
-                                if (c->y == output->y && output->x + output->width == c->x) {
-                                        sway_log(L_DEBUG, "%s is right of current output %s", c->name, output->name);
+                                if (abs_pos->y >= c->y && abs_pos->y <= c->y + c->height) {
+                                        delta_y = 0;
                                         adjacent = c;
                                         break;
+                                } else if (pick_closest) {
+                                        // track closest adjacent output
+                                        double top_y = c->y, bottom_y = c->y + c->height;
+                                        if (top_y >= output->y && top_y <= output->y + output->height) {
+                                                double delta = top_y - abs_pos->y;
+                                                if (delta < 0) delta = -delta;
+                                                if (delta < delta_y || !adjacent) {
+                                                        delta_y = delta;
+                                                        adjacent = c;
+                                                }
+                                        }
+                                        // we check both points and pick the closest
+                                        if (bottom_y >= output->y && bottom_y <= output->y + output->height) {
+                                                double delta = bottom_y - abs_pos->y;
+                                                if (delta < 0) delta = -delta;
+                                                if (delta < delta_y || !adjacent) {
+                                                        delta_y = delta;
+                                                        adjacent = c;
+                                                }
+                                        }
                                 }
                         }
+                        dir_text = dir == MOVE_LEFT ? "left of" : "right of";
+                        if (adjacent && delta_y == 0) {
+                                sway_log(L_DEBUG, "%s (%.0fx%.0f+%.0f+%.0f) is %s current output %s (y-position %i)",
+                                                adjacent->name, adjacent->width, adjacent->height, adjacent->x, adjacent->y,
+                                                dir_text, output->name, abs_pos->y);
+                        } else if (adjacent) {
+                                // so we end up picking the closest adjacent output because
+                                // there is no directly adjacent to the given position
+                                sway_log(L_DEBUG, "%s (%.0fx%.0f+%.0f+%.0f) is %s current output %s (y-position %i, delta: %.0f)",
+                                        adjacent->name, adjacent->width, adjacent->height, adjacent->x, adjacent->y,
+                                        dir_text, output->name, abs_pos->y, delta_y);
+                        }
                         break;
                 case MOVE_UP:
+                case MOVE_DOWN: ;
+                        double delta_x = 0;
                         for(int i = 0; i < root_container.children->length; ++i) {
                                 swayc_t *c = root_container.children->items[i];
                                 if (c == output || c->type != C_OUTPUT) {
                                         continue;
                                 }
-                                if (output->x == c->x && c->y + c->height == output->y) {
-                                        sway_log(L_DEBUG, "%s is above current output %s", c->name, output->name);
-                                        adjacent = c;
-                                        break;
-                                }
-                        }
-                        break;
-                case MOVE_DOWN:
-                        for(int i = 0; i < root_container.children->length; ++i) {
-                                swayc_t *c = root_container.children->items[i];
-                                if (c == output || c->type != C_OUTPUT) {
+                                bool y_aligned = dir == MOVE_UP ?
+                                        c->y + c->height == output->y :
+                                        c->y == output->y + output->height;
+                                if (!y_aligned) {
                                         continue;
                                 }
-                                if (output->x == c->x && output->y + output->height == c->y) {
-                                        sway_log(L_DEBUG, "%s is below current output %s", c->name, output->name);
+                                if (abs_pos->x >= c->x && abs_pos->x <= c->x + c->width) {
+                                        delta_x = 0;
                                         adjacent = c;
                                         break;
+                                } else if (pick_closest) {
+                                        // track closest adjacent output
+                                        double left_x = c->x, right_x = c->x + c->width;
+                                        if (left_x >= output->x && left_x <= output->x + output->width) {
+                                                double delta = left_x - abs_pos->x;
+                                                if (delta < 0) delta = -delta;
+                                                if (delta < delta_x || !adjacent) {
+                                                        delta_x = delta;
+                                                        adjacent = c;
+                                                }
+                                        }
+                                        // we check both points and pick the closest
+                                        if (right_x >= output->x && right_x <= output->x + output->width) {
+                                                double delta = right_x - abs_pos->x;
+                                                if (delta < 0) delta = -delta;
+                                                if (delta < delta_x || !adjacent) {
+                                                        delta_x = delta;
+                                                        adjacent = c;
+                                                }
+                                        }
                                 }
                         }
+                        dir_text = dir == MOVE_UP ? "above" : "below";
+                        if (adjacent && delta_x == 0) {
+                                sway_log(L_DEBUG, "%s (%.0fx%.0f+%.0f+%.0f) is %s current output %s (x-position %i)",
+                                                adjacent->name, adjacent->width, adjacent->height, adjacent->x, adjacent->y,
+                                                dir_text, output->name, abs_pos->x);
+                        } else if (adjacent) {
+                                // so we end up picking the closest adjacent output because
+                                // there is no directly adjacent to the given position
+                                sway_log(L_DEBUG, "%s (%.0fx%.0f+%.0f+%.0f) is %s current output %s (x-position %i, delta: %.0f)",
+                                        adjacent->name, adjacent->width, adjacent->height, adjacent->x, adjacent->y,
+                                        dir_text, output->name, abs_pos->x, delta_x);
+                        }
                         break;
                 default:
                         sway_abort("Function called with invalid argument.");
@@ -89,3 +149,31 @@ swayc_t *swayc_adjacent_output(swayc_t *output, enum movement_direction dir) {
         }
         return adjacent;
 }
+
+void get_absolute_position(swayc_t *container, struct wlc_point *point) {
+        if (!container || !point)
+                sway_abort("Need container and wlc_point (was %p, %p).", container, point);
+
+        if (container->type == C_OUTPUT) {
+                // Coordinates are already absolute.
+                point->x = container->x;
+                point->y = container->y;
+        } else {
+                swayc_t *output = swayc_parent_by_type(container, C_OUTPUT);
+                if (container->type == C_WORKSPACE) {
+                        // Workspace coordinates are actually wrong/arbitrary, but should
+                        // be same as output.
+                        point->x = output->x;
+                        point->y = output->y;
+                } else {
+                        point->x = output->x + container->x;
+                        point->y = output->y + container->y;
+                }
+        }
+}
+
+void get_absolute_center_position(swayc_t *container, struct wlc_point *point) {
+        get_absolute_position(container, point);
+        point->x += container->width/2;
+        point->y += container->height/2;
+}