Resize only current and immediate siblings rather than all siblings

For example, create layout V[view view view] and resize the leftmost
view using mod+rightclick. Previously, the edge between view 2 and 3
would be adjusted as well. Now this edge will remain constant, which
matches the behaviour of i3.

To do this operation correctly, the resize tiling seatop now keeps track
of two containers, as the container that resizes horizontally will be a
different container to the one which resizes vertically (one will be an
ancestor). The tiling resize seatop now figures out these containers
during the start of the operation and keeps references to them in the
event. A new function container_find_resize_parent has been introduced
to do this. This function is also used by the resize command.

During cursor motion, the seatop logic is similar to before, but now has
to choose the correct container to resize.

In resize.c, container_resize_tiled and resize_tiled have been merged
into one. One of them originally did nothing except pass the values
through to the other.

container_resize_tiled now takes a simplified approach where it just
finds the immediate siblings on either side and resizes them without
worrying about the others. The parellel_coord and parallel_size
functions are no longer needed and have been removed.

1 files changed, 86 insertions, 153 deletions

diff --git a/sway/commands/resize.c b/sway/commands/resize.c
index fad1ecb1..f6141afc 100644
--- a/sway/commands/resize.c
+++ b/sway/commands/resize.c
@@ -130,177 +130,108 @@ static bool is_horizontal(uint32_t axis) {
         return axis & (WLR_EDGE_LEFT | WLR_EDGE_RIGHT);
 }
 
-static int parallel_coord(struct sway_container *c, uint32_t axis) {
-        return is_horizontal(axis) ? c->x : c->y;
-}
-
-static int parallel_size(struct sway_container *c, uint32_t axis) {
-        return is_horizontal(axis) ? c->width : c->height;
-}
-
-static void container_recursive_resize(struct sway_container *container,
-                double amount, enum wlr_edges edge) {
-        bool layout_match = true;
-        wlr_log(WLR_DEBUG, "Resizing %p with amount: %f", container, amount);
-        if (edge & (WLR_EDGE_LEFT | WLR_EDGE_RIGHT)) {
-                container->width += amount;
-                layout_match = container->layout == L_HORIZ;
-        } else if (edge & (WLR_EDGE_TOP | WLR_EDGE_BOTTOM)) {
-                container->height += amount;
-                layout_match = container->layout == L_VERT;
-        }
-        if (container->children) {
-                for (int i = 0; i < container->children->length; i++) {
-                        struct sway_container *child = container->children->items[i];
-                        double amt = layout_match ?
-                                amount / container->children->length : amount;
-                        container_recursive_resize(child, amt, edge);
+struct sway_container *container_find_resize_parent(struct sway_container *con,
+                uint32_t axis) {
+        enum sway_container_layout parallel_layout =
+                is_horizontal(axis) ? L_HORIZ : L_VERT;
+        bool allow_first = axis != WLR_EDGE_TOP && axis != WLR_EDGE_LEFT;
+        bool allow_last = axis != WLR_EDGE_RIGHT && axis != WLR_EDGE_BOTTOM;
+
+        while (con) {
+                list_t *siblings = container_get_siblings(con);
+                int index = container_sibling_index(con);
+                if (container_parent_layout(con) == parallel_layout &&
+                                siblings->length > 1 && (allow_first || index > 0) &&
+                                (allow_last || index < siblings->length - 1)) {
+                        return con;
                 }
+                con = con->parent;
         }
+
+        return NULL;
 }
 
-static void resize_tiled(struct sway_container *parent, int amount,
-                uint32_t axis) {
-        struct sway_container *focused = parent;
-        if (!parent) {
+void container_resize_tiled(struct sway_container *con,
+                uint32_t axis, int amount) {
+        if (!con) {
                 return;
         }
 
-        enum sway_container_layout parallel_layout =
-                is_horizontal(axis) ? L_HORIZ : L_VERT;
-        int minor_weight = 0;
-        int major_weight = 0;
-        while (parent) {
-                list_t *siblings = container_get_siblings(parent);
-                if (container_parent_layout(parent) == parallel_layout) {
-                        for (int i = 0; i < siblings->length; i++) {
-                                struct sway_container *sibling = siblings->items[i];
-
-                                int sibling_pos = parallel_coord(sibling, axis);
-                                int focused_pos = parallel_coord(focused, axis);
-                                int parent_pos = parallel_coord(parent, axis);
-
-                                if (sibling_pos != focused_pos) {
-                                        if (sibling_pos < parent_pos) {
-                                                minor_weight++;
-                                        } else if (sibling_pos > parent_pos) {
-                                                major_weight++;
-                                        }
-                                }
-                        }
-                        if (major_weight || minor_weight) {
-                                break;
-                        }
-                }
-                parent = parent->parent;
-        }
-        if (!parent) {
+        con = container_find_resize_parent(con, axis);
+        if (!con) {
                 // Can't resize in this direction
                 return;
         }
 
-        // Implement up/down/left/right direction by zeroing one of the weights
-        if (axis == WLR_EDGE_TOP || axis == WLR_EDGE_LEFT) {
-                major_weight = 0;
-        } else if (axis == WLR_EDGE_RIGHT || axis == WLR_EDGE_BOTTOM) {
-                minor_weight = 0;
-        }
-
-        bool horizontal = is_horizontal(axis);
-        int min_sane = horizontal ? MIN_SANE_W : MIN_SANE_H;
-
-        //TODO: Ensure rounding is done in such a way that there are NO pixel leaks
-        // ^ ?????
-        list_t *siblings = container_get_siblings(parent);
-
-        for (int i = 0; i < siblings->length; i++) {
-                struct sway_container *sibling = siblings->items[i];
-
-                int sibling_pos = parallel_coord(sibling, axis);
-                int focused_pos = parallel_coord(focused, axis);
-                int parent_pos = parallel_coord(parent, axis);
-
-                int sibling_size = parallel_size(sibling, axis);
-                int parent_size = parallel_size(parent, axis);
-
-                if (sibling_pos != focused_pos) {
-                        if (sibling_pos < parent_pos && minor_weight) {
-                                double pixels = -amount / minor_weight;
-                                if (major_weight && (sibling_size + pixels / 2) < min_sane) {
-                                        return; // Too small
-                                } else if (!major_weight && sibling_size + pixels < min_sane) {
-                                        return; // Too small
-                                }
-                        } else if (sibling_pos > parent_pos && major_weight) {
-                                double pixels = -amount / major_weight;
-                                if (minor_weight && (sibling_size + pixels / 2) < min_sane) {
-                                        return; // Too small
-                                } else if (!minor_weight && sibling_size + pixels < min_sane) {
-                                        return; // Too small
-                                }
-                        }
-                } else {
-                        double pixels = amount;
-                        if (parent_size + pixels < min_sane) {
-                                return; // Too small
-                        }
+        // For HORIZONTAL or VERTICAL, we are growing in two directions so select
+        // both adjacent siblings. For RIGHT or DOWN, just select the next sibling.
+        // For LEFT or UP, convert it to a RIGHT or DOWN resize and reassign con to
+        // the previous sibling.
+        struct sway_container *prev = NULL;
+        struct sway_container *next = NULL;
+        list_t *siblings = container_get_siblings(con);
+        int index = container_sibling_index(con);
+
+        if (axis == AXIS_HORIZONTAL || axis == AXIS_VERTICAL) {
+                prev = siblings->items[index - 1];
+                next = siblings->items[index + 1];
+        } else if (axis == WLR_EDGE_TOP || axis == WLR_EDGE_LEFT) {
+                if (!sway_assert(index > 0, "Didn't expect first child")) {
+                        return;
                 }
+                next = con;
+                con = siblings->items[index - 1];
+                amount = -amount;
+        } else {
+                if (!sway_assert(index < siblings->length - 1,
+                                        "Didn't expect last child")) {
+                        return;
+                }
+                next = siblings->items[index + 1];
         }
 
-        enum wlr_edges minor_edge = horizontal ? WLR_EDGE_LEFT : WLR_EDGE_TOP;
-        enum wlr_edges major_edge = horizontal ? WLR_EDGE_RIGHT : WLR_EDGE_BOTTOM;
-
-        for (int i = 0; i < siblings->length; i++) {
-                struct sway_container *sibling = siblings->items[i];
-
-                int sibling_pos = parallel_coord(sibling, axis);
-                int focused_pos = parallel_coord(focused, axis);
-                int parent_pos = parallel_coord(parent, axis);
-
-                if (sibling_pos != focused_pos) {
-                        if (sibling_pos < parent_pos && minor_weight) {
-                                double pixels = -1 * amount;
-                                pixels /= minor_weight;
-                                if (major_weight) {
-                                        container_recursive_resize(sibling, pixels / 2, major_edge);
-                                } else {
-                                        container_recursive_resize(sibling, pixels, major_edge);
-                                }
-                        } else if (sibling_pos > parent_pos && major_weight) {
-                                double pixels = -1 * amount;
-                                pixels /= major_weight;
-                                if (minor_weight) {
-                                        container_recursive_resize(sibling, pixels / 2, minor_edge);
-                                } else {
-                                        container_recursive_resize(sibling, pixels, minor_edge);
-                                }
-                        }
-                } else {
-                        if (major_weight != 0 && minor_weight != 0) {
-                                double pixels = amount;
-                                pixels /= 2;
-                                container_recursive_resize(parent, pixels, minor_edge);
-                                container_recursive_resize(parent, pixels, major_edge);
-                        } else if (major_weight) {
-                                container_recursive_resize(parent, amount, major_edge);
-                        } else if (minor_weight) {
-                                container_recursive_resize(parent, amount, minor_edge);
-                        }
+        // Apply new dimensions
+        int sibling_amount = prev ? amount / 2 : amount;
+
+        if (is_horizontal(axis)) {
+                if (con->width + amount < MIN_SANE_W) {
+                        return;
+                }
+                if (next->width - sibling_amount < MIN_SANE_W) {
+                        return;
+                }
+                if (prev && prev->width - sibling_amount < MIN_SANE_W) {
+                        return;
+                }
+                con->width += amount;
+                next->width -= sibling_amount;
+                if (prev) {
+                        prev->width -= sibling_amount;
+                }
+        } else {
+                if (con->height + amount < MIN_SANE_H) {
+                        return;
+                }
+                if (next->height - sibling_amount < MIN_SANE_H) {
+                        return;
+                }
+                if (prev && prev->height - sibling_amount < MIN_SANE_H) {
+                        return;
+                }
+                con->height += amount;
+                next->height -= sibling_amount;
+                if (prev) {
+                        prev->height -= sibling_amount;
                 }
         }
 
-        if (parent->parent) {
-                arrange_container(parent->parent);
+        if (con->parent) {
+                arrange_container(con->parent);
         } else {
-                arrange_workspace(parent->workspace);
+                arrange_workspace(con->workspace);
         }
 }
 
-void container_resize_tiled(struct sway_container *parent,
-                enum wlr_edges edge, int amount) {
-        resize_tiled(parent, amount, edge);
-}
-
 /**
  * Implement `resize <grow|shrink>` for a floating container.
  */
@@ -379,7 +310,7 @@ static struct cmd_results *resize_adjust_tiled(uint32_t axis,
 
         double old_width = current->width;
         double old_height = current->height;
-        resize_tiled(current, amount->amount, axis);
+        container_resize_tiled(current, axis, amount->amount);
         if (current->width == old_width && current->height == old_height) {
                 return cmd_results_new(CMD_INVALID, "Cannot resize any further");
         }
@@ -407,7 +338,8 @@ static struct cmd_results *resize_set_tiled(struct sway_container *con,
                         width->unit = RESIZE_UNIT_PX;
                 }
                 if (width->unit == RESIZE_UNIT_PX) {
-                        resize_tiled(con, width->amount - con->width, AXIS_HORIZONTAL);
+                        container_resize_tiled(con, AXIS_HORIZONTAL,
+                                        width->amount - con->width);
                 }
         }
 
@@ -427,7 +359,8 @@ static struct cmd_results *resize_set_tiled(struct sway_container *con,
                         height->unit = RESIZE_UNIT_PX;
                 }
                 if (height->unit == RESIZE_UNIT_PX) {
-                        resize_tiled(con, height->amount - con->height, AXIS_VERTICAL);
+                        container_resize_tiled(con, AXIS_VERTICAL,
+                                        height->amount - con->height);
                 }
         }