3 files changed, 33 insertions, 6 deletions

diff --git a/include/sway/tree/container.h b/include/sway/tree/container.h
index 099a8089..62c6556b 100644
--- a/include/sway/tree/container.h
+++ b/include/sway/tree/container.h
@@ -92,6 +92,11 @@ struct sway_container {
         double width_fraction;
         double height_fraction;
 
+        // The share of space of the parent container that all children occupy
+        // Used for doing the resize calculations
+        double child_total_width;
+        double child_total_height;
+
         // These are in layout coordinates.
         double content_x, content_y;
         int content_width, content_height;
diff --git a/sway/commands/resize.c b/sway/commands/resize.c
index 0c9af12d..7ff4ef7b 100644
--- a/sway/commands/resize.c
+++ b/sway/commands/resize.c
@@ -172,9 +172,19 @@ void container_resize_tiled(struct sway_container *con,
                 if (prev && prev->width - sibling_amount < MIN_SANE_W) {
                         return;
                 }
+                if (con->child_total_width <= 0) {
+                        return;
+                }
+
+                // We're going to resize so snap all the width fractions to full pixels
+                // to avoid rounding issues
+                list_t *siblings = container_get_siblings(con);
+                for (int i = 0; i < siblings->length; ++i) {
+                        struct sway_container *con = siblings->items[i];
+                        con->width_fraction = con->width / con->child_total_width;
+                }
 
-                double amount_fraction =
-                        ((double)amount / con->width) * con->width_fraction;
+                double amount_fraction = (double)amount / con->child_total_width;
                 double sibling_amount_fraction =
                         prev ? amount_fraction / 2.0 : amount_fraction;
 
@@ -193,9 +203,19 @@ void container_resize_tiled(struct sway_container *con,
                 if (prev && prev->height - sibling_amount < MIN_SANE_H) {
                         return;
                 }
+                if (con->child_total_height <= 0) {
+                        return;
+                }
+
+                // We're going to resize so snap all the height fractions to full pixels
+                // to avoid rounding issues
+                list_t *siblings = container_get_siblings(con);
+                for (int i = 0; i < siblings->length; ++i) {
+                        struct sway_container *con = siblings->items[i];
+                        con->height_fraction = con->height / con->child_total_height;
+                }
 
-                double amount_fraction =
-                        ((double)amount / con->height) * con->height_fraction;
+                double amount_fraction = (double)amount / con->child_total_height;
                 double sibling_amount_fraction =
                         prev ? amount_fraction / 2.0 : amount_fraction;
 
diff --git a/sway/tree/arrange.c b/sway/tree/arrange.c
index 7b88b3a2..e4f59110 100644
--- a/sway/tree/arrange.c
+++ b/sway/tree/arrange.c
@@ -78,9 +78,10 @@ static void apply_horiz_layout(list_t *children, struct wlr_box *parent) {
         double child_x = parent->x;
         for (int i = 0; i < children->length; ++i) {
                 struct sway_container *child = children->items[i];
+                child->child_total_width = child_total_width;
                 child->x = child_x;
                 child->y = parent->y;
-                child->width = floor(child->width_fraction * child_total_width);
+                child->width = round(child->width_fraction * child_total_width);
                 child->height = parent->height;
                 child_x += child->width + inner_gap;
 
@@ -156,10 +157,11 @@ static void apply_vert_layout(list_t *children, struct wlr_box *parent) {
         double child_y = parent->y;
         for (int i = 0; i < children->length; ++i) {
                 struct sway_container *child = children->items[i];
+                child->child_total_height = child_total_height;
                 child->x = parent->x;
                 child->y = child_y;
                 child->width = parent->width;
-                child->height = floor(child->height_fraction * child_total_height);
+                child->height = round(child->height_fraction * child_total_height);
                 child_y += child->height + inner_gap;
 
                 // Make last child use remaining height of parent