fix randrew#15 and randrew#20, add some test case.

Author: haoyu234

layout.h

@@ -1066,7 +1066,7 @@ void lay_arrange_overlay(lay_context *ctx, lay_id item, int dim)
 
         switch (b_flags & LAY_HFILL) {
         case LAY_HCENTER:
-            child_rect[dim] += (space - child_rect[2 + dim]) / 2 - child_margins[wdim];
+            child_rect[dim] += lay_scalar_max(0, (space - child_rect[2 + dim]) / 2 - child_margins[wdim]);
             break;
         case LAY_RIGHT:
             child_rect[dim] += space - child_rect[2 + dim] - child_margins[dim] - child_margins[wdim];
@@ -1101,7 +1101,7 @@ void lay_arrange_overlay_squeezed_range(
         switch (b_flags & LAY_HFILL) {
             case LAY_HCENTER:
                 rect[2 + dim] = lay_scalar_min(rect[2 + dim], min_size);
-                rect[dim] += (space - rect[2 + dim]) / 2 - margins[wdim];
+                rect[dim] += lay_scalar_max(0, (space - rect[2 + dim]) / 2 - margins[wdim]);
                 break;
             case LAY_RIGHT:
                 rect[2 + dim] = lay_scalar_min(rect[2 + dim], min_size);
@@ -1159,8 +1159,19 @@ static void lay_arrange(lay_context *ctx, lay_id item, int dim)
             lay_arrange_stacked(ctx, item, 1, true);
             lay_scalar offset = lay_arrange_wrapped_overlay_squeezed(ctx, item, 0);
             ctx->rects[item][2 + 0] = offset - ctx->rects[item][0];
+
+            // The X coordinates are calculated above, and all children nodes need to be updated here
+            lay_id child = pitem->first_child;
+            while (child != LAY_INVALID_ID) {
+                lay_arrange(ctx, child, 0);
+                lay_item_t *pchild = lay_get_item(ctx, child);
+                child = pchild->next_sibling;
+            }
+            break;
+        } else {
+            // To prevent repeated calculations, it should be returned directly here
+            return;
         }
-        break;
     case LAY_ROW | LAY_WRAP:
         if (dim == 0)
             lay_arrange_stacked(ctx, item, 0, true);

test_layout.c

@@ -920,6 +920,89 @@ LTEST_DECLARE(anchor_right_margin2)
     LTEST_VEC4EQ(lay_get_rect(ctx, child), 40, 40, 50, 50);
 }
 
+// issue #15
+LTEST_DECLARE(child_expands_container1)
+{
+    lay_id root = lay_item(ctx);
+    lay_set_size_xy(ctx, root, 1, 100);
+
+    lay_id row = lay_item(ctx);
+    lay_set_contain(ctx, row, LAY_ROW);
+    lay_insert(ctx, root, row);
+
+    lay_id child = lay_item(ctx);
+    lay_set_size_xy(ctx, child, 1, 50);
+    lay_set_margins_ltrb(ctx, child, 0, 0, 0, 10);
+    lay_insert(ctx, row, child);
+
+    lay_run_context(ctx);
+    lay_vec4 root_rect = lay_get_rect(ctx, root);
+    lay_vec4 row_rect = lay_get_rect(ctx, row);
+    lay_vec4 child_rect = lay_get_rect(ctx, child);
+
+    LTEST_VEC4EQ(root_rect, 0, 0, 1, 100);
+    LTEST_VEC4EQ(row_rect, 0, 20, 1, 60);
+    LTEST_VEC4EQ(child_rect, 0, 20, 1, 50);
+}
+
+// issue #15
+LTEST_DECLARE(child_expands_container2)
+{
+    lay_id root = lay_item(ctx);
+	lay_set_size_xy(ctx, root, 400, 400);
+	lay_set_margins_ltrb(ctx, root, 50, 50, 50, 50);
+	lay_set_contain(ctx, root, LAY_COLUMN | LAY_WRAP);
+
+	lay_id child1 = lay_item(ctx);
+	lay_set_size_xy(ctx, child1 , 50, 50);
+	lay_set_margins_ltrb(ctx, child1 , 5, 5, 5, 5);
+	lay_insert(ctx, root, child1);
+
+	lay_id child2 = lay_item(ctx);
+	lay_set_size_xy(ctx, child2, 50, 50);
+	lay_set_margins_ltrb(ctx, child2, 5, 5, 5, 5);
+	lay_insert(ctx, root, child2);
+
+	lay_run_context(ctx);
+
+	lay_vec4 root_rect = lay_get_rect(ctx, root);
+	lay_vec4 child1_rect = lay_get_rect(ctx, child1);
+	lay_vec4 child2_rect = lay_get_rect(ctx, child2);
+
+	LTEST_VEC4EQ(root_rect, 50, 50, 60, 400);
+	LTEST_VEC4EQ(child1_rect, 55, 195, 50, 50);
+	LTEST_VEC4EQ(child2_rect, 55, 255, 50, 50);
+}
+
+// issue #20
+LTEST_DECLARE(column_wrap_grandson)
+{
+    lay_id root = lay_item(ctx);
+    lay_set_size_xy(ctx, root, 200, 200);
+    lay_set_margins_ltrb(ctx, root, 50, 50, 50, 50);
+    lay_set_contain(ctx, root, LAY_WRAP | LAY_COLUMN);
+
+    lay_id child1 = lay_item(ctx);
+    lay_set_size_xy(ctx, child1, 50, 50);
+    lay_set_margins_ltrb(ctx, child1, 5, 5, 5, 5);
+    lay_insert(ctx, root, child1);
+
+    lay_id child2 = lay_item(ctx);
+    lay_set_size_xy(ctx, child2, 50, 50);
+    lay_set_margins_ltrb(ctx, child2, 5, 5, 5, 5);
+    lay_insert(ctx, child1, child2);
+
+    lay_run_context(ctx);
+
+	lay_vec4 root_rect = lay_get_rect(ctx, root);
+	lay_vec4 child1_rect = lay_get_rect(ctx, child1);
+	lay_vec4 child2_rect = lay_get_rect(ctx, child2);
+
+	LTEST_VEC4EQ(root_rect, 50, 50, 60, 200);
+	LTEST_VEC4EQ(child1_rect, 55, 125, 50, 50);
+	LTEST_VEC4EQ(child2_rect, 60, 130, 50, 50);
+}
+
 // Call in main to run a test by name
 //
 // Resets string buffer and lay context before running test
@@ -966,6 +1049,9 @@ int main(int argc, char** argv)
     LTEST_RUN(wrap_column_4);
     LTEST_RUN(anchor_right_margin1);
     LTEST_RUN(anchor_right_margin2);
+    LTEST_RUN(child_expands_container1);
+    LTEST_RUN(child_expands_container2);
+    LTEST_RUN(column_wrap_grandson);
 
     printf("Finished tests\n");