From 5d574d980d98a80779d2d51e6a2fd1c8420b6533 Mon Sep 17 00:00:00 2001
From: Leonardo Christino <leomilho@gmail.com>
Date: Wed, 24 Jun 2020 16:59:41 -0300
Subject: [PATCH] Make GraphNode handle children with EXPAND flag

---
 scene/gui/graph_node.cpp | 132 +++++++++++++++++++++++++++++++++------
 1 file changed, 114 insertions(+), 18 deletions(-)

diff --git a/scene/gui/graph_node.cpp b/scene/gui/graph_node.cpp
index b615cdb2664e..c80fc516e83a 100644
--- a/scene/gui/graph_node.cpp
+++ b/scene/gui/graph_node.cpp
@@ -32,6 +32,12 @@
 
 #include "core/string/translation.h"
 
+struct _MinSizeCache {
+	int min_size;
+	bool will_stretch;
+	int final_size;
+};
+
 bool GraphNode::_set(const StringName &p_name, const Variant &p_value) {
 	String str = p_name;
 	if (str.begins_with("opentype_features/")) {
@@ -171,15 +177,23 @@ void GraphNode::_get_property_list(List<PropertyInfo> *p_list) const {
 }
 
 void GraphNode::_resort() {
-	int sep = get_theme_constant("separation");
+	/** First pass, determine minimum size AND amount of stretchable elements */
+
+	Size2i new_size = get_size();
 	Ref<StyleBox> sb = get_theme_stylebox("frame");
-	bool first = true;
 
-	Size2 minsize;
+	int sep = get_theme_constant("separation");
+
+	bool first = true;
+	int children_count = 0;
+	int stretch_min = 0;
+	int stretch_avail = 0;
+	float stretch_ratio_total = 0;
+	Map<Control *, _MinSizeCache> min_size_cache;
 
 	for (int i = 0; i < get_child_count(); i++) {
 		Control *c = Object::cast_to<Control>(get_child(i));
-		if (!c) {
+		if (!c || !c->is_visible_in_tree()) {
 			continue;
 		}
 		if (c->is_set_as_top_level()) {
@@ -187,38 +201,120 @@ void GraphNode::_resort() {
 		}
 
 		Size2i size = c->get_combined_minimum_size();
+		_MinSizeCache msc;
 
-		minsize.y += size.y;
-		minsize.x = MAX(minsize.x, size.x);
+		stretch_min += size.height;
+		msc.min_size = size.height;
+		msc.will_stretch = c->get_v_size_flags() & SIZE_EXPAND;
 
-		if (first) {
-			first = false;
-		} else {
-			minsize.y += sep;
+		if (msc.will_stretch) {
+			stretch_avail += msc.min_size;
+			stretch_ratio_total += c->get_stretch_ratio();
 		}
+		msc.final_size = msc.min_size;
+		min_size_cache[c] = msc;
+		children_count++;
 	}
 
-	int vofs = 0;
-	int w = get_size().x - sb->get_minimum_size().x;
+	if (children_count == 0) {
+		return;
+	}
+
+	int stretch_max = new_size.height - (children_count - 1) * sep;
+	int stretch_diff = stretch_max - stretch_min;
+	if (stretch_diff < 0) {
+		//avoid negative stretch space
+		stretch_diff = 0;
+	}
+
+	stretch_avail += stretch_diff - sb->get_margin(SIDE_BOTTOM) - sb->get_margin(SIDE_TOP); //available stretch space.
+	/** Second, pass sucessively to discard elements that can't be stretched, this will run while stretchable
+		elements exist */
+
+	while (stretch_ratio_total > 0) { // first of all, don't even be here if no stretchable objects exist
+		bool refit_successful = true; //assume refit-test will go well
+
+		for (int i = 0; i < get_child_count(); i++) {
+			Control *c = Object::cast_to<Control>(get_child(i));
+			if (!c || !c->is_visible_in_tree()) {
+				continue;
+			}
+			if (c->is_set_as_top_level()) {
+				continue;
+			}
 
+			ERR_FAIL_COND(!min_size_cache.has(c));
+			_MinSizeCache &msc = min_size_cache[c];
+
+			if (msc.will_stretch) { //wants to stretch
+				//let's see if it can really stretch
+
+				int final_pixel_size = stretch_avail * c->get_stretch_ratio() / stretch_ratio_total;
+				if (final_pixel_size < msc.min_size) {
+					//if available stretching area is too small for widget,
+					//then remove it from stretching area
+					msc.will_stretch = false;
+					stretch_ratio_total -= c->get_stretch_ratio();
+					refit_successful = false;
+					stretch_avail -= msc.min_size;
+					msc.final_size = msc.min_size;
+					break;
+				} else {
+					msc.final_size = final_pixel_size;
+				}
+			}
+		}
+
+		if (refit_successful) { //uf refit went well, break
+			break;
+		}
+	}
+
+	/** Final pass, draw and stretch elements **/
+
+	int ofs = sb->get_margin(SIDE_TOP);
+
+	first = true;
+	int idx = 0;
 	cache_y.clear();
+	int w = new_size.width - sb->get_minimum_size().x;
+
 	for (int i = 0; i < get_child_count(); i++) {
 		Control *c = Object::cast_to<Control>(get_child(i));
-		if (!c) {
+		if (!c || !c->is_visible_in_tree()) {
 			continue;
 		}
 		if (c->is_set_as_top_level()) {
 			continue;
 		}
 
-		Size2i size = c->get_combined_minimum_size();
+		_MinSizeCache &msc = min_size_cache[c];
+
+		if (first) {
+			first = false;
+		} else {
+			ofs += sep;
+		}
 
-		Rect2 r(sb->get_margin(SIDE_LEFT), sb->get_margin(SIDE_TOP) + vofs, w, size.y);
+		int from = ofs;
+		int to = ofs + msc.final_size;
 
-		fit_child_in_rect(c, r);
-		cache_y.push_back(vofs + size.y * 0.5);
+		if (msc.will_stretch && idx == children_count - 1) {
+			//adjust so the last one always fits perfect
+			//compensating for numerical imprecision
 
-		vofs += size.y + sep;
+			to = new_size.height - sb->get_margin(SIDE_BOTTOM);
+		}
+
+		int size = to - from;
+
+		Rect2 rect(sb->get_margin(SIDE_LEFT), from, w, size);
+
+		fit_child_in_rect(c, rect);
+		cache_y.push_back(from - sb->get_margin(SIDE_TOP) + size * 0.5);
+
+		ofs = to;
+		idx++;
 	}
 
 	update();