WIP subtree offsetting

The current wip code is problematic because it relies on the computed_size of the nodes, which conflicts with dirty-redrawing because it is always be a frame behind.

gui/gui.c

@@ -170,6 +170,9 @@ struct GUI_Subtree {
 	GUI_Subtree *structural_parent;
 
 	RDIC_Node_Reference relative_to;
+	int flat_offset_x;
+	int flat_offset_y;
+
 	GUI_Draw_Command *first_draw_command;
 	int num_draw_commands;
 	Pixel_Buffer *pixel_buffer;
@@ -639,6 +642,8 @@ void gui_generate_draw_commands(
 		y_offset = relative_rectangle->y0;
 		//printf("%.*s: %d, %d\n", relative_node->debug_string.length, relative_node->debug_string.cstring, x_offset, y_offset);
 	}
+	x_offset += subtree->flat_offset_x;
+	y_offset += subtree->flat_offset_y;
 
 	GUI_Node *root = (GUI_Node*)subtree->rdic.root;
 	assert(root != NULL);
@@ -1386,6 +1391,7 @@ void test_gui__subtree(
 	static RDIC_Node_Reference middle = {0};
 	static RDIC_Node_Reference bottom = {0};
 
+	static RDIC_Node_Reference slider = {0};
 	static float slider_value = 0.25f;
 	top = gui_layout(
 		context, top, GUI_LAYOUT_HORIZONTAL, &outer_style, top_bottom_size);
@@ -1396,7 +1402,7 @@ void test_gui__subtree(
 		static GUI_Size slider_size[2] = {
 			{GUI_SIZERULE_PIXELS, 200, 100},
 			{GUI_SIZERULE_PIXELS,  40, 100}};
-		static RDIC_Node_Reference slider = {0};
+		//static RDIC_Node_Reference slider = {0};
 		static RDIC_Node_Reference slider_inner = {0};
 		// NOTE(Zelaven): This line is not good because it causes jankyness when
 		//  using the slider, and the slider behaves properly without it.
@@ -1436,6 +1442,23 @@ void test_gui__subtree(
 		inner_top = gui_dumb_block(context, inner_top, &outer_style, element_size);
 		((GUI_Node*)inner_top.node)->image = &test_image;
 	} gui_pop_subtree(context);
+	int middle_height =
+		((GUI_Node*)middle.node)->computed_size[GUI_AXIS2_Y];
+	int subtree_height =
+		((GUI_Node*)middle_subtree_root.node)->computed_size[GUI_AXIS2_Y];
+	int overfill = subtree_height - middle_height;
+	printf("\n%d = %d - %d\n", overfill, subtree_height, middle_height);
+	if(overfill >= 0)
+	{
+		printf("?\n");
+		middle_subtree.flat_offset_y = -(slider_value * overfill);
+		printf("%d\n", middle_subtree.flat_offset_x);
+	}
+	else
+	{
+		middle_subtree.flat_offset_y = 0;
+	}
+	((GUI_Node*)middle_subtree_root.node)->dirty = ((GUI_Node*)slider.node)->dirty;
 
 	bottom = gui_dumb_block(context, bottom, &outer_style, top_bottom_size);