From a3b58a0ba3f9db08a6232f6f9a0aa441b029920c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Felix=20Sch=C3=BCtt?= <felix.schuett@maps4print.com>
Date: Fri, 5 Oct 2018 15:43:37 +0200
Subject: [PATCH] Improved layout constraint insertion performance

Crashes with stack overflow in recursive push_iframe function -
shouldn't happen, of course.
---
 src/display_list.rs       | 22 ++++++++++++++++------
 src/dom.rs                |  5 +++++
 src/ui_solver.rs          | 10 +++++++---
 src/widgets/table_view.rs |  4 ++--
 4 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/src/display_list.rs b/src/display_list.rs
index 66f62c9e7..7b335b3b7 100644
--- a/src/display_list.rs
+++ b/src/display_list.rs
@@ -343,26 +343,38 @@ fn insert_constraints_into_solver<'a, T: Layout>(
 
     if changeset.is_some() {
 
+        println!("4!");
+
         // inefficient for now, but prevents memory leak
         dom_solver.clear_all_constraints();
+        let mut constraints = Vec::new();
+
         for rect_idx in rectangles.linear_iter() {
-            let constraints = dom_solver.create_layout_constraints(rect_idx, &rectangles, &*ui_description.ui_descr_arena.borrow());
-            dom_solver.insert_css_constraints_for_rect(&constraints);
-            dom_solver.push_added_constraints(rect_idx, constraints);
+            constraints.extend(dom_solver.create_layout_constraints(rect_idx, &rectangles, &*ui_description.ui_descr_arena.borrow()));
         }
 
+        println!("constraints: {:?}", constraints.len());
+
+        dom_solver.insert_css_constraints(&constraints);
+
+        println!("5!");
+
         // If we push or pop constraints that means we also need to re-layout the window
         has_window_size_changed = true;
     }
+    println!("6!");
 
     // TODO: early return based on changeset?
 
     // Recalculate the actual layout
     if has_window_size_changed {
-        dom_solver.update_window_size(&bounds_size);
+        dom_solver.update_window_size(&bounds_size); // unknown
     }
+    println!("7!");
 
     dom_solver.update_layout_cache();
+    println!("8!");
+
     println!("end of insert constraints into DOM!");
 }
 
@@ -648,8 +660,6 @@ fn push_iframe<'a, 'b, 'c, T: Layout>(
 
     referenced_mutable_content.ui_solver.insert_dom(new_dom_id, dom_solver);
 
-    // ui_description.ui_descr_arena.borrow().print_tree(|t| format!("{}", t)); // REMOVE
-
     println!("push_iframe");
     insert_constraints_into_solver(
         &ui_description,
diff --git a/src/dom.rs b/src/dom.rs
index 3b026689c..2cda01fee 100644
--- a/src/dom.rs
+++ b/src/dom.rs
@@ -860,6 +860,11 @@ impl<T: Layout> Dom<T> {
     pub fn push_default_callback_id(&mut self, on: On, id: DefaultCallbackId) {
         self.arena.borrow_mut()[self.head].data.default_callback_ids.insert(on, id);
     }
+
+    /// Prints a debug formatted version of the DOM for easier debugging
+    pub fn debug_dump(&self) {
+        println!("{}", self.arena.borrow().print_tree(|t| format!("{}", t)));
+    }
 }
 
 pub type TagId = u64;
diff --git a/src/ui_solver.rs b/src/ui_solver.rs
index adf17a110..6b29cda66 100644
--- a/src/ui_solver.rs
+++ b/src/ui_solver.rs
@@ -146,14 +146,14 @@ impl DomSolver {
         changeset
     }
 
-    pub(crate) fn insert_css_constraints_for_rect(&mut self, constraints: &[Constraint]) {
+    pub(crate) fn insert_css_constraints(&mut self, constraints: &[Constraint]) {
         self.solver.add_constraints(constraints).unwrap();
     }
 
     /// Notifies the solver that the window size has changed
     pub(crate) fn update_window_size(&mut self, window_size: &LogicalSize) {
-        self.solver.suggest_value(self.root_constraints.width_var, window_size.width).unwrap();
-        self.solver.suggest_value(self.root_constraints.height_var, window_size.height).unwrap();
+        println!("{:?}", self.solver.suggest_value(self.root_constraints.width_var, window_size.width));
+        println!("{:?}", self.solver.suggest_value(self.root_constraints.height_var, window_size.height));
     }
 
     pub(crate) fn update_layout_cache(&mut self) {
@@ -190,6 +190,7 @@ impl DomSolver {
         self.edit_variable_cache.map.get(&dom_hash.data).and_then(|rect| Some(rect.1))
     }
 
+    /// TODO: Make this an iterator, so we can avoid the unnecessary collections!
     pub(crate) fn create_layout_constraints<'a, T: Layout>(
         &self,
         rect_id: NodeId,
@@ -205,12 +206,15 @@ impl DomSolver {
     }
 
     pub(crate) fn clear_all_constraints(&mut self) {
+        /*
         for entry in self.added_constraints.values() {
             for constraint in entry {
                 self.solver.remove_constraint(constraint).unwrap();
             }
         }
         self.added_constraints = BTreeMap::new();
+        */
+        self.solver.reset();
     }
 
     pub(crate) fn get_window_constraints(&self) -> RootSizeConstraints {
diff --git a/src/widgets/table_view.rs b/src/widgets/table_view.rs
index 5b6f49982..d95ddbd2b 100644
--- a/src/widgets/table_view.rs
+++ b/src/widgets/table_view.rs
@@ -91,7 +91,7 @@ fn render_table<T: Layout>(state: &mut TableViewState, info: WindowInfo<T>, dime
             .with_class("__azul-native-table-column-name")
             .with_sibling(
                 // Rows - "1", "2", "3"
-                (0..necessary_rows - 1)
+                (0..necessary_rows.saturating_sub(1))
                 .map(|row_idx|
                     NodeData {
                         node_type: NodeType::Label(format!("{}", row_idx + 1)),
@@ -116,7 +116,7 @@ fn render_table<T: Layout>(state: &mut TableViewState, info: WindowInfo<T>, dime
                 .with_class("__azul-native-table-column-name")
                 .with_sibling(
                     // Actual rows - if no content is given, they are simply empty
-                    (0..necessary_rows - 1)
+                    (0..necessary_rows.saturating_sub(1))
                     .map(|row_idx|
                         NodeData {
                             node_type: if let Some(data) = state.work_sheet.data.get(&col_idx).and_then(|col| col.get(&row_idx)) {