From 878fa96896da94c80dcbf0ce588adfff8cae270f Mon Sep 17 00:00:00 2001
From: omar <omarcornut@gmail.com>
Date: Thu, 28 Sep 2017 19:57:24 +0200
Subject: [PATCH] Nav: Re-arranged ItemAdd() to maximize early out (#787)

---
 imgui.cpp | 67 +++++++++++++++++++++++++++++--------------------------
 1 file changed, 35 insertions(+), 32 deletions(-)

diff --git a/imgui.cpp b/imgui.cpp
index 2dc87ddc..e79a6f46 100644
--- a/imgui.cpp
+++ b/imgui.cpp
@@ -2182,41 +2182,44 @@ bool ImGui::ItemAdd(const ImRect& bb, const ImGuiID* id, const ImRect* nav_bb_ar
     //      We could early out with `if (is_clipped && !g.NavInitDefaultRequest) return false;` but when we wouldn't be able to reach unclipped widgets. This would work if user had explicit scrolling control (e.g. mapped on a stick)
     //      A more pragmatic solution for handling long lists is relying on the fact that they are likely evenly spread items (so that clipper can be used) and we could Nav at higher-level (apply index, etc.)
     //      So eventually we would like to provide the user will the primitives to be able to implement that customized/efficient navigation handling whenever necessary.
-    if (id != NULL && g.IO.NavUsable && g.NavWindow == window->RootNavWindow)
-    {
-        const ImRect& nav_bb = nav_bb_arg ? *nav_bb_arg : bb;
-        const ImRect nav_bb_rel(nav_bb.Min - g.NavWindow->Pos, nav_bb.Max - g.NavWindow->Pos);
-        if (g.NavInitDefaultRequest && g.NavLayer == window->DC.NavLayerCurrent)
-        {
-            if (!(window->DC.ItemFlags & ImGuiItemFlags_NoNavDefaultFocus))
-            // Even if 'ImGuiItemFlags_NoNavDefaultFocus' is on (typically collapse/close button) we record the first ResultId so they can be used as a fallback
-                g.NavInitDefaultRequest = g.NavInitDefaultResultExplicit = false; // Found a match, clear request
-            if (g.NavInitDefaultResultId == 0 || !(window->DC.ItemFlags & ImGuiItemFlags_NoNavDefaultFocus))
+    if (id != NULL && g.NavWindow == window->RootNavWindow)
+        if (g.NavId == *id || g.NavMoveRequest || g.NavInitDefaultRequest)
+            if (g.IO.NavUsable)
             {
-                g.NavInitDefaultResultId = *id;
-                g.NavInitDefaultResultRectRel = nav_bb_rel;
-            }
-        }
+                const ImRect& nav_bb = nav_bb_arg ? *nav_bb_arg : bb;
+                const ImRect nav_bb_rel(nav_bb.Min - g.NavWindow->Pos, nav_bb.Max - g.NavWindow->Pos);
+                if (g.NavInitDefaultRequest && g.NavLayer == window->DC.NavLayerCurrent)
+                {
+                    // Even if 'ImGuiItemFlags_NoNavDefaultFocus' is on (typically collapse/close button) we record the first ResultId so they can be used as a fallback
+                    const ImGuiItemFlags item_flags = window->DC.ItemFlags;
+                    if (!(item_flags & ImGuiItemFlags_NoNavDefaultFocus))
+                        g.NavInitDefaultRequest = g.NavInitDefaultResultExplicit = false; // Found a match, clear request
+                    if (g.NavInitDefaultResultId == 0 || !(item_flags & ImGuiItemFlags_NoNavDefaultFocus))
+                    {
+                        g.NavInitDefaultResultId = *id;
+                        g.NavInitDefaultResultRectRel = nav_bb_rel;
+                    }
+                }
 
-        //const bool DEBUG_NAV = false; // [DEBUG] Enable to test scoring on all items.
-        if ((g.NavMoveRequest /*|| DEBUG_NAV*/) && g.NavId != *id)
-        {
-            //if (DEBUG_NAV && !g.NavMoveRequest) g.NavMoveDir = ImGuiDir_N;
-            if (NavScoreItem(nav_bb)) //if (!DEBUG || g.NavMoveRequest)
-            {
-                g.NavMoveResultId = *id;
-                g.NavMoveResultRectRel = nav_bb_rel;
-            }
-        }
+                //const bool DEBUG_NAV = false; // [DEBUG] Enable to test scoring on all items.
+                if ((g.NavMoveRequest /*|| DEBUG_NAV*/) && g.NavId != *id)
+                {
+                    //if (DEBUG_NAV && !g.NavMoveRequest) g.NavMoveDir = ImGuiDir_N;
+                    if (NavScoreItem(nav_bb)) //if (!DEBUG || g.NavMoveRequest)
+                    {
+                        g.NavMoveResultId = *id;
+                        g.NavMoveResultRectRel = nav_bb_rel;
+                    }
+                }
 
-        // Update window-relative bounding box of navigated item
-        if (g.NavId == *id)
-        {
-            g.NavRefRectRel = nav_bb_rel;
-            g.NavIdIsAlive = true;
-            g.NavIdTabCounter = window->FocusIdxTabCounter;
-        }
-    }
+                // Update window-relative bounding box of navigated item
+                if (g.NavId == *id)
+                {
+                    g.NavRefRectRel = nav_bb_rel;
+                    g.NavIdIsAlive = true;
+                    g.NavIdTabCounter = window->FocusIdxTabCounter;
+                }
+            }
 
     if (is_clipped)
         return false;