Shortcuts: reorganize route scoring so values are easier to read. (#9004)

Score now require 16-bits but ImGuiKeyRoutingData doesn't grow size.

imgui.cpp

@@ -9378,7 +9378,7 @@ static void ImGui::UpdateKeyRoutingTable(ImGuiKeyRoutingTable* rt)
             routing_entry->RoutingCurrScore = routing_entry->RoutingNextScore;
             routing_entry->RoutingCurr = routing_entry->RoutingNext; // Update entry
             routing_entry->RoutingNext = ImGuiKeyOwner_NoOwner;
-            routing_entry->RoutingNextScore = 255;
+            routing_entry->RoutingNextScore = 0;
             if (routing_entry->RoutingCurr == ImGuiKeyOwner_NoOwner)
                 continue;
             rt->EntriesNext.push_back(*routing_entry); // Write alive ones into new buffer
@@ -9447,23 +9447,24 @@ ImGuiKeyRoutingData* ImGui::GetShortcutRoutingData(ImGuiKeyChord key_chord)
     return routing_data;
 }
 
-// Current score encoding (lower is highest priority):
-//  -   0: ImGuiInputFlags_RouteGlobal | ImGuiInputFlags_RouteOverActive
-//  -   1: ImGuiInputFlags_ActiveItem or ImGuiInputFlags_RouteFocused (if item active)
-//  -   2: ImGuiInputFlags_RouteGlobal | ImGuiInputFlags_RouteOverFocused
-//  -  3+: ImGuiInputFlags_RouteFocused (if window in focus-stack)
-//  - 254: ImGuiInputFlags_RouteGlobal
-//  - 255: never route
+// Current score encoding
+//  -        0: Never route
+//  -        1: ImGuiInputFlags_RouteGlobal    (lower priority)
+//  - 100..199: ImGuiInputFlags_RouteFocused   (if window in focus-stack)
+//         200: ImGuiInputFlags_RouteGlobal  | ImGuiInputFlags_RouteOverFocused
+//         300: ImGuiInputFlags_RouteActive or ImGuiInputFlags_RouteFocused (if item active)
+//         400: ImGuiInputFlags_RouteGlobal  | ImGuiInputFlags_RouteOverActive
+//  - 500..599: ImGuiInputFlags_RouteFocused | ImGuiInputFlags_RouteOverActive (if window in focus-stack) (higher priority)
 // 'flags' should include an explicit routing policy
 static int CalcRoutingScore(ImGuiID focus_scope_id, ImGuiID owner_id, ImGuiInputFlags flags)
 {
     ImGuiContext& g = *GImGui;
     if (flags & ImGuiInputFlags_RouteFocused)
     {
-        // ActiveID gets top priority
+        // ActiveID gets high priority
         // (we don't check g.ActiveIdUsingAllKeys here. Routing is applied but if input ownership is tested later it may discard it)
         if (owner_id != 0 && g.ActiveId == owner_id)
-            return 1;
+            return 300;
 
         // Score based on distance to focused window (lower is better)
         // Assuming both windows are submitting a routing request,
@@ -9473,25 +9474,27 @@ static int CalcRoutingScore(ImGuiID focus_scope_id, ImGuiID owner_id, ImGuiInput
         // - When Window/ChildB is focused -> Window scores 4 (best), Window/ChildB doesn't have a score.
         // This essentially follow the window->ParentWindowForFocusRoute chain.
         if (focus_scope_id == 0)
-            return 255;
+            return 0;
         for (int index_in_focus_path = 0; index_in_focus_path < g.NavFocusRoute.Size; index_in_focus_path++)
             if (g.NavFocusRoute.Data[index_in_focus_path].ID == focus_scope_id)
-                return 3 + index_in_focus_path;
-        return 255;
+                return 199 - index_in_focus_path;
+        return 0;
     }
     else if (flags & ImGuiInputFlags_RouteActive)
     {
         if (owner_id != 0 && g.ActiveId == owner_id)
-            return 1;
-        return 255;
+            return 300;
+        return 0;
     }
     else if (flags & ImGuiInputFlags_RouteGlobal)
     {
         if (flags & ImGuiInputFlags_RouteOverActive)
-            return 0;
+            return 400;
+        if (owner_id != 0 && g.ActiveId == owner_id)
+            return 300;
         if (flags & ImGuiInputFlags_RouteOverFocused)
-            return 2;
-        return 254;
+            return 200;
+        return 1;
     }
     IM_ASSERT(0);
     return 0;
@@ -9587,17 +9590,17 @@ bool ImGui::SetShortcutRouting(ImGuiKeyChord key_chord, ImGuiInputFlags flags, I
 
     const int score = CalcRoutingScore(focus_scope_id, owner_id, flags);
     IMGUI_DEBUG_LOG_INPUTROUTING("SetShortcutRouting(%s, flags=%04X, owner_id=0x%08X) -> score %d\n", GetKeyChordName(key_chord), flags, owner_id, score);
-    if (score == 255)
+    if (score == 0)
         return false;
 
     // Submit routing for NEXT frame (assuming score is sufficient)
-    // FIXME: Could expose a way to use a "serve last" policy for same score resolution (using <= instead of <).
+    // FIXME: Could expose a way to use a "serve last" policy for same score resolution (using >= instead of >).
     ImGuiKeyRoutingData* routing_data = GetShortcutRoutingData(key_chord);
-    //const bool set_route = (flags & ImGuiInputFlags_ServeLast) ? (score <= routing_data->RoutingNextScore) : (score < routing_data->RoutingNextScore);
-    if (score < routing_data->RoutingNextScore)
+    //const bool set_route = (flags & ImGuiInputFlags_ServeLast) ? (score >= routing_data->RoutingNextScore) : (score > routing_data->RoutingNextScore);
+    if (score > routing_data->RoutingNextScore)
     {
         routing_data->RoutingNext = owner_id;
-        routing_data->RoutingNextScore = (ImU8)score;
+        routing_data->RoutingNextScore = (ImU16)score;
     }
 
     // Return routing state for CURRENT frame

imgui_internal.h

@@ -1556,12 +1556,12 @@ struct ImGuiKeyRoutingData
 {
     ImGuiKeyRoutingIndex            NextEntryIndex;
     ImU16                           Mods;               // Technically we'd only need 4-bits but for simplify we store ImGuiMod_ values which need 16-bits.
-    ImU8                            RoutingCurrScore;   // [DEBUG] For debug display
-    ImU8                            RoutingNextScore;   // Lower is better (0: perfect score)
+    ImU16                           RoutingCurrScore;   // [DEBUG] For debug display
+    ImU16                           RoutingNextScore;   // Lower is better (0: perfect score)
     ImGuiID                         RoutingCurr;
     ImGuiID                         RoutingNext;
 
-    ImGuiKeyRoutingData()           { NextEntryIndex = -1; Mods = 0; RoutingCurrScore = RoutingNextScore = 255; RoutingCurr = RoutingNext = ImGuiKeyOwner_NoOwner; }
+    ImGuiKeyRoutingData()           { NextEntryIndex = -1; Mods = 0; RoutingCurrScore = RoutingNextScore = 0; RoutingCurr = RoutingNext = ImGuiKeyOwner_NoOwner; }
 };
 
 // Routing table: maintain a desired owner for each possible key-chord (key + mods), and setup owner in NewFrame() when mods are matching.