Simpified code in GetKeyData() and used ImGuiKey_KeysData_OFFSET for consistency. Rework demo, Comments. Moved ImGuiKey_KeysData_OFFSET to internal.h (#4921, #6191)

imgui.cpp

@@ -7660,18 +7660,14 @@ ImGuiKeyData* ImGui::GetKeyData(ImGuiKey key)
     if (key & ImGuiMod_Mask_)
         key = ConvertSingleModFlagToKey(key);
 
-    int index;
 #ifndef IMGUI_DISABLE_OBSOLETE_KEYIO
     IM_ASSERT(key >= ImGuiKey_LegacyNativeKey_BEGIN && key < ImGuiKey_NamedKey_END);
-    if (IsLegacyKey(key))
+    if (IsLegacyKey(key) && g.IO.KeyMap[key] != -1)
-        index = (g.IO.KeyMap[key] != -1) ? g.IO.KeyMap[key] : key; // Remap native->imgui or imgui->native
+        key = (ImGuiKey)g.IO.KeyMap[key];  // Remap native->imgui or imgui->native
-    else
-        index = key;
 #else
     IM_ASSERT(IsNamedKey(key) && "Support for user key indices was dropped in favor of ImGuiKey. Please update backend & user code.");
-    index = key - ImGuiKey_NamedKey_BEGIN;
 #endif
-    return &g.IO.KeysData[index];
+    return &g.IO.KeysData[key - ImGuiKey_KeysData_OFFSET];
 }
 
 #ifndef IMGUI_DISABLE_OBSOLETE_KEYIO
@@ -13584,7 +13580,7 @@ void ImGui::ShowMetricsWindow(bool* p_open)
         Text("KEYBOARD/GAMEPAD/MOUSE KEYS");
         {
             // We iterate both legacy native range and named ImGuiKey ranges, which is a little odd but this allows displaying the data for old/new backends.
-            // User code should never have to go through such hoops: old code may use native keycodes, new code may use ImGuiKey codes.
+            // User code should never have to go through such hoops! You can generally iterate between ImGuiKey_NamedKey_BEGIN and ImGuiKey_NamedKey_END.
             Indent();
 #ifdef IMGUI_DISABLE_OBSOLETE_KEYIO
             struct funcs { static bool IsLegacyNativeDupe(ImGuiKey) { return false; } };

imgui.h

@@ -1353,6 +1353,7 @@ enum ImGuiSortDirection_
 // All our named keys are >= 512. Keys value 0 to 511 are left unused as legacy native/opaque key values (< 1.87).
 // Since >= 1.89 we increased typing (went from int to enum), some legacy code may need a cast to ImGuiKey.
 // Read details about the 1.87 and 1.89 transition : https://github.com/ocornut/imgui/issues/4921
+// Note that "Keys" related to physical keys and are not the same concept as input "Characters", the later are submitted via io.AddInputCharacter().
 enum ImGuiKey : int
 {
     // Keyboard
@@ -1460,15 +1461,16 @@ enum ImGuiKey : int
 
     // [Internal] Prior to 1.87 we required user to fill io.KeysDown[512] using their own native index + the io.KeyMap[] array.
     // We are ditching this method but keeping a legacy path for user code doing e.g. IsKeyPressed(MY_NATIVE_KEY_CODE)
+    // If you need to iterate all keys (for e.g. an input mapper) you may use ImGuiKey_NamedKey_BEGIN..ImGuiKey_NamedKey_END.
     ImGuiKey_NamedKey_BEGIN         = 512,
     ImGuiKey_NamedKey_END           = ImGuiKey_COUNT,
     ImGuiKey_NamedKey_COUNT         = ImGuiKey_NamedKey_END - ImGuiKey_NamedKey_BEGIN,
 #ifdef IMGUI_DISABLE_OBSOLETE_KEYIO
     ImGuiKey_KeysData_SIZE          = ImGuiKey_NamedKey_COUNT,  // Size of KeysData[]: only hold named keys
-    ImGuiKey_KeysData_OFFSET        = ImGuiKey_NamedKey_BEGIN,          // First key stored in io.KeysData[0]. Accesses to io.KeysData[] must use (key - ImGuiKey_KeysData_OFFSET).
+    ImGuiKey_KeysData_OFFSET        = ImGuiKey_NamedKey_BEGIN,  // Accesses to io.KeysData[] must use (key - ImGuiKey_KeysData_OFFSET) index.
 #else
     ImGuiKey_KeysData_SIZE          = ImGuiKey_COUNT,           // Size of KeysData[]: hold legacy 0..512 keycodes + named keys
-    ImGuiKey_KeysData_OFFSET        = 0,                                // First key stored in io.KeysData[0]. Accesses to io.KeysData[] must use (key - ImGuiKey_KeysData_OFFSET).
+    ImGuiKey_KeysData_OFFSET        = 0,                        // Accesses to io.KeysData[] must use (key - ImGuiKey_KeysData_OFFSET) index.
 #endif
 
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS

imgui_demo.cpp

@@ -5736,13 +5736,15 @@ static void ShowDemoWindowInputs()
             ImGui::Text("Mouse wheel: %.1f", io.MouseWheel);
 
             // We iterate both legacy native range and named ImGuiKey ranges, which is a little odd but this allows displaying the data for old/new backends.
-            // User code should never have to go through such hoops: old code may use native keycodes, new code may use ImGuiKey codes.
+            // User code should never have to go through such hoops! You can generally iterate between ImGuiKey_NamedKey_BEGIN and ImGuiKey_NamedKey_END.
 #ifdef IMGUI_DISABLE_OBSOLETE_KEYIO
             struct funcs { static bool IsLegacyNativeDupe(ImGuiKey) { return false; } };
+            ImGuiKey start_key = ImGuiKey_NamedKey_BEGIN;
 #else
             struct funcs { static bool IsLegacyNativeDupe(ImGuiKey key) { return key < 512 && ImGui::GetIO().KeyMap[key] != -1; } }; // Hide Native<>ImGuiKey duplicates when both exists in the array
+            ImGuiKey start_key = (ImGuiKey)0;
 #endif
-            ImGui::Text("Keys down:");         for (ImGuiKey key = ImGuiKey_KeysData_OFFSET; key < ImGuiKey_COUNT; key = (ImGuiKey)(key + 1)) { if (funcs::IsLegacyNativeDupe(key) || !ImGui::IsKeyDown(key)) continue; ImGui::SameLine(); ImGui::Text((key < ImGuiKey_NamedKey_BEGIN) ? "\"%s\"" : "\"%s\" %d", ImGui::GetKeyName(key), key); ImGui::SameLine(); ImGui::Text("(%.02f)", ImGui::GetKeyData(key)->DownDuration); }
+            ImGui::Text("Keys down:");         for (ImGuiKey key = start_key; key < ImGuiKey_NamedKey_END; key = (ImGuiKey)(key + 1)) { if (funcs::IsLegacyNativeDupe(key) || !ImGui::IsKeyDown(key)) continue; ImGui::SameLine(); ImGui::Text((key < ImGuiKey_NamedKey_BEGIN) ? "\"%s\"" : "\"%s\" %d", ImGui::GetKeyName(key), key); ImGui::SameLine(); ImGui::Text("(%.02f)", ImGui::GetKeyData(key)->DownDuration); }
             ImGui::Text("Keys mods: %s%s%s%s", io.KeyCtrl ? "CTRL " : "", io.KeyShift ? "SHIFT " : "", io.KeyAlt ? "ALT " : "", io.KeySuper ? "SUPER " : "");
             ImGui::Text("Chars queue:");       for (int i = 0; i < io.InputQueueCharacters.Size; i++) { ImWchar c = io.InputQueueCharacters[i]; ImGui::SameLine();  ImGui::Text("\'%c\' (0x%04X)", (c > ' ' && c <= 255) ? (char)c : '?', c); } // FIXME: We should convert 'c' to UTF-8 here but the functions are not public.
 

imgui_internal.h

@@ -1205,6 +1205,7 @@ struct ImGuiPtrOrIndex
 // [SECTION] Inputs support
 //-----------------------------------------------------------------------------
 
+// Bit array for named keys
 typedef ImBitArray<ImGuiKey_NamedKey_COUNT, -ImGuiKey_NamedKey_BEGIN>    ImBitArrayForNamedKeys;
 
 // [Internal] Key ranges