Collect input counts over one frame to avoid missing inputs within the same frame

examples/imgui_impl_win32.cpp

@@ -315,13 +315,15 @@ IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hwnd, UINT msg, WPARA
         return 0;
     case WM_KEYDOWN:
     case WM_SYSKEYDOWN:
-        if (wParam < 256)
-            io.KeysDown[wParam] = 1;
+        // Win32 sets bit 30 if the key is repeating. We handle that internally so we
+        // only want the first down.
+        if ((wParam < 256) && !(lParam & (1 << 30)))
+            io.KeysDown[wParam]++;
         return 0;
     case WM_KEYUP:
     case WM_SYSKEYUP:
         if (wParam < 256)
-            io.KeysDown[wParam] = 0;
+            io.KeysUp[wParam]++;
         return 0;
     case WM_CHAR:
         // You can also use ToAscii()+GetKeyboardState() to retrieve characters.

imgui.cpp

@@ -3758,8 +3758,18 @@ void ImGui::NewFrame()
     // Synchronize io.KeyMods with individual modifiers io.KeyXXX bools
     g.IO.KeyMods = GetMergedKeyModFlags();
     memcpy(g.IO.KeysDownDurationPrev, g.IO.KeysDownDuration, sizeof(g.IO.KeysDownDuration));
-    for (int i = 0; i < IM_ARRAYSIZE(g.IO.KeysDown); i++)
-        g.IO.KeysDownDuration[i] = g.IO.KeysDown[i] ? (g.IO.KeysDownDuration[i] < 0.0f ? 0.0f : g.IO.KeysDownDuration[i] + g.IO.DeltaTime) : -1.0f;
+    for (int i = 0; i < IM_ARRAYSIZE(g.IO.KeysDown); i++) {
+        g.IO.KeysDown[i] -= g.IO.KeysUpPrev[i];
+        if(g.IO.KeysDown[i])
+            if(g.IO.KeysDownDuration[i] < 0.0f)
+                g.IO.KeysDownDuration[i] = 0.0f;
+            else
+                g.IO.KeysDownDuration[i] += g.IO.DeltaTime;
+        else
+            g.IO.KeysDownDuration[i] = -1.0f;
+    }
+    memcpy(g.IO.KeysUpPrev, g.IO.KeysUp, sizeof(g.IO.KeysUp));
+    memset(g.IO.KeysUp, 0, sizeof(g.IO.KeysUp));
 
     // Update gamepad/keyboard navigation
     NavUpdate();

imgui.h

@@ -1525,16 +1525,19 @@ struct ImGuiIO
     // Input - Fill before calling NewFrame()
     //------------------------------------------------------------------
 
-    ImVec2      MousePos;                       // Mouse position, in pixels. Set to ImVec2(-FLT_MAX, -FLT_MAX) if mouse is unavailable (on another screen, etc.)
-    bool        MouseDown[5];                   // Mouse buttons: 0=left, 1=right, 2=middle + extras (ImGuiMouseButton_COUNT == 5). Dear ImGui mostly uses left and right buttons. Others buttons allows us to track if the mouse is being used by your application + available to user as a convenience via IsMouse** API.
-    float       MouseWheel;                     // Mouse wheel Vertical: 1 unit scrolls about 5 lines text.
-    float       MouseWheelH;                    // Mouse wheel Horizontal. Most users don't have a mouse with an horizontal wheel, may not be filled by all back-ends.
-    bool        KeyCtrl;                        // Keyboard modifier pressed: Control
-    bool        KeyShift;                       // Keyboard modifier pressed: Shift
-    bool        KeyAlt;                         // Keyboard modifier pressed: Alt
-    bool        KeySuper;                       // Keyboard modifier pressed: Cmd/Super/Windows
-    bool        KeysDown[512];                  // Keyboard keys that are pressed (ideally left in the "native" order your engine has access to keyboard keys, so you can use your own defines/enums for keys).
-    float       NavInputs[ImGuiNavInput_COUNT]; // Gamepad inputs. Cleared back to zero by EndFrame(). Keyboard keys will be auto-mapped and be written here by NewFrame().
+    ImVec2        MousePos;                       // Mouse position, in pixels. Set to ImVec2(-FLT_MAX, -FLT_MAX) if mouse is unavailable (on another screen, etc.)
+    bool          MouseDown[5];                   // Mouse buttons: 0 = left, 1=right, 2=middle + extras (ImGuiMouseButton_COUNT == 5). Dear ImGui mostly uses left and right buttons. Others buttons allows us to track if the mouse is being used by your application + available to user as a convenience via IsMouse** API.
+    bool          MouseUp[5];                     // Mouse buttons: 0 = left, 1=right, 2=middle + extras (ImGuiMouseButton_COUNT == 5). Dear ImGui mostly uses left and right buttons. Others buttons allows us to track if the mouse is being used by your application + available to user as a convenience via IsMouse** API.
+    float         MouseWheel;                     // Mouse wheel Vertical: 1 unit scrolls about 5 lines text.
+    float         MouseWheelH;                    // Mouse wheel Horizontal. Most users don't have a mouse with an horizontal wheel, may not be filled by all back-ends.
+    bool          KeyCtrl;                        // Keyboard modifier pressed: Control
+    bool          KeyShift;                       // Keyboard modifier pressed: Shift
+    bool          KeyAlt;                         // Keyboard modifier pressed: Alt
+    bool          KeySuper;                       // Keyboard modifier pressed: Cmd/Super/Windows
+    unsigned char KeysDown[512];                  // Number of keyboard key inputs that are pressed since last frame (ideally left in the "native" order your engine has access to keyboard keys, so you can use your own defines/enums for keys).
+    unsigned char KeysUp[512];                    // Number of keyboard up inputs since last frame
+    unsigned char KeysUpPrev[512];                // Number of keyboard up inputs since last frame - 1
+    float         NavInputs[ImGuiNavInput_COUNT]; // Gamepad inputs. Cleared back to zero by EndFrame(). Keyboard keys will be auto-mapped and be written here by NewFrame().
 
     // Functions
     IMGUI_API void  AddInputCharacter(unsigned int c);          // Queue new character input