Inputs: Fixed a miscalculation in the keyboard/mouse "typematic" repeat delay/rate calculation, used by keys and e.g. repeating mouse buttons as well as the GetKeyPressedAmount() function.

IMPORTANT: Renamed internal CalcTypematicPressedRepeatAmount to CalcTypematicRepeatAmount and reordered the t1, t0 arguments to t0, t1 !!
If you were using a non-default value for io.KeyRepeatRate (previous default was 0.250), you can add +io.KeyRepeatDelay to it to compensate for the fix.  The function was triggering on: 0.0 and (delay+rate*N) where (N>=1). Fixed formula responds to (N>=0).
Effectively it made io.KeyRepeatRate behave like it was set to (io.KeyRepeatRate + io.KeyRepeatDelay).
Fixed the code and altered default io.KeyRepeatRate,Delay from 0.250,0.050 to 0.300,0.050 to compensate.
If you never altered io.KeyRepeatRate nor used GetKeyPressedAmount() this won't affect you.

docs/CHANGELOG.txt

@@ -34,11 +34,18 @@ HOW TO UPDATE?
 -----------------------------------------------------------------------
 
 Breaking Changes:
--
+- Inputs: Fixed a miscalculation in the keyboard/mouse "typematic" repeat delay/rate calculation, used
+  by keys and e.g. repeating mouse buttons as well as the GetKeyPressedAmount() function.
+  If you were using a non-default value for io.KeyRepeatRate (previous default was 0.250), you can
+  add +io.KeyRepeatDelay to it to compensate for the fix.
+  The function was triggering on: 0.0 and (delay+rate*N) where (N>=1). Fixed formula responds to (N>=0).
+  Effectively it made io.KeyRepeatRate behave like it was set to (io.KeyRepeatRate + io.KeyRepeatDelay).
+  Fixed the code and altered default io.KeyRepeatRate,Delay from 0.250,0.050 to 0.300,0.050 to compensate.
+  If you never altered io.KeyRepeatRate nor used GetKeyPressedAmount() this won't affect you.
 
 Other Changes:
 - InputText, Nav: Fixed Home/End key broken when activating Keyboard Navigation. (#787)
-- InputText: Filter out Ascii 127 (DEL) emitted by low-level OSX layer, as we are using the Key value. (#2578)
+- InputText: Filter out ASCII 127 (DEL) emitted by low-level OSX layer, as we are using the Key value. (#2578)
 - TreeNode: Fixed combination of ImGuiTreeNodeFlags_SpanFullWidth and ImGuiTreeNodeFlags_OpenOnArrow
   incorrectly locating the arrow hit position to the left of the frame. (#2451, #2438, #1897)
 - DragScalar, SliderScalar, InputScalar: Added p_ prefix to parameter that are pointers to the data

imgui.cpp

@@ -369,6 +369,10 @@ CODE
  When you are not sure about a old symbol or function name, try using the Search/Find function of your IDE to look for comments or references in all imgui files.
  You can read releases logs https://github.com/ocornut/imgui/releases for more details.
 
+ - 2019/10/14 (1.74) - inputs: Fixed a miscalculation in the keyboard/mouse "typematic" repeat delay/rate calculation, used by keys and e.g. repeating mouse buttons as well as the GetKeyPressedAmount() function.
+                       if you were using a non-default value for io.KeyRepeatRate (previous default was 0.250), you can add +io.KeyRepeatDelay to it to compensate for the fix.
+                       The function was triggering on: 0.0 and (delay+rate*N) where (N>=1). Fixed formula responds to (N>=0). Effectively it made io.KeyRepeatRate behave like it was set to (io.KeyRepeatRate + io.KeyRepeatDelay).
+                       If you never altered io.KeyRepeatRate nor used GetKeyPressedAmount() this won't affect you.
  - 2019/07/15 (1.72) - removed TreeAdvanceToLabelPos() which is rarely used and only does SetCursorPosX(GetCursorPosX() + GetTreeNodeToLabelSpacing()). Kept redirection function (will obsolete).
  - 2019/07/12 (1.72) - renamed ImFontAtlas::CustomRect to ImFontAtlasCustomRect. Kept redirection typedef (will obsolete).
  - 2019/06/14 (1.72) - removed redirecting functions/enums names that were marked obsolete in 1.51 (June 2017): ImGuiCol_Column*, ImGuiSetCond_*, IsItemHoveredRect(), IsPosHoveringAnyWindow(), IsMouseHoveringAnyWindow(), IsMouseHoveringWindow(), IMGUI_ONCE_UPON_A_FRAME. Grep this log for details and new names.
@@ -1206,7 +1210,7 @@ ImGuiIO::ImGuiIO()
     MouseDoubleClickMaxDist = 6.0f;
     for (int i = 0; i < ImGuiKey_COUNT; i++)
         KeyMap[i] = -1;
-    KeyRepeatDelay = 0.250f;
+    KeyRepeatDelay = 0.275f;
     KeyRepeatRate = 0.050f;
     UserData = NULL;
 
@@ -4402,14 +4406,22 @@ bool ImGui::IsKeyDown(int user_key_index)
     return g.IO.KeysDown[user_key_index];
 }
 
-int ImGui::CalcTypematicPressedRepeatAmount(float t, float t_prev, float repeat_delay, float repeat_rate)
+// t0 = previous time (e.g.: g.Time - g.IO.DeltaTime)
+// t1 = current time (e.g.: g.Time)
+// An event is triggered at:
+//  t = 0.0f     t = repeat_delay,    t = repeat_delay + repeat_rate*N
+int ImGui::CalcTypematicRepeatAmount(float t0, float t1, float repeat_delay, float repeat_rate)
 {
-    if (t == 0.0f)
+    if (t1 == 0.0f)
         return 1;
-    if (t <= repeat_delay || repeat_rate <= 0.0f)
+    if (t0 >= t1)
         return 0;
-    const int count = (int)((t - repeat_delay) / repeat_rate) - (int)((t_prev - repeat_delay) / repeat_rate);
-    return (count > 0) ? count : 0;
+    if (repeat_rate <= 0.0f)
+        return (t0 < repeat_delay) && (t1 >= repeat_delay);
+    const int count_t0 = (t0 < repeat_delay) ? -1 : (int)((t0 - repeat_delay) / repeat_rate);
+    const int count_t1 = (t1 < repeat_delay) ? -1 : (int)((t1 - repeat_delay) / repeat_rate);
+    const int count = count_t1 - count_t0;
+    return count;
 }
 
 int ImGui::GetKeyPressedAmount(int key_index, float repeat_delay, float repeat_rate)
@@ -4419,7 +4431,7 @@ int ImGui::GetKeyPressedAmount(int key_index, float repeat_delay, float repeat_r
         return 0;
     IM_ASSERT(key_index >= 0 && key_index < IM_ARRAYSIZE(g.IO.KeysDown));
     const float t = g.IO.KeysDownDuration[key_index];
-    return CalcTypematicPressedRepeatAmount(t, t - g.IO.DeltaTime, repeat_delay, repeat_rate);
+    return CalcTypematicRepeatAmount(t - g.IO.DeltaTime, t, repeat_delay, repeat_rate);
 }
 
 bool ImGui::IsKeyPressed(int user_key_index, bool repeat)
@@ -4471,7 +4483,7 @@ bool ImGui::IsMouseClicked(int button, bool repeat)
     if (repeat && t > g.IO.KeyRepeatDelay)
     {
         // FIXME: 2019/05/03: Our old repeat code was wrong here and led to doubling the repeat rate, which made it an ok rate for repeat on mouse hold.
-        int amount = CalcTypematicPressedRepeatAmount(t, t - g.IO.DeltaTime, g.IO.KeyRepeatDelay, g.IO.KeyRepeatRate * 0.5f);
+        int amount = CalcTypematicRepeatAmount(t - g.IO.DeltaTime, t, g.IO.KeyRepeatDelay, g.IO.KeyRepeatRate * 0.50f);
         if (amount > 0)
             return true;
     }
@@ -8228,11 +8240,11 @@ float ImGui::GetNavInputAmount(ImGuiNavInput n, ImGuiInputReadMode mode)
     if (mode == ImGuiInputReadMode_Pressed)               // Return 1.0f when just pressed, no repeat, ignore analog input.
         return (t == 0.0f) ? 1.0f : 0.0f;
     if (mode == ImGuiInputReadMode_Repeat)
-        return (float)CalcTypematicPressedRepeatAmount(t, t - g.IO.DeltaTime, g.IO.KeyRepeatDelay * 0.80f, g.IO.KeyRepeatRate * 0.80f);
+        return (float)CalcTypematicRepeatAmount(t - g.IO.DeltaTime, t, g.IO.KeyRepeatDelay * 0.72f, g.IO.KeyRepeatRate * 0.80f);
     if (mode == ImGuiInputReadMode_RepeatSlow)
-        return (float)CalcTypematicPressedRepeatAmount(t, t - g.IO.DeltaTime, g.IO.KeyRepeatDelay * 1.00f, g.IO.KeyRepeatRate * 2.00f);
+        return (float)CalcTypematicRepeatAmount(t - g.IO.DeltaTime, t, g.IO.KeyRepeatDelay * 1.25f, g.IO.KeyRepeatRate * 2.00f);
     if (mode == ImGuiInputReadMode_RepeatFast)
-        return (float)CalcTypematicPressedRepeatAmount(t, t - g.IO.DeltaTime, g.IO.KeyRepeatDelay * 0.80f, g.IO.KeyRepeatRate * 0.30f);
+        return (float)CalcTypematicRepeatAmount(t - g.IO.DeltaTime, t, g.IO.KeyRepeatDelay * 0.72f, g.IO.KeyRepeatRate * 0.30f);
     return 0.0f;
 }
 

imgui_internal.h

@@ -1581,7 +1581,7 @@ namespace ImGui
     IMGUI_API void          NavMoveRequestTryWrapping(ImGuiWindow* window, ImGuiNavMoveFlags move_flags);
     IMGUI_API float         GetNavInputAmount(ImGuiNavInput n, ImGuiInputReadMode mode);
     IMGUI_API ImVec2        GetNavInputAmount2d(ImGuiNavDirSourceFlags dir_sources, ImGuiInputReadMode mode, float slow_factor = 0.0f, float fast_factor = 0.0f);
-    IMGUI_API int           CalcTypematicPressedRepeatAmount(float t, float t_prev, float repeat_delay, float repeat_rate);
+    IMGUI_API int           CalcTypematicRepeatAmount(float t0, float t1, float repeat_delay, float repeat_rate);
     IMGUI_API void          ActivateItem(ImGuiID id);   // Remotely activate a button, checkbox, tree node etc. given its unique ID. activation is queued and processed on the next frame when the item is encountered again.
     IMGUI_API void          SetNavID(ImGuiID id, int nav_layer);
     IMGUI_API void          SetNavIDWithRectRel(ImGuiID id, int nav_layer, const ImRect& rect_rel);

imgui_widgets.cpp

@@ -487,7 +487,7 @@ bool ImGui::ButtonBehavior(const ImRect& bb, ImGuiID id, bool* out_hovered, bool
         {
             hovered = true;
             SetHoveredID(id);
-            if (CalcTypematicPressedRepeatAmount(g.HoveredIdTimer + 0.0001f, g.HoveredIdTimer + 0.0001f - g.IO.DeltaTime, 0.01f, 0.70f)) // FIXME: Our formula for CalcTypematicPressedRepeatAmount() is fishy
+            if (CalcTypematicRepeatAmount(g.HoveredIdTimer + 0.0001f - g.IO.DeltaTime, g.HoveredIdTimer + 0.0001f, 0.70f, 0.00f))
             {
                 pressed = true;
                 FocusWindow(window);