Inputs: added IsMouseReleasedWithDelay() helper. (#8337, #8320)

docs/CHANGELOG.txt

@@ -51,6 +51,12 @@ Other changes:
   snapped to pixels. Effectively it would only be noticeable when hinting
   is disabled with ImGuiFreeTypeBuilderFlags_NoHinting, as hinting itself
   snaps glyph advances.
+- Inputs: added IsMouseReleasedWithDelay() helper. (#8337, #8320)
+  Use if you absolutely need to distinguish single-click from double-clicks
+  by introducing a delay. This is a very rarely used UI idiom, but some apps
+  use this: e.g. MS Explorer single-click on an icon triggers a rename.
+  Generally use with 'delay >= io.MouseDoubleClickTime' + combine with a
+  'io.MouseClickedLastCount == 1' check.
 - Windows: legacy SetWindowFontScale() is properly inherited by nested child
   windows. Note that an upcoming major release should make this obsolete,
   but in the meanwhile it works better now. (#2701, #8138, #1018)

imgui.cpp

@@ -9210,6 +9210,17 @@ bool ImGui::IsMouseReleased(ImGuiMouseButton button, ImGuiID owner_id)
     return g.IO.MouseReleased[button] && TestKeyOwner(MouseButtonToKey(button), owner_id); // Should be same as IsKeyReleased(MouseButtonToKey(button), owner_id)
 }
 
+// Use if you absolutely need to distinguish single-click from double-click by introducing a delay.
+// Generally use with 'delay >= io.MouseDoubleClickTime' + combined with a 'io.MouseClickedLastCount == 1' test.
+// This is a very rarely used UI idiom, but some apps use this: e.g. MS Explorer single click on an icon to rename.
+bool ImGui::IsMouseReleasedWithDelay(ImGuiMouseButton button, float delay)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(button >= 0 && button < IM_ARRAYSIZE(g.IO.MouseDown));
+    const float time_since_release = (float)(g.Time - g.IO.MouseReleasedTime[button]);
+    return !IsMouseDown(button) && (time_since_release - g.IO.DeltaTime < delay) && (time_since_release >= delay);
+}
+
 bool ImGui::IsMouseDoubleClicked(ImGuiMouseButton button)
 {
     ImGuiContext& g = *GImGui;
@@ -9483,6 +9494,8 @@ static void ImGui::UpdateMouseInputs()
         io.MouseClicked[i] = io.MouseDown[i] && io.MouseDownDuration[i] < 0.0f;
         io.MouseClickedCount[i] = 0; // Will be filled below
         io.MouseReleased[i] = !io.MouseDown[i] && io.MouseDownDuration[i] >= 0.0f;
+        if (io.MouseReleased[i])
+            io.MouseReleasedTime[i] = g.Time;
         io.MouseDownDurationPrev[i] = io.MouseDownDuration[i];
         io.MouseDownDuration[i] = io.MouseDown[i] ? (io.MouseDownDuration[i] < 0.0f ? 0.0f : io.MouseDownDuration[i] + io.DeltaTime) : -1.0f;
         if (io.MouseClicked[i])

imgui.h

@@ -1011,6 +1011,7 @@ namespace ImGui
     IMGUI_API bool          IsMouseClicked(ImGuiMouseButton button, bool repeat = false);       // did mouse button clicked? (went from !Down to Down). Same as GetMouseClickedCount() == 1.
     IMGUI_API bool          IsMouseReleased(ImGuiMouseButton button);                           // did mouse button released? (went from Down to !Down)
     IMGUI_API bool          IsMouseDoubleClicked(ImGuiMouseButton button);                      // did mouse button double-clicked? Same as GetMouseClickedCount() == 2. (note that a double-click will also report IsMouseClicked() == true)
+    IMGUI_API bool          IsMouseReleasedWithDelay(ImGuiMouseButton button, float delay);     // delayed mouse release (use very sparingly!). Generally used with 'delay >= io.MouseDoubleClickTime' + combined with a 'io.MouseClickedLastCount==1' test. This is a very rarely used UI idiom, but some apps use this: e.g. MS Explorer single click on an icon to rename.
     IMGUI_API int           GetMouseClickedCount(ImGuiMouseButton button);                      // return the number of successive mouse-clicks at the time where a click happen (otherwise 0).
     IMGUI_API bool          IsMouseHoveringRect(const ImVec2& r_min, const ImVec2& r_max, bool clip = true);// is mouse hovering given bounding rect (in screen space). clipped by current clipping settings, but disregarding of other consideration of focus/window ordering/popup-block.
     IMGUI_API bool          IsMousePosValid(const ImVec2* mouse_pos = NULL);                    // by convention we use (-FLT_MAX,-FLT_MAX) to denote that there is no mouse available
@@ -2405,6 +2406,7 @@ struct ImGuiIO
     ImU16       MouseClickedCount[5];               // == 0 (not clicked), == 1 (same as MouseClicked[]), == 2 (double-clicked), == 3 (triple-clicked) etc. when going from !Down to Down
     ImU16       MouseClickedLastCount[5];           // Count successive number of clicks. Stays valid after mouse release. Reset after another click is done.
     bool        MouseReleased[5];                   // Mouse button went from Down to !Down
+    double      MouseReleasedTime[5];               // Time of last released (rarely used! but useful to handle delayed single-click when trying to disambiguate them from double-click).
     bool        MouseDownOwned[5];                  // Track if button was clicked inside a dear imgui window or over void blocked by a popup. We don't request mouse capture from the application if click started outside ImGui bounds.
     bool        MouseDownOwnedUnlessPopupClose[5];  // Track if button was clicked inside a dear imgui window.
     bool        MouseWheelRequestAxisSwap;          // On a non-Mac system, holding SHIFT requests WheelY to perform the equivalent of a WheelX event. On a Mac system this is already enforced by the system.

imgui_demo.cpp

@@ -7407,6 +7407,8 @@ static void ShowDemoWindowInputs()
             ImGui::Text("Mouse down:");
             for (int i = 0; i < IM_ARRAYSIZE(io.MouseDown); i++) if (ImGui::IsMouseDown(i)) { ImGui::SameLine(); ImGui::Text("b%d (%.02f secs)", i, io.MouseDownDuration[i]); }
             ImGui::Text("Mouse wheel: %.1f", io.MouseWheel);
+            ImGui::Text("Mouse clicked count:");
+            for (int i = 0; i < IM_ARRAYSIZE(io.MouseDown); i++) if (io.MouseClickedCount[i] > 0) { ImGui::SameLine(); ImGui::Text("b%d: %d", i, io.MouseClickedCount[i]); }
 
             // We iterate both legacy native range and named ImGuiKey ranges. This is a little unusual/odd but this allows
             // displaying the data for old/new backends.