MouseWheel: Add functions to allow a hovered items to block imgui fro…

…m processing mouse wheel events in various scenarios.
ocornut · Nov 12, 2019 · 33e9986 · 33e9986
1 parent 6e8e2c0
commit 33e9986
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Showing 2 changed files with 34 additions and 1 deletion.
diff --git a/imgui.cpp b/imgui.cpp
@@ -2724,6 +2724,7 @@ void ImGui::SetHoveredID(ImGuiID id)
     ImGuiContext& g = *GImGui;
     g.HoveredId = id;
     g.HoveredIdAllowOverlap = false;
+    g.HoveredIdUsingMouseWheel = false;
     if (id != 0 && g.HoveredIdPreviousFrame != id)
         g.HoveredIdTimer = g.HoveredIdNotActiveTimer = 0.0f;
 }
@@ -3360,6 +3361,9 @@ void ImGui::UpdateMouseWheel()
     if (g.IO.MouseWheel == 0.0f && g.IO.MouseWheelH == 0.0f)
         return;
 
+    if (IsHoveredIdUsingMouseWheel())
+        return;
+
     ImGuiWindow* window = g.WheelingWindow ? g.WheelingWindow : g.HoveredWindow;
     if (!window || window->Collapsed)
         return;
@@ -3648,6 +3652,8 @@ void ImGui::NewFrame()
     // Mouse wheel scrolling, scale
     UpdateMouseWheel();
 
+    g.HoveredIdUsingMouseWheel = false; // clear after processing mouse wheel
+
     // Pressing TAB activate widget focus
     g.FocusTabPressed = (g.NavWindow && g.NavWindow->Active && !(g.NavWindow->Flags & ImGuiWindowFlags_NoNavInputs) && !g.IO.KeyCtrl && IsKeyPressedMap(ImGuiKey_Tab));
     if (g.ActiveId == 0 && g.FocusTabPressed)
@@ -4510,6 +4516,27 @@ void ImGui::SetItemAllowOverlap()
         g.ActiveIdAllowOverlap = true;
 }
 
+void ImGui::SetItemUsesMouseWheel()
+{
+    ImGuiContext& g = *GImGui;
+    if (g.HoveredId == g.CurrentWindow->DC.LastItemId)
+        g.HoveredIdUsingMouseWheel = true;
+}
+
+void ImGui::SetActiveItemUsesMouseWheel()
+{
+    ImGuiContext& g = *GImGui;
+    SetActiveItemUsesMouseWheel(g.CurrentWindow->DC.LastItemId);
+}
+
+void ImGui::SetActiveItemUsesMouseWheel(ImGuiID id)
+{
+    IM_ASSERT(id != 0);
+    ImGuiContext& g = *GImGui;
+    if (g.ActiveId == id && g.HoveredId == g.CurrentWindow->DC.LastItemId)
+        g.HoveredIdUsingMouseWheel = true;
+}
+
 ImVec2 ImGui::GetItemRectMin()
 {
     ImGuiWindow* window = GetCurrentWindowRead();
@@ -9870,7 +9897,7 @@ void ImGui::ShowMetricsWindow(bool* p_open)
         const char* input_source_names[] = { "None", "Mouse", "Nav", "NavKeyboard", "NavGamepad" }; IM_ASSERT(IM_ARRAYSIZE(input_source_names) == ImGuiInputSource_COUNT);
         ImGui::Text("HoveredWindow: '%s'", g.HoveredWindow ? g.HoveredWindow->Name : "NULL");
         ImGui::Text("HoveredRootWindow: '%s'", g.HoveredRootWindow ? g.HoveredRootWindow->Name : "NULL");
-        ImGui::Text("HoveredId: 0x%08X/0x%08X (%.2f sec), AllowOverlap: %d", g.HoveredId, g.HoveredIdPreviousFrame, g.HoveredIdTimer, g.HoveredIdAllowOverlap); // Data is "in-flight" so depending on when the Metrics window is called we may see current frame information or not
+        ImGui::Text("HoveredId: 0x%08X/0x%08X (%.2f sec), AllowOverlap: %d, Blocks Mouse Wheel: %s", g.HoveredId, g.HoveredIdPreviousFrame, g.HoveredIdTimer, g.HoveredIdAllowOverlap, g.HoveredIdUsingMouseWheel ? "Yes" : "No"); // Data is "in-flight" so depending on when the Metrics window is called we may see current frame information or not
         ImGui::Text("ActiveId: 0x%08X/0x%08X (%.2f sec), AllowOverlap: %d, Source: %s", g.ActiveId, g.ActiveIdPreviousFrame, g.ActiveIdTimer, g.ActiveIdAllowOverlap, input_source_names[g.ActiveIdSource]);
         ImGui::Text("ActiveIdWindow: '%s'", g.ActiveIdWindow ? g.ActiveIdWindow->Name : "NULL");
         ImGui::Text("MovingWindow: '%s'", g.MovingWindow ? g.MovingWindow->Name : "NULL");

diff --git a/imgui_internal.h b/imgui_internal.h
@@ -935,6 +935,7 @@ struct ImGuiContext
     // Item/widgets state and tracking information
     ImGuiID                 HoveredId;                          // Hovered widget
     bool                    HoveredIdAllowOverlap;
+    bool                    HoveredIdUsingMouseWheel;           // When hovered, the widget blocks imgui from processing mouse wheel (i.e. scrolling)
     ImGuiID                 HoveredIdPreviousFrame;
     float                   HoveredIdTimer;                     // Measure contiguous hovering time
     float                   HoveredIdNotActiveTimer;            // Measure contiguous hovering time where the item has not been active
@@ -1129,6 +1130,7 @@ struct ImGuiContext
 
         HoveredId = 0;
         HoveredIdAllowOverlap = false;
+        HoveredIdUsingMouseWheel = false;
         HoveredIdPreviousFrame = 0;
         HoveredIdTimer = HoveredIdNotActiveTimer = 0.0f;
         ActiveId = 0;
@@ -1636,11 +1638,15 @@ namespace ImGui
     inline bool             IsActiveIdUsingNavDir(ImGuiDir dir)                         { ImGuiContext& g = *GImGui; return (g.ActiveIdUsingNavDirMask & (1 << dir)) != 0; }
     inline bool             IsActiveIdUsingNavInput(ImGuiNavInput input)                { ImGuiContext& g = *GImGui; return (g.ActiveIdUsingNavInputMask & (1 << input)) != 0; }
     inline bool             IsActiveIdUsingKey(ImGuiKey key)                            { ImGuiContext& g = *GImGui; IM_ASSERT(key < 64); return (g.ActiveIdUsingKeyInputMask & ((ImU64)1 << key)) != 0; }
+    inline bool             IsHoveredIdUsingMouseWheel() { ImGuiContext& g = *GImGui; return g.HoveredIdUsingMouseWheel; }
     IMGUI_API bool          IsMouseDragPastThreshold(int button, float lock_threshold = -1.0f);
     inline bool             IsKeyPressedMap(ImGuiKey key, bool repeat = true)           { ImGuiContext& g = *GImGui; const int key_index = g.IO.KeyMap[key]; return (key_index >= 0) ? IsKeyPressed(key_index, repeat) : false; }
     inline bool             IsNavInputDown(ImGuiNavInput n)                             { ImGuiContext& g = *GImGui; return g.IO.NavInputs[n] > 0.0f; }
     inline bool             IsNavInputPressed(ImGuiNavInput n, ImGuiInputReadMode mode) { return GetNavInputAmount(n, mode) > 0.0f; }
     inline bool             IsNavInputPressedAnyOfTwo(ImGuiNavInput n1, ImGuiNavInput n2, ImGuiInputReadMode mode) { return (GetNavInputAmount(n1, mode) + GetNavInputAmount(n2, mode)) > 0.0f; }
+    IMGUI_API void          SetItemUsesMouseWheel();                   // block Imgui from using mouse wheel when last item is hovered.
+    IMGUI_API void          SetActiveItemUsesMouseWheel();             // block Imgui from using mouse wheel when last item is hovered AND active.
+    IMGUI_API void          SetActiveItemUsesMouseWheel(ImGuiID id);   // block Imgui from using mouse wheel when last item is hovered AND the given ID is active. Used when making composite controls where the active item isn't the hovered item.
 
     // Drag and Drop
     IMGUI_API bool          BeginDragDropTargetCustom(const ImRect& bb, ImGuiID id);