Internals: Added IM_NEW, IM_DELETE helper macros (#1517, #484, #504)

imgui.cpp

@@ -1859,8 +1859,7 @@ ImGuiWindow::ImGuiWindow(ImGuiContext* context, const char* name)
     ItemWidthDefault = 0.0f;
     FontWindowScale = 1.0f;
 
-    DrawList = (ImDrawList*)ImGui::MemAlloc(sizeof(ImDrawList));
-    IM_PLACEMENT_NEW(DrawList) ImDrawList(&context->DrawListSharedData);
+    DrawList = IM_NEW(ImDrawList)(&context->DrawListSharedData);
     DrawList->_OwnerName = Name;
     ParentWindow = NULL;
     RootWindow = NULL;
@@ -1873,11 +1872,8 @@ ImGuiWindow::ImGuiWindow(ImGuiContext* context, const char* name)
 
 ImGuiWindow::~ImGuiWindow()
 {
-    DrawList->~ImDrawList();
-    ImGui::MemFree(DrawList);
-    DrawList = NULL;
-    ImGui::MemFree(Name);
-    Name = NULL;
+    IM_DELETE(DrawList);
+    IM_DELETE(Name);
 }
 
 ImGuiID ImGuiWindow::GetID(const char* str, const char* str_end)
@@ -2579,8 +2575,7 @@ static void SettingsHandlerWindow_WriteAll(ImGuiContext& g, ImGuiTextBuffer* buf
 void ImGui::Initialize()
 {
     ImGuiContext& g = *GImGui;
-    g.LogClipboard = (ImGuiTextBuffer*)ImGui::MemAlloc(sizeof(ImGuiTextBuffer));
-    IM_PLACEMENT_NEW(g.LogClipboard) ImGuiTextBuffer();
+    g.LogClipboard = IM_NEW(ImGuiTextBuffer)();
 
     // Add .ini handle for ImGuiWindow type
     ImGuiSettingsHandler ini_handler;
@@ -2613,10 +2608,7 @@ void ImGui::Shutdown()
     SaveIniSettingsToDisk(g.IO.IniFilename);
 
     for (int i = 0; i < g.Windows.Size; i++)
-    {
-        g.Windows[i]->~ImGuiWindow();
-        ImGui::MemFree(g.Windows[i]);
-    }
+        IM_DELETE(g.Windows[i]);
     g.Windows.clear();
     g.WindowsSortBuffer.clear();
     g.CurrentWindow = NULL;
@@ -2628,7 +2620,7 @@ void ImGui::Shutdown()
     g.ActiveIdWindow = NULL;
     g.MovingWindow = NULL;
     for (int i = 0; i < g.SettingsWindows.Size; i++)
-        ImGui::MemFree(g.SettingsWindows[i].Name);
+        IM_DELETE(g.SettingsWindows[i].Name);
     g.ColorModifiers.clear();
     g.StyleModifiers.clear();
     g.FontStack.clear();
@@ -2653,10 +2645,7 @@ void ImGui::Shutdown()
         g.LogFile = NULL;
     }
     if (g.LogClipboard)
-    {
-        g.LogClipboard->~ImGuiTextBuffer();
-        ImGui::MemFree(g.LogClipboard);
-    }
+        IM_DELETE(g.LogClipboard);
 
     g.Initialized = false;
 }
@@ -4157,8 +4146,7 @@ static ImGuiWindow* CreateNewWindow(const char* name, ImVec2 size, ImGuiWindowFl
     ImGuiContext& g = *GImGui;
 
     // Create window the first time
-    ImGuiWindow* window = (ImGuiWindow*)ImGui::MemAlloc(sizeof(ImGuiWindow));
-    IM_PLACEMENT_NEW(window) ImGuiWindow(&g, name);
+    ImGuiWindow* window = IM_NEW(ImGuiWindow)(&g, name);
     window->Flags = flags;
     g.WindowsById.SetVoidPtr(window->ID, window);
 

imgui_draw.cpp

@@ -1461,15 +1461,9 @@ ImFont* ImFontAtlas::AddFont(const ImFontConfig* font_cfg)
 
     // Create new font
     if (!font_cfg->MergeMode)
-    {
-        ImFont* font = (ImFont*)ImGui::MemAlloc(sizeof(ImFont));
-        IM_PLACEMENT_NEW(font) ImFont();
-        Fonts.push_back(font);
-    }
+        Fonts.push_back(IM_NEW(ImFont));
     else
-    {
         IM_ASSERT(!Fonts.empty()); // When using MergeMode make sure that a font has already been added before. You can use ImGui::GetIO().Fonts->AddFontDefault() to add the default imgui font.
-    }
 
     ConfigData.push_back(*font_cfg);
     ImFontConfig& new_font_cfg = ConfigData.back();

imgui_internal.h

@@ -160,10 +160,14 @@ static inline ImVec2 ImMul(const ImVec2& lhs, const ImVec2& rhs)
 
 // We call C++ constructor on own allocated memory via the placement "new(ptr) Type()" syntax.
 // Defining a custom placement new() with a dummy parameter allows us to bypass including <new> which on some platforms complains when user has disabled exceptions.
-struct ImPlacementNewDummy {};
-inline void* operator new(size_t, ImPlacementNewDummy, void* ptr) { return ptr; }
-inline void operator delete(void*, ImPlacementNewDummy, void*) {}
-#define IM_PLACEMENT_NEW(_PTR)  new(ImPlacementNewDummy(), _PTR)
+struct ImNewAllocDummy {};
+struct ImNewPlacementDummy {};
+inline void* operator   new(size_t, ImNewPlacementDummy, void* ptr) { return ptr; }
+inline void  operator   delete(void*, ImNewPlacementDummy, void*)   {} // This is only required so we can use the symetrical new()
+inline void  operator   delete(void* p, ImNewAllocDummy)            { ImGui::MemFree(p); }
+#define IM_PLACEMENT_NEW(_PTR)  new(ImNewPlacementDummy(), _PTR)
+#define IM_NEW(_TYPE)           new(ImNewPlacementDummy(), ImGui::MemAlloc(sizeof(_TYPE))) _TYPE
+#define IM_DELETE(_PTR)         delete(ImNewAllocDummy(), _PTR), _PTR = NULL
 
 //-----------------------------------------------------------------------------
 // Types