Added optional misc/stl/imgui_stl.h wrapper to use with STL types (e.g. InputText with std::string). (#2035, #2006, #1443, #1008)

CHANGELOG.txt

@@ -70,6 +70,7 @@ Other Changes:
  - Drag and Drop: Added ImGuiDragDropFlags_SourceAutoExpirePayload flag to force payload to expire if the source stops being submitted. (#1725, #143).
  - IsItemHovered(): Added ImGuiHoveredFlags_AllowWhenDisabled flag to query hovered status on disabled items. (#1940, #211)
  - Selectable: Added ImGuiSelectableFlags_Disabled flag in the public API. (#211)
+ - Misc; Added optional misc/stl/imgui_stl.h wrapper to use with STL types (e.g. InputText with std::string). (#2006, #1443, #1008)
  - Misc: Added IMGUI_VERSION_NUM for easy compile-time testing. (#2025)
  - Misc: Added ImGuiMouseCursor_Hand cursor enum + corresponding software cursor. (#1913, 1914) [@aiekick, @ocornut] 
  - Misc: Tweaked software mouse cursor offset to match the offset of the corresponding Windows 10 cursors.

imgui.cpp

@@ -10715,7 +10715,8 @@ static bool InputTextFilterCharacter(unsigned int* p_char, ImGuiInputTextFlags f
 //   This is so we can easily call InputText() on static arrays using ARRAYSIZE() and to match 
 //   Note that in std::string world, capacity() would omit 1 byte used by the zero-terminator.
 // - When active, hold on a privately held copy of the text (and apply back to 'buf'). So changing 'buf' while the InputText is active has no effect.
-// FIXME: Rather messy function partly because we are doing UTF8 > u16 > UTF8 conversions on the go to more easily handle stb_textedit calls. Ideally we should stay in UTF-8 all the time. See https://github.com/nothings/stb/issues/188
+// - If you want to use ImGui::InputText() with std::string, see misc/stl/imgui_stl.h
+// (FIXME: Rather messy function partly because we are doing UTF8 > u16 > UTF8 conversions on the go to more easily handle stb_textedit calls. Ideally we should stay in UTF-8 all the time. See https://github.com/nothings/stb/issues/188)
 bool ImGui::InputTextEx(const char* label, char* buf, int buf_size, const ImVec2& size_arg, ImGuiInputTextFlags flags, ImGuiInputTextCallback callback, void* callback_user_data)
 {
     ImGuiWindow* window = GetCurrentWindow();

imgui.h

@@ -373,6 +373,7 @@ namespace ImGui
     IMGUI_API bool          DragScalarN(const char* label, ImGuiDataType data_type, void* v, int components, float v_speed, const void* v_min = NULL, const void* v_max = NULL, const char* format = NULL, float power = 1.0f);
 
     // Widgets: Input with Keyboard
+    // If you want to use InputText() with a dynamic string type such as std::string or your own, see misc/stl/imgui_stl.h
     IMGUI_API bool          InputText(const char* label, char* buf, size_t buf_size, ImGuiInputTextFlags flags = 0, ImGuiInputTextCallback callback = NULL, void* user_data = NULL);
     IMGUI_API bool          InputTextMultiline(const char* label, char* buf, size_t buf_size, const ImVec2& size = ImVec2(0,0), ImGuiInputTextFlags flags = 0, ImGuiInputTextCallback callback = NULL, void* user_data = NULL);
     IMGUI_API bool          InputFloat(const char* label, float* v, float step = 0.0f, float step_fast = 0.0f, const char* format = "%.3f", ImGuiInputTextFlags extra_flags = 0);
@@ -652,7 +653,7 @@ enum ImGuiInputTextFlags_
     ImGuiInputTextFlags_Password            = 1 << 15,  // Password mode, display all characters as '*'
     ImGuiInputTextFlags_NoUndoRedo          = 1 << 16,  // Disable undo/redo. Note that input text owns the text data while active, if you want to provide your own undo/redo stack you need e.g. to call ClearActiveID().
     ImGuiInputTextFlags_CharsScientific     = 1 << 17,  // Allow 0123456789.+-*/eE (Scientific notation input)
-    ImGuiInputTextFlags_CallbackResize      = 1 << 18,  // Allow buffer capacity resize + notify when the string wants to be resized (for string types which hold a cache of their Size)
+    ImGuiInputTextFlags_CallbackResize      = 1 << 18,  // Allow buffer capacity resize + notify when the string wants to be resized (for string types which hold a cache of their Size) (see misc/stl/imgui_stl.h for an example of using this)
     // [Internal]
     ImGuiInputTextFlags_Multiline           = 1 << 20   // For internal use by InputTextMultiline()
 };

imgui_demo.cpp

@@ -353,7 +353,7 @@ void ImGui::ShowDemoWindow(bool* p_open)
                 static char str0[128] = "Hello, world!";
                 static int i0 = 123;
                 ImGui::InputText("input text", str0, IM_ARRAYSIZE(str0));
-                ImGui::SameLine(); ShowHelpMarker("Hold SHIFT or use mouse to select text.\n" "CTRL+Left/Right to word jump.\n" "CTRL+A or double-click to select all.\n" "CTRL+X,CTRL+C,CTRL+V clipboard.\n" "CTRL+Z,CTRL+Y undo/redo.\n" "ESCAPE to revert.\n");
+                ImGui::SameLine(); ShowHelpMarker("USER:\nHold SHIFT or use mouse to select text.\n" "CTRL+Left/Right to word jump.\n" "CTRL+A or double-click to select all.\n" "CTRL+X,CTRL+C,CTRL+V clipboard.\n" "CTRL+Z,CTRL+Y undo/redo.\n" "ESCAPE to revert.\n\nPROGRAMMER:\nYou can use the ImGuiInputTextFlags_CallbackResize facility if you need to wire InputText() to a dynamic string type. See misc/stl/imgui_stl.h for an example (this is not demonstrated in imgui_demo.cpp).");
 
                 ImGui::InputInt("input int", &i0);
                 ImGui::SameLine(); ShowHelpMarker("You can apply arithmetic operators +,*,/ on numerical values.\n  e.g. [ 100 ], input \'*2\', result becomes [ 200 ]\nUse +- to subtract.\n");
@@ -800,10 +800,10 @@ void ImGui::ShowDemoWindow(bool* p_open)
                 "label:\n"
                 "\tlock cmpxchg8b eax\n";
 
-            ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(0,0));
+            ShowHelpMarker("You can use the ImGuiInputTextFlags_CallbackResize facility if you need to wire InputTextMultiline() to a dynamic string type. See misc/stl/imgui_stl.h for an example. (This is not demonstrated in imgui_demo.cpp)");
             ImGui::Checkbox("Read-only", &read_only);
-            ImGui::PopStyleVar();
-            ImGui::InputTextMultiline("##source", text, IM_ARRAYSIZE(text), ImVec2(-1.0f, ImGui::GetTextLineHeight() * 16), ImGuiInputTextFlags_AllowTabInput | (read_only ? ImGuiInputTextFlags_ReadOnly : 0));
+            ImGuiInputTextFlags flags = ImGuiInputTextFlags_AllowTabInput | (read_only ? ImGuiInputTextFlags_ReadOnly : 0);
+            ImGui::InputTextMultiline("##source", text, IM_ARRAYSIZE(text), ImVec2(-1.0f, ImGui::GetTextLineHeight() * 16), flags);
             ImGui::TreePop();
         }
 

misc/stl/imgui_stl.cpp

@@ -0,0 +1,55 @@
+// imgui_stl.cpp
+// Wrappers for STL types (std::string, etc.)
+// This is also an example of how you may wrap your own similar types.
+
+#include "imgui.h"
+#include "imgui_stl.h"
+
+struct InputTextCallback_UserData
+{
+    std::string*            Str;
+    ImGuiInputTextCallback  ChainCallback;
+    void*                   ChainCallbackUserData;
+};
+
+static int InputTextCallback(ImGuiInputTextCallbackData* data)
+{
+    InputTextCallback_UserData* user_data = (InputTextCallback_UserData*)data->UserData;
+    if (data->EventFlag == ImGuiInputTextFlags_CallbackResize)
+    {
+        // Resize string callback
+        std::string* str = user_data->Str;
+        IM_ASSERT(data->Buf == str->c_str());
+        str->resize(data->BufTextLen);
+        data->Buf = (char*)str->c_str();
+    }
+    else if (user_data->ChainCallback)
+    {
+        // Forward to user callback, if any
+        data->UserData = user_data->ChainCallbackUserData;
+        return user_data->ChainCallback(data);
+    }
+    return 0;
+}
+
+bool ImGui::InputText(const char* label, std::string* str, ImGuiInputTextFlags flags, ImGuiInputTextCallback callback, void* user_data)
+{
+    flags |= ImGuiInputTextFlags_CallbackResize;
+
+    InputTextCallback_UserData cb_user_data;
+    cb_user_data.Str = str;
+    cb_user_data.ChainCallback = callback;
+    cb_user_data.ChainCallbackUserData = user_data;
+    return InputText(label, (char*)str->c_str(), str->capacity() + 1, flags, InputTextCallback, &cb_user_data);
+}
+
+bool ImGui::InputTextMultiline(const char* label, std::string* str, const ImVec2& size, ImGuiInputTextFlags flags, ImGuiInputTextCallback callback, void* user_data)
+{
+    flags |= ImGuiInputTextFlags_CallbackResize;
+
+    InputTextCallback_UserData cb_user_data;
+    cb_user_data.Str = str;
+    cb_user_data.ChainCallback = callback;
+    cb_user_data.ChainCallbackUserData = user_data;
+    return InputTextMultiline(label, (char*)str->c_str(), str->capacity() + 1, size, flags, InputTextCallback, &cb_user_data);
+}

misc/stl/imgui_stl.h

@@ -0,0 +1,18 @@
+// imgui_stl.h
+// Wrappers for STL types (std::string, etc.)
+// This is also an example of how you may wrap your own similar types.
+
+// Changelog:
+// - v0.10: Initial version. Added InputText() / InputTextMultiline() calls with std::string
+
+#pragma once
+
+#include <string>
+
+namespace ImGui
+{
+    // ImGui::InputText() with std::string
+    // Because text input needs dynamic resizing, we need to setup a callback to grow the capacity
+    IMGUI_API bool  InputText(const char* label, std::string* str, ImGuiInputTextFlags flags = 0, ImGuiInputTextCallback callback = NULL, void* user_data = NULL);
+    IMGUI_API bool  InputTextMultiline(const char* label, std::string* str, const ImVec2& size = ImVec2(0, 0), ImGuiInputTextFlags flags = 0, ImGuiInputTextCallback callback = NULL, void* user_data = NULL);
+}