InputText: Add ImGuiInputTextFlags_CallbackEdit, selection helpers in ImGuiInputTextCallbackData(). Add simple InputText() callbacks demo.

docs/CHANGELOG.txt

@@ -37,8 +37,13 @@ HOW TO UPDATE?
 
 Other Changes:
 
+- InputText: Added selection helpers in ImGuiInputTextCallbackData().
+- InputText: Added ImGuiInputTextFlags_CallbackEdit to modify internally owned buffer after an edit.
+  (note that InputText() already returns true on edit, the callback is useful mainly to manipulate the
+  underlying buffer while focus is active).
 - DragFloat, DragScalar: Fixed ImGuiSliderFlags_ClampOnInput not being honored in the special case
   where v_min == v_max. (#3361)
+- Demo: Add simple InputText() callbacks demo (aside from the more elaborate ones in 'Examples->Console').
 
 
 -----------------------------------------------------------------------

imgui.h

@@ -854,6 +854,7 @@ enum ImGuiInputTextFlags_
     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,  // Callback on buffer capacity changes request (beyond 'buf_size' parameter value), allowing the string to grow. Notify when the string wants to be resized (for string types which hold a cache of their Size). You will be provided a new BufSize in the callback and NEED to honor it. (see misc/cpp/imgui_stdlib.h for an example of using this)
+    ImGuiInputTextFlags_CallbackEdit        = 1 << 19,  // Callback on any edit (note that InputText() already returns true on edit, the callback is useful mainly to manipulate the underlying buffer while focus is active)
     // [Internal]
     ImGuiInputTextFlags_Multiline           = 1 << 20,  // For internal use by InputTextMultiline()
     ImGuiInputTextFlags_NoMarkEdited        = 1 << 21   // For internal use by functions using InputText() before reformatting data
@@ -1634,9 +1635,10 @@ struct ImGuiIO
 // Shared state of InputText(), passed as an argument to your callback when a ImGuiInputTextFlags_Callback* flag is used.
 // The callback function should return 0 by default.
 // Callbacks (follow a flag name and see comments in ImGuiInputTextFlags_ declarations for more details)
+// - ImGuiInputTextFlags_CallbackEdit:        Callback on buffer edit (note that InputText() already returns true on edit, the callback is useful mainly to manipulate the underlying buffer while focus is active)
+// - ImGuiInputTextFlags_CallbackAlways:      Callback on each iteration
 // - ImGuiInputTextFlags_CallbackCompletion:  Callback on pressing TAB
 // - ImGuiInputTextFlags_CallbackHistory:     Callback on pressing Up/Down arrows
-// - ImGuiInputTextFlags_CallbackAlways:      Callback on each iteration
 // - ImGuiInputTextFlags_CallbackCharFilter:  Callback on character inputs to replace or discard them. Modify 'EventChar' to replace or discard, or return 1 in callback to discard.
 // - ImGuiInputTextFlags_CallbackResize:      Callback on buffer capacity changes request (beyond 'buf_size' parameter value), allowing the string to grow.
 struct ImGuiInputTextCallbackData
@@ -1663,7 +1665,9 @@ struct ImGuiInputTextCallbackData
     IMGUI_API ImGuiInputTextCallbackData();
     IMGUI_API void      DeleteChars(int pos, int bytes_count);
     IMGUI_API void      InsertChars(int pos, const char* text, const char* text_end = NULL);
-    bool                HasSelection() const { return SelectionStart != SelectionEnd; }
+    void                SelectAll()             { SelectionStart = 0; SelectionEnd = BufTextLen; }
+    void                ClearSelection()        { SelectionStart = SelectionEnd = BufTextLen; }
+    bool                HasSelection() const    { return SelectionStart != SelectionEnd; }
 };
 
 // Resizing callback data to apply custom constraint. As enabled by SetNextWindowSizeConstraints(). Callback is called during the next Begin().

imgui_demo.cpp

@@ -1177,8 +1177,11 @@ static void ShowDemoWindowWidgets()
             static char buf4[64] = ""; ImGui::InputText("uppercase",   buf4, 64, ImGuiInputTextFlags_CharsUppercase);
             static char buf5[64] = ""; ImGui::InputText("no blank",    buf5, 64, ImGuiInputTextFlags_CharsNoBlank);
             static char buf6[64] = ""; ImGui::InputText("\"imgui\" letters", buf6, 64, ImGuiInputTextFlags_CallbackCharFilter, TextFilters::FilterImGuiLetters);
+            ImGui::TreePop();
+        }
 
-            ImGui::Text("Password input");
+        if (ImGui::TreeNode("Password Input"))
+        {
             static char password[64] = "password123";
             ImGui::InputText("password", password, IM_ARRAYSIZE(password), ImGuiInputTextFlags_Password);
             ImGui::SameLine(); HelpMarker("Display all characters as '*'.\nDisable clipboard cut and copy.\nDisable logging.\n");
@@ -1187,6 +1190,62 @@ static void ShowDemoWindowWidgets()
             ImGui::TreePop();
         }
 
+        if (ImGui::TreeNode("Completion, History, Edit Callbacks"))
+        {
+            struct Funcs
+            {
+                static int MyCallback(ImGuiInputTextCallbackData* data)
+                {
+                    if (data->EventFlag == ImGuiInputTextFlags_CallbackCompletion)
+                    {
+                        data->InsertChars(data->CursorPos, "..");
+                    }
+                    else if (data->EventFlag == ImGuiInputTextFlags_CallbackHistory)
+                    {
+                        if (data->EventKey == ImGuiKey_UpArrow)
+                        {
+                            data->DeleteChars(0, data->BufTextLen);
+                            data->InsertChars(0, "Pressed Up!");
+                            data->SelectAll();
+                        }
+                        else if (data->EventKey == ImGuiKey_DownArrow)
+                        {
+                            data->DeleteChars(0, data->BufTextLen);
+                            data->InsertChars(0, "Pressed Down!");
+                            data->SelectAll();
+                        }
+                    }
+                    else if (data->EventFlag == ImGuiInputTextFlags_CallbackEdit)
+                    {
+                        // Toggle casing of first character
+                        char c = data->Buf[0];
+                        if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')) data->Buf[0] ^= 32;
+                        data->BufDirty = true;
+
+                        // Increment a counter
+                        int* p_int = (int*)data->UserData;
+                        *p_int = *p_int + 1;
+                    }
+                    return 0;
+                }
+            };
+            static char buf1[64];
+            ImGui::InputText("Completion", buf1, 64, ImGuiInputTextFlags_CallbackCompletion, Funcs::MyCallback);
+            ImGui::SameLine(); HelpMarker("Here we append \"..\" each time Tab is pressed. See 'Examples>Console' for a more meaningful demonstration of using this callback.");
+
+            static char buf2[64];
+            ImGui::InputText("History", buf2, 64, ImGuiInputTextFlags_CallbackHistory, Funcs::MyCallback);
+            ImGui::SameLine(); HelpMarker("Here we replace and select text each time Up/Down are pressed. See 'Examples>Console' for a more meaningful demonstration of using this callback.");
+
+            static char buf3[64];
+            static int edit_count = 0;
+            ImGui::InputText("Edit", buf3, 64, ImGuiInputTextFlags_CallbackEdit, Funcs::MyCallback, (void*)&edit_count);
+            ImGui::SameLine(); HelpMarker("Here we toggle the casing of the first character on every edits + count edits.");
+            ImGui::SameLine(); ImGui::Text("(%d)", edit_count);
+
+            ImGui::TreePop();
+        }
+
         if (ImGui::TreeNode("Resize Callback"))
         {
             // To wire InputText() with std::string or any other custom string type,

imgui_internal.h

@@ -858,6 +858,7 @@ struct IMGUI_API ImGuiInputTextState
     float                   CursorAnim;             // timer for cursor blink, reset on every user action so the cursor reappears immediately
     bool                    CursorFollow;           // set when we want scrolling to follow the current cursor position (not always!)
     bool                    SelectedAllMouseLock;   // after a double-click to select all, we ignore further mouse drags to update selection
+    bool                    Edited;                 // edited this frame
     ImGuiInputTextFlags     UserFlags;              // Temporarily set while we call user's callback
     ImGuiInputTextCallback  UserCallback;           // "
     void*                   UserCallbackData;       // "

imgui_widgets.cpp

@@ -3514,6 +3514,7 @@ static void STB_TEXTEDIT_DELETECHARS(STB_TEXTEDIT_STRING* obj, int pos, int n)
     ImWchar* dst = obj->TextW.Data + pos;
 
     // We maintain our buffer length in both UTF-8 and wchar formats
+    obj->Edited = true;
     obj->CurLenA -= ImTextCountUtf8BytesFromStr(dst, dst + n);
     obj->CurLenW -= n;
 
@@ -3548,6 +3549,7 @@ static bool STB_TEXTEDIT_INSERTCHARS(STB_TEXTEDIT_STRING* obj, int pos, const Im
         memmove(text + pos + new_text_len, text + pos, (size_t)(text_len - pos) * sizeof(ImWchar));
     memcpy(text + pos, new_text, (size_t)new_text_len * sizeof(ImWchar));
 
+    obj->Edited = true;
     obj->CurLenW += new_text_len;
     obj->CurLenA += new_text_len_utf8;
     obj->TextW[obj->CurLenW] = '\0';
@@ -3946,6 +3948,7 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
     {
         IM_ASSERT(state != NULL);
         backup_current_text_length = state->CurLenA;
+        state->Edited = false;
         state->BufCapacityA = buf_size;
         state->UserFlags = flags;
         state->UserCallback = callback;
@@ -4183,7 +4186,7 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
             }
 
             // User callback
-            if ((flags & (ImGuiInputTextFlags_CallbackCompletion | ImGuiInputTextFlags_CallbackHistory | ImGuiInputTextFlags_CallbackAlways)) != 0)
+            if ((flags & (ImGuiInputTextFlags_CallbackCompletion | ImGuiInputTextFlags_CallbackHistory | ImGuiInputTextFlags_CallbackEdit | ImGuiInputTextFlags_CallbackAlways)) != 0)
             {
                 IM_ASSERT(callback != NULL);
 
@@ -4205,8 +4208,14 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
                     event_flag = ImGuiInputTextFlags_CallbackHistory;
                     event_key = ImGuiKey_DownArrow;
                 }
+                else if ((flags & ImGuiInputTextFlags_CallbackEdit) && state->Edited)
+                {
+                    event_flag = ImGuiInputTextFlags_CallbackEdit;
+                }
                 else if (flags & ImGuiInputTextFlags_CallbackAlways)
+                {
                     event_flag = ImGuiInputTextFlags_CallbackAlways;
+                }
 
                 if (event_flag)
                 {