InputText: fixed a bug (regression in 1.91.2) where modifying text buffer within a callback would sometimes prevents further appending to the buffer. (#7925)

There's a confusion between TextA.Size and CurLenA we should be merging them.
Amend 19accb14a

docs/CHANGELOG.txt

@@ -48,6 +48,8 @@ Other changes:
 - Buttons: using ImGuiItemFlags_ButtonRepeat makes default button behavior use
   PressedOnClick instead of PressedOnClickRelease when unspecified.
 - Fonts: removed const qualifiers from most font functions.
+- InputText: fixed a bug (regression in 1.91.2) where modifying text buffer within
+  a callback would sometimes prevents further appending to the buffer.
 - Log/Capture: better decorating of BeginMenu() and TabItem() output.
 - Log/Capture: a non terminated log ends automatically in the window which called it.
 - Log/Capture: added experimental io.ConfigWindowsCopyContentsWithCtrlC option to

imgui.h

@@ -29,7 +29,7 @@
 // Library Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals, e.g. '#if IMGUI_VERSION_NUM >= 12345')
 #define IMGUI_VERSION       "1.91.5 WIP"
-#define IMGUI_VERSION_NUM   19142
+#define IMGUI_VERSION_NUM   19143
 #define IMGUI_HAS_TABLE
 
 /*

imgui_internal.h

@@ -1111,7 +1111,7 @@ struct IMGUI_API ImGuiInputTextState
     ImStbTexteditState*     Stb;                    // State for stb_textedit.h
     ImGuiID                 ID;                     // widget id owning the text state
     int                     CurLenA;                // UTF-8 length of the string in TextA (in bytes)
-    ImVector<char>          TextA;                  // main UTF8 buffer.
+    ImVector<char>          TextA;                  // main UTF8 buffer. TextA.Size is a buffer size! Should always be >= buf_size passed by user (and of course >= CurLenA + 1).
     ImVector<char>          InitialTextA;           // value to revert to when pressing Escape = backup of end-user buffer at the time of focus (in UTF-8, unaltered)
     ImVector<char>          CallbackTextBackup;     // temporary storage for callback to support automatic reconcile of undo-stack
     int                     BufCapacityA;           // end-user buffer capacity

imgui_widgets.cpp

@@ -4200,6 +4200,7 @@ void ImGuiInputTextCallbackData::InsertChars(int pos, const char* new_text, cons
     if (new_text == new_text_end)
         return;
 
+    // Grow internal buffer if needed
     const bool is_resizable = (Flags & ImGuiInputTextFlags_CallbackResize) != 0;
     const int new_text_len = new_text_end ? (int)(new_text_end - new_text) : (int)strlen(new_text);
     if (new_text_len + BufTextLen >= BufSize)
@@ -4213,7 +4214,7 @@ void ImGuiInputTextCallbackData::InsertChars(int pos, const char* new_text, cons
         IM_ASSERT(edit_state->ID != 0 && g.ActiveId == edit_state->ID);
         IM_ASSERT(Buf == edit_state->TextA.Data);
         int new_buf_size = BufTextLen + ImClamp(new_text_len * 4, 32, ImMax(256, new_text_len)) + 1;
-        edit_state->TextA.reserve(new_buf_size + 1);
+        edit_state->TextA.resize(new_buf_size + 1);
         Buf = edit_state->TextA.Data;
         BufSize = edit_state->BufCapacityA = new_buf_size;
     }
@@ -5034,7 +5035,6 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
                         IM_ASSERT(callback_data.BufTextLen == (int)strlen(callback_data.Buf)); // You need to maintain BufTextLen if you change the text!
                         InputTextReconcileUndoStateAfterUserCallback(state, callback_data.Buf, callback_data.BufTextLen); // FIXME: Move the rest of this block inside function and rename to InputTextReconcileStateAfterUserCallback() ?
                         state->CurLenA = callback_data.BufTextLen;  // Assume correct length and valid UTF-8 from user, saves us an extra strlen()
-                        state->TextA.Size = state->CurLenA + 1;
                         state->CursorAnimReset();
                     }
                 }
@@ -5342,6 +5342,8 @@ void ImGui::DebugNodeInputTextState(ImGuiInputTextState* state)
     Text("ID: 0x%08X, ActiveID: 0x%08X", state->ID, g.ActiveId);
     DebugLocateItemOnHover(state->ID);
     Text("CurLenA: %d, Cursor: %d, Selection: %d..%d", state->CurLenA, stb_state->cursor, stb_state->select_start, stb_state->select_end);
+    Text("TextA.Size: %d, Capacity: %d", state->TextA.Size, state->TextA.Capacity);
+    Text("BufCapacityA: %d", state->BufCapacityA);
     Text("has_preferred_x: %d (%.2f)", stb_state->has_preferred_x, stb_state->preferred_x);
     Text("undo_point: %d, redo_point: %d, undo_char_point: %d, redo_char_point: %d", undo_state->undo_point, undo_state->redo_point, undo_state->undo_char_point, undo_state->redo_char_point);
     if (BeginChild("undopoints", ImVec2(0.0f, GetTextLineHeight() * 10), ImGuiChildFlags_Borders | ImGuiChildFlags_ResizeY)) // Visualize undo state