InputText: use TextSrc more consistently to facilitate accessing user buffer in text processing code. (#8242)

Followup to e900571
Removed SetClipboardText() trick used in abd07f6 (#7925)

Author: ocornut

imgui_internal.h

@@ -1124,6 +1124,7 @@ struct IMGUI_API ImGuiInputTextState
     ImGuiInputTextFlags     Flags;                  // copy of InputText() flags. may be used to check if e.g. ImGuiInputTextFlags_Password is set.
     ImGuiID                 ID;                     // widget id owning the text state
     int                     TextLen;                // UTF-8 length of the string in TextA (in bytes)
+    const char*             TextSrc;                // == TextA.Data unless read-only, in which case == buf passed to InputText(). Field only set and valid _inside_ the call InputText() call.
     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>          TextToRevertTo;         // 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

imgui_widgets.cpp

@@ -3938,12 +3938,12 @@ static ImVec2 InputTextCalcTextSize(ImGuiContext* ctx, const char* text_begin, c
 namespace ImStb
 {
 static int     STB_TEXTEDIT_STRINGLEN(const ImGuiInputTextState* obj)                             { return obj->TextLen; }
-static char    STB_TEXTEDIT_GETCHAR(const ImGuiInputTextState* obj, int idx)                      { IM_ASSERT(idx <= obj->TextLen); return obj->TextA[idx]; }
-static float   STB_TEXTEDIT_GETWIDTH(ImGuiInputTextState* obj, int line_start_idx, int char_idx)  { unsigned int c; ImTextCharFromUtf8(&c, obj->TextA.Data + line_start_idx + char_idx, obj->TextA.Data + obj->TextLen); if ((ImWchar)c == '\n') return IMSTB_TEXTEDIT_GETWIDTH_NEWLINE; ImGuiContext& g = *obj->Ctx; return g.Font->GetCharAdvance((ImWchar)c) * g.FontScale; }
+static char    STB_TEXTEDIT_GETCHAR(const ImGuiInputTextState* obj, int idx)                      { IM_ASSERT(idx <= obj->TextLen); return obj->TextSrc[idx]; }
+static float   STB_TEXTEDIT_GETWIDTH(ImGuiInputTextState* obj, int line_start_idx, int char_idx)  { unsigned int c; ImTextCharFromUtf8(&c, obj->TextSrc + line_start_idx + char_idx, obj->TextSrc + obj->TextLen); if ((ImWchar)c == '\n') return IMSTB_TEXTEDIT_GETWIDTH_NEWLINE; ImGuiContext& g = *obj->Ctx; return g.Font->GetCharAdvance((ImWchar)c) * g.FontScale; }
 static char    STB_TEXTEDIT_NEWLINE = '\n';
 static void    STB_TEXTEDIT_LAYOUTROW(StbTexteditRow* r, ImGuiInputTextState* obj, int line_start_idx)
 {
-    const char* text = obj->TextA.Data;
+    const char* text = obj->TextSrc;
     const char* text_remaining = NULL;
     const ImVec2 size = InputTextCalcTextSize(obj->Ctx, text + line_start_idx, text + obj->TextLen, &text_remaining, NULL, true);
     r->x0 = 0.0f;
@@ -3962,15 +3962,15 @@ static int IMSTB_TEXTEDIT_GETNEXTCHARINDEX_IMPL(ImGuiInputTextState* obj, int id
     if (idx >= obj->TextLen)
         return obj->TextLen + 1;
     unsigned int c;
-    return idx + ImTextCharFromUtf8(&c, obj->TextA.Data + idx, obj->TextA.Data + obj->TextLen);
+    return idx + ImTextCharFromUtf8(&c, obj->TextSrc + idx, obj->TextSrc + obj->TextLen);
 }
 
 static int IMSTB_TEXTEDIT_GETPREVCHARINDEX_IMPL(ImGuiInputTextState* obj, int idx)
 {
     if (idx <= 0)
         return -1;
-    const char* p = ImTextFindPreviousUtf8Codepoint(obj->TextA.Data, obj->TextA.Data + idx);
-    return (int)(p - obj->TextA.Data);
+    const char* p = ImTextFindPreviousUtf8Codepoint(obj->TextSrc, obj->TextSrc + idx);
+    return (int)(p - obj->TextSrc);
 }
 
 static bool ImCharIsSeparatorW(unsigned int c)
@@ -3993,10 +3993,10 @@ static int is_word_boundary_from_right(ImGuiInputTextState* obj, int idx)
     if ((obj->Flags & ImGuiInputTextFlags_Password) || idx <= 0)
         return 0;
 
-    const char* curr_p = obj->TextA.Data + idx;
-    const char* prev_p = ImTextFindPreviousUtf8Codepoint(obj->TextA.Data, curr_p);
-    unsigned int curr_c; ImTextCharFromUtf8(&curr_c, curr_p, obj->TextA.Data + obj->TextLen);
-    unsigned int prev_c; ImTextCharFromUtf8(&prev_c, prev_p, obj->TextA.Data + obj->TextLen);
+    const char* curr_p = obj->TextSrc + idx;
+    const char* prev_p = ImTextFindPreviousUtf8Codepoint(obj->TextSrc, curr_p);
+    unsigned int curr_c; ImTextCharFromUtf8(&curr_c, curr_p, obj->TextSrc + obj->TextLen);
+    unsigned int prev_c; ImTextCharFromUtf8(&prev_c, prev_p, obj->TextSrc + obj->TextLen);
 
     bool prev_white = ImCharIsBlankW(prev_c);
     bool prev_separ = ImCharIsSeparatorW(prev_c);
@@ -4009,10 +4009,10 @@ static int is_word_boundary_from_left(ImGuiInputTextState* obj, int idx)
     if ((obj->Flags & ImGuiInputTextFlags_Password) || idx <= 0)
         return 0;
 
-    const char* curr_p = obj->TextA.Data + idx;
-    const char* prev_p = ImTextFindPreviousUtf8Codepoint(obj->TextA.Data, curr_p);
-    unsigned int prev_c; ImTextCharFromUtf8(&prev_c, curr_p, obj->TextA.Data + obj->TextLen);
-    unsigned int curr_c; ImTextCharFromUtf8(&curr_c, prev_p, obj->TextA.Data + obj->TextLen);
+    const char* curr_p = obj->TextSrc + idx;
+    const char* prev_p = ImTextFindPreviousUtf8Codepoint(obj->TextSrc, curr_p);
+    unsigned int prev_c; ImTextCharFromUtf8(&prev_c, curr_p, obj->TextSrc + obj->TextLen);
+    unsigned int curr_c; ImTextCharFromUtf8(&curr_c, prev_p, obj->TextSrc + obj->TextLen);
 
     bool prev_white = ImCharIsBlankW(prev_c);
     bool prev_separ = ImCharIsSeparatorW(prev_c);
@@ -4050,6 +4050,7 @@ static int  STB_TEXTEDIT_MOVEWORDRIGHT_IMPL(ImGuiInputTextState* obj, int idx)
 static void STB_TEXTEDIT_DELETECHARS(ImGuiInputTextState* obj, int pos, int n)
 {
     // Offset remaining text (+ copy zero terminator)
+    IM_ASSERT(obj->TextSrc == obj->TextA.Data);
     char* dst = obj->TextA.Data + pos;
     char* src = obj->TextA.Data + pos + n;
     memmove(dst, src, obj->TextLen - n - pos + 1);
@@ -4067,11 +4068,13 @@ static bool STB_TEXTEDIT_INSERTCHARS(ImGuiInputTextState* obj, int pos, const ch
         return false;
 
     // Grow internal buffer if needed
+    IM_ASSERT(obj->TextSrc == obj->TextA.Data);
     if (new_text_len + text_len + 1 > obj->TextA.Size)
     {
         if (!is_resizable)
             return false;
         obj->TextA.resize(text_len + ImClamp(new_text_len, 32, ImMax(256, new_text_len)) + 1);
+        obj->TextSrc = obj->TextA.Data;
     }
 
     char* text = obj->TextA.Data;
@@ -4218,6 +4221,7 @@ void ImGuiInputTextCallbackData::InsertChars(int pos, const char* new_text, cons
         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.resize(new_buf_size + 1);
+        edit_state->TextSrc = edit_state->TextA.Data;
         Buf = edit_state->TextA.Data;
         BufSize = edit_state->BufCapacity = new_buf_size;
     }
@@ -4507,7 +4511,6 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
     const bool init_changed_specs = (state != NULL && state->Stb->single_line != !is_multiline); // state != NULL means its our state.
     const bool init_make_active = (user_clicked || user_scroll_finish || input_requested_by_nav);
     const bool init_state = (init_make_active || user_scroll_active);
-    bool readonly_swapped_text_data = false;
     if (init_reload_from_user_buf)
     {
         int new_len = (int)strlen(buf);
@@ -4612,22 +4615,15 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
         // Expose scroll in a manner that is agnostic to us using a child window
         if (is_multiline && state != NULL)
             state->Scroll.y = draw_window->Scroll.y;
-    }
 
-    if (g.ActiveId == id && is_readonly)
-    {
-        // FIXME: Refresh buffer because cursor/selection code uses that data (see repro #8242)
-        // The "simple" way would be to copy buf into state->TextA, like in the block above.
-        // But because we like to live dangerously, we do a little swap....
-        // Removing the swap and only doing a TextA.clear() is a way to identify who's using TextA.Data.
-        state->TextLen = (int)strlen(buf);
-        state->TextA.clear();
-        state->TextA.Data = buf; // Ouch
-        state->TextA.Size = state->TextLen + 1;
-        readonly_swapped_text_data = true; // Need to always ensure that every code path below lead to this being handled
-        //state->TextA.resize(buf_size + 1);
-        //memcpy(state->TextA.Data, buf, state->TextLen + 1);
+        // Read-only mode always ever read from source buffer. Refresh TextLen when active.
+        if (is_readonly && state != NULL)
+            state->TextLen = (int)strlen(buf);
+        //if (is_readonly && state != NULL)
+        //    state->TextA.clear(); // Uncomment to facilitate debugging, but we otherwise prefer to keep/amortize th allocation.
     }
+    if (state != NULL)
+        state->TextSrc = is_readonly ? buf : state->TextA.Data;
 
     // We have an edge case if ActiveId was set through another widget (e.g. widget being swapped), clear id immediately (don't wait until the end of the function)
     if (g.ActiveId == id && state == NULL)
@@ -4892,13 +4888,13 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
             // Cut, Copy
             if (g.PlatformIO.Platform_SetClipboardTextFn != NULL)
             {
+                // SetClipboardText() only takes null terminated strings + state->TextSrc may point to read-only user buffer, so we need to make a copy.
                 const int ib = state->HasSelection() ? ImMin(state->Stb->select_start, state->Stb->select_end) : 0;
                 const int ie = state->HasSelection() ? ImMax(state->Stb->select_start, state->Stb->select_end) : state->TextLen;
-
-                char backup = state->TextA.Data[ie];
-                state->TextA.Data[ie] = 0; // A bit of a hack since SetClipboardText only takes null terminated strings
-                SetClipboardText(state->TextA.Data + ib);
-                state->TextA.Data[ie] = backup;
+                g.TempBuffer.reserve(ie - ib + 1);
+                memcpy(g.TempBuffer.Data, state->TextSrc, ie - ib);
+                g.TempBuffer.Data[ie] = 0;
+                SetClipboardText(g.TempBuffer.Data);
             }
             if (is_cut)
             {
@@ -5028,7 +5024,7 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
 
                     // FIXME-OPT: Undo stack reconcile needs a backup of the data until we rework API, see #7925
                     char* callback_buf = is_readonly ? buf : state->TextA.Data;
-
+                    IM_ASSERT(callback_buf == state->TextSrc);
                     state->CallbackTextBackup.resize(state->TextLen + 1);
                     memcpy(state->CallbackTextBackup.Data, callback_buf, state->TextLen + 1);
 
@@ -5066,9 +5062,9 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
             }
 
             // Will copy result string if modified
-            if (!is_readonly && strcmp(state->TextA.Data, buf) != 0)
+            if (!is_readonly && strcmp(state->TextSrc, buf) != 0)
             {
-                apply_new_text = state->TextA.Data;
+                apply_new_text = state->TextSrc;
                 apply_new_text_length = state->TextLen;
                 value_changed = true;
             }
@@ -5324,13 +5320,6 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
     if (is_password && !is_displaying_hint)
         PopFont();
 
-    if (readonly_swapped_text_data)
-    {
-        IM_ASSERT(state->TextA.Data == buf);
-        state->TextA.Size = 0;
-        state->TextA.Data = NULL;
-    }
-
     if (is_multiline)
     {
         // For focus requests to work on our multiline we need to ensure our child ItemAdd() call specifies the ImGuiItemFlags_Inputable (see #4761, #7870)...
@@ -5349,6 +5338,8 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
             g.LastItemData.StatusFlags = item_data_backup.StatusFlags;
         }
     }
+    if (state)
+        state->TextSrc = NULL;
 
     // Log as text
     if (g.LogEnabled && (!is_password || is_displaying_hint))