InputText: Internal: added reload from user-buf feature. (#2890)

Very highly requested feature (#6962, #5219, #3290, #4627, #5054, #3878, #2881, #1506, #1216, #968).
Also useful for interactive completion/selection popups (#2057, #718)
Based on @kudaba PR. Design for Inputtext V2 should make this obsolete.

docs/CHANGELOG.txt

@@ -68,8 +68,10 @@ Other changes:
   update stopped setting default values. (#7232) [@GrigoryGraborenko]
 - Backends: WebGPU: Fixed pipeline layout leak. (#7245) [@rajveermalviya]
 - Backends: OpenGL3: Backup and restore GL_PIXEL_UNPACK_BUFFER. (#7253)
-- Internals: Various improvements related to yet unpublicized shortcut routing and input ownership
-  systems.
+- Internals: Many improvements related to yet unpublicized shortcut routing and input ownership systems.
+- Internals: InputText: Add way to force reload of user-buf when active. (#2890) [@kudaba, @ocornut]
+  Often requested in some form (#6962, #5219, #3290, #4627, #5054, #3878, #2881, #1506, #1216, #968),
+  and useful for interactive completion/suggestions popups (#2057, #718)
 
 
 -----------------------------------------------------------------------

imgui.cpp

@@ -12257,6 +12257,8 @@ void ImGui::NavMoveRequestApplyResult()
         g.NavWindow = result->Window;
         g.NavLastValidSelectionUserData = ImGuiSelectionUserData_Invalid;
     }
+
+    // FIXME: Could become optional e.g. ImGuiNavMoveFlags_NoClearActiveId if we later want to apply navigation requests without altering active input.
     if (g.ActiveId != result->ID)
         ClearActiveID();
 

imgui.h

@@ -24,7 +24,7 @@
 // Library Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals, e.g. '#if IMGUI_VERSION_NUM >= 12345')
 #define IMGUI_VERSION       "1.90.2 WIP"
-#define IMGUI_VERSION_NUM   19016
+#define IMGUI_VERSION_NUM   19017
 #define IMGUI_HAS_TABLE
 
 /*

imgui_internal.h

@@ -1079,6 +1079,9 @@ struct IMGUI_API ImGuiInputTextState
     bool                    SelectedAllMouseLock;   // after a double-click to select all, we ignore further mouse drags to update selection
     bool                    Edited;                 // edited this frame
     ImGuiInputTextFlags     Flags;                  // copy of InputText() flags. may be used to check if e.g. ImGuiInputTextFlags_Password is set.
+    bool                    ReloadUserBuf;          // force a reload of user buf so it may be modified externally. may be automatic in future version.
+    int                     ReloadSelectionStart;   // POSITIONS ARE IN IMWCHAR units *NOT* UTF-8 this is why this is not exposed yet.
+    int                     ReloadSelectionEnd;
 
     ImGuiInputTextState()                   { memset(this, 0, sizeof(*this)); }
     void        ClearText()                 { CurLenW = CurLenA = 0; TextW[0] = 0; TextA[0] = 0; CursorClamp(); }
@@ -1096,6 +1099,16 @@ struct IMGUI_API ImGuiInputTextState
     int         GetSelectionStart() const   { return Stb.select_start; }
     int         GetSelectionEnd() const     { return Stb.select_end; }
     void        SelectAll()                 { Stb.select_start = 0; Stb.cursor = Stb.select_end = CurLenW; Stb.has_preferred_x = 0; }
+
+    // Reload user buf (WIP #2890)
+    // If you modify underlying user-passed const char* while active you need to call this (InputText V2 may lift this)
+    //   strcpy(my_buf, "hello");
+    //   if (ImGuiInputTextState* state = ImGui::GetInputTextState(id)) // id may be ImGui::GetItemID() is last item
+    //       state->ReloadUserBufAndSelectAll();
+    void        ReloadUserBufAndSelectAll()     { ReloadUserBuf = true; ReloadSelectionStart = 0; ReloadSelectionEnd = INT_MAX; }
+    void        ReloadUserBufAndKeepSelection() { ReloadUserBuf = true; ReloadSelectionStart = Stb.select_start; ReloadSelectionEnd = Stb.select_end; }
+    void        ReloadUserBufAndMoveToEnd()     { ReloadUserBuf = true; ReloadSelectionStart = ReloadSelectionEnd = INT_MAX; }
+
 };
 
 enum ImGuiNextWindowDataFlags_

imgui_widgets.cpp

@@ -4185,14 +4185,16 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
 
     float scroll_y = is_multiline ? draw_window->Scroll.y : FLT_MAX;
 
+    const bool init_reload_from_user_buf = (state != NULL && state->ReloadUserBuf);
     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);
-    if ((init_state && g.ActiveId != id) || init_changed_specs)
+    if ((init_state && g.ActiveId != id) || init_changed_specs || init_reload_from_user_buf)
     {
         // Access state even if we don't own it yet.
         state = &g.InputTextState;
         state->CursorAnimReset();
+        state->ReloadUserBuf = false;
 
         // Backup state of deactivating item so they'll have a chance to do a write to output buffer on the same frame they report IsItemDeactivatedAfterEdit (#4714)
         InputTextDeactivateHook(state->ID);
@@ -4204,8 +4206,8 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
         memcpy(state->InitialTextA.Data, buf, buf_len + 1);
 
         // Preserve cursor position and undo/redo stack if we come back to same widget
-        // FIXME: Since we reworked this on 2022/06, may want to differenciate recycle_cursor vs recycle_undostate?
-        bool recycle_state = (state->ID == id && !init_changed_specs);
+        // FIXME: Since we reworked this on 2022/06, may want to differentiate recycle_cursor vs recycle_undostate?
+        bool recycle_state = (state->ID == id && !init_changed_specs && !init_reload_from_user_buf);
         if (recycle_state && (state->CurLenA != buf_len || (state->TextAIsValid && strncmp(state->TextA.Data, buf, buf_len) != 0)))
             recycle_state = false;
 
@@ -4230,7 +4232,13 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
             stb_textedit_initialize_state(&state->Stb, !is_multiline);
         }
 
-        if (!is_multiline)
+        if (init_reload_from_user_buf)
+        {
+            state->Stb.select_start = state->ReloadSelectionStart;
+            state->Stb.cursor = state->Stb.select_end = state->ReloadSelectionEnd;
+            state->CursorClamp();
+        }
+        else if (!is_multiline)
         {
             if (flags & ImGuiInputTextFlags_AutoSelectAll)
                 select_all = true;