Tables: Solved an ID conflict issue with multiple-instances of a same table. Storing instance id for convenience. (#6140)

TableGetColumnResizeID() are still using an incorrect table, but having only one-level left tends to cancel things out.

docs/CHANGELOG.txt

@@ -59,6 +59,8 @@ All changes:
 - Tables: Raised max Columns count from 64 to 512. (#6094, #5305, #4876, #3572)
   The previous limit was due to using 64-bit integers but we moved to bits-array
   and tweaked the system enough to ensure no performance loss.
+- Tables: Solved an ID conflict issue with multiple-instances of a same table,
+  due to how unique table instance id was generated. (#6140) [@ocornut, @rodrigorc]
 - Text: Fixed layouting of wrapped-text block skipping successive empty lines,
   regression from the fix in 1.89.2. (#5720, #5919)
 - Text: Fixed clipping of single-character "..." ellipsis (U+2026 or U+0085) when font

imgui.h

@@ -23,7 +23,7 @@
 // Library Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals, e.g. '#if IMGUI_VERSION_NUM > 12345')
 #define IMGUI_VERSION               "1.89.3 WIP"
-#define IMGUI_VERSION_NUM           18926
+#define IMGUI_VERSION_NUM           18927
 #define IMGUI_HAS_TABLE
 
 /*

imgui_internal.h

@@ -2509,14 +2509,15 @@ struct ImGuiTableCellData
     ImGuiTableColumnIdx         Column;     // Column number
 };
 
-// Per-instance data that needs preserving across frames (seemingly most others do not need to be preserved aside from debug needs, does that needs they could be moved to ImGuiTableTempData ?)
+// Per-instance data that needs preserving across frames (seemingly most others do not need to be preserved aside from debug needs. Does that means they could be moved to ImGuiTableTempData?)
 struct ImGuiTableInstanceData
 {
+    ImGuiID                     TableInstanceID;
     float                       LastOuterHeight;            // Outer height from last frame
     float                       LastFirstRowHeight;         // Height of first row from last frame (FIXME: this is used as "header height" and may be reworked)
     float                       LastFrozenHeight;           // Height of frozen section from last frame
 
-    ImGuiTableInstanceData()    { LastOuterHeight = LastFirstRowHeight = LastFrozenHeight = 0.0f; }
+    ImGuiTableInstanceData()    { TableInstanceID = 0; LastOuterHeight = LastFirstRowHeight = LastFrozenHeight = 0.0f; }
 };
 
 // FIXME-TABLE: more transient data could be stored in a stacked ImGuiTableTempData: e.g. SortSpecs, incoming RowData
@@ -2996,7 +2997,8 @@ namespace ImGui
     IMGUI_API void          TableDrawContextMenu(ImGuiTable* table);
     IMGUI_API bool          TableBeginContextMenuPopup(ImGuiTable* table);
     IMGUI_API void          TableMergeDrawChannels(ImGuiTable* table);
-    inline ImGuiTableInstanceData*   TableGetInstanceData(ImGuiTable* table, int instance_no) { if (instance_no == 0) return &table->InstanceDataFirst; return &table->InstanceDataExtra[instance_no - 1]; }
+    inline ImGuiTableInstanceData*  TableGetInstanceData(ImGuiTable* table, int instance_no) { if (instance_no == 0) return &table->InstanceDataFirst; return &table->InstanceDataExtra[instance_no - 1]; }
+    inline ImGuiID                  TableGetInstanceID(ImGuiTable* table, int instance_no)   { return TableGetInstanceData(table, instance_no)->TableInstanceID; }
     IMGUI_API void          TableSortSpecsSanitize(ImGuiTable* table);
     IMGUI_API void          TableSortSpecsBuild(ImGuiTable* table);
     IMGUI_API ImGuiSortDirection TableGetColumnNextSortDirection(ImGuiTableColumn* column);
@@ -3008,7 +3010,7 @@ namespace ImGui
     IMGUI_API void          TableEndCell(ImGuiTable* table);
     IMGUI_API ImRect        TableGetCellBgRect(const ImGuiTable* table, int column_n);
     IMGUI_API const char*   TableGetColumnName(const ImGuiTable* table, int column_n);
-    IMGUI_API ImGuiID       TableGetColumnResizeID(const ImGuiTable* table, int column_n, int instance_no = 0);
+    IMGUI_API ImGuiID       TableGetColumnResizeID(ImGuiTable* table, int column_n, int instance_no = 0);
     IMGUI_API float         TableGetMaxColumnWidth(const ImGuiTable* table, int column_n);
     IMGUI_API void          TableSetColumnWidthAutoSingle(ImGuiTable* table, int column_n);
     IMGUI_API void          TableSetColumnWidthAutoAll(ImGuiTable* table);

imgui_tables.cpp

@@ -332,11 +332,7 @@ bool    ImGui::BeginTableEx(const char* name, ImGuiID id, int columns_count, ImG
 
     // Acquire storage for the table
     ImGuiTable* table = g.Tables.GetOrAddByKey(id);
-    const int instance_no = (table->LastFrameActive != g.FrameCount) ? 0 : table->InstanceCurrent + 1;
-    const ImGuiID instance_id = id + instance_no;
     const ImGuiTableFlags table_last_flags = table->Flags;
-    if (instance_no > 0)
-        IM_ASSERT(table->ColumnsCount == columns_count && "BeginTable(): Cannot change columns count mid-frame while preserving same ID");
 
     // Acquire temporary buffers
     const int table_idx = g.Tables.GetIndex(table);
@@ -352,17 +348,34 @@ bool    ImGui::BeginTableEx(const char* name, ImGuiID id, int columns_count, ImG
     flags = TableFixFlags(flags, outer_window);
 
     // Initialize
+    const int instance_no = (table->LastFrameActive != g.FrameCount) ? 0 : table->InstanceCurrent + 1;
     table->ID = id;
     table->Flags = flags;
-    table->InstanceCurrent = (ImS16)instance_no;
     table->LastFrameActive = g.FrameCount;
     table->OuterWindow = table->InnerWindow = outer_window;
     table->ColumnsCount = columns_count;
     table->IsLayoutLocked = false;
     table->InnerWidth = inner_width;
     temp_data->UserOuterSize = outer_size;
-    if (instance_no > 0 && table->InstanceDataExtra.Size < instance_no)
-        table->InstanceDataExtra.push_back(ImGuiTableInstanceData());
+
+    // Instance data (for instance 0, TableID == TableInstanceID)
+    ImGuiID instance_id;
+    table->InstanceCurrent = (ImS16)instance_no;
+    if (instance_no > 0)
+    {
+        IM_ASSERT(table->ColumnsCount == columns_count && "BeginTable(): Cannot change columns count mid-frame while preserving same ID");
+        if (table->InstanceDataExtra.Size < instance_no)
+            table->InstanceDataExtra.push_back(ImGuiTableInstanceData());
+        char instance_desc[12];
+        int instance_desc_len = ImFormatString(instance_desc, IM_ARRAYSIZE(instance_desc), "##Instance%d", instance_no);
+        instance_id = GetIDWithSeed(instance_desc, instance_desc + instance_desc_len, id);
+    }
+    else
+    {
+        instance_id = id;
+    }
+    ImGuiTableInstanceData* table_instance = TableGetInstanceData(table, table->InstanceCurrent);
+    table_instance->TableInstanceID = instance_id;
 
     // When not using a child window, WorkRect.Max will grow as we append contents.
     if (use_child_window)
@@ -412,7 +425,9 @@ bool    ImGui::BeginTableEx(const char* name, ImGuiID id, int columns_count, ImG
     }
 
     // Push a standardized ID for both child-using and not-child-using tables
-    PushOverrideID(instance_id);
+    PushOverrideID(id);
+    if (instance_no > 0)
+        PushOverrideID(instance_id); // FIXME: Somehow this is not resolved by stack-tool, even tho GetIDWithSeed() submitted the symbol.
 
     // Backup a copy of host window members we will modify
     ImGuiWindow* inner_window = table->InnerWindow;
@@ -1348,8 +1363,10 @@ void    ImGui::EndTable()
     }
 
     // Pop from id stack
-    IM_ASSERT_USER_ERROR(inner_window->IDStack.back() == table->ID + table->InstanceCurrent, "Mismatching PushID/PopID!");
+    IM_ASSERT_USER_ERROR(inner_window->IDStack.back() == table_instance->TableInstanceID, "Mismatching PushID/PopID!");
     IM_ASSERT_USER_ERROR(outer_window->DC.ItemWidthStack.Size >= temp_data->HostBackupItemWidthStackSize, "Too many PopItemWidth!");
+    if (table->InstanceCurrent > 0)
+        PopID();
     PopID();
 
     // Restore window data that we modified
@@ -1619,11 +1636,11 @@ ImRect ImGui::TableGetCellBgRect(const ImGuiTable* table, int column_n)
 }
 
 // Return the resizing ID for the right-side of the given column.
-ImGuiID ImGui::TableGetColumnResizeID(const ImGuiTable* table, int column_n, int instance_no)
+ImGuiID ImGui::TableGetColumnResizeID(ImGuiTable* table, int column_n, int instance_no)
 {
     IM_ASSERT(column_n >= 0 && column_n < table->ColumnsCount);
-    ImGuiID id = table->ID + 1 + (instance_no * table->ColumnsCount) + column_n;
-    return id;
+    ImGuiID instance_id = TableGetInstanceID(table, instance_no);
+    return instance_id + 1 + column_n; // FIXME: #6140: still not ideal
 }
 
 // Return -1 when table is not hovered. return columns_count if the unused space at the right of visible columns is hovered.
@@ -2878,10 +2895,9 @@ void ImGui::TableHeadersRow()
             continue;
 
         // Push an id to allow unnamed labels (generally accidental, but let's behave nicely with them)
-        // - in your own code you may omit the PushID/PopID all-together, provided you know they won't collide
-        // - table->InstanceCurrent is only >0 when we use multiple BeginTable/EndTable calls with same identifier.
+        // In your own code you may omit the PushID/PopID all-together, provided you know they won't collide.
         const char* name = (TableGetColumnFlags(column_n) & ImGuiTableColumnFlags_NoHeaderLabel) ? "" : TableGetColumnName(column_n);
-        PushID(table->InstanceCurrent * table->ColumnsCount + column_n);
+        PushID(column_n);
         TableHeader(name);
         PopID();
     }