Tables: TableSetupColumn() user id uses ImGuiID as intended (typedef ImU32). internals: added GetCurrentTable(), LeftMostEnabledColumn. Demo/docs tweaks.

docs/BACKENDS.md

@@ -9,13 +9,13 @@ your application or engine to easily integrate Dear ImGui.** Each backend is typ
   e.g. Windows ([imgui_impl_win32.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_win32.cpp)), GLFW ([imgui_impl_glfw.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_glfw.cpp)), SDL2 ([imgui_impl_sdl.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_sdl.cpp)), etc.
 
 - The 'Renderer' backends are in charge of: creating atlas texture, rendering imgui draw data.<BR>
-  e.g. DirectX11 ([imgui_impl_dx11.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_dx11.cpp)), OpenGL/WebGL ([imgui_impl_opengl3.cpp]((https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_opengl3.cpp)), Vulkan ([imgui_impl_vulkan.cpp]((https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_vulkan.cpp)), etc.
+  e.g. DirectX11 ([imgui_impl_dx11.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_dx11.cpp)), OpenGL/WebGL ([imgui_impl_opengl3.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_opengl3.cpp), Vulkan ([imgui_impl_vulkan.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_vulkan.cpp), etc.
 
 - For some high-level frameworks, a single backend usually handle both 'Platform' and 'Renderer' parts.<BR>
   e.g. Allegro 5 ([imgui_impl_allegro5.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_allegro5.cpp)), Marmalade ([imgui_impl_marmalade.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_marmalade.cpp)). If you end up creating a custom backend for your engine, you may want to do the same.
 
 An application usually combines 1 Platform backend + 1 Renderer backend + main Dear ImGui sources.
-For example, the [example_win32_directx11](https://github.com/ocornut/imgui/tree/master/examples/example_win32_directx11) application combines imgui_impl_win32.cpp + imgui_impl_dx11.cpp. See [EXAMPLES.MD](https://github.com/ocornut/imgui/blob/master/docs/EXAMPLES.md) for details.
+For example, the [example_win32_directx11](https://github.com/ocornut/imgui/tree/master/examples/example_win32_directx11) application combines imgui_impl_win32.cpp + imgui_impl_dx11.cpp. There are 20+ examples in the [examples/](https://github.com/ocornut/imgui/blob/master/examples/) folder. See [EXAMPLES.MD](https://github.com/ocornut/imgui/blob/master/docs/EXAMPLES.md) for details.
 
 
 ### What are backends
@@ -36,7 +36,7 @@ Dear ImGui is highly portable and only requires a few things to run and render,
  - Optional: multi-viewports support.
  etc.
 
-This is essentially what each backends are doing + obligatory portability cruft.
+This is essentially what each backends are doing + obligatory portability cruft. Using default backends ensure you can get all those features including the ones that would be harder to implement on your side (e.g. multi-viewports support).
 
 It is important to understand the difference between the core Dear ImGui library (files in the root folder)
 and backends which we are describing here (backends/ folder).
@@ -46,6 +46,11 @@ and backends which we are describing here (backends/ folder).
   e.g. you can get creative and use software rendering or render remotely on a different machine.
 
 
+### Integrating a backend
+
+See "Getting Started" section of [EXAMPLES.MD](https://github.com/ocornut/imgui/blob/master/docs/EXAMPLES.md) for more details.
+
+
 ### List of backends
 
 In the [backends/](https://github.com/ocornut/imgui/blob/master/backends) folder:

imgui.h

@@ -701,7 +701,7 @@ namespace ImGui
     // - You may manually submit headers using TableNextRow() + TableHeader() calls, but this is only useful in
     //   some advanced use cases (e.g. adding custom widgets in header row).
     // - Use TableSetupScrollFreeze() to lock columns/rows so they stay visible when scrolled.
-    IMGUI_API void          TableSetupColumn(const char* label, ImGuiTableColumnFlags flags = 0, float init_width_or_weight = 0.0f, ImU32 user_id = 0);
+    IMGUI_API void          TableSetupColumn(const char* label, ImGuiTableColumnFlags flags = 0, float init_width_or_weight = 0.0f, ImGuiID user_id = 0);
     IMGUI_API void          TableSetupScrollFreeze(int cols, int rows); // lock columns/rows so they stay visible when scrolled.
     IMGUI_API void          TableHeadersRow();                          // submit all headers cells based on data provided to TableSetupColumn() + submit context menu
     IMGUI_API void          TableHeader(const char* label);             // submit one header cell manually (rarely used)
@@ -711,7 +711,7 @@ namespace ImGui
     //   since last call, or the first time. Make sure to set 'SpecsDirty = false' after sorting, else you may
     //   wastefully sort your data every frame!
     // - Lifetime: don't hold on this pointer over multiple frames or past any subsequent call to BeginTable().
-    IMGUI_API ImGuiTableSortSpecs* TableGetSortSpecs();                        // get latest sort specs for the table (NULL if not sorting).
+    IMGUI_API ImGuiTableSortSpecs*  TableGetSortSpecs();                        // get latest sort specs for the table (NULL if not sorting).
     // Tables: Miscellaneous functions
     // - Functions args 'int column_n' treat the default value of -1 as the same as passing the current column index.
     IMGUI_API int                   TableGetColumnCount();                      // return number of columns (value passed to BeginTable)

imgui_demo.cpp

@@ -4856,6 +4856,9 @@ static void ShowDemoWindowTables()
         ImGui::TreePop();
     }
 
+    // In this example we'll expose most table flags and settings.
+    // For specific flags and settings refer to the corresponding section for more detailed explanation.
+    // This section is mostly useful to experiment with combining certain flags or settings with each others.
     //ImGui::SetNextItemOpen(true, ImGuiCond_Once); // [DEBUG]
     if (open_action != -1)
         ImGui::SetNextItemOpen(open_action != 0);
@@ -4994,7 +4997,7 @@ static void ShowDemoWindowTables()
             ImGui::TreePop();
         }
 
-        // Recreate/reset item list if we changed the number of items
+        // Update item list if we changed the number of items
         static ImVector<MyItem> items;
         static ImVector<int> selection;
         static bool items_need_sort = false;
@@ -5016,6 +5019,7 @@ static void ShowDemoWindowTables()
         ImVec2 table_scroll_cur, table_scroll_max; // For debug display
         const ImDrawList* table_draw_list = NULL;  // "
 
+        // Submit table
         const float inner_width_to_use = (flags & ImGuiTableFlags_ScrollX) ? inner_width_with_scroll : 0.0f;
         if (ImGui::BeginTable("table_advanced", 6, flags, outer_size_enabled ? outer_size_value : ImVec2(0, 0), inner_width_to_use))
         {
@@ -5074,9 +5078,9 @@ static void ShowDemoWindowTables()
                     const bool item_is_selected = selection.contains(item->ID);
                     ImGui::PushID(item->ID);
                     ImGui::TableNextRow(ImGuiTableRowFlags_None, row_min_height);
-                    ImGui::TableNextColumn();
 
                     // For the demo purpose we can select among different type of items submitted in the first column
+                    ImGui::TableSetColumnIndex(0);
                     char label[32];
                     sprintf(label, "%04d", item->ID);
                     if (contents_type == CT_Text)
@@ -5107,14 +5111,14 @@ static void ShowDemoWindowTables()
                         }
                     }
 
-                    if (ImGui::TableNextColumn())
+                    if (ImGui::TableSetColumnIndex(1))
                         ImGui::TextUnformatted(item->Name);
 
                     // Here we demonstrate marking our data set as needing to be sorted again if we modified a quantity,
                     // and we are currently sorting on the column showing the Quantity.
                     // To avoid triggering a sort while holding the button, we only trigger it when the button has been released.
                     // You will probably need a more advanced system in your code if you want to automatically sort when a specific entry changes.
-                    if (ImGui::TableNextColumn())
+                    if (ImGui::TableSetColumnIndex(2))
                     {
                         if (ImGui::SmallButton("Chop")) { item->Quantity += 1; }
                         if (sorts_specs_using_quantity && ImGui::IsItemDeactivated()) { items_need_sort = true; }
@@ -5123,16 +5127,16 @@ static void ShowDemoWindowTables()
                         if (sorts_specs_using_quantity && ImGui::IsItemDeactivated()) { items_need_sort = true; }
                     }
 
-                    if (ImGui::TableNextColumn())
+                    if (ImGui::TableSetColumnIndex(3))
                         ImGui::Text("%d", item->Quantity);
 
-                    ImGui::TableNextColumn();
+                    ImGui::TableSetColumnIndex(4);
                     if (show_wrapped_text)
                         ImGui::TextWrapped("Lorem ipsum dolor sit amet");
                     else
                         ImGui::Text("Lorem ipsum dolor sit amet");
 
-                    if (ImGui::TableNextColumn())
+                    if (ImGui::TableSetColumnIndex(5))
                         ImGui::Text("1234");
 
                     ImGui::PopID();

imgui_internal.h

@@ -2091,9 +2091,10 @@ struct ImGuiTable
     ImGuiTableColumnIdx         HeldHeaderColumn;           // Index of column header being held.
     ImGuiTableColumnIdx         ReorderColumn;              // Index of column being reordered. (not cleared)
     ImGuiTableColumnIdx         ReorderColumnDir;           // -1 or +1
+    ImGuiTableColumnIdx         LeftMostEnabledColumn;      // Index of left-most non-hidden column.
+    ImGuiTableColumnIdx         RightMostEnabledColumn;     // Index of right-most non-hidden column.
     ImGuiTableColumnIdx         LeftMostStretchedColumn;    // Index of left-most stretched column.
     ImGuiTableColumnIdx         RightMostStretchedColumn;   // Index of right-most stretched column.
-    ImGuiTableColumnIdx         RightMostEnabledColumn;     // Index of right-most non-hidden column.
     ImGuiTableColumnIdx         ContextPopupColumn;         // Column right-clicked on, of -1 if opening context menu from a neutral/empty spot
     ImGuiTableColumnIdx         FreezeRowsRequest;          // Requested frozen rows count
     ImGuiTableColumnIdx         FreezeRowsCount;            // Actual frozen row count (== FreezeRowsRequest, or == 0 when no scrolling offset)
@@ -2349,6 +2350,7 @@ namespace ImGui
     IMGUI_API void          TablePopBackgroundChannel();
 
     // Tables: Internals
+    inline    ImGuiTable*   GetCurrentTable() { ImGuiContext& g = *GImGui; return g.CurrentTable; }
     IMGUI_API ImGuiTable*   TableFindByID(ImGuiID id);
     IMGUI_API bool          BeginTableEx(const char* name, ImGuiID id, int columns_count, ImGuiTableFlags flags = 0, const ImVec2& outer_size = ImVec2(0, 0), float inner_width = 0.0f);
     IMGUI_API void          TableBeginInitMemory(ImGuiTable* table, int columns_count);

imgui_tables.cpp

@@ -687,13 +687,14 @@ void ImGui::TableUpdateLayout(ImGuiTable* table)
     table->ColumnsEnabledCount = 0;
     table->EnabledMaskByIndex = 0x00;
     table->EnabledMaskByDisplayOrder = 0x00;
+    table->LeftMostEnabledColumn = -1;
     table->MinColumnWidth = ImMax(1.0f, g.Style.FramePadding.x * 1.0f); // g.Style.ColumnsMinSpacing; // FIXME-TABLE
 
     // [Part 1] Apply/lock Enabled and Order states. Calculate auto/ideal width for columns. Count fixed/stretch columns.
     // Process columns in their visible orders as we are building the Prev/Next indices.
     int count_fixed = 0;                // Number of columns that have fixed sizing policies
     int count_stretch = 0;              // Number of columns that have stretch sizing policies
-    int last_visible_column_idx = -1;
+    int prev_visible_column_idx = -1;
     bool has_auto_fit_request = false;
     bool has_resizable = false;
     float stretch_sum_width_auto = 0.0f;
@@ -741,14 +742,16 @@ void ImGui::TableUpdateLayout(ImGuiTable* table)
         }
 
         // Mark as enabled and link to previous/next enabled column
-        column->PrevEnabledColumn = (ImGuiTableColumnIdx)last_visible_column_idx;
+        column->PrevEnabledColumn = (ImGuiTableColumnIdx)prev_visible_column_idx;
         column->NextEnabledColumn = -1;
-        if (last_visible_column_idx != -1)
-            table->Columns[last_visible_column_idx].NextEnabledColumn = (ImGuiTableColumnIdx)column_n;
+        if (prev_visible_column_idx != -1)
+            table->Columns[prev_visible_column_idx].NextEnabledColumn = (ImGuiTableColumnIdx)column_n;
+        else
+            table->LeftMostEnabledColumn = (ImGuiTableColumnIdx)column_n;
         column->IndexWithinEnabledSet = table->ColumnsEnabledCount++;
         table->EnabledMaskByIndex |= (ImU64)1 << column_n;
         table->EnabledMaskByDisplayOrder |= (ImU64)1 << column->DisplayOrder;
-        last_visible_column_idx = column_n;
+        prev_visible_column_idx = column_n;
         IM_ASSERT(column->IndexWithinEnabledSet <= column->DisplayOrder);
 
         // Calculate ideal/auto column width (that's the width required for all contents to be visible without clipping)
@@ -778,8 +781,8 @@ void ImGui::TableUpdateLayout(ImGuiTable* table)
     }
     if ((table->Flags & ImGuiTableFlags_Sortable) && table->SortSpecsCount == 0 && !(table->Flags & ImGuiTableFlags_SortTristate))
         table->IsSortSpecsDirty = true;
-    table->RightMostEnabledColumn = (ImGuiTableColumnIdx)last_visible_column_idx;
-    IM_ASSERT(table->RightMostEnabledColumn >= 0);
+    table->RightMostEnabledColumn = (ImGuiTableColumnIdx)prev_visible_column_idx;
+    IM_ASSERT(table->LeftMostEnabledColumn >= 0 && table->RightMostEnabledColumn >= 0);
 
     // [Part 2] Disable child window clipping while fitting columns. This is not strictly necessary but makes it possible
     // to avoid the column fitting having to wait until the first visible frame of the child container (may or not be a good thing).