Tables: Made it possible to change style.CellPadding.y between rows. Added demo.

docs/CHANGELOG.txt

@@ -49,6 +49,7 @@ Other changes:
 
 - Tables: Made it possible to use SameLine(0,0) after TableNextColumn() or
   TableSetColumnIndex() in order to reuse line height from previous cell. (#3740)
+- Tables: Made it possible to change style.CellPadding.y between rows. (#3740)
 - Nav, TreeNode: Pressing Left with ImGuiTreeNodeFlags_NavLeftJumpsBackHere now goes
   through proper navigation logic: honor scrolling and selection. (#1079, #1131)
 - Sliders: Fixed an integer overflow and div-by-zero in SliderInt() when
@@ -78,7 +79,9 @@ Other changes:
 - Debug Tools: Metrics: Fixed "Drawlists" section and per-viewport equivalent
   appearing empty (regression in 1.89.8).
 - Demo: Reorganized "Examples" menu.
-- Demo: Demonstrate out-of-order rendering using ImDrawListSplitter.
+- Demo: Tables: Demonstrate using SameLine() between cells. (#3740)
+- Demo: Tables: Demonstrate altering CellPadding.y between rows. (#3740)
+- Demo: Custom Rendering: Demonstrate out-of-order rendering using ImDrawListSplitter.
 - Backends: SDL2,SDL3: added ImGui_ImplSDL2_InitForOther()/ImGui_ImplSDL3_InitForOther()
   for consistency (matching GLFW backend) and as most initialization paths don't actually
   need to care about rendering backend.

imgui.cpp

@@ -1166,7 +1166,7 @@ ImGuiStyle::ImGuiStyle()
     FrameBorderSize         = 0.0f;             // Thickness of border around frames. Generally set to 0.0f or 1.0f. Other values not well tested.
     ItemSpacing             = ImVec2(8,4);      // Horizontal and vertical spacing between widgets/lines
     ItemInnerSpacing        = ImVec2(4,4);      // Horizontal and vertical spacing between within elements of a composed widget (e.g. a slider and its label)
-    CellPadding             = ImVec2(4,2);      // Padding within a table cell
+    CellPadding             = ImVec2(4,2);      // Padding within a table cell. CellPadding.y may be altered between different rows.
     TouchExtraPadding       = ImVec2(0,0);      // Expand reactive bounding box for touch-based system where touch position is not accurate enough. Unfortunately we don't sort widgets so priority on overlap will always be given to the first widget. So don't grow this too much!
     IndentSpacing           = 21.0f;            // Horizontal spacing when e.g. entering a tree node. Generally == (FontSize + FramePadding.x*2).
     ColumnsMinSpacing       = 6.0f;             // Minimum horizontal spacing between two columns. Preferably > (FramePadding.x + 1).

imgui.h

@@ -1901,7 +1901,7 @@ struct ImGuiStyle
     float       FrameBorderSize;            // Thickness of border around frames. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly).
     ImVec2      ItemSpacing;                // Horizontal and vertical spacing between widgets/lines.
     ImVec2      ItemInnerSpacing;           // Horizontal and vertical spacing between within elements of a composed widget (e.g. a slider and its label).
-    ImVec2      CellPadding;                // Padding within a table cell
+    ImVec2      CellPadding;                // Padding within a table cell. CellPadding.y may be altered between different rows.
     ImVec2      TouchExtraPadding;          // Expand reactive bounding box for touch-based system where touch position is not accurate enough. Unfortunately we don't sort widgets so priority on overlap will always be given to the first widget. So don't grow this too much!
     float       IndentSpacing;              // Horizontal indentation when e.g. entering a tree node. Generally == (FontSize + FramePadding.x*2).
     float       ColumnsMinSpacing;          // Minimum horizontal spacing between two columns. Preferably > (FramePadding.x + 1).

imgui_demo.cpp

@@ -4790,7 +4790,7 @@ static void ShowDemoWindowTables()
         HelpMarker("You can pass a 'min_row_height' to TableNextRow().\n\nRows are padded with 'style.CellPadding.y' on top and bottom, so effectively the minimum row height will always be >= 'style.CellPadding.y * 2.0f'.\n\nWe cannot honor a _maximum_ row height as that would require a unique clipping rectangle per row.");
         if (ImGui::BeginTable("table_row_height", 1, ImGuiTableFlags_Borders))
         {
-            for (int row = 0; row < 10; row++)
+            for (int row = 0; row < 8; row++)
             {
                 float min_row_height = (float)(int)(TEXT_BASE_HEIGHT * 0.30f * row);
                 ImGui::TableNextRow(ImGuiTableRowFlags_None, min_row_height);
@@ -4821,6 +4821,23 @@ static void ShowDemoWindowTables()
             ImGui::EndTable();
         }
 
+        HelpMarker("Showcase altering CellPadding.y between rows. Note that CellPadding.x is locked for the entire table.");
+        if (ImGui::BeginTable("table_changing_cellpadding_y", 1, ImGuiTableFlags_Borders))
+        {
+            ImGuiStyle& style = ImGui::GetStyle();
+            for (int row = 0; row < 8; row++)
+            {
+                if ((row % 3) == 2)
+                    ImGui::PushStyleVar(ImGuiStyleVar_CellPadding, ImVec2(style.CellPadding.x, 20.0f));
+                ImGui::TableNextRow(ImGuiTableRowFlags_None);
+                ImGui::TableNextColumn();
+                ImGui::Text("CellPadding.y = %.2f", style.CellPadding.y);
+                if ((row % 3) == 2)
+                    ImGui::PopStyleVar();;
+            }
+            ImGui::EndTable();
+        }
+
         ImGui::TreePop();
     }
 

imgui_internal.h

@@ -2630,9 +2630,9 @@ struct IMGUI_API ImGuiTable
     float                       HostIndentX;
     float                       MinColumnWidth;
     float                       OuterPaddingX;
-    float                       CellPaddingX;               // Padding from each borders
-    float                       CellPaddingY;
-    float                       CellSpacingX1;              // Spacing between non-bordered cells
+    float                       CellPaddingX;               // Padding from each borders. Locked in BeginTable()/Layout.
+    float                       CellPaddingY;               // Top and bottom padding. Reloaded during row change.
+    float                       CellSpacingX1;              // Spacing between non-bordered cells. Locked in BeginTable()/Layout.
     float                       CellSpacingX2;
     float                       InnerWidth;                 // User value passed to BeginTable(), see comments at the top of BeginTable() for details.
     float                       ColumnsGivenWidth;          // Sum of current column width

imgui_tables.cpp

@@ -1750,6 +1750,7 @@ void ImGui::TableNextRow(ImGuiTableRowFlags row_flags, float row_min_height)
 
     // We honor min_row_height requested by user, but cannot guarantee per-row maximum height,
     // because that would essentially require a unique clipping rectangle per-cell.
+    table->CellPaddingY = g.Style.CellPadding.y;
     table->RowPosY2 += table->CellPaddingY * 2.0f;
     table->RowPosY2 = ImMax(table->RowPosY2, table->RowPosY1 + row_min_height);