Tables: setup and maintain ItemWidth per column.

Author: ocornut

imgui.h

@@ -1092,7 +1092,6 @@ enum ImGuiTableFlags_
 };
 
 // Flags for ImGui::TableSetupColumn()
-// FIXME-TABLE: Rename to ImGuiColumns_*, stick old columns api flags in there under an obsolete api block
 enum ImGuiTableColumnFlags_
 {
     ImGuiTableColumnFlags_None                      = 0,

imgui_demo.cpp

@@ -4021,47 +4021,87 @@ static void ShowDemoWindowTables()
         ImVec2 outer_size(0, TEXT_BASE_HEIGHT * 7);
         if (ImGui::BeginTable("##nways", column_count, flags, outer_size))
         {
-            for (int row = 0; row < 10; row++)
+            for (int cell = 0; cell < 10 * column_count; cell++)
+            {
+                ImGui::TableNextColumn();
+                int column = ImGui::TableGetColumnIndex();
+                int row = ImGui::TableGetRowIndex();
+
+                ImGui::PushID(cell);
+                char label[32];
+                static char text_buf[32] = "";
+                sprintf(label, "Hello %d,%d", column, row);
+                switch (contents_type)
+                {
+                case CT_ShortText:  ImGui::TextUnformatted(label); break;
+                case CT_LongText:   ImGui::Text("Some longer text %d,%d\nOver two lines..", column, row); break;
+                case CT_Button:     ImGui::Button(label); break;
+                case CT_FillButton: ImGui::Button(label, ImVec2(-FLT_MIN, 0.0f)); break;
+                case CT_InputText:  ImGui::SetNextItemWidth(-FLT_MIN); ImGui::InputText("##", text_buf, IM_ARRAYSIZE(text_buf)); break;
+                }
+                ImGui::PopID();
+            }
+            ImGui::EndTable();
+        }
+
+        ImGui::TextUnformatted("Item Widths");
+        ImGui::SameLine();
+        HelpMarker("Showcase using PushItemWidth() and how it is preserved on a per-column basis");
+        if (ImGui::BeginTable("##table2", 3, ImGuiTableFlags_Borders))
+        {
+            ImGui::TableSetupColumn("small");
+            ImGui::TableSetupColumn("half");
+            ImGui::TableSetupColumn("right-align");
+            ImGui::TableHeadersRow();
+
+            for (int row = 0; row < 3; row++)
             {
                 ImGui::TableNextRow();
-                for (int column = 0; column < column_count; column++)
+                if (row == 0)
                 {
-                    ImGui::TableSetColumnIndex(column);
-                    char label[32];
-                    static char text_buf[32] = "";
-                    sprintf(label, "Hello %d,%d", column, row);
-                    switch (contents_type)
-                    {
-                    case CT_ShortText:  ImGui::TextUnformatted(label); break;
-                    case CT_LongText:   ImGui::Text("Some longer text %d,%d\nOver two lines..", column, row); break;
-                    case CT_Button:     ImGui::Button(label); break;
-                    case CT_FillButton: ImGui::Button(label, ImVec2(-FLT_MIN, 0.0f)); break;
-                    case CT_InputText:  ImGui::SetNextItemWidth(-FLT_MIN); ImGui::InputText("##", text_buf, IM_ARRAYSIZE(text_buf)); break;
-                    }
+                    // Setup ItemWidth once (instead of setting up every time, which is also possible but less efficient)
+                    ImGui::TableSetColumnIndex(0);
+                    ImGui::PushItemWidth(TEXT_BASE_WIDTH * 3.0f); // Small
+                    ImGui::TableSetColumnIndex(1);
+                    ImGui::PushItemWidth(-ImGui::GetContentRegionAvail().x * 0.5f);
+                    ImGui::TableSetColumnIndex(2);
+                    ImGui::PushItemWidth(-FLT_MIN); // Right-aligned
                 }
+
+                // Draw our contents
+                static float dummy_f = 0.0f;
+                ImGui::PushID(row);
+                ImGui::TableSetColumnIndex(0);
+                ImGui::SliderFloat("float0", &dummy_f, 0.0f, 1.0f);
+                ImGui::TableSetColumnIndex(1);
+                ImGui::SliderFloat("float1", &dummy_f, 0.0f, 1.0f);
+                ImGui::TableSetColumnIndex(2);
+                ImGui::SliderFloat("float2", &dummy_f, 0.0f, 1.0f);
+                ImGui::PopID();
             }
             ImGui::EndTable();
         }
 
+        ImGui::TextUnformatted("Stretch + ScrollX");
+        ImGui::SameLine();
         HelpMarker(
             "Showcase using Stretch columns + ScrollX together: "
             "this is rather unusual and only makes sense when specifying an 'inner_width' for the table!\n"
             "Without an explicit value, inner_width is == outer_size.x and therefore using Stretch columns + ScrollX together doesn't make sense.");
-        static ImGuiTableFlags flags2 = ImGuiTableFlags_ColumnsWidthStretch | ImGuiTableFlags_ScrollX | ImGuiTableFlags_ScrollY | ImGuiTableFlags_BordersOuter | ImGuiTableFlags_RowBg;
+        static ImGuiTableFlags flags3 = ImGuiTableFlags_ColumnsWidthStretch | ImGuiTableFlags_ScrollX | ImGuiTableFlags_ScrollY | ImGuiTableFlags_BordersOuter | ImGuiTableFlags_RowBg;
         static float inner_width = 1000.0f;
         PushStyleCompact();
-        ImGui::PushID("flags2");
-        ImGui::CheckboxFlags("ImGuiTableFlags_ScrollX", &flags2, ImGuiTableFlags_ScrollX);
-        if (ImGui::CheckboxFlags("ImGuiTableFlags_ColumnsWidthStretch", &flags2, ImGuiTableFlags_ColumnsWidthStretch))
-            flags2 &= ~ImGuiTableFlags_ColumnsWidthFixed;      // Can't specify both sizing polices so we clear the other
-        if (ImGui::CheckboxFlags("ImGuiTableFlags_ColumnsWidthFixed", &flags2, ImGuiTableFlags_ColumnsWidthFixed))
-            flags2 &= ~ImGuiTableFlags_ColumnsWidthStretch;    // Can't specify both sizing polices so we clear the other
+        ImGui::PushID("flags3");
+        ImGui::CheckboxFlags("ImGuiTableFlags_ScrollX", &flags3, ImGuiTableFlags_ScrollX);
+        if (ImGui::CheckboxFlags("ImGuiTableFlags_ColumnsWidthStretch", &flags3, ImGuiTableFlags_ColumnsWidthStretch))
+            flags3 &= ~ImGuiTableFlags_ColumnsWidthFixed;      // Can't specify both sizing polices so we clear the other
+        if (ImGui::CheckboxFlags("ImGuiTableFlags_ColumnsWidthFixed", &flags3, ImGuiTableFlags_ColumnsWidthFixed))
+            flags3 &= ~ImGuiTableFlags_ColumnsWidthStretch;    // Can't specify both sizing polices so we clear the other
         ImGui::SetNextItemWidth(TEXT_BASE_WIDTH * 10.0f);
         ImGui::DragFloat("inner_width", &inner_width, 1.0f, 0.0f, FLT_MAX, "%.1f");
         ImGui::PopID();
         PopStyleCompact();
-
-        if (ImGui::BeginTable("##table2", 7, flags2 | ImGuiTableFlags_ColumnsWidthStretch | ImGuiTableFlags_ContextMenuInBody, outer_size, inner_width))
+        if (ImGui::BeginTable("##table3", 7, flags3 | ImGuiTableFlags_ColumnsWidthStretch | ImGuiTableFlags_ContextMenuInBody, outer_size, inner_width))
         {
             for (int cell = 0; cell < 20 * 7; cell++)
             {

imgui_internal.h

@@ -1893,7 +1893,7 @@ struct ImGuiTabBar
 #define IMGUI_TABLE_MAX_COLUMNS         64                  // sizeof(ImU64) * 8. This is solely because we frequently encode columns set in a ImU64.
 #define IMGUI_TABLE_MAX_DRAW_CHANNELS   (4 + 64 * 2)        // See TableUpdateDrawChannels()
 
-// [Internal] sizeof() ~ 100
+// [Internal] sizeof() ~ 104
 // We use the terminology "Visible" to refer to a column that is not Hidden by user or settings. However it may still be out of view and clipped (see IsClipped).
 struct ImGuiTableColumn
 {
@@ -1910,6 +1910,7 @@ struct ImGuiTableColumn
     float                   WidthGiven;                     // Final/actual width visible == (MaxX - MinX), locked in TableUpdateLayout(). May be > WidthRequest to honor minimum width, may be < WidthRequest to honor shrinking columns down in tight space.
     float                   WorkMinX;                       // Start position for the frame, currently ~(MinX + CellPaddingX)
     float                   WorkMaxX;
+    float                   ItemWidth;
     float                   ContentMaxXFrozen;              // Contents maximum position for frozen rows (apart from headers), from which we can infer content width.
     float                   ContentMaxXUnfrozen;
     float                   ContentMaxXHeadersUsed;         // Contents maximum position for headers rows (regardless of freezing). TableHeader() automatically softclip itself + report ideal desired size, to avoid creating extraneous draw calls
@@ -2009,7 +2010,9 @@ struct ImGuiTable
     ImRect                      HostBackupParentWorkRect;   // Backup of InnerWindow->ParentWorkRect at the end of BeginTable()
     ImRect                      HostBackupClipRect;         // Backup of InnerWindow->ClipRect during PushTableBackground()/PopTableBackground()
     ImVec2                      HostBackupCursorMaxPos;     // Backup of InnerWindow->DC.CursorMaxPos at the end of BeginTable()
-    ImVec1                      HostBackupColumnsOffset;    // Backup of OuterWindow->ColumnsOffset at the end of BeginTable()
+    ImVec1                      HostBackupColumnsOffset;    // Backup of OuterWindow->DC.ColumnsOffset at the end of BeginTable()
+    float                       HostBackupItemWidth;        // Backup of OuterWindow->DC.ItemWidth at the end of BeginTable()
+    int                         HostBackupItemWidthStackSize;// Backup of OuterWindow->DC.ItemWidthStack.Size at the end of BeginTable()
     ImGuiWindow*                OuterWindow;                // Parent window for the table
     ImGuiWindow*                InnerWindow;                // Window holding the table data (== OuterWindow or a child window)
     ImGuiTextBuffer             ColumnsNames;               // Contiguous buffer holding columns names

imgui_tables.cpp

@@ -82,8 +82,8 @@
 //    | TableEndRow()                           - finish existing row
 //    | TableBeginRow()                         - add a new row
 // - TableSetColumnIndex() / TableNextColumn()  user begin into a cell
-//    | TableEndCell()                          - close existing cell
-//    | TableBeginCell()                        - enter into current cell
+//    | TableEndCell()                          - close existing column/cell
+//    | TableBeginCell()                        - enter into current column/cell
 // - [...]                                      user emit contents
 //-----------------------------------------------------------------------------
 // - EndTable()                                 user ends the table
@@ -320,6 +320,8 @@ bool    ImGui::BeginTableEx(const char* name, ImGuiID id, int columns_count, ImG
     table->HostBackupParentWorkRect = inner_window->ParentWorkRect;
     table->HostBackupColumnsOffset = outer_window->DC.ColumnsOffset;
     table->HostBackupCursorMaxPos = inner_window->DC.CursorMaxPos;
+    table->HostBackupItemWidth = outer_window->DC.ItemWidth;
+    table->HostBackupItemWidthStackSize = outer_window->DC.ItemWidthStack.Size;
     inner_window->ParentWorkRect = table->WorkRect;
 
     // Padding and Spacing
@@ -826,6 +828,7 @@ void    ImGui::TableUpdateLayout(ImGuiTable* table)
             column->ClipRect.Max.y = FLT_MAX;
             column->ClipRect.ClipWithFull(host_clip_rect);
             column->IsClipped = column->IsSkipItems = true;
+            column->ItemWidth = 1.0f;
             continue;
         }
 
@@ -866,6 +869,7 @@ void    ImGui::TableUpdateLayout(ImGuiTable* table)
         column->MaxX = offset_x + column->WidthGiven + table->CellSpacingX1 + table->CellSpacingX2 + table->CellPaddingX * 2.0f;
         column->WorkMinX = column->MinX + table->CellPaddingX + table->CellSpacingX1;
         column->WorkMaxX = column->MaxX - table->CellPaddingX - table->CellSpacingX2; // Expected max
+        column->ItemWidth = ImFloor(column->WidthGiven * 0.65f);
         column->ClipRect.Min.x = column->MinX;
         column->ClipRect.Min.y = work_rect.Min.y;
         column->ClipRect.Max.x = column->MaxX; // column->WorkMaxX;
@@ -1128,11 +1132,14 @@ void    ImGui::EndTable()
 
     // Layout in outer window
     IM_ASSERT_USER_ERROR(inner_window->IDStack.back() == table->ID + table->InstanceCurrent, "Mismatching PushID/PopID!");
+    IM_ASSERT_USER_ERROR(outer_window->DC.ItemWidthStack.Size >= table->HostBackupItemWidthStackSize, "Too many PopItemWidth!");
     PopID();
     inner_window->WorkRect = table->HostBackupWorkRect;
     inner_window->ParentWorkRect = table->HostBackupParentWorkRect;
     inner_window->SkipItems = table->HostSkipItems;
     outer_window->DC.CursorPos = table->OuterRect.Min;
+    outer_window->DC.ItemWidth = table->HostBackupItemWidth;
+    outer_window->DC.ItemWidthStack.Size = table->HostBackupItemWidthStackSize;
     outer_window->DC.ColumnsOffset = table->HostBackupColumnsOffset;
     if (inner_window != outer_window)
     {
@@ -1927,6 +1934,7 @@ void    ImGui::TableBeginCell(ImGuiTable* table, int column_n)
     window->WorkRect.Min.y = window->DC.CursorPos.y;
     window->WorkRect.Min.x = column->WorkMinX;
     window->WorkRect.Max.x = column->WorkMaxX;
+    window->DC.ItemWidth = column->ItemWidth;
 
     // To allow ImGuiListClipper to function we propagate our row height
     if (!column->IsVisible)
@@ -1961,6 +1969,7 @@ void    ImGui::TableEndCell(ImGuiTable* table)
         p_max_pos_x = table->IsUnfrozen ? &column->ContentMaxXUnfrozen : &column->ContentMaxXFrozen;
     *p_max_pos_x = ImMax(*p_max_pos_x, window->DC.CursorMaxPos.x);
     table->RowPosY2 = ImMax(table->RowPosY2, window->DC.CursorMaxPos.y + table->CellPaddingY);
+    column->ItemWidth = window->DC.ItemWidth;
 
     // Propagate text baseline for the entire row
     // FIXME-TABLE: Here we propagate text baseline from the last line of the cell.. instead of the first one.