Columns: Fixed Separator from creating an extraneous draw command. Fixed Selectable with SpanAllColumns flag from creating an extraneous draw command. (#125)

docs/CHANGELOG.txt

@@ -35,6 +35,8 @@ HOW TO UPDATE?
 Breaking Changes:
 
 Other Changes:
+- Columns: Fixed Separator from creating an extraneous draw command. (#125)
+- Columns: Fixed Selectable with SpanAllColumns flag from creating an extraneous draw command. (#125)
 
 
 -----------------------------------------------------------------------

imgui.cpp

@@ -8400,13 +8400,13 @@ void ImGui::NextColumn()
     {
         // New column (columns 1+ cancels out IndentX)
         window->DC.ColumnsOffset.x = GetColumnOffset(columns->Current) - window->DC.Indent.x + g.Style.ItemSpacing.x;
-        window->DrawList->ChannelsSetCurrent(columns->Current);
+        window->DrawList->ChannelsSetCurrent(columns->Current + 1);
     }
     else
     {
         // New row/line
         window->DC.ColumnsOffset.x = 0.0f;
-        window->DrawList->ChannelsSetCurrent(0);
+        window->DrawList->ChannelsSetCurrent(1);
         columns->Current = 0;
         columns->LineMinY = columns->LineMaxY;
     }
@@ -8415,7 +8415,7 @@ void ImGui::NextColumn()
     window->DC.CurrentLineSize = ImVec2(0.0f, 0.0f);
     window->DC.CurrentLineTextBaseOffset = 0.0f;
 
-    PushColumnClipRect();
+    PushColumnClipRect(columns->Current);
     PushItemWidth(GetColumnWidth() * 0.65f);  // FIXME-COLUMNS: Move on columns setup
 }
 
@@ -8543,6 +8543,25 @@ void ImGui::PushColumnClipRect(int column_index)
     PushClipRect(column->ClipRect.Min, column->ClipRect.Max, false);
 }
 
+// Get into the columns background draw command (which is generally the same draw command as before we called BeginColumns)
+void ImGui::PushColumnsBackground()
+{
+    ImGuiWindow* window = GetCurrentWindowRead();
+    ImGuiColumns* columns = window->DC.CurrentColumns;
+    window->DrawList->ChannelsSetCurrent(0);
+    int cmd_size = window->DrawList->CmdBuffer.Size;
+    PushClipRect(columns->BackupClipRect.Min, columns->BackupClipRect.Max, false); 
+    IM_ASSERT(cmd_size == window->DrawList->CmdBuffer.Size); // Being in channel 0 this should not have created an ImDrawCmd
+}
+
+void ImGui::PopColumnsBackground()
+{
+    ImGuiWindow* window = GetCurrentWindowRead();
+    ImGuiColumns* columns = window->DC.CurrentColumns;
+    window->DrawList->ChannelsSetCurrent(columns->Current + 1);
+    PopClipRect();
+}
+
 ImGuiColumns* ImGui::FindOrCreateColumns(ImGuiWindow* window, ImGuiID id)
 {
     // We have few columns per window so for now we don't need bother much with turning this into a faster lookup.
@@ -8593,6 +8612,7 @@ void ImGui::BeginColumns(const char* str_id, int columns_count, ImGuiColumnsFlag
     columns->MaxX = ImMax(content_region_width - window->Scroll.x, columns->MinX + 1.0f);
     columns->BackupCursorPosY = window->DC.CursorPos.y;
     columns->BackupCursorMaxPosX = window->DC.CursorMaxPos.x;
+    columns->BackupClipRect = window->ClipRect;
     columns->LineMinY = columns->LineMaxY = window->DC.CursorPos.y;
     window->DC.ColumnsOffset.x = 0.0f;
     window->DC.CursorPos.x = (float)(int)(window->Pos.x + window->DC.Indent.x + window->DC.ColumnsOffset.x);
@@ -8626,8 +8646,9 @@ void ImGui::BeginColumns(const char* str_id, int columns_count, ImGuiColumnsFlag
 
     if (columns->Count > 1)
     {
-        window->DrawList->ChannelsSplit(columns->Count);
-        PushColumnClipRect();
+        window->DrawList->ChannelsSplit(1 + columns->Count);
+        window->DrawList->ChannelsSetCurrent(1);
+        PushColumnClipRect(0);
     }
     PushItemWidth(GetColumnWidth() * 0.65f);
 }

imgui_internal.h

@@ -683,6 +683,7 @@ struct ImGuiColumns
     float               LineMinY, LineMaxY;
     float               BackupCursorPosY;       // Backup of CursorPos at the time of BeginColumns()
     float               BackupCursorMaxPosX;    // Backup of CursorMaxPos at the time of BeginColumns()
+    ImRect              BackupClipRect;
     ImVector<ImGuiColumnData> Columns;
 
     ImGuiColumns()      { Clear(); }
@@ -1502,7 +1503,9 @@ namespace ImGui
     // New Columns API (FIXME-WIP)
     IMGUI_API void          BeginColumns(const char* str_id, int count, ImGuiColumnsFlags flags = 0); // setup number of columns. use an identifier to distinguish multiple column sets. close with EndColumns().
     IMGUI_API void          EndColumns();                                                             // close columns
-    IMGUI_API void          PushColumnClipRect(int column_index = -1);
+    IMGUI_API void          PushColumnClipRect(int column_index);
+    IMGUI_API void          PushColumnsBackground();
+    IMGUI_API void          PopColumnsBackground();
     IMGUI_API ImGuiID       GetColumnsID(const char* str_id, int count);
     IMGUI_API ImGuiColumns* FindOrCreateColumns(ImGuiWindow* window, ImGuiID id);
 

imgui_widgets.cpp

@@ -1216,7 +1216,7 @@ void ImGui::Separator()
 
     // Horizontal Separator
     if (window->DC.CurrentColumns)
-        PopClipRect();
+        PushColumnsBackground();
 
     float x1 = window->Pos.x;
     float x2 = window->Pos.x + window->Size.x;
@@ -1228,7 +1228,7 @@ void ImGui::Separator()
     if (!ItemAdd(bb, 0))
     {
         if (window->DC.CurrentColumns)
-            PushColumnClipRect();
+            PopColumnsBackground();
         return;
     }
 
@@ -1239,7 +1239,7 @@ void ImGui::Separator()
 
     if (window->DC.CurrentColumns)
     {
-        PushColumnClipRect();
+        PopColumnsBackground();
         window->DC.CurrentColumns->LineMinY = window->DC.CursorPos.y;
     }
 }
@@ -5311,7 +5311,7 @@ bool ImGui::Selectable(const char* label, bool selected, ImGuiSelectableFlags fl
     const ImGuiStyle& style = g.Style;
 
     if ((flags & ImGuiSelectableFlags_SpanAllColumns) && window->DC.CurrentColumns) // FIXME-OPT: Avoid if vertically clipped.
-        PopClipRect();
+        PushColumnsBackground();
 
     ImGuiID id = window->GetID(label);
     ImVec2 label_size = CalcTextSize(label, NULL, true);
@@ -5355,7 +5355,7 @@ bool ImGui::Selectable(const char* label, bool selected, ImGuiSelectableFlags fl
     if (!item_add)
     {
         if ((flags & ImGuiSelectableFlags_SpanAllColumns) && window->DC.CurrentColumns)
-            PushColumnClipRect();
+            PopColumnsBackground();
         return false;
     }
 
@@ -5401,7 +5401,7 @@ bool ImGui::Selectable(const char* label, bool selected, ImGuiSelectableFlags fl
 
     if ((flags & ImGuiSelectableFlags_SpanAllColumns) && window->DC.CurrentColumns)
     {
-        PushColumnClipRect();
+        PopColumnsBackground();
         bb.Max.x -= (GetContentRegionMax().x - max_x);
     }