From b263a9d9c55b70cae441f870d6720ec82ac7ccc8 Mon Sep 17 00:00:00 2001
From: anmcgrath <andrew.n.mcgrath@gmail.com>
Date: Sun, 30 Jun 2024 15:36:05 +1000
Subject: [PATCH] Better handle merges with hidden rows/columns.

---
 src/BlazorDatasheet/DatasheetRow.razor        | 68 +++++++++++++------
 .../VirtualMergesRenderer.razor               |  4 +-
 2 files changed, 48 insertions(+), 24 deletions(-)

diff --git a/src/BlazorDatasheet/DatasheetRow.razor b/src/BlazorDatasheet/DatasheetRow.razor
index 353d64ac..f6d183fa 100644
--- a/src/BlazorDatasheet/DatasheetRow.razor
+++ b/src/BlazorDatasheet/DatasheetRow.razor
@@ -5,11 +5,11 @@
 @for (int j = VisualSheet.Viewport.VisibleRegion.Left; j <= VisualSheet.Viewport.VisibleRegion.Right; j++)
 {
     var col = j;
-    var cell = VisualSheet.GetVisualCell(Row, col);
-    
-    if(!cell.IsVisible)
+    var visualCell = VisualSheet.GetVisualCell(Row, col);
+
+    if (!visualCell.IsVisible)
         continue;
-    
+
     var k = col;
 
     var rowSpan = 1;
@@ -17,17 +17,41 @@
     var dataCol = col;
     var dataRow = Row;
 
-    if (!Virtualise && cell.Merge != null)
+    if (!Virtualise && visualCell.Merge != null)
     {
-        if (cell.Merge.Top == Row && cell.Merge.Left == col)
+        if (!Sheet.Rows.IsVisible(Row) || !Sheet.Rows.IsVisible(col))
+            continue;
+
+        if (Sheet.Rows.IsVisible(visualCell.Merge.Top) && Sheet.Columns.IsVisible(visualCell.Merge.Left))
         {
-            rowSpan = cell.Merge.Height;
-            colSpan = cell.Merge.Width;
-            dataCol = cell.Merge.Left;
-            dataRow = cell.Merge.Top;
+            if (visualCell.Merge.Top == Row && visualCell.Merge.Left == col)
+            {
+                rowSpan = Sheet.Rows.CountVisible(Row, visualCell.Merge.Bottom);
+                colSpan = Sheet.Columns.CountVisible(col, visualCell.Merge.Right);
+                dataCol = visualCell.Merge.Left;
+                dataRow = visualCell.Merge.Top;
+            }
+            else
+                continue;
+        }
+        else // cell top left is not visible
+        {
+            var nextVisibleRow = Sheet.Rows.GetNextVisible(visualCell.Merge.Top - 1);
+            var nextVisibleCol = Sheet.Columns.GetNextVisible(visualCell.Merge.Left - 1);
+
+            if (nextVisibleCol == col && nextVisibleRow == Row)
+            {
+                rowSpan = Sheet.Rows.CountVisible(Row, visualCell.Merge.Bottom);
+                colSpan = Sheet.Columns.CountVisible(col, visualCell.Merge.Right);
+                dataCol = visualCell.Merge.Left;
+                dataRow = visualCell.Merge.Top;
+                visualCell = VisualSheet.GetVisualCell(visualCell.Merge.Top, visualCell.Merge.Left);
+            }
+            else
+            {
+                continue;
+            }
         }
-        else
-            continue;
     }
 
     <td
@@ -37,34 +61,34 @@
         colspan="@colSpan"
         rowspan="@rowSpan"
         class="sheet-cell"
-        style="@cell.FormatStyleString">
+        style="@visualCell.FormatStyleString">
         <div style="display: flex;">
-            @if (cell.Icon != null)
+            @if (visualCell.Icon != null)
             {
                 <div
-                    style="margin-right:2px; float:left; color: @(cell.Format?.IconColor ?? "var(--icon-color)");">
-                    @GetIconRenderFragment(cell.Icon)
+                    style="margin-right:2px; float:left; color: @(visualCell.Format?.IconColor ?? "var(--icon-color)");">
+                    @GetIconRenderFragment(visualCell.Icon)
                 </div>
             }
-            @switch (cell.CellType)
+            @switch (visualCell.CellType)
             {
                 case "default":
                 case "datetime":
                     <div style="width: 100%;">
-                        @cell.FormattedString
+                        @visualCell.FormattedString
                     </div>
                     break;
                 case "boolean":
-                    <BoolRenderer Cell="cell" Sheet="Sheet"/>
+                    <BoolRenderer Cell="visualCell" Sheet="Sheet"/>
                     break;
                 case "select":
-                    <SelectRenderer Cell="cell" Sheet="Sheet"/>
+                    <SelectRenderer Cell="visualCell" Sheet="Sheet"/>
                     break;
 
                 default:
                     <DynamicComponent
-                        Parameters="@GetCellRendererParameters(cell)"
-                        Type="@GetCellRendererType(cell.CellType)"/>
+                        Parameters="@GetCellRendererParameters(visualCell)"
+                        Type="@GetCellRendererType(visualCell.CellType)"/>
                     break;
             }
         </div>
diff --git a/src/BlazorDatasheet/VirtualMergesRenderer.razor b/src/BlazorDatasheet/VirtualMergesRenderer.razor
index 35bbbe1e..c316e621 100644
--- a/src/BlazorDatasheet/VirtualMergesRenderer.razor
+++ b/src/BlazorDatasheet/VirtualMergesRenderer.razor
@@ -122,11 +122,11 @@
         if (isMergeStartVisible)
             return true;
 
-        var nextVisibleRow = Sheet.Rows.GetNextVisible(merge.Top);
+        var nextVisibleRow = Sheet.Rows.GetNextVisible(merge.Top - 1);
         if (!merge.Spans(nextVisibleRow, Axis.Row))
             return false;
         
-        var nextVisibleCol = Sheet.Columns.GetNextVisible(merge.Left);
+        var nextVisibleCol = Sheet.Columns.GetNextVisible(merge.Left - 1);
         if (!merge.Spans(nextVisibleCol, Axis.Col))
             return false;
         return true;