wxGrid breaks on DPI change if hidden columns are present (Issue #26079)

[dsa-t]

dsa-t created an issue (wxWidgets/wxWidgets#26079)

Description

If wxGrid has hidden columns, then a DPI change occurs, XYToCell stops working correctly and some rendering artifacts appear when scrolling.

This can be traced down to this code:

https://github.com/wxWidgets/wxWidgets/blob/1b582af60d99388b56b383fe240b647387a5e4b4/src/generic/grid.cpp#L6245-L6264

Hidden columns have negative width, so due to the condition if ( width <= 0 ), m_colRights values are not updated which breaks binary search in wxGrid::PosToLinePos.

IMO, negative values in m_colWidths should be scaled too.

image.png (view on web)

Platform and version information

• wxWidgets version you use: 3.3
• wxWidgets port you use: wxMSW
• OS and its version: Windows 11

---

KiCad issue: https://gitlab.com/kicad/code/kicad/-/issues/15641

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[VZ]

vadz left a comment (wxWidgets/wxWidgets#26079)

I see, thanks. Would just this fix the problem?

diff --git a/src/generic/grid.cpp b/src/generic/grid.cpp
index f33c9fc1a3..1ee736f306 100644
--- a/src/generic/grid.cpp
+++ b/src/generic/grid.cpp
@@ -6225,14 +6225,16 @@ void wxGrid::OnDPIChanged(wxDPIChangedEvent& event)
         {
             int height = m_rowHeights[i];
 
-            // Skip hidden rows.
-            if ( height <= 0 )
-                continue;
-
+            // Note that even hidden rows heights must be scaled to ensure that
+            // they appear in the expected size if they are shown again.
             height = event.ScaleY(height);
-            total += height;
 
             m_rowHeights[i] = height;
+
+            // But don't count hidden rows for the total height.
+            if ( height > 0 )
+                total += height;
+
             m_rowBottoms[i] = total;
         }
     }
@@ -6249,13 +6251,13 @@ void wxGrid::OnDPIChanged(wxDPIChangedEvent& event)
         {
             int width = m_colWidths[i];
 
-            if ( width <= 0 )
-                continue;
-
             width = event.ScaleX(width);
-            total += width;
 
             m_colWidths[i] = width;
+
+            if ( width > 0 )
+                total += width;
+
             m_colRights[i] = total;
 
             if ( colHeader )

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[dsa-t]

dsa-t left a comment (wxWidgets/wxWidgets#26079)

Thanks, looks like this should fix it.

(can't test in KiCad currently)

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[VZ]

vadz left a comment (wxWidgets/wxWidgets#26079)

I'll push this soon and will backport this to 3.2 later if you can confirm that this fixes the problem in KiCad. TIA!

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[VZ]

Closed #26079 as completed via 4bd7fe2.

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