wxGrid::AutoSizeColumns() asserts with 0 rows

[mghie]

wxWidgets trunk, updated 2010-07-06

This is a regression compared to version 2.8, where calling wxGrid::AutoSizeColumns() worked fine even when there were no rows in the grid - it would then size the columns according to the header text widths.

[vadz]

What's the easiest way to reproduce this?

[mghie]

Yes, sorry for not providing this in the first place.

Use the grid sample, let the BugsGridTable::GetNumberRows() method return 0. That's line 1261 for the 2.8 branch (where it works, a correctly sized header-only grid appears), and it's line 1507 for the trunk, where it asserts, and on pressing "Cancel" it shows a grid with default-width columns.

[vadz]

Thanks, I see the bug and it's just due to the use of an uninitialized (or, rather, carefully initialized with invalid value to suppress compiler warnings...) variable. The following patch should fix it:

src/generic/grid.cpp

@@ -7865 +7865 @@
     HideCellEditControl();
     SaveEditControlValue();
 
-    // initialize both of them just to avoid compiler warnings
-    int row = -1,
+    // initialize both of them just to avoid compiler warnings even if only
+    // really needs to be initialized here
+    int row,
+        col;
+    if ( column )
+    {
+        row = -1;
+        col = colOrRow;
+    }
+    else
+    {
+        row = colOrRow;
         col = -1;
+    }
 
     wxCoord extent, extentMax = 0;
     int max = column ? m_numRows : m_numCols;
     for ( int rowOrCol = 0; rowOrCol < max; rowOrCol++ )
     {
         if ( column )
-        {
             row = rowOrCol;
-            col = colOrRow;
-        }
         else
-        {
-            row = colOrRow;
             col = rowOrCol;
-        }
 
         // we need to account for the cells spanning multiple columns/rows:
         // while they may need a lot of space, they don't need all of it in

Please let me know if you have any problems with it, if none arise I'll commit this in a few days.

[mghie]

Thank you very much, your patch takes care of the issue without any negative side effects that I could observe. AFAICS this can be closed as fixed when the patch is committed.

[VZ]

(In [64885]) Don't use uninitialized variables in wxGrid::AutoSize().

The code in wxGrid::AutoSizeColOrRow() was using uninitialized col/row
variable if the grid had no rows/columns, resulting in assertion failures when
trying to automatically size the columns of an empty grid.

Do initialize them now and also remove duplicate assignments to the variables
which never change inside the loop.

Closes #12206.