Datagrid internal error

[Paul Dupuis]

On 8/10/2022 5:02 PM, Trevor DeVore via use-livecode wrote:
> 32,767 is the max for width as well. If there are enough columns it is
> possible that the DataGrid is rendering a group that exceeds this limit and
> hence the error. The DataGrid works around the limit when rendering rows,
> but not when rendering columns.
>
> I suppose a quick test would be to create a DataGrid with 330 columns that
> are at least 100 pixels wide and see if you get the same error.
>

So I created 2 test stacks with a Datagrid and a button to set the 
number of columns and populate a row of data. One stack I did in 
Livecode 4.6.4 (the oldest I have) and one I built in Livecode 9.6.8 to 
see if there were differences in the handling of the error condition 
between versions of the Datagrid object.

[Note: Some of the Datagrids in our app are from LC 4.6.4 and we've 
never removed them and replaced them with newer versions and I don't 
believe Livecode does anything to automatically update the Datagrid 
objects in an old stack when opened in a new version of Livecode]

Under LC464, trying to create a number of columns with default widths 
that would exceed the 32,767 pixel width limit of the group object 
(using 330 columns with a default width of 100px or 33,000 pixels) produces:

1) A blank header (no columns)
2) Visible column for data, where only the visible columns of the first 
row (8 columns) are populated with data and when you scroll to the 
right, all remaining column of the 1st row of data are empty. The grid 
is scrollable horizontally to what looks to be around 320-330 columns.

Using 320 columns, works as expected. 325 works; 327 works. 328 only 
produces 327 columns in the header with 327 values for data in the first 
row. 329 produces a header with 329 columns and no data is rendered in 
the 1st row.

Under LC968, the LC968 test version of this with 330 columns produces:

1) Columns headers 1 to 8 (the header that are the visible width of the 
Datagrid)
2) No data is rendered and the grid is not scrollable.

Using 320 columns, works as expected. 325 works. 327 works. 328 produces 
327 columns in the header and no data in the first row. 329 is the same 
as 330 (only 8 visible column headers and no data and no scrolling).

So, the results are subtly different from Datagrids from LC4.6.4 and 
Datagrids from LC9.6.8, but both fail to do what a user would expect 
without any visible errors.

However, having the number of columns exceed the width of a Livecode 
group object in pixels does not seem to be the source of the error I am 
trying to track down which was:

Line 139 set the dgProp["columns"] of grp "rwMatrixObj_DataGrid" to 
tColumnNames

tColumnNames is a variable containing a list of text lines that are 
customer entered column names, so they could be ANYTHING (up to 255 
chars, no control characters, including DEL (127)) that a user could 
type or paste into a field, including words in any language using Unicode.

As the executionContexts data does not contain the actual values of the 
variable tColumnNames when the error occurs AND (for reasons) I can not 
get the data from the customer, does ANYONE have any idea what 
tColumnNames might contain that could produce the error(s) show below?

Technical information:
Property: value is not a number: (Line 11, column 1)
Object: can't set object property: (Line 11, column 5)
set: can't set property: (Line 11, column 1)
Handler: error in statement: LayoutControl (Line 11, column 1)
Object ID: stack "RevDataGridLibraryBehaviorsDefaultHeaderButtonBehavior"
-
repeat: error in statement: (Line 5066, column 1)
Handler: error in statement: _table.ResizeHeaders (Line 5052, column 1)
Object ID: stack "RevDataGridLibraryBehaviorsDataGridButtonBehavior"
-
Handler: error in statement: _table.ResizeColumns (Line 4967, column 1)
Object ID: stack "RevDataGridLibraryBehaviorsDataGridButtonBehavior"
-
Handler: error in statement: _table.CreateColumns (Line 4737, column 1)
Object ID: stack "RevDataGridLibraryBehaviorsDataGridButtonBehavior"
-
Handler: error in statement: _table.RegenerateColumns (Line 4538, column 1)
Object ID: stack "RevDataGridLibraryBehaviorsDataGridButtonBehavior"
-
switch: error in statement: (Line 6150, column 1)
Handler: error in statement: dgProps (Line 5553, column 1)
Object ID: stack "RevDataGridLibraryBehaviorsDataGridButtonBehavior"
-
set: can't set property: (Line 5529, column 1)
Handler: error in statement: dgProp (Line 5529, column 1)
Object ID: stack "RevDataGridLibraryBehaviorsDataGridButtonBehavior"
-
set: can't set property: (Line 139, column 1)
if-then: error in statement: (Line 139, column 1)
Handler: error in statement: populateMe (Line 138, column 1)
Object: group "Table" of card "FrequencyReport" of stack "FreqReport.rwtl"
Object ID: group id 1162 of card id 1002 of stack 
"/Applications/HyperRESEARCH 4.5.4/Components/Tools/FreqReport.rwtl"