TStringGrid refresh
lazarus / 10-Designer

----------------------------------------------------------------------
GAlex · 2004-12-26 12:26

:?: Why the TStringGrid component does not refresh in runtime?

To better explain, let me say that when the application modify the
content of the cells using the cells[] property in response to a
keypress or another event (edit option disabled), and then change the
position of the cursor by using the "row" and "col" properties, the
control does not update the cursor position (the dotted red square),
leaving the first cell selected (in negative gfx) together with
garbage drawing (dotted lines, selected cells, and so on...).

It doesn't redraw itself even after a gridname.refresh() call; only by
clicking with the mouse on the grid, the control redraws and cleans
the bad graph remains.

Any advice :?:  :?:  :?:

----------------------------------------------------------------------
jesusr · 2004-12-27 09:14

Quote from: "GAlex":?: Why the TStringGrid component does not refresh
in runtime?

To better explain, let me say that when the application modify the
content of the cells using the cells[] property in response to a
keypress or another event (edit option disabled), and then change the
position of the cursor by using the "row" and "col" properties, the
control does not update the cursor position (the dotted red square),
leaving the first cell selected (in negative gfx) together with
garbage drawing (dotted lines, selected cells, and so on...).

It doesn't redraw itself even after a gridname.refresh() call; only by
clicking with the mouse on the grid, the control redraws and cleans
the bad graph remains.

Any advice :?:  :?:  :?:

Tried to reproduce without success after two tests.
test 1) drop a TStringgrid in a form, make a keypress event and write
this code:
Code: [Select]
  Grid.Cells[Grid.Col,Grid.Row]:=Key;
  Grid.Col := Grid.Col+1;

test 2) drop a TStringgrid and a TEdit, make a TEdit OnChange and
TEdit KeyDown, in OnChange I Write:
Code: [Select]
  Grid.Cells[Grid.Col,Grid.Row]:=Edit1.Text

in KeyDown I write:
Code: [Select]
  if Key=VK_RETURN then
    Grid.Col := Grid.Col + 1;


I think this test follow your description, however both test work fine
in windows and with a recent lazarus version. Can you give more
details, code, screenshots, anything to help to reproduce the problem
so it gets fixed, thanks.

----------------------------------------------------------------------
GAlex · 2004-12-27 17:11

:arrow: Here You are, as requested; the dev platform currently is
win32, Lazarus version is of 10th dec 2004 (the latest I presume);
I've not yet tested this code in Linux-GTK;
(commented code portions follows):

Code: [Select]
procedure TCruci.thegridKeyPress(Sender: TObject; var Key: char);
var
  x: LongInt;
  y: LongInt;
  c: char;
begin
     if key in ['a'..'z', 'A'..'Z'] then begin
          c:=upcase(key);
          x:=thegrid.col;
          y:=thegrid.row;
          if thegrid.cells[x,y] = '' then begin
             thegrid.cells[x,y]:=c;

Here the char is inserted in the appropriate cell on the grid, and the
cell gfx switch to selected (negative) ...
Code: [Select]
... (if conditionals)
                repeat begin
                            if x < 14 then thegrid.col+=1
                            else thegrid.col:=0
                       end
                until (thegrid.cells[thegrid.col,y] = '') or
(thegrid.col <> x);
... (else conditional)

... and here the cursor (red dotted square) is not updated on the grid
during the loop, nor at the end, and the cell[x,y] (i.e. the first
cell that originates the event) is always in selected gfx ...
Code: [Select]
... (previous conditionals)
     else if key = chr(08) then begin  // the backspace key (I know
use of chr(ascii-code) it's deprecated, and I should use defined
constants VK_*, but I'm only in an early debug stage and that will be
fixed  :? )

                if thegrid.col>0 then thegrid.col-=1
                else thegrid.col:=15;
                if thegrid.cells[thegrid.col, thegrid.row]<>'' then
begin
                   thegrid.cells[thegrid.col, thegrid.row]:='';
                   p1p-=1;
                end

... this leaves the grid cursor (the red dotted square) drawed in the
cell that generated the event ...
Code: [Select]
     thegrid.refresh()
end;

... this is the end of the procedure, but the .refresh() call does not
seem to work.
I'm unable to post a screenshot (I don't know how to insert an image
in this post), but seems that losing focus (the form) clears the bad
red squares, leaving the "selected" cells in negative gfx ...

I've looked for the TStringGrid control source code, but found nothing
wrong :!:

Thanks in advance for anyone who knows how to fix.
[/img]

----------------------------------------------------------------------
jesusr · 2004-12-27 18:15

Quote from: "GAlex":arrow: Here You are, as requested; the dev
platform currently is win32, Lazarus version is of 10th dec 2004 (the
latest I presume); I've not yet tested this code in Linux-GTK;
(commented code portions follows):

Code: [Select]
....snip....
                repeat begin
                            if x < 14 then thegrid.col+=1
                            else thegrid.col:=0
.... snip .....
                if thegrid.col>0 then thegrid.col-=1
                else thegrid.col:=15;
                if thegrid.cells[thegrid.col, thegrid.row]<>'' then
begin
                   thegrid.cells[thegrid.col, thegrid.row]:='';
                   p1p-=1;
                end

... this leaves the grid cursor (the red dotted square) drawed in the
cell that generated the event ...
Code: [Select]
     thegrid.refresh()
end;

... this is the end of the procedure, but the .refresh() call does not
seem to work.
I'm unable to post a screenshot (I don't know how to insert an image
in this post), but seems that losing focus (the form) clears the bad
red squares, leaving the "selected" cells in negative gfx ...

I've looked for the TStringGrid control source code, but found nothing
wrong :!:

Thanks in advance for anyone who knows how to fix.
[/img]

The problem is the use of the operators +=, -= in properties that have
methods as does Grid.Col, the method Grid.SetCol is never called. The
operators seems to access the properties directly and so, the grid's
mechanism to refresh and update internal values is not triggered.

Try to replace all expressions that use +=,-= operators with normal
pascal expressions: Grid.Col := Grid.Col + 1; and Grid.Col := Grid.Col
- 1;

----------------------------------------------------------------------
GAlex · 2004-12-27 19:36

It works :!:
Now I should do 2 things:

1. stop using C-like construct and assignments while writing programs
in Pascal :cry: ;

2. stop using this nasty emoticons :twisted: arghhh :evil: in my
posts.

Thanks alot.

----------------------------------------------------------------------
Marc · 2004-12-28 14:42

Maybe you should also file a bug on fpc. IMO, modifying properties
with += should not be allowed.
It is the same as Inc(Grid.Col, 1), that is also not allowed (AFAIK)

----------------------------------------------------------------------
jesusr · 2004-12-28 18:14

done: bug id=3488, I had chosen a better description, though.