[solved] Inherited  TCustomStringGrid component : add a property in
TGridColumn
lazarus / 31-LCL

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Selzig Hem · 2011-11-21 10:07

Hello,

In an inherited  TCustomStringGrid component, I would add a property
in TGridColumn = class (TCollectionItem) (which is originally defined
in /lcl/grids.pas). Is it possible in a simple way?

Regards. Gilles

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Selzig Hem · 2011-11-21 11:07

Hello,
I found a  part of the answer in this forum :
http://forum.lazarus.freepascal.org/index.php/topic,12562.0.html.
It's complicated as I expected... and not usable.

Regards. Gilles

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Blaazen · 2011-11-21 13:26

What properties are you planning to add to columns?

Adding them directly to TGridCoumn is probably impossible, it is too
complex.

Maybe you can have your own dynamic structure (list) of your
properties and you can add/remove them each time you will add/remove
column.
Then you will need to introduce your own Add/RemoveColumn methods
which will manage adding/removing both columns (natively) and your
properties (your own list).

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wp · 2011-11-21 14:53

Derive your new column from TGridColumn and override the grid's
CreateColumns method

Code: [Select]type
  TMyGridColumn = class(TGridColumn)
  private
    FNewProperty : integer;
  published
    property NewProperty: integer read FNewProperty write
FNewProperty;
  end;

  TMyStringGrid = class(TCustomStringGrid)
  protected
    function CreateColumns: TGridColumns; override;
  end;

  function TMyStringGrid.CreateColumns: TGridColumns;
  begin
    Result := TGridColumns.Create(Self, TMyGridColumn);
end;
     

The grid component is well-designed and has many virtual methods which
allow you to change almost everything. Have a look at the source code.
If you need an example see my posting at
http://www.lazarus.freepascal.org/index.php/topic,15259.0.html. It has
some issues, though; but these are not related to your question.

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Selzig Hem · 2011-11-22 08:08

Hello,

thanks for yours answers.

@wp :
It works fine.
I am not sure that the grid component is well-designed.
Code: [Select]With StringGrid1 do begin
 Cells[1,1] := 'Test'+#0+'anything';
 Showmessage(IntToStr(length(Cells[1,1]));
end; The result is 4 !
If Cells is really an AnsiString why does not it accept null
characters ? There are other problems.

Again thanks for your solution. I tried something similar but it did
not work. I guess it's still a problem to recompile the component: it
is common when I change or add some properties or methods. A simple
compilation of the component is not always sufficient. To be sure of
the result, I have to  recompile Lazarus with the option Clean All +
Build ... and this requires a lot of time... so I do not recompile
lazarus systematically.

Regards. Gilles

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wp · 2011-11-22 11:27

Sorry, I cannot comment much because I do not know exactly what you
want to do. I get the impression that you modify TStringGrid directly.
You shouldn't do that, you should always create a new component
derived from the one that you want to change, and override its virtual
methods. In that sense, the grids are really well-designed because you
can change almost everything this way.

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Selzig Hem · 2011-11-23 09:12

Hello wp,

the problem is solved. Your answer works fine.

I added just two comments :
It is (often) necessary to completely rebuild lazarus for the changes
of the components are taken into account. It's very heavy... and
that's why one of my tests similar to yours, did not seem to work.The
StringGrids are not as well designed as that. Impossible to directly
enter strings with null characters (exemple I added). The Kgrid does
it very well. Now the cells are strings ... but we can not fill them
as string.Regards. Gilles

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jesusr · 2011-11-24 08:21

Quote from: Selzig Hem on November 22, 2011, 09:08:48 amI am not sure
that the grid component is well-designed.
Code: [Select]With StringGrid1 do begin
 Cells[1,1] := 'Test'+#0+'anything';
 Showmessage(IntToStr(length(Cells[1,1]));
end; The result is 4 !
If Cells is really an AnsiString why does not it accept null
characters ? There are other problems.

Under the scene, the stringgrid uses pchar which supposedly in
addition of other things, should save some bytes on big grids.

Anyway changing to use string instead of pchar it's almost trivial,
but your example makes me wonder if it's really necesary. A grid that
uses ansistring should show in your case "Test?anything" is that the
intended behaviour? On the other hand if it only shows "Test" then it
would be treating the ansistring as pchar which is cheating too.
Editing such cell would lose data, I'm guessing. So how could it
something like your example be treated the right way?

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Selzig Hem · 2011-11-26 10:16

Hello Jesus,

I hope what I write is understandable. My english is really bad.

First I want to say that I regard Lazarus as an excellent IDE that I
use daily in my work. However, your reaction is the same as your team
has had when I asked that we can put an underscore character (&) in
the title.caption of columns. What's the use? The problem is not there
... but it is the same. The title.caption is a caption ... It should
work like any caption. The analogy is the same. The cells are strings.
They should work just like any other string.

"Anyway changing to use string instead of pchar it's almost trivial".
Probably, but not for maintenance of my component if it is me who
incorporates it into my component (that  currently is inherited of 
TCustomStringGrid). I've had to incorporate sorting and searching on
the columns header, a real multi-selection [eg Rows 1, 8, 9 and 25],
basic things that should be incorporated to the users of Lazarus. I
remember that Columns.visible only works since 0.9.29 ! Nobody used
invisible cells in TStringGrids before 0.9.29 ? I said this bug  in
the bugtracker when I used  0.9.26 version. I believe that
TCustomStringGrid  is the inheritor poor of Lazarus.

Let me also say that on the use of string, I do not understand why the
function Pos (or strpos) does not detect either null characters. Here
too, I guess it has no interest. StrReplace function could be a
solution to my problem but it is a maddeningly slow.

To answer your question precisely, to manage my databases, I use
Internet connections that are not always persistent. This forbids the
use of  Connector-dataset-datasource-DBGrid because in case of rupture
of the connection, the DBGrid is erased.

So I use a TStringGrid.  This allows me to load my tables with 2
steps. Let's say the first 100 records in the main thread and the rest
in a parallel thread. Thus, my form is not frozen.  An Internet
connection is slower than an local access. I use parallel thread to
get a real Fetch.

Now, suppose that in my component 'dbStringGrid', from my database, I
want to load the blobs (the strings only - without displaying the
images) .  Then I want when the mouse is over the grid lines, the
images appear instantly in a TImage placed on the Form. The blobs
contain null characters.  I had to associate my StringGrid to an array
of String (or more "badly" with TObject) to get the desired effect.

This is certainly unusual as managing ... But why can not I do it
simply with Lazarus?

Regards. Gilles

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jesusr · 2011-11-26 20:22

QuoteWhat's the use? The problem is not there ... but it is the same.
The title.caption is a caption ... It should work like any caption.
The reaction was, I think, normal, a & is associated to a shortcut
that trigger some action, is not for decorating, I agree we can
disagree on this. But to me, shortcuts defined this way are handled by
the control that contain such caption, for example a label will focus
the associated component, a button will click, a menu will trigger
it's action, etc. for grid colums "&" was asked but without related
action .

QuoteThe analogy is the same. The cells are strings. They should work
just like any other string. StringGrid do show and edit strings.
Editors are not prepared to handle #0 in the middle of strings that I
know, even if they are ansi strings. Forcing it's use when you don't
know how the control will react is not good, as I don't know how the
editor will react, I didn't plan to handle this situation.  but... as
I wrote before, it's very easy to me to change this behaviour so it
will use real string instead of pchar, I expressed my doubt about how
it will work, meanly that I find there will be two cases, but you do
nothing to resolve my doubt.

Quote I've had to incorporate sorting and searching on the columns
header, a real multi-selection [eg Rows 1, 8, 9 and 25], basic things
that should be incorporated to the users of Lazarus.Sorting is
incorporated, and even can be selected as default action when clicking
column title, searching is basically application specific, what would
the grid do when it by itself is not interested in what it contains?.
Multiselection maybe useful, indeed I use multiselection in some
application and I find it much better to store selected status in user
data than in the cells, so multiselect is not implemented by default,
nobody ever asked for it, that I know too.
QuoteI remember that Columns.visible only works since 0.9.29 ! Nobody
used invisible cells in TStringGrids before 0.9.29 ? I said this bug 
in the bugtracker when I used  0.9.26 version. I believe that
TCustomStringGrid  is the inheritor poor of Lazarus. It seems not.
There are multiple reasons to not fix everything immediately, the
available free time it's perhaps the more common, and sad but true,
when it took long time to work in bugs reports many have accumulated,
and some are more time demanding than others, some receive more
attention, and it may happen that some very easy to fix are "obscured"
by others, in reality there are may reasons. That particular case I
don't remember, if the bug still exists please direct me to the bug
report.

Quote I believe that TCustomStringGrid  is the inheritor poor of
Lazarus. Sorry I don't quite understand this.

QuoteNow, suppose that in my component 'dbStringGrid', from my
database, I want to load the blobs (the strings only - without
displaying the images) .  Then I want when the mouse is over the grid
lines, the images appear instantly in a TImage placed on the Form. The
blobs contain null characters.  I had to associate my StringGrid to an
array of String (or more "badly" with TObject) to get the desired
effect.

This is certainly unusual as managing ... But why can not I do it
simply with Lazarus?And have you asked yourself if this is the best
approach you can take?, why not for example use the grids.Objecs[x,y]
property and store the blob data in a object. Every solution depends
on your point of view of course and I might be missing something
obvious, but form your description grids.Objecs[x,y] seems a much
better choice.


Jesus Reyes A.

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Selzig Hem · 2011-11-27 11:56

Hello Jesus,

As I said, in the software that I currently developing, my approach is
unusual because the circumstances require it. I consider a language as
Lazarus must be versatile to successfully challenge. If I want to
emphasize the fluidity of a software, cut and thread my access to a
database whose connection is not persistent, I must be able to do it.
And with Lazarus, I can do this.

BUT, now as a developer, I need to focus on the process logic
("business rules"). When I use your StringGrids, 80% of the time is
assigned to create basic functions for the component: the multiselect
only works for continuous block. This is very inadequate. In your
work, all your selections in a grid form a continuous block? Why is it
necessary to reinvent the wheel? This can not be integrated into the
basic StringGrid? Therefore spend less time : bugs :
http://62.166.198.202/view.php?id=20607,
http://62.166.198.202/view.php?id=20494, waiting, waiting....

I leave you to your beliefs ... and your work. I think I'll learn to
do without Lazarus that I practice since version 0.9.24.  As a
developer, it is not productive enough for the reasons I explained.

The best. Bye.
Gilles

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Avishai · 2011-11-27 12:20

Maybe if you offer a bounty someone can write this special code for
you.

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Selzig Hem · 2011-11-27 14:53

Hello Avishai,

For me the discussion is closed: It's been three years since I worked
with Lazarus because Borland  abandoned Kylix.

In Lazarus, the "developed" components are missing. The product is
very nice but in my opinion poorly controlled. Compatibility with
Delphi 7 is not (more) be a target or a straitjacket. Delphi 7 is
finished. It's FireMonkey now.

To give scale to the product, some components need to be more prepared
... In production, it is not rentalisable even pay someone to do the
job. In my case, the job is done and functional but it required too
much time. In addition, it lacks many of the add-on of modern IDE that
facilitate and automate the work. It's already a huge defect in
productivity: It remained as Delphi 7. Given the small size of the
community, its ever-changing code (and therefore non-stabilized),
requires that the Lazarus team creates these components.

Well, I stop here my reasons for quitting: I already expressed my
fears in vain ... I respect the work of the team lazarus but the
conclusion is that I can not productively use this platform in the
time available for my project. I agree also willing to admit my
failure. I get the desired result... but too slowly.

I wish good luck to the team which I will try to continue to monitor
the progress of the IDE.

Regards. Gilles

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jesusr · 2011-11-27 19:16

Quote from: Selzig Hem on November 27, 2011, 12:56:14 pmHello Jesus,

As I said, in the software that I currently developing, my approach is
unusual because the circumstances require it. I consider a language as
Lazarus must be versatile to successfully challenge. If I want to
emphasize the fluidity of a software, cut and thread my access to a
database whose connection is not persistent, I must be able to do it.
And with Lazarus, I can do this.
What seems unusual is the way you want to solve the problems, but of
course we will not discuss this  it's all about developer preferences,
but if you want to include something in the grid and it is of general
use patches are welcomed. Or given the time and a good spec I will try
to implement.
QuoteBUT, now as a developer, I need to focus on the process logic
("business rules"). When I use your StringGrids, 80% of the time is
assigned to create basic functions for the component: the multiselect
only works for continuous block. This is very inadequate.
 I'm sorry, the grid is not a magical box that has all and every
feature needed or imagined, we can join all efforts and make it
happen, but currently it's not, so some work is needed from the
developer part and do the work that is missing.
unfortunately one can only came to one conclusion, no effort seems
enough, every developer has it's own idea on what a component should
do or behave and if you make happy some most certainly will make
others sad.
Quote In your work, all your selections in a grid form a continuous
block? Why is it necessary to reinvent the wheel? This can not be
integrated into the basic StringGrid? Therefore spend less time : bugs
: http://62.166.198.202/view.php?id=20607,
http://62.166.198.202/view.php?id=20494, waiting, waiting....
 In all except one where I, with few lines of code, made it work the
way I need, so I though that is not that bad for a generic grid. The
problem might be in the details and what works perfect for me may not
work nice for you.

But lets see, have you ever requested a multiselect feature for the
grid?, if so please direct me to the post or bug tracker request where
you have set forth the specs for such feature. That's to say that I'm
not closed to add features.

About the bug reports you mention, 20494 submitted by you on
2011-10-16 was set target version 1.2 by manager (and take into a
count 1.0 is not yet released) I resolved the problem a day after and
you give feedback on 2011-10-24 that's 7 days after I fixed it, a
correction by me 4 days after and until now I don't know if it worked
because you have not closed the report. About 20607 submitted on
2011-11-01, the manager hadn't time to set the target but anyway I
fixed it 3 days after and still the same result I don't know if the
fix worked for you because you have not closed the report. I think I
could say the same: waiting, waiting....  of course nobody has to
reply me that I don't fix all bugs that quick

QuoteI leave you to your beliefs ... and your work.  I think I'll
learn to do without Lazarus that I practice since version 0.9.24.  I
don't fully understand the sense of this so I won't comment.

QuoteAs a developer, it is not productive enough for the reasons I
explained.

The best. Bye.
Gilles
I'm sad, I wish it would be as productive for other as it is for me
...

Regards.

Jesus Reyes A.

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Selzig Hem · 2011-11-27 19:39

Hello Jesus,

I do not agree with you but thank you for your answers.
Regards. Gilles