Solved

Writing code refering to a Ttable on a form from a custom component

Posted on 2003-10-22
5
200 Views
Last Modified: 2010-04-05
I am wondering if it is posible to write code refering to a specific Ttable on a form in a custom component.  I am trying to write code on the onClick and onContextPopup event of a customised TLabel and TImage so a user can access a database from a dynamically created Image and label that have being created on the OnMouseUp event of the form.  
I am using delphi 5.
Hope this makes sence
Thanks

Graeme
0
Comment
Question by:KiwiGraeme
5 Comments
 
LVL 27

Accepted Solution

by:
kretzschmar earned 84 total points
ID: 9597384
?

....
procedure TForm1.MyPredefinedOnClick(Sender : TObject);
begin
  //whatever needed here
end;

procedure TForm1.MyPredefinedOnContextPopUp(Sender : TObject; MousePos: TPoint;
  var Handled: Boolean););
begin
  //whatever needed here
end;


....
Procedure TForm1.CreateLabel;
begin
  with Tlabel.Create(self) do
  begin
    top := WhatEver;
    left := WhatEver;
    parent := self;
    OnClick := MyPredefinedOnClick;
    OnContextPopUp := MyPredefinedOnContextPopUp;
    //...maybe more
  end;
end;
...


meikl ;-)

0
 
LVL 6

Assisted Solution

by:swift99
swift99 earned 83 total points
ID: 9597446
It is generally bad to break encapsulation.

If you really need to talk to the TTable component then ensure that the table is exposed as a property on the custom component.  From there on it's just like any other variable.

What you are suggesting is very straightforward.  meikl gave you most of what you need.
0
 
LVL 22

Assisted Solution

by:Ferruccio Accalai
Ferruccio Accalai earned 83 total points
ID: 9597928
BTW, if you're going to create these cmp dinamically maybe you need some differents procedures for every one...
And also you can have more than a Dataset on your form that must be linked to the cmps...

So an example to code these customized components should be this:

unit MyLabelAndImage;

interface

uses
  Windows, Messages, SysUtils, Classes, Controls, StdCtrls,db,extctrls;

type
  TLabel1 = class(TLabel)
  private
  fDataset: TDataset; //so you can use all TDataset descendents (ADO, IB, BDE...)
    { Private declarations }
  protected
    { Protected declarations }
    procedure Click; Override;
  public
    { Public declarations }
  published
    { Published declarations }
    property Dataset: TDataset read fDataset write fDataset;
  end;
  TImage1 = class(TImage)
  private
  fDataset: TDataset;
 
    { Private declarations }
  protected
    { Protected declarations }
    procedure DoContextPopup(MousePos: TPoint; var Handled: Boolean); override;
   
  public
    { Public declarations }
  published
    { Published declarations }
    property Dataset: TDataset read fDataset write fDataset;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('Standard', [TLabel1,TImage1]);
end;
procedure TLabel1.Click;
begin
      inherited;
      if Assigned(fDataset) then
         caption := fDataset.Name;//just an example
   
end;
procedure TIMAGE1.DoContextPopup(MousePos: TPoint; var Handled: Boolean);
begin
      Inherited;
   if Assigned(fDataset) then
         Messagebox(0,PCHAR(Fdataset.name),PCHAR('Info'),0);//just an example
end;    
end.

F68 ;-)
0

Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

A lot of questions regard threads in Delphi.   One of the more specific questions is how to show progress of the thread.   Updating a progressbar from inside a thread is a mistake. A solution to this would be to send a synchronized message to the…
Objective: - This article will help user in how to convert their numeric value become words. How to use 1. You can copy this code in your Unit as function 2. than you can perform your function by type this code The Code   (CODE) The Im…
Although Jacob Bernoulli (1654-1705) has been credited as the creator of "Binomial Distribution Table", Gottfried Leibniz (1646-1716) did his dissertation on the subject in 1666; Leibniz you may recall is the co-inventor of "Calculus" and beat Isaac…

821 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question