asked on

Making a component inherited from TControl and TCustompanel

Hi , I wanna make my own component that should have the functions as follow:
contains a image component to display image
contains a label for display text
when mouse move on & move out ,change the background color

What I have done:
1.try to write a component inherited from TControl.
2. use Tcontrolcanvas to change the background color in the mouse move and mouse out event(in the paint api message)
but I can not use insertcontrol to insert the image ,panel ,label in my Tcontrol type component ,there has no insertcontrol method but insertcomponent .

and I change the component parent class to TCustompanel
1. inserting the panel ,image, label successful by insertcontrol method
2. but the color does not change when I active the mouse on and mouse out event

Anyone has the idea to create this component ??
With Details is better

Regards,
Sam

andrewjb

Roughly:

Derive from TCustomControl - it's more helpful

class TMyControl = class(TCustomControl)
private:
fImage : TImage;
fLabel : TLabel;
public
constructor Create( TComponent pOwner );
end;

constructor TMyControl.Create( pOwner : TComponent )
{
inherited;
fLabel := TLabel.Create( Self );
fLabel.Parent := Self;
fLabel.Width := 50; // etc

fImage := TImage.Create( Self );
fImage.Parent := Self;
// Set size etc.
}

Then just set 'Color' to change you background color, I think, and you've got fLabel and fImage components to play with.

DeerBear

Hi,

Use TCustomControl as it's been told you and use composition inheritance.
Plus, I would use a factory pattern, in order to allow further customization of the
whole component.

Something like this:

unit uMyComponent;

uses Classes, Controls, StdCtrls;

Type

TCustomMyComponent = class( TCustomControl )
private
FImage : TImage;
FPanel : TCustomPanel;
protected
function CreateImage : TImage;virtual;abstract;
function CreatePanel : TCustomPanel;virtual;abstract;
public
constructor Create( AOwner : TComponent );override;
destructor Destroy;override;
end;

implementation

constructor TCustomMyComponent.Create;
begin
Inherited;
FImage := CreateImage;
FPanel := CreatePanel;
end;

destructor TCustomMyComponent.Destroy;
begin
FPanel.Free;
FImage.Free;
inherited;
end;

end.

Then you add a "real" CreateImage and CreatePanel overrided in a descendant class and you're done :-)

HTH,

Andrew

Sam80

ASKER

Thanks ,guys.
Andrew , you mean I should write the code in function createimage to setsize or set position the Flabel or FImage?

function createimage:Timage
var
img:Timage;
begin
img:=Timage.create(self);
img.parent:=self;
img.width=50 //etc
result := img ;
end;

Is that like above ?
I cant figure out what is the " virtual;abstract; " , can you tell me a little bit more ?

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DeerBear

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