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font problem with forms and paintboxes

font problem with forms and paintboxes

I have an app that uses a form and objects derived from a paintbox that are created at run-time. In the constructor for the objects I assign to the event handlers and some of the properties. The remainder of the properties are assigned from a text file after the object is created. The problem is that I cannot assign to the font of the paintbox canvas. I read the font name, size and color from the text file and assign them to the paintbox canvas font but the font always reverts back to the same font - the font of the underlying form. This occurs even if I subsequently change the underlying form's font - any objects subsequently created still take on the font that the form had at design-time. All other properties behave fine - apart from the font.

I have set the ParentFont property to FALSE in the constructor.

A paintbox added to the form at design time does not suffer from the problem - only ones created at run-time.

JimBob091197

Hi

There must be something else wrong. The following code works fine at run-time: (PBox is a control inherited from TPaintBox.)

procedure TForm1.FormCreate(Sender: TObject);
var
PBox: TNewPaintBox;
begin
PBox := TPaintBox.Create(Self);
PBox.Parent := Self;
PBox.ParentFont := False;
PBox.Font.Style := [fsBold];
PBox.Font.Name := 'Times New Roman';
PBox.Font.Size := 18;
PBox.OnPaint := DoPaint;
end;

procedure TForm1.DoPaint(Sender: TObject);
begin
with TPaintBox(Sender) do
Canvas.TextOut(10, 10, 'Hello');
end;

Could you provide some of your code?

JB

rossmcm

ASKER

Hi,

I agree I must be doing something wrong! The code you supplied works fine. What follows below doesn't. I will be interested to know why.

My paint method for the paintbox is a method of the paintbox, rather than the form as it was in your example. That seems to make no difference.

Thanks for your time

Ross.

........................................

unit Pbform;

interface

uses
SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,
Forms, Dialogs, stdctrls, extctrls ;

type
TForm1 = class(TForm)
procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
private
{ Private declarations }

public
{ Public declarations }
end;

type
TMyPaintbox = class (TPaintBox)

private
procedure MyPaintboxClick (Sender : TObject) ;
procedure MyPaintboxDblClick (Sender : TObject) ;
procedure MyPaintboxPaint (Sender :TObject) ;
constructor Create (Owner : TComponent) ; override ;
destructor Destroy ; override ;
end ;

var
Form1: TForm1;

implementation

{$R *.DFM}

var
MyPaintbox : TMyPaintbox ;

constructor TMyPaintbox.Create (Owner : TComponent) ;

begin
inherited Create (owner) ;
width := 100 ;
height := 25 ;
parent := TForm1 (owner) ;
visible := true ;
enabled := true ;

OnClick := MyPaintboxClick ;
OnDblClick := MyPaintboxDblClick ;
OnPaint := MyPaintboxPaint ;

ParentFont := false ;
canvas.font.name := 'Courier' ;
canvas.font.size := 6 ;
canvas.font.color := clBlack ;
end ;

destructor TMyPaintbox.Destroy ;

begin
inherited Destroy ;
end ;

procedure TMyPaintbox.MyPaintboxClick (Sender : TObject) ;

begin
BringToFront ;
invalidate ;
end ;

procedure TMyPaintbox.MyPaintboxPaint (Sender : TObject) ;

begin
canvas.roundrect (0, 0, width, height, 2, 2) ;
canvas.textout (4, 4, canvas.font.name) ;
end ;

procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
MyPaintbox := TMyPaintbox.create (self) ;
with MyPaintbox do
begin
left := X ;
top := Y ;
canvas.font.name := 'Courier' ; { ignored }
canvas.font.size := 20 ;
canvas.font.color := clRed ;
end ;
end;

procedure TMyPaintbox.MyPaintboxDblClick (Sender: TObject);
begin
canvas.font.name := 'Arial' ; { ignored }
canvas.font.size := 10 ;
canvas.font.color := clBlue ;
invalidate ;
end;

end.

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JimBob091197

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rossmcm

ASKER

That cured it all right. Many thanks. I am baffled however as to why the paintbox itself has a font property - what is this used for ?

Thanks again,

Ross.

JimBob091197

I think the paintbox has a font property so that at design-time it appears in the Object Inspector. (The canvas property doesn't appear there...)

JB