TImage and visabillity
lazarus / 39-Graphics

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madref · 2015-03-14 18:26

I have several images onto of each other and depending on the input i
want to show that image.
I use the following code:
Code: [Select]  case MsgT of
    mNone     : begin
                  Image_UitroepTeken.Visible := False;
                  Image_VraagTeken.Visible := False;
                  Image_Informatie.Visible := False;
                  Image_Stop.Visible := False;
                  //Ook lblMessage verschuiven
                  Label_Message.Left := 10;
                  Label_Message.Top := 10;
                  Label_Message.Width := 380;
                end;     // mNone
    mStop     : begin
                  Image_UitroepTeken.Visible := False;
                  Image_VraagTeken.Visible := False;
                  Image_Informatie.Visible := False;
                  Image_Stop.Visible := True;
                end;     // mStop
    mInfo     : begin
                  Image_UitroepTeken.Visible := False;
                  Image_VraagTeken.Visible := False;
                  Image_Informatie.Visible := True;
                  Image_Stop.Visible := False;
                end;     // mInfo
    mQuestion : begin
                  Image_UitroepTeken.Visible := False;
                  Image_VraagTeken.Visible := True;
                  Image_Informatie.Visible := False;
                  Image_Stop.Visible := False;
                end;     // mQuestion
    mWarning  : begin
                  Image_UitroepTeken.Visible := True;
                  Image_VraagTeken.Visible := False;
                  Image_Informatie.Visible := False;
                  Image_Stop.Visible := False;
                end;     // mWarning
  end;     // MsgT
If MsgT = mInfo then i get an error on the Image_Informatie.Visible :=
True statement.
I don't know why but can anyone help me?

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Never · 2015-03-14 19:08

what is the error you are getting?

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madref · 2015-03-14 19:34

Error:

Project raised exception class 'External: EXC_BAD_ECCESS'.

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Never · 2015-03-14 19:48

the error means this object Image_Informatie is not yet created or is
freed

beyond this it might be a good idea
to have only on image control and change images usinng an image list

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madref · 2015-03-16 09:18

How do you do that.
Because i am new to Lazarus

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mm7 · 2015-03-17 15:47

You should create the object before you try to use it.
Image_Informatie := TImage.Create...

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Never · 2015-03-17 16:10

here you are have a look  to get the idea
create a project and
add a button
add a timage
add an imagelist -->add 3 images same size (height/width)
add a spinedit-->set minvalue to 0 set maxvalue to the count of
imagelist items wich will be 2
copy paste the code
Code: [Select]unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs,
ExtCtrls, StdCtrls, Spin;

type

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    Image1: TImage;
    ImageList1: TImageList;
    SpinEdit1: TSpinEdit;
    procedure Button1Click(Sender: TObject);
  private
    { private declarations }
  public
    { public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
var loc_Index:Integer;
begin
     loc_Index:=SpinEdit1.Value;
     Image1.Canvas.Clear;
   Image1.Picture.Bitmap.SetSize(ImageList1.Width, ImageList1.Height);
     ImageList1.Draw(Image1.Picture.Bitmap.Canvas, 0, 0, loc_Index);
end;

end.

and run the project change the number in spinedit and click the button
to see the images in timage