Multi-Form Referencing

[cdbc]

Hi J-G
I'll bet you didn't see this one coming... \o/\ö/\o/
Have a 'LookSee' at THIS repo. (the zip is just a smidgen over 500Kb.)
Regards Benny

edit: Added a screeshot...

[J-G]

Hi J-G
I'll bet you didn't see this one coming... \o/\ö/\o/
Have a 'LookSee' at THIS repo. (the zip is just a smidgen over 500Kb.)
Regards Benny

edit: Added a screeshot...

You're not wrong there Benny 🤪

There are many (MANY) lessons to be learned from a study of that small program - some of which have already found a home 😄   -   whether they will still be with me tomorrow is another story!  -  I hope so but (as I'm sure you will appreciate) many new questions are already being formed  -  even though the embedded comments are very useful.

It has long puzzled me as to how there can be many procedures/functions with ostensibly the same name - -  Reading through your code I came to realize that the ARGUMENTS can (do?) differentiate them. 

To force a program to close I've generally used Application.Terminate - specifically at the end of a Form 'OnClose' event (which does any 'tidying up') so seeing your call to simply 'Close' is interesting - - -  stepping through, I see that BeforeDestruction does the tidying up (Clear/Free) but I cannot see such an 'event' in the object inspector. Just as I cannot see AfterConstruction.

None of this advances my current project (yet) - I have much work to do before that comes to fruition - but it's well worthwhile nonetheless and I am already looking at the TBitmap 'thing'.  As an example though, your showing the images at their natural size after a [Form.ReSize] is not what I need. if the Form is enlarged, then my image must also be enlarged in the same proportion. Likewise with a reduction.  I'm sure that is just a matter of code adjustment  -  My 'Plot' already handles that, I just need to change the 'Canvas' to a TBitmap.

[cdbc]

Hi
1)

It has long puzzled me as to how there can be many procedures/functions with ostensibly the same name - -  Reading through your code I came to realize that the ARGUMENTS can (do?) differentiate them.

   A: Yes the argumentlists set them apart, FPC is smart \o/

2)

I see that BeforeDestruction does the tidying up (Clear/Free) but I cannot see such an 'event' in the object inspector. Just as I cannot see AfterConstruction.

   A: They're -not- events, but virtual methods of 'TObject', we just override
   them, quicker than events...

3)

I just need to change the 'Canvas' to a TBitmap.

   A: Ahum, what's wrong with 'TBitmap.Canvas'? It'll do mighty fine...
Regards Benny

[J-G]

Well!  -   I've given up for today 

I've tried myriad different options :   drawing the TBitmap on the TPanel.Canvas, on a  TImage.Canvas, on a TPaintBox.Canvas etc. all without any benefit  -  ie. Form.ReSize ALWAYS clears the canvas at the end of the draw (such as Output.PaintBox.Canvas.Draw(0,0,D_Bmp); )

I do see a brief 'flash' of the image on occasion just prior to the process completing, which tells me that the image HAS been drawn.

I haven't fully investigated the behaviour of Form.ReSize when using a TPaintBox but that did seem to interfere with the ReSize (restricting it ?), and the TImage backgound is always black even though I've set its brush to clMoneyGreen.

The lesson learned seems to be that even using TBitmap - the image doesn't persist after a Form.ReSize.

There must be something that I've still not understood (I still haven't invoked an 'OnPaint' Event ? could that be the 🗝️ ?)  but I'll give my brain a rest and see if I can fathom what needs to be done tomorrow.

It seems that I don't have a virtual Uncle Bob 🤣🤣

[jamie]

The OnSize Event should not be used to modify the form it came from, that will cause a loop and most likely generate a flashing form with artifacts on it.
years ago, the OnSize Event used to work correctly because it's supposed to be generated when the user resizes the form, however, during Delphi early years, they decided to have that triggered during any method of resizing and that causes issues.

 If you are trying to maintain an aspect ratio there are ways to do this with smoothly operating effects and that is a specific windows message you can process that allows you to make changes to values that are getting ready to go into effect, sort of intercepting the size change.

 Let me know if you are interested, otherwise I'll go back to sleep;

Btw, using the OnPaint even should be the correct time to paint your updates.

Jamie

[cdbc]

Hi
· Draw on the internal bitmap
· In the O N P A I N T-handler the
  canvas now handles the scaling, when drawing the bitmap onto itself \o/
· It doesn't matter if you paint a photo or a technical drawing, it scales...
:: I changed 1 line in the O N P A I N T-handler, to achieve this!!!

Stop trying "useless" and do what you're shown and told!

Code: Pascal  [Select][+][-]

1. unit view.main;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6. (* Copyright ©2026 Benny Christensen a.k.a. cdbc,    *)
7. (* released as PUBLIC DOMAIN - Use at your own risk! *)
8. uses
9.   Classes, ExtCtrls,StdCtrls,SysUtils, Forms, Controls, Graphics, Dialogs,
10.   cdbc.istreams;
11.  
12. type
13.   { TfrmMain }
14.   TfrmMain = class(TForm)
15.     Bevel1: TBevel;
16.     btnClose: TButton;
17.     btnMagic: TButton;
18.     gbxResult: TGroupBox;
19.     pnlImg: TPanel;
20.     pnlTop: TPanel;
21.     procedure btnCloseClick(Sender: TObject);
22.     procedure btnMagicClick(Sender: TObject);
23.     procedure pnlImgPaint(Sender: TObject);
24.   private
25.     fArrayImg: array[0..2] of IMemoryStream;
26.     fBmp: TBitmap;
27.     fDrawing: boolean;
28.     procedure DrawByIndex(const anIdx: ptrint);
29.   public
30.     procedure AfterConstruction; override;
31.     procedure BeforeDestruction; override;
32.   end;
33.  
34. var
35.   frmMain: TfrmMain;
36.  
37. implementation
38.  
39. {$R *.lfm}
40. resourcestring
41.   rsCaption = '(O)ff (S)creen (P)ainting';
42.  
43. { TfrmMain }
44. procedure TfrmMain.btnCloseClick(Sender: TObject);
45. begin
46.   Close;
47. end;
48.  
49. procedure TfrmMain.btnMagicClick(Sender: TObject);
50. const lidx: ptrint = 0; { static variable }
51. begin
52.   DrawByIndex(lidx);
53.   inc(lidx);
54.   if lidx > 2 then lidx:= 0;
55. end;
56.  
57. procedure TfrmMain.pnlImgPaint(Sender: TObject);
58. begin
59.   if fDrawing then exit; { first we check our /lock/, a missed beat doesn't kill us }
60.   pnlImg.Canvas.CopyMode:= cmSrcCopy; { actually the default behaviour }
61. ///  pnlImg.Canvas.StretchDraw(rect(0,0,315,234),fBmp); { fixed image-sizes regardsless of form-size }
62.   { if the user resizes the form, we scale with the new size :o) }
63.   pnlImg.Canvas.StretchDraw(rect(0,0,pnlImg.Width,pnlImg.Height),fBmp);
64. end;
65.  
66. procedure TfrmMain.DrawByIndex(const anIdx: ptrint);
67. begin
68.   fDrawing:= true;     { we don't want the canvas blitting while we're drawing }
69.   fBmp.Clear;               { not entirely sure, this is necessary, but hey... }
70.   fBmp.LoadFromStream(fArrayImg[anIdx].AsTStream);  { preloaded to streamarray }
71.   fArrayImg[anIdx].Position:= 0;  { reset after use, or we'll see a black rect }
72.   fDrawing:= false;  { release our lock and notify panel about a redraw needed }
73.   pnlImg.Invalidate;                   { sends a WM_PAINT message to our panel }
74. end;
75.  
76. procedure TfrmMain.AfterConstruction;
77. begin
78.   inherited AfterConstruction; { here we'll preload the images - for speed :o) }
79.   fArrayImg[0]:= CreMemStreamFromFile('img'+PathDelim+'316x235_Novigrad_Castle.bmp');
80.   fArrayImg[0].Position:= 0; { muy importante! }
81.   fArrayImg[1]:= CreMemStreamFromFile('img'+PathDelim+'316x235_Novigrad_Sunset.bmp');
82.   fArrayImg[1].Position:= 0; { muy importante! }        
83.   fArrayImg[2]:= CreMemStreamFromFile('img'+PathDelim+'316x235_Novigrad_Wauw.bmp');
84.   fArrayImg[2].Position:= 0; { muy importante! }
85.   fBmp:= TBitmap.Create; { create once and reuse :: -much- quicker \o/ }
86.   fBmp.SetSize(316,235); { i've created the photos, so i know :: otherwise... }
87.   Caption:= rsCaption;
88. end;
89.  
90. procedure TfrmMain.BeforeDestruction;
91. begin
92.   fArrayImg[0]:= nil; fArrayImg[1]:= nil; fArrayImg[2]:= nil; { com-objects }
93.   fBmp.Clear; fBmp.Free; { class }
94.   inherited BeforeDestruction;
95. end;
96.  
97. end.
98.  

Regards Benny

[J-G]

Morning All, 

It is always challenging to comunicate one intentions (as far as what is envisaged by the programmer wishes to achieve). It's also something of an issue to provide a fully compileable code when there are 'personal' Units used.

It maybe that all I need to do to make a Project Compilable is to [Publish] it but add the various Unit .PAS files to the .ZIP  - but no one has ever confirmed this thought. There is nothing 'confidential' in my Personal Units, they are simply collections of procedures/function which I've found over time to be useful in multiple projects, giving me a commonallity. I suspect that is a 'normal' process for most of us.

These thought gave rise to me considering posting a fully compiled (ie. working) program (as a .ZIP since .EXE files cannot be attached) so that anyone could at least see what I'm attempting.

Currently the code is in a state of 'test' where I have multiple options as to the component on which the output is displayed, so I'd first strip it back to the working state before I tried to solve the 'no-show' on ReSize.

Which method would be the most effective?  Published + Unit .PAS files or a zipped .EXE ?

!!  SORRY @Benny  !!  -  I've just seen your new post 
I'll read that properly to see if I get a better understanding.

I'll also respond to @Jamie

[cdbc]

Good morning J-G
Q: "Which method would be the most effective?  Published + Unit .PAS files or a zipped .EXE ?"
A: Published + Unit .PAS files, just make a copy of your units in a subfolder under 'published' and zip the lot...
Regards Benny

[J-G]

The OnSize Event should not be used to modify the form it came from, that will cause a loop and most likely generate a flashing form with artifacts on it.
years ago, the OnSize Event used to work correctly because it's supposed to be generated when the user resizes the form, however, during Delphi early years, they decided to have that triggered during any method of resizing and that causes issues.

 If you are trying to maintain an aspect ratio there are ways to do this with smoothly operating effects and that is a specific windows message you can process that allows you to make changes to values that are getting ready to go into effect, sort of intercepting the size change.

 Let me know if you are interested, otherwise I'll go back to sleep;

Btw, using the OnPaint even should be the correct time to paint your updates.

Jamie

Thanks for your input @Jamie, I'm always interested in anything anyone has to offer.

The Event I'm using is 'OnReSize' (rather than 'OnSize' which I don't see in the OI) this seems to me to be reasonable, but I take your point that things have evolved over time.

The aspect ratio is no longer an issue, that part is fully operational; including the control of Max/Mix/Screen position - and I now also understand that I can probably (certainly?) achieve my goal without needing to call the 'Plot' proc after a Form ReSize. (Re: @Benny)

[J-G]

Good morning J-G
Q: "Which method would be the most effective?  Published + Unit .PAS files or a zipped .EXE ?"
A: Published + Unit .PAS files, just make a copy of your units in a subfolder under 'published' and zip the lot...
Regards Benny

Thanks @Benny  -  I'll do the clean up first   -  and maybe do the corrections you've previously suggested 

[J-G]

A: Published + Unit .PAS files, just make a copy of your units in a subfolder under 'published' and zip the lot...
Regards Benny

Right!  -  I'm at a 'Half-way-house'  -  I have been able to fathom the workflow to incorporate an OnPaint event and included some parts of the 'Plot' routine within that.

It's still not 'fully formed' but to provide a better understanding about my intentions and the differences I've added a Button to make the Bitmap (and OnPaint) active or not.

With the bitmap 'Active' I see a black background to the output (rather than clMoneyGreen). So I still haven't understood that aspect.

The issue about the personal Units files seems an odd one - but I think I have a reason  -  I did make a copy of them all and intended to add them to the .ZIP file but when I opened the .ZIP - - - - - they were all there !!!

The fact that it appears that they are not available I suspect is because I keep them in a separate sub-folder and that is added to the [Paths] Option in the Project Options under 'Other Unit Files (-Fu):'.

To foil any problem that the UnZip program may create I've made a separate .Zip of just those files.

Because I use two screens, the option to have the [Output] Form 'Floating' or 'Docked' gives the flexability to have a larger display on the second screen.

I'm getting there, but still need guidance so I hope that compilation is posible so that you can clearly see what I do.

Time for a late 'Breakfast' !

[J-G]

Oooops -  I've just remembered that I've modified the Canvas.inc file line 690 from LineTo(x1,y1)  to  MoveTo(x1,x2) to eliminate the line drawn from the 'centre' of the Arc.

This will affect what you see when the Reuleaux lines are drawn (Odd N° of Sides < 13).

It's not material to the problem but it's better that you know.

[cdbc]

Hi J-G
Sorry mate someone else will have to look at your project, because in two hours I'm flying on holiday with the Missus \o/
Regards Benny

[J-G]

No matter Benny, Have a good journey.

[WonderNomad]

Add Poly's unit to the uses clause of display.pas (under implementation to avoid circular references), and you'll be able to access its components directly.