Resize PNG in Delphi 11

[dmitrok2006 2]

Hello! Need help on this topic. In general, I will describe in more detail. I throw Image1 on the form. Manually (just manually) I load a Png image there, say 600x700, with transparency. Using the code, I need to resize this image loaded in Image1 and then save it to disk in new sizes. The Stretch property doesn't help, because on the contrary, Image1 is adjusted to fit the image and as a result, when saved, Png of the same sizes. I tried Image1.Picture.graphic.setsize, but then a piece of the picture is saved

Help. pliz......

[programmerdelphi2k 237]

I think that is VCL, not?  Image1.Picture.Graphic.SetSize(...) ...

procedure TForm1.Button1Click(Sender: TObject);
var
  LPictureSource: TPicture;  // load a PNG
  LPictureTarget: TPicture;  // to resize like a Bitmap
  LPNGresulted  : TPngImage; // to save PNG resulted
begin
  LPictureSource := TPicture.Create;
  LPictureTarget := TPicture.Create;
  LPNGresulted   := TPngImage.Create;
  try
    LPictureSource.LoadFromFile('Spiderman.png'); // with transparent background on png
    LPictureSource.Graphic.Transparent := True;
    //
    Memo1.Text := 'Spiderman.png = ' + LPictureSource.Width.ToString + 'x' + LPictureSource.Height.ToString;
    //
    LPictureTarget.Bitmap.Create(1, 1); // just for create internal values to canvas, etc...
    LPictureTarget.Graphic.Transparent := True;
    //
    // new size
    LPictureTarget.Bitmap.Width  := Trunc(LPictureSource.Width * 4.0); // size x 4
    LPictureTarget.Bitmap.Height := Trunc(LPictureSource.Height * 4.0);
    //
    // draw on new canvas resized
    LPictureTarget.Bitmap.Canvas.StretchDraw(LPictureTarget.Bitmap.Canvas.ClipRect, LPictureSource.Graphic);
    //
    Memo1.Lines.Add(LPictureTarget.Width.ToString + 'x' + LPictureTarget.Height.ToString);
    //
    LPNGresulted.Assign(LPictureTarget.Bitmap);
    //
    Memo1.Lines.Add('PNG = ' + LPNGresulted.Width.ToString + 'x' + LPNGresulted.Height.ToString);
    //
    LPNGresulted.SaveToFile('resulted.png'); // just for test load file...
    //
    Image1.Picture.LoadFromFile('resulted.png');
    Image1.Proportional := True;
  finally
    LPNGresulted.Free;
    LPictureTarget.Free;
    LPictureSource.Free;
  end;
end;

     

Edited February 9, 2023 by programmerdelphi2k

[dmitrok2006 2]

programmerdelphi2k,  thank you very much. I will try.  ))))

[dmitrok2006 2]

programmerdelphi2k, I want to ask ....
Maybe I don't understand something...
But the code uses LoadFromFile, and I need to load the image manually, without using LoadFromFile.

[programmerdelphi2k 237]

@dmitrok2006

you need "load" your image using any way... file, stream, resource, etc...! you decide how to?

[dmitrok2006 2]

I'm fine with any boot method that doesn't access the disk while the exe file is running...
For example, in my project, I manually loaded PNG into Image1....

[programmerdelphi2k 237]

@dmitrok2006

when loading in "design-time" your image is "embedded" in you exe!

[programmerdelphi2k 237]

11 hours ago, programmerdelphi2k said:

// draw on new canvas resized

  LPictureTarget.Bitmap.Canvas.StretchDraw(LPictureTarget.Bitmap.Canvas.ClipRect, LPictureSource.Graphic);

after this line, "LPictureSource" it's not necessary anymore, then, you can " LPictureSource.Graphic := nil"

[dmitrok2006 2]

58 minutes ago, programmerdelphi2k said:

@dmitrok2006

you need "load" your image using any way... file, stream, resource, etc...! you decide how to?

On Form1 I don't need to put Image1 ?

[programmerdelphi2k 237]

To tell the truth, you would only need to embed a "resource" (image, sound, etc...) in strictly necessary case, where to load it... would be something very time consuming, or if the resource doesn't cost much for your system (memory, performance, etc...)!
Overall you could just load it "on-demand"

 

Using a component is just to make the job easier, in fact you can create it at run-time. Or, if you don't need a component, you can just create the component class to do your background work... in code!

Edited February 9, 2023 by programmerdelphi2k

[dmitrok2006 2]

Thank you very much, I'll look into it ))))

[programmerdelphi2k 237]

var
  MyImage: TImage;
begin
  MyImage := TImage.Create(nil);
  try
    MyImage.Left  := 0; // any values ...
    MyImage.Top   := 0;
    MyImage.Width := 0;
    // ...
    MyImage.Picture.LoadFromFile('....');
    //
    MyImage.Parent := self; // self = form1 -> "parent" to appears on screen of form area!!
  finally
    MyImage.Free;
  end;

 

Edited February 9, 2023 by programmerdelphi2k

[dmitrok2006 2]

That is, in the last code at the development stage, the image will be loaded and the file on disk can be deleted?

[programmerdelphi2k 237]

not necessary! just if you want and be sure about this!

[programmerdelphi2k 237]

thanks for all "like",  , :)))

[dmitrok2006 2]

It's a bit hard to understand, but I'll try. Thank you )))))

[programmerdelphi2k 237]

you're wellcome!

[dmitrok2006 2]

Programmerdelphi2k...

One more question....
I made this code, but the transparency seems to have disappeared in the saved PNG. Why?

var
  Form1: TForm1;
  PNGSource: TPicture;
  PNGTarget: TPicture;
  PNGresult: TPngImage;
implementation

{$R *.dfm}

uses Unit2;

procedure TForm1.a0Click(Sender: TObject);
begin
  PNGSource:= TPicture.Create;
  PNGTarget:= TPicture.Create;
  PNGresult:= TPngImage.Create;

  PNGSource:=form2.Aa.Picture;
  PNGSource.Graphic.Transparent := True;

  PNGTarget.Bitmap.Width  := Trunc(PNGSource.Width / 4.0);
  PNGTarget.Bitmap.Height := Trunc(PNGSource.Height / 4.0);

  PNGTarget.Bitmap.Canvas.StretchDraw(PNGTarget.Bitmap.Canvas.ClipRect, PNGSource.Graphic);

  PNGresult.Assign(PNGTarget.Bitmap);
  PNGresult.SaveToFile('c:\1DU\As.png');

 

[programmerdelphi2k 237]

form2.Aa.Picture = "AA" have a "transparence" activated or have a transparence?

[dmitrok2006 2]

[programmerdelphi2k 237]

https://www.pngegg.com/en/png-zhwea   <-- IronMan PNG images!!!

 

Here my TImage2 components is using a "Iron men PNG" in design-time, then I just assign it to my "var LPictureSource" look the code... the rest is the same as above

   

Edited February 9, 2023 by programmerdelphi2k

[dmitrok2006 2]

Can I email the project for you to fix? Please)

[dmitrok2006 2]

There I forgot to write in Var ....

[programmerdelphi2k 237]

a little fix to avoid a "memory leaks"...

Quote

replace this

LPictureTarget.Bitmap.Create(1, 1); // just for create internal values to canvas, etc...   = memory leaks on end-app!!!

with a new obj TBitmap as usual

Quote

BmpTmp := TBitmap.Create(1,1);

...

LPictureTarget.Bitmap.Assign(BmpTmp);

...

BmpTmp.free; // when it's not more necessary!

 

[dmitrok2006 2]

Programmerdelphi2k...   Wow, such a big code)))) I need a few hours to understand. So I'll write the answer tomorrow, ok?
Thank you, you are a good person )