delphidelphi-10.3-rioskiaskia4delphi

How to resize image using Skia4Delphi


I can load and save image files using Skia4Delphi.

Here is my code:

var
  LImage: ISkImage;
  LSurface: ISkSurface;
  LPaint: ISkPaint;
begin
  LImage := TSkImage.MakeFromEncodedFile('C:\IMAGE-OLD.PNG');
  LPaint := TSkPaint.Create;
  LSurface := TSkSurface.MakeRaster(LImage.Width, LImage.Height);
  LSurface.Canvas.DrawImage(LImage, 0, 0, LPaint);
  LSurface.MakeImageSnapshot.EncodeToFile('C:\IMAGE-NEW.PNG');
end;

How can I resize the image to a defined size (width and height) before saving? (Delphi 10.3.3 VCL)


Solution

  • Here is the code for a simple (stretched) resize:

    uses
      System.UITypes, Skia;
    
    function GetResizedImage(const AImage: ISkImage; const ANewWidth, ANewHeight: Integer): ISkImage;
    var
      LSurface: ISkSurface;
    begin
      LSurface := TSkSurface.MakeRaster(ANewWidth, ANewHeight);
      LSurface.Canvas.Clear(TAlphaColors.Null);
      LSurface.Canvas.Scale(ANewWidth / AImage.Width, ANewHeight / AImage.Height);
      LSurface.Canvas.DrawImage(AImage, 0, 0, TSkSamplingOptions.High);
      Result := LSurface.MakeImageSnapshot;
    end;
    
    procedure TForm1.FormCreate(Sender: TObject);
    var
      LImage: ISkImage;
    begin
      LImage := TSkImage.MakeFromEncodedFile('a.png');
      LImage := GetResizedImage(LImage, 24, 24);
      LImage.EncodeToFile('a.png', 100);
    end;