Is TFPImageCanvas.StretchDraw slow
lazarus / 39-Graphics

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Zaher · 2019-12-28 11:04

My project is small bitmap font editor, I am adding new control to
edit small png transparent image with alpha pixles.

Drawing pixels started being slow at size > 64, with scaling it 10
times

here the part of code of painting it
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i var  Img:
TBitmap;  fpimage: TLazIntfImage;begin  if IsChanged then  begin   
IsChanged := False;    if (PaintTool <> nil) and not (ptsDirect in
PaintTool.Style) then    begin      ScrachImage.CopyPixels(FImage);  
  PaintTool.Paint(FScrachCanvas);      fpimage := ScrachImage;    end 
  else      fpimage := Image;    
ScaledImage.CopyPixels(BackgroundImage);    ScaledCanvas.DrawingMode
:= dmAlphaBlend;    //ScaledCanvas.Interpolation :=
TFPBoxInterpolation.Create; moved to after create ScaledCanvas   
ScaledCanvas.StretchDraw(0, 0, ScaledImage.Width, ScaledImage.Height,
fpimage);  end;   Img := TBitmap.Create;  try   
Img.LoadFromIntfImage(ScaledImage);    vCanvas.Draw(0, 0, Img); 
finally    Img.Free;  end;end; 
and images created here
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i   FImage :=
TLazIntfImage.Create(cDefaultWidth, cDefaultHeight, [riqfRGB,
riqfAlpha]);  FCanvas := TFPImageCanvas.Create(FImage);  FDrawer :=
TIntfFreeTypeDrawer.Create(FImage);  FFont := TFreeTypeFont.Create; 
FFont.Name := 'c:\Windows\fonts\Arial.ttf';  FFont.SizeInPixels := 9; 
FFont.Hinted := False;  FFont.ClearType := False;  FFont.Quality :=
grqLowQuality;   FScrachImage :=
TLazIntfImage.CreateCompatible(FImage, cDefaultWidth,
cDefaultHeight);  FScrachCanvas :=
TFPImageCanvas.Create(FScrachImage);   ScaledImage :=
TLazIntfImage.CreateCompatible(ScrachImage, ScrachImage.Width *
DotSize, ScrachImage.Height * DotSize);  ScaledCanvas :=
TFPImageCanvas.Create(ScaledImage);  ScaledCanvas.Interpolation :=
TFPBoxInterpolation.Create;   BackgroundImage :=
TLazIntfImage.CreateCompatible(ScrachImage, ScrachImage.Width *
DotSize, ScrachImage.Height * DotSize);  BackgroundCanvas :=
TFPImageCanvas.Create(BackgroundImage);   FHistory :=
TntvHistory.Create;   SetSize(cDefaultWidth, cDefaultHeight); 
my project is opensource https://github.com/parmaja/minictrls/blob/mas
ter/native/ntvPixelGrids.pas#L612

Where is my fault, or Is there any way to make it faster painting or
generating scaled image?