[ SOLVED ] Lazarus/FPC FillRect drives me nuts and crazy
lazarus / 39-Graphics

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jipété · 2024-05-26 10:03

Hello,

found in an old project, related to TImage :
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 procedure
TForm1.btnTestClick(Sender: TObject);begin  with Image1.Canvas do
begin    Clear; // ! \\ // ! \\ MANDATORY if not, black display // !
\\     // http://forum.lazarus.freepascal.org/index.php?topic=12558.0 
  Brush.Style := bsSolid;    Brush.Color := clRed;    FillRect(0, 0,
Width, Height); // ok    { Save to file }    image1.Picture.SaveToFile
('test+4params_DrawTest.png'); // ok  end;end;
That's ok, but

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 ...   
Brush.Color := clRed;    FillRect(image1.BoundsRect); // other way,
see https://forum.lazarus.freepascal.org/index.php/topic,12558.msg6466
2.html#msg64662    { Save to file }    image1.Picture.SaveToFile
('test+BoundsRect_DrawTest.png'); // NOT ok !  end;end;
For BoundsRect, see https://forum.lazarus.freepascal.org/index.php/top
ic,12558.msg64659.html#msg64659.

I really don't understand...

Have a nice day,

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jamie · 2024-05-26 13:41

BoundsRect reports location of image within the parent control.

If you look at the LEFT, TOP of Timage you should see it match the
BoundsRect you are getting minus some special border operations.

If the image isn't fully left,top of the parent control, it will
report an offset.

also, beware that using the Width,Height of the canvas isn't reliable
because it can grow larger than what your drawing surface is.

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KodeZwerg · 2024-05-26 13:50

From what I see two mini lessons, never use TImage to actually draw
something and second always use a image format that does do what you
want to do and when you finished painting assign it to display
control, like TImage.
At least my ruleset is like that. TImage for display, TSomeImage for
drawing (TBitmap exemplary)

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KodeZwerg · 2024-05-26 14:27

Here is your doing in a (for my knowledge) corrected way:
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 procedure
TForm1.Button1Click(Sender: TObject);  procedure FillTImage(const
AImage: TImage; const AColor: TColor);  var    LBitmap: TBitmap; 
begin    LBitmap := TBitmap.Create;    try      // to simplify, use
controls size      LBitmap.SetSize(AImage.Width, AImage.Height);     
LBitmap.Canvas.Brush.Style := bsSolid;      LBitmap.Canvas.Brush.Color
:= AColor;      LBitmap.Canvas.FillRect(LBitmap.Canvas.ClipRect);    
AImage.Picture.Assign(LBitmap);    finally      LBitmap.Free;    end; 
end;  function SaveTImageAsPNG(const AImage: TImage; const AFilename:
string): Boolean;  var    png: TPortableNetworkGraphic;  begin   
Result := False;    // not overwrite files    if FileExists(AFilename)
then      Exit;    png := TPortableNetworkGraphic.Create;    try     
png.Assign(AImage.Picture.Graphic);      png.SaveToFile(AFilename);  
finally      png.Free;    end;    Result := FileExists(AFilename); 
end;var  R, G, B: Byte;begin  Randomize;  R := Random(High(Byte));  G
:= Random(High(Byte));  B := Random(High(Byte));  FillTImage(Image1,
RGBToColor(R, G, B));  SaveTImageAsPNG(Image1,
'DrawTest.png');end;What this code does:
It create and fills a TBitmap with some random color, including its
assignment to TImage class
Saves whatever content the TImage got as a PNG file.
I've nested the methods, feel free to re-use elsewhere.

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jipété · 2024-05-26 16:31

Quote from: jamie on May 26, 2024, 03:41:41 pmBoundsRect reports
location of image within the parent control.Understood, I'll remove
BoundsRect from my mind, thank you.

Quote from: KodeZwerg on May 26, 2024, 03:50:51 pmnever use TImage...
So, why not use image1.Picture, like in that example ? :
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
Image1.Picture.Bitmap.LoadFromFile(Application.Location +
'img_sources/cielab_4ico.bmp');A oneliner which works fine, and easy
to remember, for me it's the best !

Thanks for your code, I'll use it for trying to remove TBitmap off my
life and use FPImage : too many problems with TBitmap and PixelFormat,
for example.

Quote from: KodeZwerg on May 26, 2024, 03:50:51 pm... to actually draw
something And I don't draw, I just ask the system to do that, again,
with oneliners.

Quote from: KodeZwerg on May 26, 2024, 04:27:02 pmWhat this code does:
It create and fills a TBitmap with some random color, including its
assignment to TImage class
Saves whatever content the TImage got as a PNG file.
Works fine, thanks a lot ! 

+++
Sorry, I cannot add "[ SOLVED ]" to my other topic, the Broken
Example, due to limitations from forum,..

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wp · 2024-05-26 16:49

Quote from: jipété on May 26, 2024, 06:31:31 pmCode: Pascal
 [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
Image1.Picture.Bitmap.LoadFromFile(Application.Location +
'img_sources/cielab_4ico.bmp');Better to remember the following code
which is much more universal since it works with every registered
image format while your code works only with the bmp format:
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
Image1.Picture.LoadFromFile(....);
Quote from: jipété on May 26, 2024, 06:31:31 pmtrying to remove
TBitmap off my life and use FPImage
Although I am an absolute friend of fcl-image this is not a good idea.
Many things are much easier to achieve with TBitmap than with FPImage.
And the associated fcl-image library (and to a lesser extent the
IntfGraphics library with TLazIntfImage and TLazCanvas) are not
complete: the Pen.Width in the Ellipse or Polygon methods can only be
1, there is no GradientFill, poor region support, and drawing text is
quite complicated. No - do not forget TBitmap. Like most things in
life, everything has advantages and disadvantages...

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KodeZwerg · 2024-05-26 16:52

Quote from: jipété on May 26, 2024, 06:31:31 pmQuote from: KodeZwerg
on May 26, 2024, 03:50:51 pmnever use TImage... So, why not use
image1.Picture, like in that example ? :
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
Image1.Picture.Bitmap.LoadFromFile(Application.Location +
'img_sources/cielab_4ico.bmp');A oneliner which works fine, and easy
to remember, for me it's the best !
For such purposes the display class TImage is invented for, you did
misunderstood my text.
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 with
Image1.Canvas do begin....I do not say that "with" is worse... damn I
said it :-/
You try to manipulate the canvas of the TImage container while
"Image1.Picture.Bitmap.LoadFromFile" does load and assign a bitmap
file (exact same way as I do by code).
So direct access one graphics format for loading is cool or to
simplify "Image1.Picture.LoadFromFile" should be enough to load and
display any supported format.
Accessing pixels of TImage.Canvas = just dont.
I hope you understand my meaning and I agree, oneliners are cool but
the context where those can be called must fit.