On Sat, 05 Jan 2008 19:14:51 +0000
Dominique Louis <[EMAIL PROTECTED]> wrote:
> Firstly, I'd like to propose a slight change to the scanlines example
> so that it is easier for developers to follow the code and to
> possibly incorporate bits of it into their own code.
>
> type
> TBGRA = packed record
> b, g, r, a : byte;
> end;
> PBGRA = ^TBGRA;
> TBGRAArray = array[ WORD ] of TBGRA;
> PBGRAArray = ^TBGRAArray;
>
>
> procedure TForm1.PaintToRGB32bitScanLine(Row, ImgWidth: integer;
> LineStart: Pointer);
> // LineStart is pointer to the start of a scanline with the following
> format:
> // 4 bytes per pixel. First byte is blue, second green, third is red.
> // the fourth byte is the Alpha value, which is not specified in this
> // example
> // Black is 0,0,0, white is 255,255,255
> var
> i: Integer;
> lrow : PBGRAArray
> begin
> lrow := PBGRAArray( LineStart )
>
> // fill line with gray
> for i := 0 to ImgWidth - 1 do
> begin
> lrow^[ i ].r := 128; // set red to 128
> lrow^[ i ].g := 128; // set green to 128
> lrow^[ i ].b := 128; // set blue to 128
> end;
> // set one diagonal pixel to red ( this creates a diagonal red
> line ) lrow^[ ( Row mod ImgWidth ) ].r := 255; // set red to 255 -
> full intensity
> lrow^[ ( Row mod ImgWidth ) ].g := 0; // set green to 0
> lrow^[ ( Row mod ImgWidth ) ].b := 0; // set blue to 0
> end;
>
>
> I think this is a lot easier to understand than the previous version.
Ok. Can you create a patch?
> Secondly, I have a scanline issue that I hope someone on here can
> help with. I have 2 TImages on a Form ( I'm using Mac OS X if that
> makes any difference ) one contains an image of a yellow light bulb.
> I want to copy, pixel by pixel, the image from one TImage over to the
> second TImage. Yes I know I could just assign the bitmap from one to
> the other, but this is an exercise in Scanline manipulation. The
> problem I have is that once copied the second TImage contains a blue
> light bulb instead of a yellow one.
>
> The code I'm using is..
> MyBitmap := TBitmap.Create;
> ScanLineImage := Image1.Picture.Bitmap.CreateIntfImage;
> MyBitmap.Width := ScanLineImage.Width;
> MyBitmap.Height:= ScanLineImage.Height;
> IntfImage := MyBitmap.CreateIntfImage;
> ImgFormatDescription.Init_BPP32_B8G8R8_BIO_TTB( ScanLineImage.Width,
> ScanLineImage.Height );
> IntfImage.DataDescrption := ImgFormatDescription;
>
> for y := 0 to ScanLineImage.Height do
Height-1
> begin
> lrow := ScanLineImage.GetDataLineStart( y );
> brow := IntfImage.GetDataLineStart( y );
What's brow?
> for x := 0 to ScanLineImage.Width do
Width-1
> begin
> brow^[ x ].r := lrow^[ x ].r; // set red
> brow^[ x ].g := lrow^[ x ].g; // set green
> brow^[ x ].b := lrow^[ x ].b; // set blue
> brow^[ x ].a := lrow^[ x ].a; // set alpha value
> end;
> end;
>
> MyBitmap.LoadFromIntfImage( IntfImage );
> Image2.Picture.Bitmap := MyBitmap;
>
>
> Can anyone see a flaw in my logic of using scanlines for this/this
> way?
Yes.
MyBitmap.LoadFromIntfImage( IntfImage )
does no conversion.
You created an image with the format
ImgFormatDescription.Init_BPP32_B8G8R8_BIO_TTB
which is probably not the format of your platform.
Solution:
Don't use ScanLine, but use the Colors property of IntfImage. See the
examples/lazintfimage/fadein1.lpi.
Mattias
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