using brushcopy

[frank13]

Hi, I have a large bmp which I load at run-time into a TBitmap. The background is pink but I have a bunch of images on that large bitmap. I can paint the entire pink background to white or any other colour using brushcopy.

What I would like to be able to do is be able to do the reverse, keep the pink but paint everything else, regardless of what colour the pixels are, to a single colour such as black.

Anyone know how I would do this?

Thank you

 

[jbpelletier]

Hi,

Depending on how your image looks like, maybe the FloodFill method of TCanvas could help u...

else take a look at
.Canvas.copymode:=cmSrcAnd; // and/or cmMergePaint
with
.Canvas.CopyRect(..)

the idea is to copy your image on you image taking advantage of the copymode.. if u need a concrete exemple let me know i think i have one at home

hope this help
jb

 

[frank13]

Thanks for the response. Nope, floodfill won't help because the background colour is also the transparent colour of many of the images on that bitmap. So a floodfill wouldn't change the pink within those images.

I've been looking at copymodes but I admit my understanding of many of them is lacking even though that's probably where my answer lies. I have used copyrect to blit transparent images to the screen but this is a reverse problem. I want to keep the transparent colour (the pink) and change all the other colours to black.

Currently I'm using GetPixel-PutPixel but geez is that ever slow

 

[Griffyn]

this sounds like a mask. Investigate in the help file on how to create a masked bitmap from your existing bitmap. Masks are used to paint with transparency.

 

[jbpelletier]

hi,

try this, working for me with d5


myfunction(clFuchsia,'C:\mybmp.bmp');

procedure TForm1.myfunction(clr:TColor;path:string);
var
MyRect:TRect;
BMSrc:Tbitmap;
BMTemp:Tbitmap;
begin
//Step 1 : Create bitmap
BMSrc:=TBitmap.Create;
BMTemp:=TBitmap.Create;
//Step 2 : Initialisation
BMSrc.LoadFromFile(path);
BMTemp.Assign(BMSrc);
MyRect:=Rect(0,0,BMSrc.Width,BMSrc.Height);
BMTemp.Canvas.Brush.Color:=clr;
BMTemp.Canvas.FloodFill(1,1,clr,fsBorder);
//Step 3 : apply mask
BMSrc.Mask(clr);
//Step 4 : Merge the 2 bitmap
BMTemp.Canvas.copymode:=cmSrcAnd;
BMTemp.Canvas.copyrect(MyRect,BMSrc.Canvas,MyRect);
//Step 5 : show it
Image1.Picture.Bitmap:=BMTemp;
//Step 6 : free mem
BMSrc.Free;
BMTemp.Free;
end;

jb