What file types are you rotating? Are you loading bitmaps? If so then convert the bitmaps to png then rotate will maintain the alphachannel or if loading BMP 32 bits per pixel set BMP_HandleTransparency to true. When BMP_HandleTransparency is true the extra byte is interpreted as an alpha channel, otherwise it is just ignored. So if BMP_HandleTransparency = True the image will be displayed in ImageEn with transparency. Whereas if BMP_HandleTransparency = False the transparent color will not be used.
// if BMP_HandleTransparency = true then display with transparency
ImageENVect1.IO.Params.BMP_HandleTransparency := chkBMPHandleTransparency.Checked;
ImageENVect1.IO.LoadFromFile( FilePath );
if this does not work, then convert the image to 32-bit png and set the transparent color:
var
iRGB: TRGB;
ImageEnView1.IO.Params.BitsPerSample := 8;
ImageEnView1.IO.Params.SamplesPerPixel := 4;
iRGB := ImageEnView1.IEBitmap.Pixels[0, ImageEnView1.IEBitmap.Height - 1];
ImageEnView1.Proc.SetTransparentColors(iRGB, iRGB, 0);
Generally it is best to use png image files when using transparency.
Bill Miller
Adirondack Software & Graphics
Email: w2m@hughes.net
EBook: http://www.imageen.com/ebook/
Custom Commercial ImageEn Development
Search
Roate and keep background transparent
Posted - Nov 04 2015 : 00:25:02
