TIEBitmap.AlphaLocation

Declaration

property AlphaLocation: TIEAlphaLocation;

Description

Specifies how the alpha channel (transparency) is handled by the image.

Value	Description
iaAlphaChannel	A TIEBitmap is used to store the transparency of the image. It is accessible via AlphaChannel and can be manipulated by all standard ImageEn functionality
iaRGBA	Uses the A channel of a 32bit RGBA (ie32RGB) format image. In this location, the alpha channel can only be manipulated using Pixels_ie32RGB or Alpha

ImageEn's native alpha support uses an AlphaChannel, which is TIEBitmap so it can be edited and manipulated using all standard ImageEn methods.
Some windows methods use an RGBA format, e.g. copying from a 32bit bitmap or loading an Bitmap, WebP or SVG in Native Pixel Format. In these situations, AlphaLocation will be iaRGBA, which ImageEn will use for display. Any operation that makes use of the native AlphaChannel will automatically convert the AlphaLocation to iaAlphaChannel.

Notes:
◼AlphaLocation has no effect unless the pixel format is ie32RGB
◼If you access the AlphaChannel, AlphaLocation will be set to iaAlphaChannel
◼If the AlphaLocation is iaRGBA, then setting it to iaAlphaChannel will copy the RGBA "A" channel to the AlphaChannel
◼If the AlphaLocation is iaAlphaChannel, then setting it to iaRGBA will copy the AlphaChannel to the RGBA "A" channel (if it is valid). To prevent this remove the alpha channel before setting AlphaLocation
◼To load an image in 32bit RGBA format (Bitmap, SVG, WebP or WIC formats) set NativePixelFormat := True

Default: iaAlphaChannel

Examples

// Load an SVG image in ie32RGB format using tranparency from the RGBA "A" channel
ImageEnView1.IO.Params.NativePixelFormat := True;
ImageEnView1.IO.LoadFromFile( 'D:\World.svg' );
// >>> AlphaLocation will be iaRGBA

// Load a PNG with an alpha channel and and display using RGBA
ImageEnView1.IO.LoadFromFile( 'D:\32bit Alpha.png' );
ImageEnView1.IEBitmap.PixelFormat := ie32RGB;
ImageEnView1.IEBitmap.AlphaLocation := iaRGBA; // Move alpha to RGBA channel
ImageEnView1.Update();

TIEBitmap.AlphaLocation