Basically, DDS is just a sequence of images (in the Images property). The interpretation of the image sequence depends on other fields: first of all DDSType and Mipmaps.
Note that you can write (change) many properties of this class. This allows you to create, or load and edit, DDS files. You can even later save the DDS image back to the stream (like a file) by SaveToStream or SaveToFile. Be careful though: you're responsible then to set all properties to sensible values. For example, the length (and interpretation) of Images list is determined by other properties of this class, so be sure to set them all to something sensible.
Close all loaded image data. Effectively, this releases all data loaded by LoadFromStream, reverting the object to the state right after creation.
procedure Flatten3d;
Convert 3D images in Images list into a sequences of 2D images. Useful utility for 3d (volume) textures.
Normal loading of 3d DDS textures creates single TCastleImage (using Depth possibly > 1) for each mipmap level. Such TCastleImage with depth is comfortable if you want to load this 3d texture into OpenGL (as then the image data is just a continous memory area, loadable by glTexImage3d). But it's not comfortable if you want to display it using some 2D GUI. For example, it's not comfortable for image viewer like glViewImage.
So this method will convert such TCastleImage instances (with Depth > 1) into a sequence of TCastleImage instances all with Depth = 1. This isn't difficult, memory contents on 3d TCastleImage may be splitted into many 2d TCastleImage instances without problems.
Note that it's safe to do this before saving the image. SaveToFile/SaveToStream methods accept both layouts of images (because, as said, memory contents actually are the same before and after splitting).
Note that this may free all Images (possibly even whole Images object), disregarding OwnsFirstImage (as it would be difficult, since it may or may not replace it with new images).
procedure DecompressS3TC;
Decompress S3TC images (if any) on the Images list, replacing them with uncompressed equivalents.
Just like Flatten3d: Note that this may free all Images (possibly even whole Images object), disregarding OwnsFirstImage (as it would be difficult, since it may or may not replace it with new images).
When False, then closing this DDS image will not free Images[0]. Closing happens when you call the Close method or destructor of this object. When this is False, you're responsible to storing and freeing Images[0] later yourself, or you'll get memory leaks.