ImageData

Scaleform::Render::ImageData

class ImageData;

ImageData describes the image data in addressable memory that can be accessed and modified directly. ImageData is usually initialized by Image::Map or Texture::Map functions; it can also be created as a temporary on stack. 

ImageData can include any number of channel and mip-level planes, addressable individually based on plane index. Many standard format images will have only one data plane, plane 0. The size of the image is the size of its 0th plane. 

Right now, it is assumed that there is a fixed relationship between image size and the size of all its extra planes, as reported by GetFormatPlaneSize. In the future this may change, which would require extra Image::Create functions. 

Image planes are numbered first by the order of data channels in ImageFormat, then by mip-map level index. Image_R8G8B8A8, for example, has only one channel, thus the index of a plane and mipmap is the same. Image_Y8_U2_V2, however, has three data planes, indexed as {Y = 0, U = 1, V = 2}. If such an image also has mip-map levels, the U plane of a second mipmap (first down from the top level), would have an index of 5. 

For efficiency, ImageData stores one ImagePlane directly as a data member, allocating additional planes only when they are needed. For standard system-memory formats, additional mipmap data is stored immediately following the top level data, so its location and size can be computed without keeping additional ImagePlane structure for every level. Such compact plane storage is used by default unless "SeparateMipmaps" flag is specified, so a call to GetPlane() actually computes the requested memory location based on the top-level plane and its format.

Render_Image.h