Raster object represents raster graphics image (bitmap).
It is implemented as record specifying raste dimensions, color depth, color format etc. and table of data representing raster lines. Different implementations of raster exist supporting different raster formats (BMP, PNG, JPG). It is possible to implement other types too.
Providers should represent bitmaps in their native encoding. All transformations (ie. HSV to RGB) should be handled by special filters.
width: 1..2147483647 px
height: 1..2147483647 px
depth: 1..32 bits -- number of bits per pixel
palette: table of RGB -- if the picture has Pallete format, this represents the pallete
lines: table[1..height] of Data
source_format: Id -- Void, JPEG, PNG, BMP
source_data: Data -- source data for JPEG, PNG, BMP
Lines field represents the actual raster as table of lines. Item with index 1 represents the first (top) line of the raster. One line is represented as data object containing bytes in specified format.
Some raster consumers can support some raster formats in a special way (for example PDF can include JPEG rasters directly, Windows implementation draws BMF files faster using source data). It can detect, if the raster has the proper source format using source_format property. If it is supported format, it can use source_data to access original source (where applicable).
If a raster returns other source_format than VOID, it MUST return non-null source_data object.
One of the following formats an be specified: