cairo-png-functions: PNG Support
Description
Reading and writing PNG imagesDetailed Description
The PNG functions allow reading PNG images into image surfaces, and writing
any surface to a PNG file.User Functions
cairo_read_func_t(closure, data, length)-
cairo_read_func_t is the type of function which is called when a
backend needs to read data from an input stream. It is passed the
closure which was specified by the user at the time the read
function was registered, the buffer to read the data into and the
length of the data in bytes. The read function should return
CAIRO_STATUS_SUCCESS if all the data was successfully read,
CAIRO_STATUS_READ_ERROR otherwise.
closure- [R object] the input closure
data- [char] the buffer into which to read the data
length- [integer] the amount of data to read
Returns: [CairoStatus] the status code of the read operation cairo_write_func_t(closure, data, length)-
CairoWriteFunc is the type of function which is called when a
backend needs to write data to an output stream. It is passed the
closure which was specified by the user at the time the write
function was registered, the data to write and the length of the
data in bytes. The write function should return
CAIRO_STATUS_SUCCESS if all the data was successfully written,
CAIRO_STATUS_WRITE_ERROR otherwise.
closure- [R object] the output closure
data- [char] the buffer containing the data to write
length- [integer] the amount of data to write
Returns: [CairoStatus] the status code of the write operation