The input to Harfbuzz is a series of Unicode characters, stored in a buffer. In this chapter, we'll look at how to set up a buffer with the text that we want and then customize the properties of the buffer.
As we saw in our initial example, a buffer is created and
initialized with hb_buffer_create()
. This
produces a new, empty buffer object, instantiated with some
default values and ready to accept your Unicode strings.
Harfbuzz manages the memory of objects that it creates (such as
buffers), so you don't have to. When you have finished working on
a buffer, you can call hb_buffer_destroy()
:
hb_buffer_t *buffer = hb_buffer_create(); ... hb_buffer_destroy(buffer);
This will destroy the object and free its associated memory - unless some other part of the program holds a reference to this buffer. If you acquire a Harfbuzz buffer from another subsystem and want to ensure that it is not garbage collected by someone else destroying it, you should increase its reference count:
void somefunc(hb_buffer_t *buffer) { buffer = hb_buffer_reference(buffer); ...
And then decrease it once you're done with it:
hb_buffer_destroy(buffer); }
To throw away all the data in your buffer and start from scratch,
call hb_buffer_reset(buffer)
. If you want to
throw away the string in the buffer but keep the options, you can
instead call hb_buffer_clear_contents(buffer)
.