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hb-blob

hb-blob — Binary data containers

Types and Values

Object Hierarchy

    GBoxed
    ╰── hb_blob_t
    GEnum
    ╰── hb_memory_mode_t

Includes

#include <hb.h>

Description

Blobs wrap a chunk of binary data to handle lifecycle management of data while it is passed between client and HarfBuzz. Blobs are primarily used to create font faces, but also to access font face tables, as well as pass around other binary data.

Functions

hb_blob_create ()

hb_blob_t *
hb_blob_create (const char *data,
                unsigned int length,
                hb_memory_mode_t mode,
                void *user_data,
                hb_destroy_func_t destroy);

Creates a new "blob" object wrapping data . The mode parameter is used to negotiate ownership and lifecycle of data .

[skip]

Parameters

data

Pointer to blob data.

 

length

Length of data in bytes.

 

mode

Memory mode for data .

 

user_data

Data parameter to pass to destroy .

 

destroy

Callback to call when data is not needed anymore.

 

Returns

New blob, or the empty blob if something failed or if length is zero. Destroy with hb_blob_destroy().

Since: 0.9.2


hb_blob_create_from_file ()

hb_blob_t *
hb_blob_create_from_file (const char *file_name);

Parameters

file_name

font filename.

 

Returns

A hb_blob_t pointer with the content of the file

Since: 1.7.7


hb_blob_create_sub_blob ()

hb_blob_t *
hb_blob_create_sub_blob (hb_blob_t *parent,
                         unsigned int offset,
                         unsigned int length);

Returns a blob that represents a range of bytes in parent . The new blob is always created with HB_MEMORY_MODE_READONLY, meaning that it will never modify data in the parent blob. The parent data is not expected to be modified, and will result in undefined behavior if it is.

Makes parent immutable.

Parameters

parent

Parent blob.

 

offset

Start offset of sub-blob within parent , in bytes.

 

length

Length of sub-blob.

 

Returns

New blob, or the empty blob if something failed or if length is zero or offset is beyond the end of parent 's data. Destroy with hb_blob_destroy().

Since: 0.9.2


hb_blob_copy_writable_or_fail ()

hb_blob_t *
hb_blob_copy_writable_or_fail (hb_blob_t *blob);

Makes a writable copy of blob .

Parameters

blob

A blob.

 

Returns

New blob, or nullptr if allocation failed.

Since: 1.8.0


hb_blob_destroy ()

void
hb_blob_destroy (hb_blob_t *blob);

Decreases the reference count on blob , and if it reaches zero, destroys blob , freeing all memory, possibly calling the destroy-callback the blob was created for if it has not been called already.

See TODO:link object types for more information.

[skip]

Parameters

blob

a blob.

 

Since: 0.9.2


hb_blob_get_data ()

const char *
hb_blob_get_data (hb_blob_t *blob,
                  unsigned int *length);

Parameters

blob

a blob.

 

length

.

[out]

Returns

.

[transfer none][array length=length]

Since: 0.9.2


hb_blob_get_data_writable ()

char *
hb_blob_get_data_writable (hb_blob_t *blob,
                           unsigned int *length);

Tries to make blob data writable (possibly copying it) and return pointer to data.

Fails if blob has been made immutable, or if memory allocation fails.

Parameters

blob

a blob.

 

length

output length of the writable data.

[out]

Returns

Writable blob data, or NULL if failed.

[transfer none][array length=length]

Since: 0.9.2


hb_blob_get_empty ()

hb_blob_t *
hb_blob_get_empty (void);

Returns the singleton empty blob.

See TODO:link object types for more information.

Returns

the empty blob.

[transfer full]

Since: 0.9.2


hb_blob_get_length ()

unsigned int
hb_blob_get_length (hb_blob_t *blob);

Parameters

blob

a blob.

 

Returns

the length of blob data in bytes.

Since: 0.9.2


hb_blob_get_user_data ()

void *
hb_blob_get_user_data (hb_blob_t *blob,
                       hb_user_data_key_t *key);

[skip]

Parameters

blob

a blob.

 

key

key for data to get.

 

Returns

.

[transfer none]

Since: 0.9.2


hb_blob_is_immutable ()

hb_bool_t
hb_blob_is_immutable (hb_blob_t *blob);

Parameters

blob

a blob.

 

Returns

TODO

Since: 0.9.2


hb_blob_make_immutable ()

void
hb_blob_make_immutable (hb_blob_t *blob);

Parameters

blob

a blob.

 

Since: 0.9.2


hb_blob_reference ()

hb_blob_t *
hb_blob_reference (hb_blob_t *blob);

Increases the reference count on blob .

See TODO:link object types for more information.

[skip]

Parameters

blob

a blob.

 

Returns

blob .

Since: 0.9.2


hb_blob_set_user_data ()

hb_bool_t
hb_blob_set_user_data (hb_blob_t *blob,
                       hb_user_data_key_t *key,
                       void *data,
                       hb_destroy_func_t destroy,
                       hb_bool_t replace);

[skip]

Parameters

blob

a blob.

 

key

key for data to set.

 

data

data to set.

 

destroy

callback to call when data is not needed anymore.

 

replace

whether to replace an existing data with the same key.

 

Since: 0.9.2

Types and Values

hb_blob_t

typedef struct hb_blob_t hb_blob_t;

enum hb_memory_mode_t

Members

HB_MEMORY_MODE_DUPLICATE

   

HB_MEMORY_MODE_READONLY

   

HB_MEMORY_MODE_WRITABLE

   

HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITABLE

   
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