Delta Chat Core C Interface
Getting started

This document describes how to handle the Delta Chat core library. For general information about Delta Chat itself, see https://delta.chat and https://github.com/deltachat.

Let's start.

First of all, you have to create a context object bound to a database. The database is a normal SQLite file with a "blob directory" beside it. This will create "example.db" database and "example.db-blobs" directory if they don't exist already:

dc_context_t* context = dc_context_new(NULL, "example.db", NULL);

After that, make sure you can receive events from the context. For that purpose, create an event emitter you can ask for events. If there is no event, the emitter will wait until there is one, so, in many situations, you will do this in a thread:

void* event_handler(void* context)
{
dc_event_t* event;
while ((event = dc_get_next_event(emitter)) != NULL) {
// use the event as needed, eg. dc_event_get_id() returns the type.
// once you're done, unref the event to avoid memory leakage:
}
}
static pthread_t event_thread;
pthread_create(&event_thread, NULL, event_handler, context);

The example above uses "pthreads", however, you can also use anything else for thread handling. All deltachat-core functions, unless stated otherwise, are thread-safe.

Now you can configure the context:

// use some real test credentials here
dc_set_config(context, "addr", "alice@example.org");
dc_set_config(context, "mail_pw", "***");
dc_configure(context);

dc_configure() returns immediately. The configuration itself runs in the background and may take a while. Once done, the DC_EVENT_CONFIGURE_PROGRESS reports success to the event_handler() you've defined above.

The configuration result is saved in the database. On subsequent starts it is not needed to call dc_configure() (you can check this using dc_is_configured()).

On a successfully configured context, you can finally connect to the servers:

dc_start_io(context);

Now you can send the first message:

// use a real testing address here
uint32_t contact_id = dc_create_contact(context, NULL, "bob@example.org");
uint32_t chat_id = dc_create_chat_by_contact_id(context, contact_id);
dc_send_text_msg(context, chat_id, "Hi, here is my first message!");

dc_send_text_msg() returns immediately; the sending itself is done in the background. If you check the testing address (bob), you should receive a normal email. Answer this email in any email program with "Got it!", and the IO you started above will receive the message.

You can then list all messages of a chat as follows:

dc_array_t* msglist = dc_get_chat_msgs(context, chat_id, 0, 0);
for (int i = 0; i < dc_array_get_cnt(msglist); i++)
{
uint32_t msg_id = dc_array_get_id(msglist, i);
dc_msg_t* msg = dc_get_msg(context, msg_id);
char* text = dc_msg_get_text(msg);
printf("Message %i: %s\n", i+1, text);
dc_str_unref(text);
}
dc_array_unref(msglist);

This will output the following two lines:

Message 1: Hi, here is my first message!
Message 2: Got it!

Class reference

For a class reference, see the "Classes" link atop.

Further hints

Here are some additional, unsorted hints that may be useful.

If you need further assistance, please do not hesitate to contact us through the channels shown at https://delta.chat/en/contribute

Please keep in mind, that your derived work must respect the Mozilla Public License 2.0 of libdeltachat and the respective licenses of the libraries libdeltachat links with.

See you.

dc_context_t::dc_get_msg
dc_msg_t * dc_get_msg(dc_context_t *context, uint32_t msg_id)
Get a single message object of the type dc_msg_t.
dc_context_t::dc_context_new
dc_context_t * dc_context_new(const char *os_name, const char *dbfile, const char *blobdir)
Create a new context object.
dc_context_t::dc_create_chat_by_contact_id
uint32_t dc_create_chat_by_contact_id(dc_context_t *context, uint32_t contact_id)
Create a normal chat with a single user.
dc_context_t::dc_start_io
void dc_start_io(dc_context_t *context)
Start job and IMAP/SMTP tasks.
dc_event_emitter_t::dc_event_emitter_unref
void dc_event_emitter_unref(dc_event_emitter_t *emitter)
Free a context event emitter object.
dc_context_t::dc_get_chat_msgs
dc_array_t * dc_get_chat_msgs(dc_context_t *context, uint32_t chat_id, uint32_t flags, uint32_t marker1before)
Get all message IDs belonging to a chat.
dc_array_t
dc_context_t::dc_str_unref
void dc_str_unref(char *str)
Release a string returned by another deltachat-core function.
dc_context_t::dc_get_event_emitter
dc_event_emitter_t * dc_get_event_emitter(dc_context_t *context)
Create the event emitter that is used to receive events.
dc_msg_t::dc_msg_unref
void dc_msg_unref(dc_msg_t *msg)
Free a message object.
dc_array_t::dc_array_get_id
uint32_t dc_array_get_id(const dc_array_t *array, size_t index)
Get the item at the given index as an ID.
dc_event_t
dc_context_t
dc_context_t::dc_configure
void dc_configure(dc_context_t *context)
Configure a context.
dc_event_emitter_t::dc_get_next_event
dc_event_t * dc_get_next_event(dc_event_emitter_t *emitter)
Get the next event from a context event emitter object.
dc_context_t::dc_send_text_msg
uint32_t dc_send_text_msg(dc_context_t *context, uint32_t chat_id, const char *text_to_send)
Send a simple text message a given chat.
dc_context_t::dc_create_contact
uint32_t dc_create_contact(dc_context_t *context, const char *name, const char *addr)
Add a single contact as a result of an explicit user action.
dc_array_t::dc_array_get_cnt
size_t dc_array_get_cnt(const dc_array_t *array)
Find out the number of items in an array.
dc_msg_t
dc_event_emitter_t
dc_event_t::dc_event_unref
void dc_event_unref(dc_event_t *event)
Free memory used by an event object.
dc_context_t::dc_set_config
int dc_set_config(dc_context_t *context, const char *key, const char *value)
Configure the context.
dc_array_t::dc_array_unref
void dc_array_unref(dc_array_t *array)
Free an array object.
dc_msg_t::dc_msg_get_text
char * dc_msg_get_text(const dc_msg_t *msg)
Get the text of the message.