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_emitter_t* emitter = dc_get_event_emitter(context);
    dc_event_t* event;
    while ((event = dc_get_next_event(emitter)) != NULL) {
        // use the event as needed, e.g. dc_event_get_id() returns the type.
        // once you're done, unref the event to avoid memory leakage:
        dc_event_unref(event);
    }
    dc_event_emitter_unref(emitter);
}
 
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 e-mail. Answer this e-mail in any e-mail 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_msg_unref(msg);
}
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.

• For get-functions, you have to unref the return value in some way.
• Strings in function arguments or return values are usually UTF-8 encoded.
• The issue-tracker for the core library is here: https://github.com/deltachat/deltachat-core-rust/issues

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.