Delta Chat Core C-API
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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 define an event-handler-function that is called by the library on specific events (eg. when the configuration is done or when fresh messages arrive). With this function you can create a Delta Chat context then:

#include <deltachat.h>
uintptr_t event_handler_func(dc_context_t* context, int event,
uintptr_t data1, uintptr_t data2)
{
return 0; // for unhandled events, it is always safe to return 0
}
dc_context_t* context = dc_context_new(event_handler_func, NULL, NULL);

After that, you should make sure, sending and receiving jobs are processed as needed. For this purpose, you have to create two threads:

#include <pthread.h>
void* imap_thread_func(void* context)
{
while (true) {
}
}
void* smtp_thread_func(void* context)
{
while (true) {
}
}
static pthread_t imap_thread, smtp_thread;
pthread_create(&imap_thread, NULL, imap_thread_func, context);
pthread_create(&smtp_thread, NULL, smtp_thread_func, context);

The example above uses "pthreads", however, you can also use anything else for thread handling. NB: The deltachat-core library itself does not create any threads on its own, however, functions, unless stated otherwise, are thread-safe.

After that you can define and open a database. The database is a normal sqlite-file and is created as needed:

dc_open(context, "example.db", NULL);

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 may take a while and is done by a job in the imap-thread you've defined above. Once done, the DC_EVENT_CONFIGURE_PROGRESS reports success to the event_handler_func() that is also 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()).

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 by a job in the smtp-thread you've defined above. If you check the testing address (bob) and you should have received a normal email. Answer this email in any email program with "Got it!" and the imap-thread you've create above will receive the message.

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

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);
free(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.

The following points are important mainly for the authors of the library itself:

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.