# Platform-specific functions

## Windows

These functions are declared in the following header file:

~~~~c
 #include <allegro5/allegro_windows.h>
~~~~

### API: al_get_win_window_handle

Returns the handle to the window that the passed display is using.

### API: al_win_add_window_callback

The specified callback function will intercept the window's message
before Allegro processes it. If the callback function consumes the event,
then it should return true. In that case, Allegro will not do anything
with the event.

Optionally, you may use `result` to customize what Allegro will return
return in response to this event. By default, Allegro returns `TRUE`.

The `userdata` pointer can be used to supply additional context to the
callback function. 

The callbacks are executed in the same order they were added.

Returns true if the callback was added.

Since: 5.1.2

### API: al_win_remove_window_callback

Removes the callback that was previously registered with 
[al_win_add_window_callback]. The `userdata` pointer must be the same as
what was used during the registration of the callback.

Returns true if the callback was removed.

Since: 5.1.2

## Mac OS X

These functions are declared in the following header file:

~~~~c
 #include <allegro5/allegro_osx.h>
~~~~

### API: al_osx_get_window

Retrieves the NSWindow handle associated with the Allegro display.

Since: 5.0.8, 5.1.3

## iPhone

These functions are declared in the following header file:

~~~~c
 #include <allegro5/allegro_iphone.h>
~~~~

### API: al_iphone_set_statusbar_orientation

Sets the orientation of the status bar, which can be one of the following:

-  ALLEGRO_IPHONE_STATUSBAR_ORIENTATION_PORTRAIT
-  ALLEGRO_IPHONE_STATUSBAR_ORIENTATION_PORTRAIT_UPSIDE_DOWN
-  ALLEGRO_IPHONE_STATUSBAR_ORIENTATION_LANDSCAPE_RIGHT
-  ALLEGRO_IPHONE_STATUSBAR_ORIENTATION_LANDSCAPE_LEFT

Since: 5.1.0

### API: al_iphone_get_view

Retrieves the UIView* (EAGLView*) associated with the Allegro display.

Since: 5.1.0

### API: al_iphone_get_window

Retrieves the UIWindow* associated with the Allegro display.

Since: 5.1.0

## Android

These functions are declared in the following header file:

~~~~c
 #include <allegro5/allegro_android.h>
~~~~

### API: al_android_set_apk_file_interface

This function will set up a custom [ALLEGRO_FILE_INTERFACE] that makes all
future calls of [al_fopen] read from the applicatons's APK file.

> *Note:* Currently, access to the APK file after calling this function is read
only.

Since: 5.1.2

### API: al_android_set_apk_fs_interface

This function will set up a custom [ALLEGRO_FS_INTERFACE] which allows
working within the APK filesystem. The filesystem root is your assets
directory and there is read-only access to all files within.

> *Note:* Some things like querying file size or attributes are not
supported by this. You can always use the PhysFS addon to open the APK
file (it is just a regular .zip file) and get more complete information.

Since: 5.1.13

### API: al_android_get_os_version

Returns a pointer to a static buffer that contains the version string of the
Android platform that the calling Allegro program is running on.

Since: 5.1.2

### API: al_android_get_jni_env

Returns the Android JNI environment used by Allegro to call into Java.
As a convenience this function provides it to the user so there is no
need to obtain it yourself.

For example if you have a Java method "void send(String message)" in
your activity class, you could call it like this from C code:

~~~~c
JNIEnv * env = al_android_get_jni_env();
jclass class_id = (* env)->GetObjectClass(env, al_android_get_activity());
jmethodID method_id = (* env)->GetMethodID(env, class_id, "send",
    "(Ljava/lang/String;)V");
jstring jdata = (* env)->NewStringUTF(env, "Hello Java!");
(* env)->CallVoidMethod(env, al_android_get_activity(), method_id, jdata);
(* env)->DeleteLocalRef(env, jdata);
~~~~

Since: 5.2.2

> *[Unstable API]:* This API is new and subject to refinement.

### API: al_android_get_activity

Returns the Java Android activity used by Allegro. This is the same
object created by Android from the class you specify in your manifest
and either an instance of AllegroActivity or a derived class.

Since: 5.2.2

> *[Unstable API]:* This API is new and subject to refinement.

### API: al_android_open_fd

Opens a file descriptor to access data under a Universal Resource Identifier
(URI). This function accepts content:// and file:// URI schemes. You are
responsible for closing the returned file descriptor.

The file `mode` can be `"r"`, `"w"`, `"rw"`, `"wt"`, `"wa"` or `"rwt"`. The
exact implementation of these modes differ depending on the underlying content
provider. For example, `"w"` may or may not truncate.

Returns a file descriptor on success or a negative value on an error. On an
error, the Allegro errno is set.

> *Note:* Remember to add to your manifest file the relevant permissions to
your app.

Example:

~~~~c
const char *content_uri = "content://...";
int fd = al_android_open_fd(content_uri, "r");

if (fd >= 0) {
    ALLEGRO_FILE *f = al_fopen_fd(fd, "r");

    if (f != NULL) {
        do_something_with(f);
        al_fclose(f);
    }
    else {
        handle_error(al_get_errno());
        close(fd);
    }
}
else {
    handle_error(al_get_errno());
}
~~~~

Since: 5.2.10

See also: [al_fopen_fd], [al_get_errno]

> *[Unstable API]:* This API is new and subject to refinement.

## X11

These functions are declared in the following header file:

~~~~c
 #include <allegro5/allegro_x.h>
~~~~

### API: al_get_x_window_id

Retrieves the XID associated with the Allegro display.

Since: 5.1.12

### API: al_x_set_initial_icon

On some window managers (notably Ubuntu's Unity) al_set_display_icon
doesn't work and you need to use a .desktop file. But with this function
you can set an icon before calling al_create_display. This works
by setting the icon before XMapWindow.

Since: 5.2.3

> *[Unstable API]:* New API.
