GESLayer

## GESLayer GESLayer — Non-overlapping sequence of GESClip |

## Synopsis

    #include <ges/ges.h>

                        GESLayer;
                        GESLayerClass;
    gboolean            ges_layer_add_clip                  (GESLayer *layer,
                                                             GESClip *clip);
    GESClip *           ges_layer_add_asset                 (GESLayer *layer,
                                                             GESAsset *asset,
                                                             GstClockTime start,
                                                             GstClockTime inpoint,
                                                             GstClockTime duration,
                                                             GESTrackType track_types);
    GESLayer *          ges_layer_new                       (void);
    gboolean            ges_layer_remove_clip               (GESLayer *layer,
                                                             GESClip *clip);
    void                ges_layer_set_priority              (GESLayer *layer,
                                                             guint priority);
    guint               ges_layer_get_priority              (GESLayer *layer);
    GList *             ges_layer_get_clips                 (GESLayer *layer);
    GESTimeline *       ges_layer_get_timeline              (GESLayer *layer);
    gboolean            ges_layer_get_auto_transition       (GESLayer *layer);
    void                ges_layer_set_auto_transition       (GESLayer *layer,
                                                             gboolean auto_transition);
    gboolean            ges_layer_is_empty                  (GESLayer *layer);
    #define             GES_TIMELINE_GET_LAYERS             (obj)
    #define             GES_TIMELINE_GET_TRACKS             (obj)

## Object Hierarchy

      GObject
       +----GInitiallyUnowned
             +----GESLayer
                   +----GESSimpleLayer

## Implemented Interfaces

GESLayer implements GESExtractable and GESMetaContainer.

## Properties

      "auto-transition"          gboolean              : Read / Write
      "priority"                 guint                 : Read / Write

## Signals

      "clip-added"                                     : Run First
      "clip-removed"                                   : Run First

## Description

Responsible for the ordering of the various contained Clip(s). A timeline layer has a "priority" property, which is used to manage the priorities of individual Clips. Two layers should not have the same priority within a given timeline.

## Details

### GESLayer

    typedef struct {
      GESTimeline *timeline;
    } GESLayer;

GESTimeline *`timeline`; | the GESTimeline where this layer is being used.

### GESLayerClass

    typedef struct {
      /* virtual methods for subclasses */
      GList *(*get_objects) (GESLayer * layer);
    } GESLayerClass;

Subclasses can override the `get_objects` if they can provide a more efficient way of providing the list of contained GESClip(s).

`get_objects` () | method to get the objects contained in the layer

### ges_layer_add_clip ()

    gboolean            ges_layer_add_clip                  (GESLayer *layer,
                                                             GESClip *clip);

Adds the given clip to the layer. Sets the clip's parent, and thus takes ownership of the clip.

An clip can only be added to one layer.

Calling this method will construct and properly set all the media related elements on `clip`. If you need to know when those objects (actually GESTrackElement) are constructed, you should connect to the container::child-added signal which is emited right after those elements are ready to be used.

`layer` : | a GESLayer
`clip` : | the GESClip to add. [transfer full]
Returns : | TRUE if the clip was properly added to the layer, or FALSE if the `layer` refuses to add the clip.

### ges_layer_add_asset ()

    GESClip *           ges_layer_add_asset                 (GESLayer *layer,
                                                             GESAsset *asset,
                                                             GstClockTime start,
                                                             GstClockTime inpoint,
                                                             GstClockTime duration,
                                                             GESTrackType track_types);

Creates Clip from asset, adds it to layer and returns a reference to it.

`layer` : | a GESLayer
`asset` : | The asset to add to
`start` : | The start value to set on the new GESClip
`inpoint` : | The inpoint value to set on the new GESClip
`duration` : | The duration value to set on the new GESClip
`track_types` : | The GESTrackType to set on the the new GESClip
Returns : | Created GESClip. [transfer none]

### ges_layer_new ()

    GESLayer *          ges_layer_new                       (void);

Creates a new GESLayer.

Returns : | A new GESLayer

### ges_layer_remove_clip ()

    gboolean            ges_layer_remove_clip               (GESLayer *layer,
                                                             GESClip *clip);

Removes the given `clip` from the `layer` and unparents it. Unparenting it means the reference owned by `layer` on the `clip` will be removed. If you wish to use the `clip` after this function, make sure you call `gst_object_ref()` before removing it from the `layer`.

`layer` : | a GESLayer
`clip` : | the GESClip to remove
Returns : | TRUE if the clip could be removed, FALSE if the layer does not want to remove the clip.

### ges_layer_set_priority ()

    void                ges_layer_set_priority              (GESLayer *layer,
                                                             guint priority);

Sets the layer to the given `priority`. See the documentation of the priority property for more information.

`layer` : | a GESLayer
`priority` : | the priority to set

### ges_layer_get_priority ()

    guint               ges_layer_get_priority              (GESLayer *layer);

Get the priority of `layer` within the timeline.

`layer` : | a GESLayer
Returns : | The priority of the `layer` within the timeline.

### ges_layer_get_clips ()

    GList *             ges_layer_get_clips                 (GESLayer *layer);

Get the clips this layer contains.

`layer` : | a GESLayer
Returns : | a GList of clips. The user is responsible for unreffing the contained objects and freeing the list. [transfer full][element-type GESClip]

### ges_layer_get_timeline ()

    GESTimeline *       ges_layer_get_timeline              (GESLayer *layer);

Get the GESTimeline in which GESLayer currently is.

`layer` : | The GESLayer to get the parent GESTimeline from
Returns : | the GESTimeline in which GESLayer currently is or `NULL` if not in any timeline yet. [transfer none]

### ges_layer_get_auto_transition ()

    gboolean            ges_layer_get_auto_transition       (GESLayer *layer);

Gets whether transitions are automatically added when objects overlap or not.

`layer` : | a GESLayer
Returns : | `TRUE` if transitions are automatically added, else `FALSE`.

### ges_layer_set_auto_transition ()

    void                ges_layer_set_auto_transition       (GESLayer *layer,
                                                             gboolean auto_transition);

Sets the layer to the given `auto_transition`. See the documentation of the property auto_transition for more information.

`layer` : | a GESLayer
`auto_transition` : | whether the auto_transition is active

### ges_layer_is_empty ()

    gboolean            ges_layer_is_empty                  (GESLayer *layer);

Convenience method to check if `layer` is empty (doesn't contain any clip), or not.

`layer` : | The GESLayer to check
Returns : | `TRUE` if `layer` is empty, `FALSE` if it already contains at least one GESClip

### GES_TIMELINE_GET_LAYERS()

    #define GES_TIMELINE_GET_LAYERS(obj) (GES_TIMELINE (obj)->layers)

### GES_TIMELINE_GET_TRACKS()

    #define GES_TIMELINE_GET_TRACKS(obj) (GES_TIMELINE (obj)->tracks)

## Property Details

### The `"auto-transition"` property

      "auto-transition"          gboolean              : Read / Write

Sets whether transitions are added automagically when clips overlap.

Default value: FALSE

### The `"priority"` property

      "priority"                 guint                 : Read / Write

The priority of the layer in the GESTimeline. 0 is the highest priority. Conceptually, a GESTimeline is a stack of GESLayers, and the priority of the layer represents its position in the stack. Two layers should not have the same priority within a given GESTimeline.

Default value: 0

## Signal Details

### The `"clip-added"` signal

    void                user_function                      (GESLayer *layer,
                                                            GESClip  *clip,
                                                            gpointer  user_data)      : Run First

Will be emitted after the clip was added to the layer.

`layer` : | the GESLayer
`clip` : | the GESClip that was added.
`user_data` : | user data set when the signal handler was connected.

### The `"clip-removed"` signal

    void                user_function                      (GESLayer *layer,
                                                            GESClip  *clip,
                                                            gpointer  user_data)      : Run First

Will be emitted after the clip was removed from the layer.

`layer` : | the GESLayer
`clip` : | the GESClip that was removed
`user_data` : | user data set when the signal handler was connected.