viewporter

• # wp_viewporter

  The global interface exposing surface cropping and scaling capabilities is used to instantiate an interface extension for a wl_surface object. This extended interface will then allow cropping and scaling the surface contents, effectively disconnecting the direct relationship between the buffer and the surface size.

  Requests

  • #

    destroy

    unbind from the cropping and scaling interface
    void wp_viewporter_destroy(

    struct wp_viewporter* wp_viewporter

    )
    Informs the server that the client will not be using this protocol object anymore. This does not affect any other objects, wp_viewport objects included.
  • #

    get_viewport

    extend surface interface for crop and scale
    struct wp_viewport* wp_viewporter_get_viewport(

    struct wp_viewporter* wp_viewporter,

    struct wl_surface* surface /* the surface */

    )
    Instantiate an interface extension for the given wl_surface to crop and scale its content. If the given wl_surface already has a wp_viewport object associated, the viewport_exists protocol error is raised.

  Enums

  • #

    error
    WP_VIEWPORTER_ERROR_VIEWPORT_EXISTS /* the surface already has a viewport object associated */

• # wp_viewport

  An additional interface to a wl_surface object, which allows the client to specify the cropping and scaling of the surface contents. This interface works with two concepts: the source rectangle (src_x, src_y, src_width, src_height), and the destination size (dst_width, dst_height). The contents of the source rectangle are scaled to the destination size, and content outside the source rectangle is ignored. This state is double-buffered, see wl_surface.commit. The two parts of crop and scale state are independent: the source rectangle, and the destination size. Initially both are unset, that is, no scaling is applied. The whole of the current wl_buffer is used as the source, and the surface size is as defined in wl_surface.attach. If the destination size is set, it causes the surface size to become dst_width, dst_height. The source (rectangle) is scaled to exactly this size. This overrides whatever the attached wl_buffer size is, unless the wl_buffer is NULL. If the wl_buffer is NULL, the surface has no content and therefore no size. Otherwise, the size is always at least 1x1 in surface local coordinates. If the source rectangle is set, it defines what area of the wl_buffer is taken as the source. If the source rectangle is set and the destination size is not set, then src_width and src_height must be integers, and the surface size becomes the source rectangle size. This results in cropping without scaling. If src_width or src_height are not integers and destination size is not set, the bad_size protocol error is raised when the surface state is applied. The coordinate transformations from buffer pixel coordinates up to the surface-local coordinates happen in the following order: 1. buffer_transform (wl_surface.set_buffer_transform) 2. buffer_scale (wl_surface.set_buffer_scale) 3. crop and scale (wp_viewport.set*) This means, that the source rectangle coordinates of crop and scale are given in the coordinates after the buffer transform and scale, i.e. in the coordinates that would be the surface-local coordinates if the crop and scale was not applied. If src_x or src_y are negative, the bad_value protocol error is raised. Otherwise, if the source rectangle is partially or completely outside of the non-NULL wl_buffer, then the out_of_buffer protocol error is raised when the surface state is applied. A NULL wl_buffer does not raise the out_of_buffer error. If the wl_surface associated with the wp_viewport is destroyed, all wp_viewport requests except 'destroy' raise the protocol error no_surface. If the wp_viewport object is destroyed, the crop and scale state is removed from the wl_surface. The change will be applied on the next wl_surface.commit.

  Requests

  • #

    destroy

    remove scaling and cropping from the surface
    void wp_viewport_destroy(

    struct wp_viewport* wp_viewport

    )
    The associated wl_surface's crop and scale state is removed. The change is applied on the next wl_surface.commit.
  • #

    set_source

    set the source rectangle for cropping
    void wp_viewport_set_source(

    struct wp_viewport* wp_viewport,

    wl_fixed_t x, /* source rectangle x */

    wl_fixed_t y, /* source rectangle y */

    wl_fixed_t width, /* source rectangle width */

    wl_fixed_t height /* source rectangle height */

    )
    Set the source rectangle of the associated wl_surface. See wp_viewport for the description, and relation to the wl_buffer size. If all of x, y, width and height are -1.0, the source rectangle is unset instead. Any other set of values where width or height are zero or negative, or x or y are negative, raise the bad_value protocol error. The crop and scale state is double-buffered, see wl_surface.commit.
  • #

    set_destination

    set the surface size for scaling
    void wp_viewport_set_destination(

    struct wp_viewport* wp_viewport,

    int32_t width, /* surface width */

    int32_t height /* surface height */

    )
    Set the destination size of the associated wl_surface. See wp_viewport for the description, and relation to the wl_buffer size. If width is -1 and height is -1, the destination size is unset instead. Any other pair of values for width and height that contains zero or negative values raises the bad_value protocol error. The crop and scale state is double-buffered, see wl_surface.commit.

  Enums

  • #

    error
    WP_VIEWPORT_ERROR_BAD_VALUE /* negative or zero values in width or height */
    WP_VIEWPORT_ERROR_BAD_SIZE /* destination size is not integer */
    WP_VIEWPORT_ERROR_OUT_OF_BUFFER /* source rectangle extends outside of the content area */
    WP_VIEWPORT_ERROR_NO_SURFACE /* the wl_surface was destroyed */

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