viewporter

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Version: v0.0.0-...-779b2c5 Latest Latest
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Published: Sep 17, 2021 License: BSD-2-Clause Imports: 1 Imported by: 0

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type Viewport

type Viewport struct {
	client.BaseProxy
}

Viewport : crop and scale interface to a wl_surface

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, and is applied on the next 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.

The x, y arguments of wl_surface.attach are applied as normal to the surface. They indicate how many pixels to remove from the surface size from the left and the top. In other words, they are still in the surface-local coordinate system, just like dst_width and dst_height are.

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.

func NewViewport

func NewViewport(ctx *client.Context) *Viewport

NewViewport : crop and scale interface to a wl_surface

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, and is applied on the next 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.

The x, y arguments of wl_surface.attach are applied as normal to the surface. They indicate how many pixels to remove from the surface size from the left and the top. In other words, they are still in the surface-local coordinate system, just like dst_width and dst_height are.

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.

func (*Viewport) Destroy

func (i *Viewport) Destroy() error

Destroy : remove scaling and cropping from the surface

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

func (*Viewport) SetDestination

func (i *Viewport) SetDestination(width, height int32) error

SetDestination : set the surface size for scaling

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 state, and will be applied on the next wl_surface.commit.

width: surface width
height: surface height

func (*Viewport) SetSource

func (i *Viewport) SetSource(x, y, width, height float64) error

SetSource : set the source rectangle for cropping

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 state, and will be applied on the next wl_surface.commit.

x: source rectangle x
y: source rectangle y
width: source rectangle width
height: source rectangle height

type ViewportError

type ViewportError uint32
const (
	// ViewportErrorBadValue : negative or zero values in width or height
	ViewportErrorBadValue ViewportError = 0
	// ViewportErrorBadSize : destination size is not integer
	ViewportErrorBadSize ViewportError = 1
	// ViewportErrorOutOfBuffer : source rectangle extends outside of the content area
	ViewportErrorOutOfBuffer ViewportError = 2
	// ViewportErrorNoSurface : the wl_surface was destroyed
	ViewportErrorNoSurface ViewportError = 3
)

ViewportError :

func (ViewportError) Name

func (e ViewportError) Name() string

func (ViewportError) String

func (e ViewportError) String() string

func (ViewportError) Value

func (e ViewportError) Value() string

type Viewporter

type Viewporter struct {
	client.BaseProxy
}

Viewporter : surface cropping and scaling

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.

func NewViewporter

func NewViewporter(ctx *client.Context) *Viewporter

NewViewporter : surface cropping and scaling

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.

func (*Viewporter) Destroy

func (i *Viewporter) Destroy() error

Destroy : unbind from the cropping and scaling interface

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.

func (*Viewporter) GetViewport

func (i *Viewporter) GetViewport(surface *client.Surface) (*Viewport, error)

GetViewport : extend surface interface for crop and scale

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.

surface: the surface

type ViewporterError

type ViewporterError uint32
const (
	// ViewporterErrorViewportExists : the surface already has a viewport object associated
	ViewporterErrorViewportExists ViewporterError = 0
)

ViewporterError :

func (ViewporterError) Name

func (e ViewporterError) Name() string

func (ViewporterError) String

func (e ViewporterError) String() string

func (ViewporterError) Value

func (e ViewporterError) Value() string

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