package transfer

import "gioui.org/io/transfer"

Package transfer contains operations and events for brokering data transfers.

The transfer protocol is as follows:

• Data sources are registered with SourceOps, data targets with TargetOps.
• A data source receives a RequestEvent when a transfer is initiated. It must respond with an OfferOp.
• The target receives a DataEvent when transferring to it. It must close the event data after use.

When a user initiates a pointer-guided drag and drop transfer, the source as well as all potential targets receive an InitiateEvent. Potential targets are targets with at least one MIME type in common with the source. When a drag gesture completes, a CancelEvent is sent to the source and all potential targets.

Note that the RequestEvent is sent to the source upon drop.

Index ¶

• type CancelEvent
• func (CancelEvent) ImplementsEvent()
• type DataEvent
• func (DataEvent) ImplementsEvent()
• type InitiateEvent
• func (InitiateEvent) ImplementsEvent()
• type OfferOp
• func (op OfferOp) Add(o *op.Ops)
• type RequestEvent
• func (RequestEvent) ImplementsEvent()
• type SourceOp
• func (op SourceOp) Add(o *op.Ops)
• type TargetOp
• func (op TargetOp) Add(o *op.Ops)

Types ¶

type CancelEvent ¶

type CancelEvent struct{}

CancelEvent is sent to data sources and targets to cancel the effects of an InitiateEvent.

func (CancelEvent) ImplementsEvent ¶

func (CancelEvent) ImplementsEvent()

type DataEvent ¶

type DataEvent struct {
	// Type is the MIME type of Data.
	Type string
	// Open returns the transfer data. It is only valid to call Open in the frame
	// the DataEvent is received. The caller must close the return value after use.
	Open func() io.ReadCloser
}

DataEvent is sent to the target receiving the transfer.

func (DataEvent) ImplementsEvent ¶

func (DataEvent) ImplementsEvent()

type InitiateEvent ¶

type InitiateEvent struct{}

InitiateEvent is sent to a data source when a drag-and-drop transfer gesture is initiated.

Potential data targets also receive the event.

func (InitiateEvent) ImplementsEvent ¶

func (InitiateEvent) ImplementsEvent()

type OfferOp ¶

type OfferOp struct {
	Tag event.Tag
	// Type is the MIME type of Data.
	// It must be the Type from the corresponding RequestEvent.
	Type string
	// Data contains the offered data. It is closed when the
	// transfer is complete or cancelled.
	// Data must be kept valid until closed, and it may be used from
	// a goroutine separate from the one processing the frame..
	Data io.ReadCloser
}

OfferOp is used by data sources as a response to a RequestEvent.

func (OfferOp) Add ¶

func (op OfferOp) Add(o *op.Ops)

Add the offer to the list of operations. It panics if the Data field is not set.

type RequestEvent ¶

type RequestEvent struct {
	// Type is the first matched type between the source and the target.
	Type string
}

RequestEvent requests data from a data source. The source must respond with an OfferOp.

func (RequestEvent) ImplementsEvent ¶

func (RequestEvent) ImplementsEvent()

type SourceOp ¶

type SourceOp struct {
	Tag event.Tag
	// Type is the MIME type supported by this source.
	Type string
}

SourceOp registers a tag as a data source for a MIME type. Use multiple SourceOps if a tag supports multiple types.

func (SourceOp) Add ¶

func (op SourceOp) Add(o *op.Ops)

type TargetOp ¶

type TargetOp struct {
	Tag event.Tag
	// Type is the MIME type accepted by this target.
	Type string
}

TargetOp registers a tag as a data target. Use multiple TargetOps if a tag supports multiple types.

func (TargetOp) Add ¶

func (op TargetOp) Add(o *op.Ops)

Source Files ¶

transfer.go