1 files changed, 109 insertions, 0 deletions
diff --git a/vendor/gioui.org/io/transfer/transfer.go b/vendor/gioui.org/io/transfer/transfer.go
new file mode 100644
index 0000000..85ab68c
--- /dev/null
+++ b/vendor/gioui.org/io/transfer/transfer.go
@@ -0,0 +1,109 @@
+// 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.
+package transfer
+
+import (
+	"io"
+
+	"gioui.org/internal/ops"
+	"gioui.org/io/event"
+	"gioui.org/op"
+)
+
+// SourceOp registers a tag as a data source for a MIME type.
+// Use multiple SourceOps if a tag supports multiple types.
+type SourceOp struct {
+	Tag event.Tag
+	// Type is the MIME type supported by this source.
+	Type string
+}
+
+// TargetOp registers a tag as a data target.
+// Use multiple TargetOps if a tag supports multiple types.
+type TargetOp struct {
+	Tag event.Tag
+	// Type is the MIME type accepted by this target.
+	Type string
+}
+
+// OfferOp is used by data sources as a response to a RequestEvent.
+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
+}
+
+func (op SourceOp) Add(o *op.Ops) {
+	data := ops.Write2(&o.Internal, ops.TypeSourceLen, op.Tag, op.Type)
+	data[0] = byte(ops.TypeSource)
+}
+
+func (op TargetOp) Add(o *op.Ops) {
+	data := ops.Write2(&o.Internal, ops.TypeTargetLen, op.Tag, op.Type)
+	data[0] = byte(ops.TypeTarget)
+}
+
+// Add the offer to the list of operations.
+// It panics if the Data field is not set.
+func (op OfferOp) Add(o *op.Ops) {
+	if op.Data == nil {
+		panic("invalid nil data in OfferOp")
+	}
+	data := ops.Write3(&o.Internal, ops.TypeOfferLen, op.Tag, op.Type, op.Data)
+	data[0] = byte(ops.TypeOffer)
+}
+
+// RequestEvent requests data from a data source. The source must
+// respond with an OfferOp.
+type RequestEvent struct {
+	// Type is the first matched type between the source and the target.
+	Type string
+}
+
+func (RequestEvent) ImplementsEvent() {}
+
+// InitiateEvent is sent to a data source when a drag-and-drop
+// transfer gesture is initiated.
+//
+// Potential data targets also receive the event.
+type InitiateEvent struct{}
+
+func (InitiateEvent) ImplementsEvent() {}
+
+// CancelEvent is sent to data sources and targets to cancel the
+// effects of an InitiateEvent.
+type CancelEvent struct{}
+
+func (CancelEvent) ImplementsEvent() {}
+
+// DataEvent is sent to the target receiving the transfer.
+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
+}
+
+func (DataEvent) ImplementsEvent() {}