mirror of
https://git.sr.ht/~eliasnaur/gio
synced 2026-07-01 15:45:38 +00:00
Pierre Curto
4c6d98879e
When the position of the cursor is required while dragging a widget around, the pointer's cannot be tracked as the drag grabs the event priority. Therefore, this patch exposes the drag's current position. Signed-off-by: Pierre Curto <pierre.curto@gmail.com>
104 lines
2.1 KiB
Go
104 lines
2.1 KiB
Go
package widget
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import (
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"io"
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"gioui.org/f32"
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"gioui.org/gesture"
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"gioui.org/io/pointer"
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"gioui.org/io/transfer"
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"gioui.org/layout"
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"gioui.org/op"
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"gioui.org/op/clip"
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)
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// Draggable makes a widget draggable.
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type Draggable struct {
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// Type contains the MIME type and matches transfer.SourceOp.
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Type string
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handle struct{}
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drag gesture.Drag
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click f32.Point
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pos f32.Point
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requested bool
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request string
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}
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func (d *Draggable) Layout(gtx layout.Context, w, drag layout.Widget) layout.Dimensions {
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if gtx.Queue == nil {
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return w(gtx)
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}
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pos := d.pos
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for _, ev := range d.drag.Events(gtx.Metric, gtx.Queue, gesture.Both) {
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switch ev.Type {
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case pointer.Press:
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d.click = ev.Position
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pos = f32.Point{}
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case pointer.Drag:
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pos = ev.Position.Sub(d.click)
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case pointer.Release:
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}
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}
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d.pos = pos
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for _, ev := range gtx.Queue.Events(&d.handle) {
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switch e := ev.(type) {
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case transfer.RequestEvent:
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d.requested = true
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d.request = e.Type
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case transfer.CancelEvent:
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d.requested = false
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d.request = ""
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}
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}
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dims := w(gtx)
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stack := clip.Rect{Max: dims.Size}.Push(gtx.Ops)
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d.drag.Add(gtx.Ops)
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transfer.SourceOp{
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Tag: &d.handle,
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Type: d.Type,
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}.Add(gtx.Ops)
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stack.Pop()
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if drag != nil && d.drag.Pressed() {
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rec := op.Record(gtx.Ops)
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op.Offset(pos).Add(gtx.Ops)
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drag(gtx)
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op.Defer(gtx.Ops, rec.Stop())
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}
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return dims
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}
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// Dragging returns whether d is being dragged.
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func (d *Draggable) Dragging() bool {
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return d.drag.Dragging()
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}
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// Requested returns the MIME type, if any, for which the Draggable was requested to offer data.
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func (d *Draggable) Requested() (mime string, requested bool) {
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mime = d.request
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requested = d.requested
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d.requested = false
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d.request = ""
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return
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}
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// Offer the data ready for a drop. Must be called after being Requested.
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// The mime must be one in the requested list.
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func (d *Draggable) Offer(ops *op.Ops, mime string, data io.ReadCloser) {
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transfer.OfferOp{
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Tag: &d.handle,
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Type: mime,
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Data: data,
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}.Add(ops)
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}
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// Pos returns the drag position relative to its area.
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func (d *Draggable) Pos() f32.Point {
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return d.pos.Add(d.click)
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}
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