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widget: add drag and drop support

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This patch adds internal Drag and Drop support to app.Windows.

The new package io/transfer adds the ability to
define draggable and droppable targets, which
are leveraged by the new widget.Draggable type.

The API is generic and could handle future use
cases, such as external Drag and Drop.

Updates gio#153

Signed-off-by: Pierre Curto <pierre.curto@gmail.com>
This commit is contained in:
Pierre Curto
2021-11-27 10:22:10 +01:00
committed by Elias Naur
parent 2d75181b51
commit 03016f0c69
7 changed files with 776 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files
io/router/pointer.go
+162 -22
View File
@@ -4,21 +4,24 @@ package router
import (
"image"
"io"
"gioui.org/f32"
"gioui.org/internal/ops"
"gioui.org/io/event"
"gioui.org/io/pointer"
"gioui.org/io/semantic"
"gioui.org/io/transfer"
)
type pointerQueue struct {
hitTree []hitNode
areas []areaNode
cursors []cursorNode
cursor pointer.CursorName
handlers map[event.Tag]*pointerHandler
pointers []pointerInfo
hitTree []hitNode
areas []areaNode
cursors []cursorNode
cursor pointer.CursorName
handlers map[event.Tag]*pointerHandler
pointers []pointerInfo
transfers []io.ReadCloser // pending data transfers
scratch []event.Tag
@@ -56,6 +59,9 @@ type pointerInfo struct {
// entered tracks the tags that contain the pointer.
entered []event.Tag
dataSource event.Tag // dragging source tag
dataTarget event.Tag // dragging target tag
}
type pointerHandler struct {
@@ -65,6 +71,11 @@ type pointerHandler struct {
types pointer.Type
// min and max horizontal/vertical scroll
scrollRange image.Rectangle
sourceMimes []string
targetMimes []string
offeredMime string
data io.ReadCloser
}
type areaOp struct {
@@ -182,7 +193,7 @@ func frect(r image.Rectangle) f32.Rectangle {
}
}
// fpt converts an point to a f32.Point.
// fpt converts a point to a f32.Point.
func fpt(p image.Point) f32.Point {
return f32.Point{
X: float32(p.X), Y: float32(p.Y),
@@ -217,6 +228,27 @@ func (c *pointerCollector) addHitNode(n hitNode) {
c.state.nodePlusOne = len(c.q.hitTree) - 1 + 1
}
// newHandler returns the current handler or a new one for tag.
func (c *pointerCollector) newHandler(tag event.Tag, events *handlerEvents) *pointerHandler {
areaID := c.currentArea()
c.addHitNode(hitNode{
area: areaID,
tag: tag,
pass: c.state.pass > 0,
})
h, ok := c.q.handlers[tag]
if !ok {
h = new(pointerHandler)
c.q.handlers[tag] = h
// Cancel handlers on (each) first appearance, but don't
// trigger redraw.
events.AddNoRedraw(tag, pointer.Event{Type: pointer.Cancel})
}
h.active = true
h.area = areaID
return h
}
func (c *pointerCollector) inputOp(op pointer.InputOp, events *handlerEvents) {
areaID := c.currentArea()
area := &c.q.areas[areaID]
@@ -225,21 +257,7 @@ func (c *pointerCollector) inputOp(op pointer.InputOp, events *handlerEvents) {
area.semantic.content.gestures |= ClickGesture
}
area.semantic.valid = area.semantic.content.gestures != 0
c.addHitNode(hitNode{
area: areaID,
tag: op.Tag,
pass: c.state.pass > 0,
})
h, ok := c.q.handlers[op.Tag]
if !ok {
h = new(pointerHandler)
c.q.handlers[op.Tag] = h
// Cancel handlers on (each) first appearance, but don't
// trigger redraw.
events.AddNoRedraw(op.Tag, pointer.Event{Type: pointer.Cancel})
}
h.active = true
h.area = areaID
h := c.newHandler(op.Tag, events)
h.wantsGrab = h.wantsGrab || op.Grab
h.types = h.types | op.Types
h.scrollRange = op.ScrollBounds
@@ -287,6 +305,22 @@ func (c *pointerCollector) cursor(name pointer.CursorName) {
})
}
func (c *pointerCollector) sourceOp(op transfer.SourceOp, events *handlerEvents) {
h := c.newHandler(op.Tag, events)
h.sourceMimes = append(h.sourceMimes, op.Type)
}
func (c *pointerCollector) targetOp(op transfer.TargetOp, events *handlerEvents) {
h := c.newHandler(op.Tag, events)
h.targetMimes = append(h.targetMimes, op.Type)
}
func (c *pointerCollector) offerOp(op transfer.OfferOp, events *handlerEvents) {
h := c.newHandler(op.Tag, events)
h.offeredMime = op.Type
h.data = op.Data
}
func (c *pointerCollector) reset(q *pointerQueue) {
q.reset()
c.resetState()
@@ -448,6 +482,8 @@ func (q *pointerQueue) reset() {
h.active = false
h.wantsGrab = false
h.types = 0
h.sourceMimes = h.sourceMimes[:0]
h.targetMimes = h.targetMimes[:0]
}
q.hitTree = q.hitTree[:0]
q.areas = q.areas[:0]
@@ -467,6 +503,12 @@ func (q *pointerQueue) reset() {
delete(q.semantic.contentIDs, k)
}
}
for _, rc := range q.transfers {
if rc != nil {
rc.Close()
}
}
q.transfers = nil
}
func (q *pointerQueue) Frame(events *handlerEvents) {
@@ -498,6 +540,7 @@ func (q *pointerQueue) Frame(events *handlerEvents) {
for i := range q.pointers {
p := &q.pointers[i]
q.deliverEnterLeaveEvents(p, events, p.last)
q.deliverTransferDataEvent(p, events)
}
}
@@ -554,10 +597,14 @@ func (q *pointerQueue) Push(e pointer.Event, events *handlerEvents) {
}
q.deliverEnterLeaveEvents(p, events, e)
q.deliverEvent(p, events, e)
if p.pressed {
q.deliverDragEvent(p, events)
}
case pointer.Release:
q.deliverEvent(p, events, e)
p.pressed = false
q.deliverEnterLeaveEvents(p, events, e)
q.deliverDropEvent(p, events)
case pointer.Scroll:
q.deliverEnterLeaveEvents(p, events, e)
q.deliverScrollEvent(p, events, e)
@@ -671,6 +718,87 @@ func (q *pointerQueue) deliverEnterLeaveEvents(p *pointerInfo, events *handlerEv
p.entered = append(p.entered[:0], hits...)
}
func (q *pointerQueue) deliverDragEvent(p *pointerInfo, events *handlerEvents) {
if p.dataSource != nil {
return
}
// Identify the data source.
for _, k := range p.entered {
src := q.handlers[k]
if len(src.sourceMimes) == 0 {
continue
}
// One data source handler per pointer.
p.dataSource = k
// Notify all potential targets.
for k, tgt := range q.handlers {
if _, ok := firstMimeMatch(src, tgt); ok {
events.Add(k, transfer.InitiateEvent{})
}
}
break
}
}
func (q *pointerQueue) deliverDropEvent(p *pointerInfo, events *handlerEvents) {
if p.dataSource == nil {
return
}
// Request data from the source.
src := q.handlers[p.dataSource]
for _, k := range p.entered {
h := q.handlers[k]
if m, ok := firstMimeMatch(src, h); ok {
p.dataTarget = k
events.Add(p.dataSource, transfer.RequestEvent{Type: m})
return
}
}
// No valid target found, abort.
q.deliverTransferCancelEvent(p, events)
}
func (q *pointerQueue) deliverTransferDataEvent(p *pointerInfo, events *handlerEvents) {
if p.dataSource == nil {
return
}
src := q.handlers[p.dataSource]
if src.data == nil {
// Data not received yet.
return
}
if p.dataTarget == nil {
q.deliverTransferCancelEvent(p, events)
return
}
// Send the offered data to the target.
transferIdx := len(q.transfers)
events.Add(p.dataTarget, transfer.DataEvent{
Type: src.offeredMime,
Open: func() io.ReadCloser {
q.transfers[transferIdx] = nil
return src.data
},
})
q.transfers = append(q.transfers, src.data)
p.dataTarget = nil
}
func (q *pointerQueue) deliverTransferCancelEvent(p *pointerInfo, events *handlerEvents) {
events.Add(p.dataSource, transfer.CancelEvent{})
// Cancel all potential targets.
src := q.handlers[p.dataSource]
for k, h := range q.handlers {
if _, ok := firstMimeMatch(src, h); ok {
events.Add(k, transfer.CancelEvent{})
}
}
src.offeredMime = ""
src.data = nil
p.dataSource = nil
p.dataTarget = nil
}
func searchTag(tags []event.Tag, tag event.Tag) (int, bool) {
for i, t := range tags {
if t == tag {
@@ -690,6 +818,18 @@ func addHandler(tags []event.Tag, tag event.Tag) []event.Tag {
return append(tags, tag)
}
// firstMimeMatch returns the first type match between src and tgt.
func firstMimeMatch(src, tgt *pointerHandler) (first string, matched bool) {
for _, m1 := range tgt.targetMimes {
for _, m2 := range src.sourceMimes {
if m1 == m2 {
return m1, true
}
}
}
return "", false
}
func (op *areaOp) Hit(pos f32.Point) bool {
pos = pos.Sub(op.rect.Min)
size := op.rect.Size()