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rui/touchEvents.go

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package rui
import (
"strconv"
"strings"
)
const (
// TouchStart is the constant for "touch-start" property tag.
// The "touch-start" event is fired when one or more touch points are placed on the touch surface.
// The main listener format: func(View, TouchEvent).
// The additional listener formats: func(TouchEvent), func(View), and func().
TouchStart = "touch-start"
// TouchEnd is the constant for "touch-end" property tag.
// The "touch-end" event fires when one or more touch points are removed from the touch surface.
// The main listener format: func(View, TouchEvent).
// The additional listener formats: func(TouchEvent), func(View), and func().
TouchEnd = "touch-end"
// TouchMove is the constant for "touch-move" property tag.
// The "touch-move" event is fired when one or more touch points are moved along the touch surface.
// The main listener format: func(View, TouchEvent).
// The additional listener formats: func(TouchEvent), func(View), and func().
TouchMove = "touch-move"
// TouchCancel is the constant for "touch-cancel" property tag.
// The "touch-cancel" event is fired when one or more touch points have been disrupted
// in an implementation-specific manner (for example, too many touch points are created).
// The main listener format: func(View, TouchEvent).
// The additional listener formats: func(TouchEvent), func(View), and func().
TouchCancel = "touch-cancel"
)
// Touch contains parameters of a single touch of a touch event
type Touch struct {
// Identifier is a unique identifier for this Touch object. A given touch point (say, by a finger)
// will have the same identifier for the duration of its movement around the surface.
// This lets you ensure that you're tracking the same touch all the time.
Identifier int
// X provides the horizontal coordinate within the view's viewport.
X float64
// Y provides the vertical coordinate within the view's viewport.
Y float64
// ClientX provides the horizontal coordinate within the application's viewport at which the event occurred.
ClientX float64
// ClientY provides the vertical coordinate within the application's viewport at which the event occurred.
ClientY float64
// ScreenX provides the horizontal coordinate (offset) of the touch pointer in global (screen) coordinates.
ScreenX float64
// ScreenY provides the vertical coordinate (offset) of the touch pointer in global (screen) coordinates.
ScreenY float64
// RadiusX is the X radius of the ellipse that most closely circumscribes the area of contact with the screen.
// The value is in pixels of the same scale as screenX.
RadiusX float64
// RadiusY is the Y radius of the ellipse that most closely circumscribes the area of contact with the screen.
// The value is in pixels of the same scale as screenX.
RadiusY float64
// RotationAngle is the angle (in degrees) that the ellipse described by radiusX and radiusY must be rotated,
// clockwise, to most accurately cover the area of contact between the user and the surface.
RotationAngle float64
// Force is the amount of pressure being applied to the surface by the user, as a float
// between 0.0 (no pressure) and 1.0 (maximum pressure).
Force float64
}
// TouchEvent contains parameters of a touch event
type TouchEvent struct {
// TimeStamp is the time at which the event was created (in milliseconds).
// This value is time since epoch—but in reality, browsers' definitions vary.
TimeStamp uint64
// Touches is the array of all the Touch objects representing all current points
// of contact with the surface, regardless of target or changed status.
Touches []Touch
// CtrlKey == true if the control key was down when the event was fired. false otherwise.
CtrlKey bool
// ShiftKey == true if the shift key was down when the event was fired. false otherwise.
ShiftKey bool
// AltKey == true if the alt key was down when the event was fired. false otherwise.
AltKey bool
// MetaKey == true if the meta key was down when the event was fired. false otherwise.
MetaKey bool
}
var touchEvents = map[string]struct{ jsEvent, jsFunc string }{
TouchStart: {jsEvent: "ontouchstart", jsFunc: "touchStartEvent"},
TouchEnd: {jsEvent: "ontouchend", jsFunc: "touchEndEvent"},
TouchMove: {jsEvent: "ontouchmove", jsFunc: "touchMoveEvent"},
TouchCancel: {jsEvent: "ontouchcancel", jsFunc: "touchCancelEvent"},
}
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func (view *viewData) setTouchListener(tag string, value any) bool {
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listeners, ok := valueToEventListeners[View, TouchEvent](value)
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if !ok {
notCompatibleType(tag, value)
return false
}
if listeners == nil {
view.removeTouchListener(tag)
} else if js, ok := touchEvents[tag]; ok {
view.properties[tag] = listeners
if view.created {
updateProperty(view.htmlID(), js.jsEvent, js.jsFunc+"(this, event)", view.Session())
}
} else {
return false
}
return true
}
func (view *viewData) removeTouchListener(tag string) {
delete(view.properties, tag)
if view.created {
if js, ok := touchEvents[tag]; ok {
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removeProperty(view.htmlID(), js.jsEvent, view.Session())
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}
}
}
func touchEventsHtml(view View, buffer *strings.Builder) {
for tag, js := range touchEvents {
if value := view.getRaw(tag); value != nil {
if listeners, ok := value.([]func(View, TouchEvent)); ok && len(listeners) > 0 {
buffer.WriteString(js.jsEvent + `="` + js.jsFunc + `(this, event)" `)
}
}
}
}
func (event *TouchEvent) init(data DataObject) {
event.Touches = []Touch{}
event.TimeStamp = getTimeStamp(data)
if node := data.PropertyWithTag("touches"); node != nil && node.Type() == ArrayNode {
for i := 0; i < node.ArraySize(); i++ {
if element := node.ArrayElement(i); element != nil && element.IsObject() {
if obj := element.Object(); obj != nil {
var touch Touch
if value, ok := obj.PropertyValue("identifier"); ok {
touch.Identifier, _ = strconv.Atoi(value)
}
touch.X = dataFloatProperty(obj, "x")
touch.Y = dataFloatProperty(obj, "y")
touch.ClientX = dataFloatProperty(obj, "clientX")
touch.ClientY = dataFloatProperty(obj, "clientY")
touch.ScreenX = dataFloatProperty(obj, "screenX")
touch.ScreenY = dataFloatProperty(obj, "screenY")
touch.RadiusX = dataFloatProperty(obj, "radiusX")
touch.RadiusY = dataFloatProperty(obj, "radiusY")
touch.RotationAngle = dataFloatProperty(obj, "rotationAngle")
touch.Force = dataFloatProperty(obj, "force")
event.Touches = append(event.Touches, touch)
}
}
}
}
event.CtrlKey = dataBoolProperty(data, "ctrlKey")
event.ShiftKey = dataBoolProperty(data, "shiftKey")
event.AltKey = dataBoolProperty(data, "altKey")
event.MetaKey = dataBoolProperty(data, "metaKey")
}
func handleTouchEvents(view View, tag string, data DataObject) {
listeners := getEventListeners[View, TouchEvent](view, nil, tag)
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if len(listeners) == 0 {
return
}
var event TouchEvent
event.init(data)
for _, listener := range listeners {
listener(view, event)
}
}
// GetTouchStartListeners returns the "touch-start" listener list. If there are no listeners then the empty list is returned.
// If the second argument (subviewID) is not specified or it is "" then a value from the first argument (view) is returned.
func GetTouchStartListeners(view View, subviewID ...string) []func(View, TouchEvent) {
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return getEventListeners[View, TouchEvent](view, subviewID, TouchStart)
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}
// GetTouchEndListeners returns the "touch-end" listener list. If there are no listeners then the empty list is returned.
// If the second argument (subviewID) is not specified or it is "" then a value from the first argument (view) is returned.
func GetTouchEndListeners(view View, subviewID ...string) []func(View, TouchEvent) {
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return getEventListeners[View, TouchEvent](view, subviewID, TouchEnd)
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}
// GetTouchMoveListeners returns the "touch-move" listener list. If there are no listeners then the empty list is returned.
// If the second argument (subviewID) is not specified or it is "" then a value from the first argument (view) is returned.
func GetTouchMoveListeners(view View, subviewID ...string) []func(View, TouchEvent) {
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return getEventListeners[View, TouchEvent](view, subviewID, TouchMove)
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}
// GetTouchCancelListeners returns the "touch-cancel" listener list. If there are no listeners then the empty list is returned.
// If the second argument (subviewID) is not specified or it is "" then a value from the first argument (view) is returned.
func GetTouchCancelListeners(view View, subviewID ...string) []func(View, TouchEvent) {
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return getEventListeners[View, TouchEvent](view, subviewID, TouchCancel)
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}