Handler for taps and clicks. 更多...
| import 语句： | import QtQuick 2.2 |
| 继承： | SinglePointHandler |
TapHandler is a handler for taps on a touchscreen or clicks on a mouse.
Detection of a valid tap gesture depends on gesturePolicy . The default value is DragThreshold, which requires the press and release to be close together in both space and time. In this case, DragHandler is able to function using only a passive grab, and therefore does not interfere with event delivery to any other Items or Input Handlers. So the default gesturePolicy is useful when you want to modify behavior of an existing control or Item by adding a TapHandler with bindings and/or JavaScript callbacks.
Note that buttons (such as
QPushButton
) are often implemented not to care whether the press and release occur close together: if you press the button and then change your mind, you need to drag all the way off the edge of the button in order to cancel the click. For this use case, set the
gesturePolicy
to
TapHandler.ReleaseWithinBounds
.
import QtQuick Rectangle { id: button signal clicked property alias text: buttonLabel.text height: Math.max(Screen.pixelDensity * 7, buttonLabel.implicitHeight * 1.2) width: Math.max(Screen.pixelDensity * 11, buttonLabel.implicitWidth * 1.3) radius: 3 property color dark: Qt.darker(palette.button, 1.3) gradient: Gradient { GradientStop { position: 0.0; color: tapHandler.pressed ? dark : palette.button } GradientStop { position: 1.0; color: dark } } TapHandler { id: tapHandler gesturePolicy: TapHandler.ReleaseWithinBounds onTapped: button.clicked() } Text { id: buttonLabel text: "Click Me" color: palette.buttonText anchors.centerIn: parent } }
For multi-tap gestures (double-tap, triple-tap etc.), the distance moved must not exceed QStyleHints::mouseDoubleClickDistance() with mouse and QStyleHints::touchDoubleTapDistance() with touch, and the time between taps must not exceed QStyleHints::mouseDoubleClickInterval() .
另请参阅 MouseArea .
| acceptedButtons : flags |
The mouse buttons which can activate this Pointer Handler.
默认情况下，此特性被设为 Qt.LeftButton . It can be set to an OR combination of mouse buttons, and will ignore events from other buttons.
For example, a control could be made to respond to left and right clicks in different ways, with two handlers:
Item { TapHandler { onTapped: console.log("left clicked") } TapHandler { acceptedButtons: Qt.RightButton onTapped: console.log("right clicked") } }
注意： Tapping on a touchscreen or tapping the stylus on a graphics tablet emulates clicking the left mouse button. This behavior can be altered via acceptedDevices or acceptedPointerTypes .
| acceptedDevices : flags |
The types of pointing devices that can activate this Pointer Handler.
默认情况下，此特性被设为 PointerDevice.AllDevices . If you set it to an OR combination of device types, it will ignore events from non-matching devices.
For example, a control could be made to respond to mouse and stylus clicks in one way, and touchscreen taps in another way, with two handlers:
Item { TapHandler { acceptedDevices: PointerDevice.Mouse | PointerDevice.Stylus onTapped: console.log("clicked") } TapHandler { acceptedDevices: PointerDevice.TouchScreen onTapped: console.log("tapped") } }
| acceptedModifiers : flags |
If this property is set, it will require the given keyboard modifiers to be pressed in order to react to pointer events, and otherwise ignore them.
If this property is set to
Qt.KeyboardModifierMask
(the default value), then the
PointerHandler
ignores the modifier keys.
For example, an Item could have two handlers of the same type, one of which is enabled only if the required keyboard modifiers are pressed:
Item { TapHandler { acceptedModifiers: Qt.ControlModifier onTapped: console.log("control-tapped") } TapHandler { acceptedModifiers: Qt.NoModifier onTapped: console.log("tapped") } }
若设置
acceptedModifiers
to an OR combination of modifier keys, it means
all
of those modifiers must be pressed to activate the handler:
Item { TapHandler { acceptedModifiers: Qt.ControlModifier | Qt.AltModifier | Qt.ShiftModifier onTapped: console.log("control-alt-shift-tapped") } }
The available modifiers are as follows:
| 常量 | 描述 |
|---|---|
NoModifier
|
No modifier key is allowed. |
ShiftModifier
|
A Shift key on the keyboard must be pressed. |
ControlModifier
|
A Ctrl key on the keyboard must be pressed. |
AltModifier
|
An Alt key on the keyboard must be pressed. |
MetaModifier
|
A Meta key on the keyboard must be pressed. |
KeypadModifier
|
A keypad button must be pressed. |
GroupSwitchModifier
|
X11 only (unless activated on Windows by a command line argument). A Mode_switch key on the keyboard must be pressed. |
KeyboardModifierMask
|
The handler does not care which modifiers are pressed. |
If you need even more complex behavior than can be achieved with combinations of multiple handlers with multiple modifier flags, you can check the modifiers in JavaScript code:
Item { TapHandler { onTapped: switch (point.modifiers) { case Qt.ControlModifier | Qt.AltModifier: console.log("CTRL+ALT"); break; case Qt.ControlModifier | Qt.AltModifier | Qt.MetaModifier: console.log("CTRL+META+ALT"); break; default: console.log("other modifiers", point.modifiers); break; } } }
另请参阅 Qt::KeyboardModifier .
| acceptedPointerTypes : flags |
The types of pointing instruments (finger, stylus, eraser, etc.) that can activate this Pointer Handler.
默认情况下，此特性被设为 PointerDevice.AllPointerTypes . If you set it to an OR combination of device types, it will ignore events from non-matching events.
For example, a control could be made to respond to mouse, touch, and stylus clicks in some way, but delete itself if tapped with an eraser tool on a graphics tablet, with two handlers:
Rectangle { id: rect TapHandler { acceptedPointerTypes: PointerDevice.GenericPointer | PointerDevice.Finger | PointerDevice.Pen onTapped: console.log("clicked") } TapHandler { acceptedPointerTypes: PointerDevice.Eraser onTapped: rect.destroy() } }
| [read-only] active : bool |
This holds true whenever this Input Handler has taken sole responsibility for handing one or more EventPoints, by successfully taking an exclusive grab of those points. This means that it is keeping its properties up-to-date according to the movements of those Event Points and actively manipulating its target (if any).
| [since 5.15] cursorShape : Qt::CursorShape |
This property holds the cursor shape that will appear whenever the mouse is hovering over the
parent
item while
active
is
true
.
The available cursor shapes are:
The default value is not set, which allows the cursor of parent item to appear. This property can be reset to the same initial condition by setting it to undefined.
注意：
When this property has not been set, or has been set to
undefined
, if you read the value it will return
Qt.ArrowCursor
.
该特性在 Qt 5.15 引入。
另请参阅 Qt::CursorShape , QQuickItem::cursor() ，和 HoverHandler::cursorShape .
| [since 5.15] dragThreshold : int |
The distance in pixels that the user must drag an event point in order to have it treated as a drag gesture.
The default value depends on the platform and screen resolution. It can be reset back to the default value by setting it to undefined. The behavior when a drag gesture begins varies in different handlers.
该特性在 Qt 5.15 引入。
| enabled : bool |
若 PointerHandler is disabled, it will reject all events and no signals will be emitted.
| gesturePolicy : enumeration |
The spatial constraint for a tap or long press gesture to be recognized, in addition to the constraint that the release must occur before longPressThreshold has elapsed. If these constraints are not satisfied, the tapped signal is not emitted, and tapCount is not incremented. If the spatial constraint is violated, pressed transitions immediately from true to false, regardless of the time held.
gesturePolicy
also affects grab behavior as described below.
| 常量 | 描述 |
|---|---|
TapHandler.DragThreshold
|
(the default value) The event point must not move significantly. If the mouse, finger or stylus moves past the system-wide drag threshold ( QStyleHints::startDragDistance ), the tap gesture is canceled, even if the button or finger is still pressed. This policy can be useful whenever TapHandler needs to cooperate with other input handlers (for example DragHandler ) or event-handling Items (for example QtQuick Controls), because in this case TapHandler will not take the exclusive grab, but merely a passive grab . |
TapHandler.WithinBounds
|
If the event point leaves the bounds of the
parent
Item, the tap gesture is canceled. The
TapHandler
will take the
exclusive grab
on press, but will release the grab as soon as the boundary constraint is no longer satisfied.
|
TapHandler.ReleaseWithinBounds
|
At the time of release (the mouse button is released or the finger is lifted), if the event point is outside the bounds of the
parent
Item, a tap gesture is not recognized. This corresponds to typical behavior for button widgets: you can cancel a click by dragging outside the button, and you can also change your mind by dragging back inside the button before release. Note that it's necessary for
TapHandler
to take the
exclusive grab
on press and retain it until release in order to detect this gesture.
|
| grabPermissions : flags |
This property specifies the permissions when this handler's logic decides to take over the exclusive grab, or when it is asked to approve grab takeover or cancellation by another handler.
| 常量 | 描述 |
|---|---|
PointerHandler.TakeOverForbidden
|
This handler neither takes from nor gives grab permission to any type of Item or Handler. |
PointerHandler.CanTakeOverFromHandlersOfSameType
|
This handler can take the exclusive grab from another handler of the same class. |
PointerHandler.CanTakeOverFromHandlersOfDifferentType
|
This handler can take the exclusive grab from any kind of handler. |
PointerHandler.CanTakeOverFromAnything
|
This handler can take the exclusive grab from any type of Item or Handler. |
PointerHandler.ApprovesTakeOverByHandlersOfSameType
|
This handler gives permission for another handler of the same class to take the grab. |
PointerHandler.ApprovesTakeOverByHandlersOfDifferentType
|
This handler gives permission for any kind of handler to take the grab. |
PointerHandler.ApprovesTakeOverByItems
|
This handler gives permission for any kind of Item to take the grab. |
PointerHandler.ApprovesCancellation
|
This handler will allow its grab to be set to null. |
PointerHandler.ApprovesTakeOverByAnything
|
This handler gives permission for any any type of Item or Handler to take the grab. |
默认为
PointerHandler.CanTakeOverFromItems | PointerHandler.CanTakeOverFromHandlersOfDifferentType | PointerHandler.ApprovesTakeOverByAnything
which allows most takeover scenarios but avoids e.g. two PinchHandlers fighting over the same touchpoints.
| longPressThreshold : real |
The time in seconds that an event point must be pressed in order to trigger a long press gesture and emit the longPressed() signal. If the point is released before this time limit, a tap can be detected if the gesturePolicy constraint is satisfied. The default value is QStyleHints::mousePressAndHoldInterval() converted to seconds.
| margin : real |
The margin beyond the bounds of the
parent
item within which an event point can activate this handler. For example, on a
PinchHandler
在哪里
target
is also the
parent
, it's useful to set this to a distance at least half the width of a typical user's finger, so that if the
parent
has been scaled down to a very small size, the pinch gesture is still possible. Or, if a
TapHandler
-based button is placed near the screen edge, it can be used to comply with Fitts's Law: react to mouse clicks at the screen edge even though the button is visually spaced away from the edge by a few pixels.
默认值为 0。
| [read-only] parent : Item |
Item which is the scope of the handler; the Item in which it was declared. The handler will handle events on behalf of this Item, which means a pointer event is relevant if at least one of its event points occurs within the Item's interior. Initially target() is the same, but it can be reassigned.
注意：
When a handler is declared in a
QtQuick3D.Model
object, the parent is not an Item, therefore this property is
null
.
另请参阅 target and QObject::parent() .
| [read-only] point : HandlerPoint |
The event point currently being handled. When no point is currently being handled, this object is reset to default values (all coordinates are 0).
| [read-only] pressed : bool |
Holds true whenever the mouse or touch point is pressed, and any movement since the press is compliant with the current gesturePolicy . When the event point is released or the policy is violated, pressed will change to false.
| [read-only] tapCount : int |
The number of taps which have occurred within the time and space constraints to be considered a single gesture. For example, to detect a triple-tap, you can write:
Rectangle { width: 100; height: 30 signal tripleTap TapHandler { acceptedButtons: Qt.AllButtons onTapped: if (tapCount == 3) tripleTap() } }
| target : Item |
The Item which this handler will manipulate.
By default, it is the same as the
parent
, the Item within which the handler is declared. However, it can sometimes be useful to set the target to a different Item, in order to handle events within one item but manipulate another; or to
null
, to disable the default behavior and do something else instead.
| [read-only] timeHeld : real |
The amount of time in seconds that a pressed point has been held, without moving beyond the drag threshold. It will be updated at least once per frame rendered, which enables rendering an animation showing the progress towards an action which will be triggered by a long-press. It is also possible to trigger one of a series of actions depending on how long the press is held.
A value of less than zero means no point is being held within this handler's Item .
| canceled ( EventPoint point ) |
If this handler has already grabbed the given point , this signal is emitted when the grab is stolen by a different Pointer Handler or Item.
注意：
相应处理程序是
onCanceled
.
[since 5.11]
doubleTapped
(
EventPoint
eventPoint
,
Qt::MouseButton
button
)
|
此信号被发射当
parent
Item is tapped twice within a short span of time (
QStyleHints::mouseDoubleClickInterval()
) and distance (
QStyleHints::mouseDoubleClickDistance()
or
QStyleHints::touchDoubleTapDistance()
). This signal always occurs after
singleTapped
,
tapped
，和
tapCountChanged
。
eventPoint
signal parameter contains information from the release event about the point that was tapped, and
button
是
mouse button
that was clicked, or
NoButton
on a touchscreen.
注意：
相应处理程序是
onDoubleTapped
.
This signal was introduced in Qt 5.11.
| grabChanged ( GrabTransition transition , EventPoint point ) |
This signal is emitted when the grab has changed in some way which is relevant to this handler.
transition (verb) tells what happened. The point (object) is the point that was grabbed or ungrabbed.
注意：
相应处理程序是
onGrabChanged
.
| longPressed () |
此信号被发射当
parent
Item is pressed and held for a time period greater than
longPressThreshold
. That is, if you press and hold a touchpoint or button, while any movement does not exceed the drag threshold, then the
longPressed
signal will be emitted at the time that
timeHeld
exceeds
longPressThreshold
.
注意：
相应处理程序是
onLongPressed
.
[since 5.11]
singleTapped
(
EventPoint
eventPoint
,
Qt::MouseButton
button
)
|
此信号被发射当
parent
Item is tapped once. After an amount of time greater than
QStyleHints::mouseDoubleClickInterval
, it can be tapped again; but if the time until the next tap is less,
tapCount
will increase. The
eventPoint
signal parameter contains information from the release event about the point that was tapped, and
button
是
mouse button
that was clicked, or
NoButton
on a touchscreen.
注意：
相应处理程序是
onSingleTapped
.
This signal was introduced in Qt 5.11.
| tapCountChanged () |
此信号被发射当
parent
Item is tapped once or more (within a specified time and distance span) and when the present
tapCount
differs from the previous
tapCount
.
注意：
相应处理程序是
onTapCountChanged
.
| tapped ( EventPoint eventPoint , Qt::MouseButton button ) |
This signal is emitted each time the
parent
Item is tapped.
That is, if you press and release a touchpoint or button within a time period less than
longPressThreshold
, while any movement does not exceed the drag threshold, then the
tapped
signal will be emitted at the time of release. The
eventPoint
signal parameter contains information from the release event about the point that was tapped, and
button
是
mouse button
that was clicked, or
NoButton
on a touchscreen.
import QtQuick Rectangle { width: 100 height: 100 TapHandler { acceptedButtons: Qt.LeftButton | Qt.RightButton onTapped: (eventPoint, button)=> console.log("tapped", eventPoint.device.name, "button", button, "@", eventPoint.scenePosition) } }
注意：
相应处理程序是
onTapped
.
