Triggers a handler at a specified interval. 更多...
import 语句: | import QtQml 2.15 |
A Timer can be used to trigger an action either once, or repeatedly at a given interval.
Here is a Timer that shows the current date and time, and updates the text every 500 milliseconds. It uses the JavaScript
Date
object to access the current time.
import QtQuick 2.0 Item { Timer { interval: 500; running: true; repeat: true onTriggered: time.text = Date().toString() } Text { id: time } }
The Timer type is synchronized with the animation timer. Since the animation timer is usually set to 60fps, the resolution of Timer will be at best 16ms.
If the Timer is running and one of its properties is changed, the elapsed time will be reset. For example, if a Timer with interval of 1000ms has its repeat property changed 500ms after starting, the elapsed time will be reset to 0, and the Timer will be triggered 1000ms later.
另请参阅 Qt Quick 演示 - 时钟 .
interval : int |
设置 interval between triggers, in milliseconds.
The default interval is 1000 milliseconds.
repeat : bool |
若 repeat is true the timer is triggered repeatedly at the specified interval; otherwise, the timer will trigger once at the specified interval and then stop (i.e. running will be set to false).
repeat defaults to false.
另请参阅 running .
running : bool |
If set to true, starts the timer; otherwise stops the timer. For a non-repeating timer, running is set to false after the timer has been triggered.
running defaults to false.
另请参阅 repeat .
triggeredOnStart : bool |
When a timer is started, the first trigger is usually after the specified interval has elapsed. It is sometimes desirable to trigger immediately when the timer is started; for example, to establish an initial state.
若 triggeredOnStart is true, the timer is triggered immediately when started, and subsequently at the specified interval. Note that if repeat is set to false, the timer is triggered twice; once on start, and again at the interval.
triggeredOnStart defaults to false.
另请参阅 running .
This signal is emitted when the Timer times out.
注意:
相应处理程序是
onTriggered
.
Restarts the timer
If the Timer is not running it will be started, otherwise it will be stopped, reset to initial state and started. The
running
property will be true following a call to
restart()
.
Starts the timer
If the timer is already running, calling this method has no effect. The
running
property will be true following a call to
start()
.
Stops the timer
If the timer is not running, calling this method has no effect. The
running
property will be false following a call to
stop()
.