A specialized Canvas type for rendering Trace objects. 更多...
import 语句: | import QtQuick.VirtualKeyboard.Styles 2.15 |
Since: | QtQuick.VirtualKeyboard 2.0 |
继承: |
This type provides capabilities for rendering Trace objects on the screen.
To make the Trace rendering available in the keyboard, this type must be declared as the KeyboardStyle.traceCanvasDelegate 组件。
traceCanvasDelegate: TraceCanvas { }
Custom drawing attributes can be initialized in the Canvas.available signal. For example:
onAvailableChanged: { if (!available) return; var ctx = getContext("2d") ctx.lineWidth = 8 * scaleHint ctx.lineCap = "round" ctx.strokeStyle = Qt.rgba(0xFF, 0xFF, 0xFF) ctx.fillStyle = ctx.strokeStyle }
The type offers built-in options for Trace rendering. Currently the following rendering options are available:
renderSmoothedLine
Renders smoothed line with round corners (the default)
The rendering function can be changed with the renderFunction 特性。
renderFunction: renderSmoothedLine
Custom rendering function is also supported. Consider the following example:
renderFunction: renderCustomLine function renderCustomLine() { getContext("2d") var points = trace.points() ... }
autoDestroy : bool |
Enables auto destruction mode.
If enabled, this item will be destroyed when the
trace
对象被销毁。
默认值为 false。
autoDestroyDelay : int |
Specifies the approximate delay in milliseconds, counted from the beginning of the auto destruction, before the object is to be destroyed.
This delay makes it possible, for example, to animate the item before destruction.
默认值为 0。
renderFunction : var |
This property defines the rendering function.
默认值为
renderSmoothedLine
trace : var |
提供访问 Trace 对象。
Renders smoothed line with round corners.
This function is incremental and renders only the new part added to the Trace.
This function does not alter any of the canvas attributes (i.e. they can be set elsewhere.)