LinearGradient QML Type

Draws a linear gradient. 更多...

import 语句：	import QtGraphicalEffects 1.0
Since:	QtGraphicalEffects 1.0
继承：	Item

所有成员列表，包括继承成员

特性

cached : bool
end : variant
gradient : Gradient
source : variant
start : variant

详细描述

A gradient is defined by two or more colors, which are blended seamlessly. The colors start from the given start point and end to the given end point.

Effect applied

注意： This effect is available when running with OpenGL.

范例

The following example shows how to apply the effect.

import QtQuick 2.0
import QtGraphicalEffects 1.0
Item {
    width: 300
    height: 300
    LinearGradient {
        anchors.fill: parent
        start: Qt.point(0, 0)
        end: Qt.point(0, 300)
        gradient: Gradient {
            GradientStop { position: 0.0; color: "white" }
            GradientStop { position: 1.0; color: "black" }
        }
    }
}

特性文档编制

cached : bool

This property allows the effect output pixels to be cached in order to improve the rendering performance.

Every time the source or effect properties are changed, the pixels in the cache must be updated. Memory consumption is increased, because an extra buffer of memory is required for storing the effect output.

It is recommended to disable the cache when the source or the effect properties are animated.

By default, the property is set to false .

end : variant

This property defines the ending point where the color at gradient position of 1.0 is rendered. Colors at smaller position values are rendered linearly towards the start point. The point is given in pixels and the default value is Qt.point(0, height). Setting the default values for the start and end results in a full height linear gradient on the y-axis.

Output examples with different end values

end: Qt.point(300, 300)	end: Qt.point(150, 150)	end: Qt.point(300, 0)
start : Qt.point(0, 0)	start : Qt.point(0, 0)	start : Qt.point(0, 0)

gradient : Gradient

A gradient is defined by two or more colors, which are blended seamlessly. The colors are specified as a set of GradientStop child items, each of which defines a position on the gradient from 0.0 to 1.0 and a color. The position of each GradientStop is defined by the position property, and the color is definded by the color property.

Output examples with different gradient values

gradient: Gradient { GradientStop { position: 0.000 color: Qt.rgba(1, 0, 0, 1) } GradientStop { position: 0.167 color: Qt.rgba(1, 1, 0, 1) } GradientStop { position: 0.333 color: Qt.rgba(0, 1, 0, 1) } GradientStop { position: 0.500 color: Qt.rgba(0, 1, 1, 1) } GradientStop { position: 0.667 color: Qt.rgba(0, 0, 1, 1) } GradientStop { position: 0.833 color: Qt.rgba(1, 0, 1, 1) } GradientStop { position: 1.000 color: Qt.rgba(1, 0, 0, 1) } }	gradient: Gradient { GradientStop { position: 0.0 color: "#F0F0F0" } GradientStop { position: 0.5 color: "#000000" } GradientStop { position: 1.0 color: "#F0F0F0" } }	gradient: Gradient { GradientStop { position: 0.0 color: "#00000000" } GradientStop { position: 1.0 color: "#FF000000" } }
start : Qt.point(0, 0)	start : Qt.point(0, 0)	start : Qt.point(0, 0)
end : Qt.point(300, 300)	end : Qt.point(300, 300)	end : Qt.point(300, 300)

source : variant

This property defines the item that is going to be filled with gradient. Source item gets rendered into an intermediate pixel buffer and the alpha values from the result are used to determine the gradient's pixels visibility in the display. The default value for source is undefined and in that case whole effect area is filled with gradient.

Output examples with different source values

source: undefined	source: Image { source: images/butterfly.png }
start : Qt.point(0, 0)	start : Qt.point(0, 0)
end : Qt.point(300, 300)	end : Qt.point(300, 300)

注意： It is not supported to let the effect include itself, for instance by setting source to the effect's parent.

start : variant

This property defines the starting point where the color at gradient position of 0.0 is rendered. Colors at larger position values are rendered linearly towards the end point. The point is given in pixels and the default value is Qt.point(0, 0). Setting the default values for the start and end results in a full height linear gradient on the y-axis.

Output examples with different start values

start: QPoint (0, 0)	start: QPoint (150, 150)	start: QPoint (300, 0)
end : QPoint (300, 300)	end : QPoint (300, 300)	end : QPoint (300, 300)