Draws a conical gradient. 更多...
| import 语句： | import QtGraphicalEffects 1.0 |
| Since: | QtGraphicalEffects 1.0 |
| 继承： | Item |
A gradient is defined by two or more colors, which are blended seamlessly. The colors start from the specified angle and end at 360 degrees larger angle value.
| Effect applied |
|---|
|
注意： This effect is available when running with OpenGL.
The following example shows how to apply the effect.
import QtQuick 2.0 import QtGraphicalEffects 1.0 Item { width: 300 height: 300 ConicalGradient { anchors.fill: parent angle: 0.0 gradient: Gradient { GradientStop { position: 0.0; color: "white" } GradientStop { position: 1.0; color: "black" } } } }
This property defines the starting angle where the color at the gradient position of 0.0 is rendered. Colors at larger position values are rendered into larger angle values and blended seamlessly. Angle values increase clockwise.
| Output examples with different angle values | ||
|---|---|---|
|
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| angle: 0 | angle: 45 | angle: 185 |
| horizontalOffset : 0 | horizontalOffset : 0 | horizontalOffset : 0 |
| verticalOffset : 0 | verticalOffset : 0 | verticalOffset : 0 |
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
.
|
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. The color is defined by the color property.
| Output examples with different gradient values | ||
|---|---|---|
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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"
}
}
|
| angle : 0 | angle : 0 | angle : 0 |
| horizontalOffset : 0 | horizontalOffset : 0 | horizontalOffset : 0 |
| verticalOffset : 0 | verticalOffset : 0 | verticalOffset : 0 |
The horizontalOffset and verticalOffset properties define the offset in pixels for the center point of the gradient compared to the item center.
The value ranges from -inf to inf. By default, the properties are set to
0
.
| Output examples with different horizontalOffset values | ||
|---|---|---|
|
|
|
| horizontalOffset: -50 | horizontalOffset: 0 | horizontalOffset: 50 |
| angle : 0 | angle : 0 | angle : 0 |
| verticalOffset : 0 | verticalOffset : 0 | verticalOffset : 0 |
|
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 | |
|---|---|
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| source: undefined | source: |
| angle : 0 | angle : 0 |
| horizontalOffset : 0 | horizontalOffset : 0 |
| verticalOffset : 0 | verticalOffset : 0 |
注意： It is not supported to let the effect include itself, for instance by setting source to the effect's parent.
The horizontalOffset and verticalOffset properties define the offset in pixels for the center point of the gradient compared to the item center.
The value ranges from -inf to inf. By default, the properties are set to
0
.
| Output examples with different horizontalOffset 值 | ||
|---|---|---|
|
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| horizontalOffset : -50 | horizontalOffset : 0 | horizontalOffset : 50 |
| angle : 0 | angle : 0 | angle : 0 |
| verticalOffset: 0 | verticalOffset: 0 | verticalOffset: 0 |
