ProxSpace/Qt/5.6/qml/QtGraphicalEffects/ConicalGradient.qml
2016-10-31 22:04:38 +01:00

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QML

/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
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** This file is part of the Qt Graphical Effects module.
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import QtQuick 2.0
import QtGraphicalEffects.private 1.0
/*!
\qmltype ConicalGradient
\inqmlmodule QtGraphicalEffects
\since QtGraphicalEffects 1.0
\inherits QtQuick2::Item
\ingroup qtgraphicaleffects-gradient
\brief Draws a conical gradient.
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.
\table
\header
\li Effect applied
\row
\li \image ConicalGradient.png
\endtable
\section1 Example
The following example shows how to apply the effect.
\snippet ConicalGradient-example.qml example
*/
Item {
id: rootItem
/*!
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 \c false.
*/
property bool cached: false
/*!
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.
\table
\header
\li Output examples with different angle values
\li
\li
\row
\li \image ConicalGradient_angle1.png
\li \image ConicalGradient_angle2.png
\li \image ConicalGradient_angle3.png
\row
\li \b { angle: 0 }
\li \b { angle: 45 }
\li \b { angle: 185 }
\row
\li \l horizontalOffset: 0
\li \l horizontalOffset: 0
\li \l horizontalOffset: 0
\row
\li \l verticalOffset: 0
\li \l verticalOffset: 0
\li \l verticalOffset: 0
\endtable
*/
property real angle: 0.0
/*!
\qmlproperty real QtGraphicalEffects::ConicalGradient::horizontalOffset
\qmlproperty real QtGraphicalEffects::ConicalGradient::verticalOffset
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 \c
0.
\table
\header
\li Output examples with different horizontalOffset values
\li
\li
\row
\li \image ConicalGradient_horizontalOffset1.png
\li \image ConicalGradient_horizontalOffset2.png
\li \image ConicalGradient_horizontalOffset3.png
\row
\li \b { horizontalOffset: -50 }
\li \b { horizontalOffset: 0 }
\li \b { horizontalOffset: 50 }
\row
\li \l angle: 0
\li \l angle: 0
\li \l angle: 0
\row
\li \l verticalOffset: 0
\li \l verticalOffset: 0
\li \l verticalOffset: 0
\endtable
*/
property real horizontalOffset: 0.0
property real verticalOffset: 0.0
/*!
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.
\table
\header
\li Output examples with different source values
\li
\row
\li \image ConicalGradient_maskSource1.png
\li \image ConicalGradient_maskSource2.png
\row
\li \b { source: undefined }
\li \b { source: }
\row
\li \l angle: 0
\li \l angle: 0
\row
\li \l horizontalOffset: 0
\li \l horizontalOffset: 0
\row
\li \l verticalOffset: 0
\li \l verticalOffset: 0
\endtable
\note It is not supported to let the effect include itself, for
instance by setting source to the effect's parent.
*/
property variant source
/*!
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.
\table
\header
\li Output examples with different gradient values
\li
\li
\row
\li \image ConicalGradient_gradient1.png
\li \image ConicalGradient_gradient2.png
\li \image ConicalGradient_gradient3.png
\row
\li \b {gradient:} \code
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)
}
}
\endcode
\li \b {gradient:} \code
Gradient {
GradientStop {
position: 0.0
color: "#F0F0F0"
}
GradientStop {
position: 0.5
color: "#000000"
}
GradientStop {
position: 1.0
color: "#F0F0F0"
}
}
\endcode
\li \b {gradient:} \code
Gradient {
GradientStop {
position: 0.0
color: "#00000000"
}
GradientStop {
position: 1.0
color: "#FF000000"
}
}
\endcode
\row
\li \l angle: 0
\li \l angle: 0
\li \l angle: 0
\row
\li \l horizontalOffset: 0
\li \l horizontalOffset: 0
\li \l horizontalOffset: 0
\row
\li \l verticalOffset: 0
\li \l verticalOffset: 0
\li \l verticalOffset: 0
\endtable
*/
property Gradient gradient: Gradient {
GradientStop { position: 0.0; color: "white" }
GradientStop { position: 1.0; color: "black" }
}
SourceProxy {
id: maskSourceProxy
input: rootItem.source
}
Rectangle {
id: gradientRect
width: 16
height: 256
gradient: rootItem.gradient
smooth: true
}
ShaderEffectSource {
id: cacheItem
anchors.fill: parent
visible: rootItem.cached
smooth: true
rotation: shaderItem.rotation
sourceItem: shaderItem
live: true
hideSource: visible
}
ShaderEffect {
id: shaderItem
property variant gradientSource: ShaderEffectSource {
sourceItem: gradientRect
smooth: true
hideSource: true
visible: false
}
property variant maskSource: maskSourceProxy.output
property real startAngle: (rootItem.angle - 90) * Math.PI/180
property variant center: Qt.point(0.5 + horizontalOffset / width, 0.5 + verticalOffset / height)
anchors.fill: parent
fragmentShader: maskSource == undefined ? noMaskShader : maskShader
onFragmentShaderChanged: startAngleChanged()
property string noMaskShader: "
varying mediump vec2 qt_TexCoord0;
uniform lowp sampler2D gradientSource;
uniform highp float qt_Opacity;
uniform highp float startAngle;
uniform highp vec2 center;
void main() {
const highp float PI = 3.14159265;
const highp float PIx2inv = 0.1591549;
highp float a = (atan((center.y - qt_TexCoord0.t), (center.x - qt_TexCoord0.s)) + PI - startAngle) * PIx2inv;
gl_FragColor = texture2D(gradientSource, vec2(0.0, fract(a))) * qt_Opacity;
}
"
property string maskShader: "
varying mediump vec2 qt_TexCoord0;
uniform lowp sampler2D gradientSource;
uniform lowp sampler2D maskSource;
uniform highp float qt_Opacity;
uniform highp float startAngle;
uniform highp vec2 center;
void main() {
lowp float maskAlpha = texture2D(maskSource, qt_TexCoord0).a;
const highp float PI = 3.14159265;
const highp float PIx2inv = 0.1591549;
highp float a = (atan((center.y - qt_TexCoord0.t), (center.x - qt_TexCoord0.s)) + PI - startAngle) * PIx2inv;
gl_FragColor = texture2D(gradientSource, vec2(0.0, fract(a))) * maskAlpha * qt_Opacity;
}
"
}
}