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| |
| import QtQuick 2.12 |
| import QtGraphicalEffects.private 1.12 |
| |
| /*! |
| \qmltype Glow |
| \inqmlmodule QtGraphicalEffects |
| \since QtGraphicalEffects 1.0 |
| \inherits QtQuick2::Item |
| \ingroup qtgraphicaleffects-glow |
| \brief Generates a halo like glow around the source item. |
| |
| The Glow effect blurs the alpha channel of the source and colorizes it |
| with \l {Glow::color}{color} and places it behind the source, resulting in a halo or glow |
| around the object. The quality of the blurred edge can be controlled using |
| \l samples and \l radius and the strength of the glow can be changed using |
| \l spread. |
| |
| \table |
| \header |
| \li Source |
| \li Effect applied |
| \row |
| \li \image Original_butterfly_black.png |
| \li \image Glow_butterfly.png |
| \endtable |
| |
| The glow is created by blurring the image live using a gaussian blur. |
| Performing blur live is a costly operation. Fullscreen gaussian blur with |
| even a moderate number of samples will only run at 60 fps on highend |
| graphics hardware. |
| |
| \note This effect is available when running with OpenGL. |
| |
| \section1 Example |
| |
| The following example shows how to apply the effect. |
| \snippet Glow-example.qml example |
| |
| */ |
| Item { |
| id: root |
| |
| DropShadowBase { |
| id: dps |
| anchors.fill: parent |
| color: "white" |
| spread: 0.5 |
| horizontalOffset: 0 |
| verticalOffset: 0 |
| } |
| |
| /*! |
| This property defines the source item that is going to be used as source |
| for the generated glow. |
| |
| \note It is not supported to let the effect include itself, for |
| instance by setting source to the effect's parent. |
| */ |
| property alias source: dps.source |
| |
| /*! |
| Radius defines the softness of the glow. A larger radius causes the |
| edges of the glow to appear more blurry. |
| |
| Depending on the radius value, value of the \l{Glow::samples}{samples} |
| should be set to sufficiently large to ensure the visual quality. |
| |
| The ideal blur is achieved by selecting \c samples and \c radius such |
| that \c {samples = 1 + radius * 2}, such as: |
| |
| \table |
| \header \li Radius \li Samples |
| \row \li 0 \e{(no blur)} \li 1 |
| \row \li 1 \li 3 |
| \row \li 2 \li 5 |
| \row \li 3 \li 7 |
| \endtable |
| |
| By default, the property is set to \c {floor(samples/2)}. |
| |
| \table |
| \header |
| \li Output examples with different radius values |
| \li |
| \li |
| \row |
| \li \image Glow_radius1.png |
| \li \image Glow_radius2.png |
| \li \image Glow_radius3.png |
| \row |
| \li \b { radius: 0 } |
| \li \b { radius: 6 } |
| \li \b { radius: 12 } |
| \row |
| \li \l samples: 25 |
| \li \l samples: 25 |
| \li \l samples: 25 |
| \row |
| \li \l color: #ffffff |
| \li \l color: #ffffff |
| \li \l color: #ffffff |
| \row |
| \li \l spread: 0 |
| \li \l spread: 0 |
| \li \l spread: 0 |
| \endtable |
| */ |
| property alias radius: dps.radius |
| |
| /*! |
| This property defines how many samples are taken per pixel when edge |
| softening blur calculation is done. Larger value produces better |
| quality, but is slower to render. |
| |
| Ideally, this value should be twice as large as the highest required |
| radius value plus one, such as: |
| |
| \table |
| \header \li Radius \li Samples |
| \row \li 0 \e{(no blur)} \li 1 |
| \row \li 1 \li 3 |
| \row \li 2 \li 5 |
| \row \li 3 \li 7 |
| \endtable |
| |
| By default, the property is set to \c 9. |
| |
| This property is not intended to be animated. Changing this property will |
| cause the underlying OpenGL shaders to be recompiled. |
| */ |
| property alias samples: dps.samples |
| |
| /*! |
| This property defines how large part of the glow color is strengthened |
| near the source edges. |
| |
| The values range from 0.0 to 1.0. By default, the property is set to \c |
| 0.5. |
| |
| \note The implementation is optimized for medium and low spread values. |
| Depending on the source, spread values closer to 1.0 may yield visually |
| asymmetrical results. |
| |
| \table |
| \header |
| \li Output examples with different spread values |
| \li |
| \li |
| \row |
| \li \image Glow_spread1.png |
| \li \image Glow_spread2.png |
| \li \image Glow_spread3.png |
| \row |
| \li \b { spread: 0.0 } |
| \li \b { spread: 0.5 } |
| \li \b { spread: 1.0 } |
| \row |
| \li \l radius: 8 |
| \li \l radius: 8 |
| \li \l radius: 8 |
| \row |
| \li \l samples: 17 |
| \li \l samples: 17 |
| \li \l samples: 17 |
| \row |
| \li \l color: #ffffff |
| \li \l color: #ffffff |
| \li \l color: #ffffff |
| \endtable |
| */ |
| property alias spread: dps.spread |
| |
| /*! |
| This property defines the RGBA color value which is used for the glow. |
| |
| By default, the property is set to \c "white". |
| |
| \table |
| \header |
| \li Output examples with different color values |
| \li |
| \li |
| \row |
| \li \image Glow_color1.png |
| \li \image Glow_color2.png |
| \li \image Glow_color3.png |
| \row |
| \li \b { color: #ffffff } |
| \li \b { color: #00ff00 } |
| \li \b { color: #aa00ff00 } |
| \row |
| \li \l radius: 8 |
| \li \l radius: 8 |
| \li \l radius: 8 |
| \row |
| \li \l samples: 17 |
| \li \l samples: 17 |
| \li \l samples: 17 |
| \row |
| \li \l spread: 0.5 |
| \li \l spread: 0.5 |
| \li \l spread: 0.5 |
| \endtable |
| |
| */ |
| property alias color: dps.color |
| |
| /*! |
| \internal |
| |
| Starting Qt 5.6, this property has no effect. It is left here |
| for source compatibility only. |
| |
| ### Qt 6: remove |
| */ |
| property bool fast: false |
| |
| /*! |
| 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 alias cached: dps.cached |
| |
| /*! |
| This property determines whether or not the effect has a transparent |
| border. |
| |
| When set to \c true, the exterior of the item is padded with a |
| transparent edge, making sampling outside the source texture use |
| transparency instead of the edge pixels. Without this property, an |
| image which has opaque edges will not get a blurred edge. |
| |
| By default, the property is set to \c true. Set it to false if the source |
| already has a transparent edge to make the blurring a tiny bit faster. |
| |
| In the snippet below, the Rectangle on the left has transparent borders |
| and has blurred edges, whereas the Rectangle on the right does not. |
| |
| \snippet Glow-transparentBorder-example.qml example |
| |
| \image Glow-transparentBorder.png |
| */ |
| property alias transparentBorder: dps.transparentBorder |
| } |