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| |
| import QtQuick 2.12 |
| import QtGraphicalEffects.private 1.12 |
| |
| /*! |
| \qmltype DropShadow |
| \inqmlmodule QtGraphicalEffects |
| \since QtGraphicalEffects 1.0 |
| \inherits QtQuick2::Item |
| \ingroup qtgraphicaleffects-drop-shadow |
| |
| \brief Generates a soft shadow behind the source item. |
| |
| The DropShadow effect blurs the alpha channel of the input, colorizes the |
| result and places it behind the source object to create a soft shadow. The |
| shadow's color can be changed using the \l {DropShadow::color}{color} |
| property. The location of the shadow can be changed with the \l |
| horizontalOffset and \l verticalOffset properties. |
| |
| \table |
| \header |
| \li Source |
| \li Effect applied |
| \row |
| \li \image Original_butterfly.png |
| \li \image DropShadow_butterfly.png |
| \endtable |
| |
| The soft shadow 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. |
| |
| When the source is static, the \l cached property can be set to allocate |
| another buffer to avoid performing the blur every time it is drawn. |
| |
| \note This effect is available when running with OpenGL. |
| |
| \section1 Example |
| |
| The following example shows how to apply the effect. |
| \snippet DropShadow-example.qml example |
| |
| */ |
| Item { |
| id: root |
| |
| DropShadowBase { |
| id: dbs |
| anchors.fill: parent |
| } |
| |
| /*! |
| This property defines the source item that is going to be used as the |
| source for the generated shadow. |
| |
| \note It is not supported to let the effect include itself, for |
| instance by setting source to the effect's parent. |
| */ |
| property alias source: dbs.source |
| |
| /*! |
| \qmlproperty int DropShadow::radius |
| |
| Radius defines the softness of the shadow. A larger radius causes the |
| edges of the shadow to appear more blurry. |
| |
| 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 DropShadow_radius1.png |
| \li \image DropShadow_radius2.png |
| \li \image DropShadow_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: #000000 |
| \li \l color: #000000 |
| \li \l color: #000000 |
| \row |
| \li \l horizontalOffset: 0 |
| \li \l horizontalOffset: 0 |
| \li \l horizontalOffset: 0 |
| \row |
| \li \l verticalOffset: 20 |
| \li \l verticalOffset: 20 |
| \li \l verticalOffset: 20 |
| \row |
| \li \l spread: 0 |
| \li \l spread: 0 |
| \li \l spread: 0 |
| \endtable |
| */ |
| property alias radius: dbs.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: dbs.samples |
| |
| /*! |
| This property defines the RGBA color value which is used for the shadow. |
| |
| By default, the property is set to \c "black". |
| |
| \table |
| \header |
| \li Output examples with different color values |
| \li |
| \li |
| \row |
| \li \image DropShadow_color1.png |
| \li \image DropShadow_color2.png |
| \li \image DropShadow_color3.png |
| \row |
| \li \b { color: #000000 } |
| \li \b { color: #0000ff } |
| \li \b { color: #aa000000 } |
| \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 horizontalOffset: 0 |
| \li \l horizontalOffset: 0 |
| \li \l horizontalOffset: 0 |
| \row |
| \li \l verticalOffset: 20 |
| \li \l verticalOffset: 20 |
| \li \l verticalOffset: 20 |
| \row |
| \li \l spread: 0 |
| \li \l spread: 0 |
| \li \l spread: 0 |
| \endtable |
| */ |
| property alias color: dbs.color |
| |
| /*! |
| \qmlproperty real QtGraphicalEffects::DropShadow::horizontalOffset |
| \qmlproperty real QtGraphicalEffects::DropShadow::verticalOffset |
| |
| HorizontalOffset and verticalOffset properties define the offset for the |
| rendered shadow compared to the DropShadow item position. Often, the |
| DropShadow item is anchored so that it fills the source element. In this |
| case, if the HorizontalOffset and verticalOffset properties are set to |
| 0, the shadow is rendered exactly under the source item. By changing the |
| offset properties, the shadow can be positioned relatively to the source |
| item. |
| |
| The values range 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 DropShadow_horizontalOffset1.png |
| \li \image DropShadow_horizontalOffset2.png |
| \li \image DropShadow_horizontalOffset3.png |
| \row |
| \li \b { horizontalOffset: -20 } |
| \li \b { horizontalOffset: 0 } |
| \li \b { horizontalOffset: 20 } |
| \row |
| \li \l radius: 4 |
| \li \l radius: 4 |
| \li \l radius: 4 |
| \row |
| \li \l samples: 9 |
| \li \l samples: 9 |
| \li \l samples: 9 |
| \row |
| \li \l color: #000000 |
| \li \l color: #000000 |
| \li \l color: #000000 |
| \row |
| \li \l verticalOffset: 0 |
| \li \l verticalOffset: 0 |
| \li \l verticalOffset: 0 |
| \row |
| \li \l spread: 0 |
| \li \l spread: 0 |
| \li \l spread: 0 |
| \endtable |
| */ |
| property alias horizontalOffset: dbs.horizontalOffset |
| property alias verticalOffset: dbs.verticalOffset |
| |
| /*! |
| This property defines how large part of the shadow color is strengthened |
| near the source edges. |
| |
| The value ranges from 0.0 to 1.0. By default, the property is set to \c |
| 0.0. |
| |
| \table |
| \header |
| \li Output examples with different spread values |
| \li |
| \li |
| \row |
| \li \image DropShadow_spread1.png |
| \li \image DropShadow_spread2.png |
| \li \image DropShadow_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: #000000 |
| \li \l color: #000000 |
| \li \l color: #000000 |
| \row |
| \li \l horizontalOffset: 0 |
| \li \l horizontalOffset: 0 |
| \li \l horizontalOffset: 0 |
| \row |
| \li \l verticalOffset: 20 |
| \li \l verticalOffset: 20 |
| \li \l verticalOffset: 20 |
| \endtable |
| */ |
| property alias spread: dbs.spread |
| |
| /*! |
| \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: dbs.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 1 pixel |
| wide 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 shadow. |
| |
| In the image below, the Rectangle on the left has transparent borders |
| and has blurred edges, whereas the Rectangle on the right does not: |
| |
| By default, this property is set to \c true. |
| |
| \snippet DropShadow-transparentBorder-example.qml example |
| |
| \image DropShadow-transparentBorder.png |
| */ |
| property alias transparentBorder: dbs.transparentBorder |
| } |