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| |
| import QtQuick 2.12 |
| import QtGraphicalEffects.private 1.12 |
| |
| /*! |
| \qmltype ZoomBlur |
| \inqmlmodule QtGraphicalEffects |
| \since QtGraphicalEffects 1.0 |
| \inherits QtQuick2::Item |
| \ingroup qtgraphicaleffects-motion-blur |
| \brief Applies directional blur effect towards source items center point. |
| |
| Effect creates perceived impression that the source item appears to be |
| moving towards the center point in Z-direction or that the camera appears |
| to be zooming rapidly. Other available motion blur effects are |
| \l{QtGraphicalEffects::DirectionalBlur}{DirectionalBlur} |
| and \l{QtGraphicalEffects::RadialBlur}{RadialBlur}. |
| |
| \table |
| \header |
| \li Source |
| \li Effect applied |
| \row |
| \li \image Original_bug.png |
| \li \image ZoomBlur_bug.png |
| \endtable |
| |
| \note This effect is available when running with OpenGL. |
| |
| \section1 Example |
| |
| The following example shows how to apply the effect. |
| \snippet ZoomBlur-example.qml example |
| |
| */ |
| Item { |
| id: rootItem |
| |
| /*! |
| This property defines the source item that is going to be blurred. |
| |
| \note It is not supported to let the effect include itself, for |
| instance by setting source to the effect's parent. |
| */ |
| property variant source |
| |
| /*! |
| This property defines the maximum perceived amount of movement for each |
| pixel. The amount is smaller near the center and reaches the specified |
| value at the edges. |
| |
| The quality of the blur depends on \l{ZoomBlur::samples}{samples} |
| property. If length value is large, more samples are needed to keep the |
| visual quality at high level. |
| |
| The value ranges from 0.0 to inf. By default the property is set to \c |
| 0.0 (no blur). |
| |
| \table |
| \header |
| \li Output examples with different length values |
| \li |
| \li |
| \row |
| \li \image ZoomBlur_length1.png |
| \li \image ZoomBlur_length2.png |
| \li \image ZoomBlur_length3.png |
| \row |
| \li \b { length: 0.0 } |
| \li \b { length: 32.0 } |
| \li \b { length: 48.0 } |
| \row |
| \li \l samples: 24 |
| \li \l samples: 24 |
| \li \l samples: 24 |
| \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 length: 0.0 |
| |
| /*! |
| This property defines how many samples are taken per pixel when blur |
| calculation is done. Larger value produces better quality, but is slower |
| to render. |
| |
| This property is not intended to be animated. Changing this property may |
| cause the underlying OpenGL shaders to be recompiled. |
| |
| Allowed values are between 0 and inf (practical maximum depends on GPU). |
| By default the property is set to \c 0 (no samples). |
| |
| */ |
| property int samples: 0 |
| |
| /*! |
| \qmlproperty real QtGraphicalEffects::ZoomBlur::horizontalOffset |
| \qmlproperty real QtGraphicalEffects::ZoomBlur::verticalOffset |
| |
| These properties define an offset in pixels for the blur direction |
| center point. |
| |
| The values range from -inf to inf. By default these properties are set |
| to \c 0. |
| |
| \table |
| \header |
| \li Output examples with different horizontalOffset values |
| \li |
| \li |
| \row |
| \li \image ZoomBlur_horizontalOffset1.png |
| \li \image ZoomBlur_horizontalOffset2.png |
| \li \image ZoomBlur_horizontalOffset3.png |
| \row |
| \li \b { horizontalOffset: 100.0 } |
| \li \b { horizontalOffset: 0.0 } |
| \li \b { horizontalOffset: -100.0 } |
| \row |
| \li \l samples: 24 |
| \li \l samples: 24 |
| \li \l samples: 24 |
| \row |
| \li \l length: 32 |
| \li \l length: 32 |
| \li \l length: 32 |
| \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 blur behavior near the edges of the item, |
| where the pixel blurring is affected by the pixels outside the source |
| edges. |
| |
| If the property is set to \c true, the pixels outside the source are |
| interpreted to be transparent, which is similar to OpenGL |
| clamp-to-border extension. The blur is expanded slightly outside the |
| effect item area. |
| |
| If the property is set to \c false, the pixels outside the source are |
| interpreted to contain the same color as the pixels at the edge of the |
| item, which is similar to OpenGL clamp-to-edge behavior. The blur does |
| not expand outside the effect item area. |
| |
| By default, the property is set to \c false. |
| |
| */ |
| property bool transparentBorder: 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 bool cached: false |
| |
| SourceProxy { |
| id: sourceProxy |
| input: rootItem.source |
| sourceRect: rootItem.transparentBorder ? Qt.rect(-1, -1, parent.width + 2.0, parent.height + 2.0) : Qt.rect(0, 0, 0, 0) |
| } |
| |
| ShaderEffectSource { |
| id: cacheItem |
| anchors.fill: shaderItem |
| visible: rootItem.cached |
| smooth: true |
| sourceItem: shaderItem |
| live: true |
| hideSource: visible |
| } |
| |
| ShaderEffect { |
| id: shaderItem |
| property variant source: sourceProxy.output |
| property variant center: Qt.point(0.5 + rootItem.horizontalOffset / width, 0.5 + rootItem.verticalOffset / height) |
| property real len: rootItem.length |
| property bool transparentBorder: rootItem.transparentBorder |
| property real samples: rootItem.samples |
| property real weight: 1.0 / Math.max(1.0, rootItem.samples) |
| property variant expandPixels: transparentBorder ? Qt.size(rootItem.samples, rootItem.samples) : Qt.size(0,0) |
| property variant expand: transparentBorder ? Qt.size(expandPixels.width / width, expandPixels.height / height) : Qt.size(0,0) |
| property variant delta: Qt.size(1.0 / rootItem.width, 1.0 / rootItem.height) |
| |
| x: transparentBorder ? -expandPixels.width - 1 : 0 |
| y: transparentBorder ? -expandPixels.height - 1 : 0 |
| width: transparentBorder ? parent.width + 2.0 * expandPixels.width + 2 : parent.width |
| height: transparentBorder ? parent.height + 2.0 * expandPixels.height + 2 : parent.height |
| |
| property string fragmentShaderSkeleton: " |
| varying highp vec2 qt_TexCoord0; |
| uniform highp float qt_Opacity; |
| uniform lowp sampler2D source; |
| uniform highp float len; |
| uniform highp float weight; |
| uniform highp float samples; |
| uniform highp vec2 center; |
| uniform highp vec2 expand; |
| uniform highp vec2 delta; |
| |
| void main(void) { |
| mediump vec2 texCoord = qt_TexCoord0; |
| mediump vec2 centerCoord = center; |
| |
| PLACEHOLDER_EXPAND_STEPS |
| |
| highp vec2 dir = vec2(centerCoord.x - texCoord.s, centerCoord.y - texCoord.t); |
| dir /= max(1.0, length(dir) * 2.0); |
| highp vec2 shift = delta * len * dir * 2.0 / max(1.0, samples - 1.0); |
| gl_FragColor = vec4(0.0); |
| |
| PLACEHOLDER_UNROLLED_LOOP |
| |
| gl_FragColor *= weight * qt_Opacity; |
| } |
| " |
| |
| function buildFragmentShader() { |
| var shader = "" |
| if (GraphicsInfo.profile == GraphicsInfo.OpenGLCoreProfile) |
| shader += "#version 150 core\n#define varying in\n#define gl_FragColor fragColor\n#define texture2D texture\nout vec4 fragColor;\n" |
| shader += fragmentShaderSkeleton |
| var expandSteps = "" |
| |
| if (transparentBorder) { |
| expandSteps += "centerCoord = (centerCoord - expand) / (1.0 - 2.0 * expand);" |
| expandSteps += "texCoord = (texCoord - expand) / (1.0 - 2.0 * expand);" |
| } |
| |
| var unrolledLoop = "gl_FragColor += texture2D(source, texCoord);\n" |
| |
| if (rootItem.samples > 1) { |
| unrolledLoop = "" |
| for (var i = 0; i < rootItem.samples; i++) |
| unrolledLoop += "gl_FragColor += texture2D(source, texCoord); texCoord += shift;\n" |
| } |
| |
| shader = shader.replace("PLACEHOLDER_EXPAND_STEPS", expandSteps) |
| fragmentShader = shader.replace("PLACEHOLDER_UNROLLED_LOOP", unrolledLoop) |
| } |
| |
| onFragmentShaderChanged: sourceChanged() |
| onSamplesChanged: buildFragmentShader() |
| onTransparentBorderChanged: buildFragmentShader() |
| Component.onCompleted: buildFragmentShader() |
| } |
| } |