BrightnessContrast QML Type

Adjusts brightness and contrast. 更多...

import 语句：	import QtGraphicalEffects 1.0
Since:	QtGraphicalEffects 1.0
继承：	Item

所有成员列表，包括继承成员

特性

brightness : real
cached : bool
contrast : real
source : variant

详细描述

This effect adjusts the source item colors. Brightness adjustment changes the perceived luminance of the source item. Contrast adjustment increases or decreases the color and brightness variations.

源	Effect applied

注意： This effect is available when running with OpenGL.

范例

The following example shows how to apply the effect.

import QtQuick 2.0
import QtGraphicalEffects 1.0
Item {
    width: 300
    height: 300
    Image {
        id: bug
        source: "images/bug.jpg"
        sourceSize: Qt.size(parent.width, parent.height)
        smooth: true
        visible: false
    }
    BrightnessContrast {
        anchors.fill: bug
        source: bug
        brightness: 0.5
        contrast: 0.5
    }
}

特性文档编制

brightness : real

This property defines how much the source brightness is increased or decreased.

The value ranges from -1.0 to 1.0. By default, the property is set to 0.0 (no change).

Output examples with different brightness values

brightness: -0.25	brightness: 0	brightness: 0.5
contrast : 0	contrast : 0	contrast : 0

cached : bool

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 .

contrast : real

This property defines how much the source contrast is increased or decreased. The decrease of the contrast is linear, but the increase is applied with a non-linear curve to allow very high contrast adjustment at the high end of the value range.

Contrast adjustment curve

The value ranges from -1.0 to 1.0. By default, the property is set to 0.0 (no change).

Output examples with different contrast values

contrast: -0.5	contrast: 0	contrast: 0.5
brightness : 0	brightness : 0	brightness : 0

source : variant

This property defines the source item that provides the source pixels for the effect.

注意： It is not supported to let the effect include itself, for instance by setting source to the effect's parent.