1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
|
// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
import QtQuick 2.0
import "private"
/*!
\qmltype BrightnessContrast
\inqmlmodule QtGraphicalEffects 1.0
\since QtGraphicalEffects 1.0
\inherits QtQuick2::Item
\ingroup qtgraphicaleffects-color
\brief Adjusts brightness and contrast.
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.
\table
\header
\li Source
\li Effect applied
\row
\li \image Original_bug.png
\li \image BrightnessContrast_bug.png
\endtable
\section1 Example
The following example shows how to apply the effect.
\snippet BrightnessContrast-example.qml example
*/
Item {
id: rootItem
/*!
This property defines the source item that provides the source pixels
for the effect.
\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 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 \c
0.0 (no change).
\table
\header
\li Output examples with different brightness values
\li
\li
\row
\li \image BrightnessContrast_brightness1.png
\li \image BrightnessContrast_brightness2.png
\li \image BrightnessContrast_brightness3.png
\row
\li \b { brightness: -0.25 }
\li \b { brightness: 0 }
\li \b { brightness: 0.5 }
\row
\li \l contrast: 0
\li \l contrast: 0
\li \l contrast: 0
\endtable
*/
property real brightness: 0.0
/*!
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.
\table
\header
\li Contrast adjustment curve
\row
\li \image BrightnessContrast_contrast_graph.png
\endtable
The value ranges from -1.0 to 1.0. By default, the property is set to \c 0.0 (no change).
\table
\header
\li Output examples with different contrast values
\li
\li
\row
\li \image BrightnessContrast_contrast1.png
\li \image BrightnessContrast_contrast2.png
\li \image BrightnessContrast_contrast3.png
\row
\li \b { contrast: -0.5 }
\li \b { contrast: 0 }
\li \b { contrast: 0.5 }
\row
\li \l brightness: 0
\li \l brightness: 0
\li \l brightness: 0
\endtable
*/
property real contrast: 0.0
/*!
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
}
ShaderEffectSource {
id: cacheItem
anchors.fill: parent
visible: rootItem.cached
smooth: true
sourceItem: shaderItem
live: true
hideSource: visible
}
ShaderEffect {
id: shaderItem
property variant source: sourceProxy.output
property real brightness: rootItem.brightness
property real contrast: rootItem.contrast
anchors.fill: parent
blending: !rootItem.cached
fragmentShader: "
varying mediump vec2 qt_TexCoord0;
uniform highp float qt_Opacity;
uniform lowp sampler2D source;
uniform highp float brightness;
uniform highp float contrast;
void main() {
highp vec4 pixelColor = texture2D(source, qt_TexCoord0);
pixelColor.rgb /= max(1.0/256.0, pixelColor.a);
highp float c = 1.0 + contrast;
highp float contrastGainFactor = 1.0 + c * c * c * c * step(0.0, contrast);
pixelColor.rgb = ((pixelColor.rgb - 0.5) * (contrastGainFactor * contrast + 1.0)) + 0.5;
pixelColor.rgb = mix(pixelColor.rgb, vec3(step(0.0, brightness)), abs(brightness));
gl_FragColor = vec4(pixelColor.rgb * pixelColor.a, pixelColor.a) * qt_Opacity;
}
"
}
}
|
