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41
42 #include "private/qdeclarativebind_p.h"
43
44 #include "private/qdeclarativenullablevalue_p_p.h"
45 #include "private/qdeclarativeguard_p.h"
46
47 #include <qdeclarativeengine.h>
48 #include <qdeclarativecontext.h>
49 #include <qdeclarativeproperty.h>
50
51 #include <QtCore/qfile.h>
52 #include <QtCore/qdebug.h>
53 #include <QtScript/qscriptvalue.h>
54 #include <QtScript/qscriptcontext.h>
55 #include <QtScript/qscriptengine.h>
56
57 #include <private/qobject_p.h>
58
59 QT_BEGIN_NAMESPACE
60
61 class QDeclarativeBindPrivate : public QObjectPrivate
62 {
63 public:
QDeclarativeBindPrivate()64 QDeclarativeBindPrivate() : when(true), componentComplete(true), obj(0) {}
65
66 bool when : 1;
67 bool componentComplete : 1;
68 QDeclarativeGuard<QObject> obj;
69 QString prop;
70 QDeclarativeNullableValue<QVariant> value;
71 };
72
73
74 /*!
75 \qmlclass Binding QDeclarativeBind
76 \ingroup qml-working-with-data
77 \since 4.7
78 \brief The Binding element allows arbitrary property bindings to be created.
79
80 Sometimes it is necessary to bind to a property of an object that wasn't
81 directly instantiated by QML - generally a property of a class exported
82 to QML by C++. In these cases, regular property binding doesn't work. Binding
83 allows you to bind any value to any property.
84
85 For example, imagine a C++ application that maps an "app.enteredText"
86 property into QML. You could use Binding to update the enteredText property
87 like this.
88 \code
89 TextEdit { id: myTextField; text: "Please type here..." }
90 Binding { target: app; property: "enteredText"; value: myTextField.text }
91 \endcode
92 Whenever the text in the TextEdit is updated, the C++ property will be
93 updated also.
94
95 If the binding target or binding property is changed, the bound value is
96 immediately pushed onto the new target.
97
98 \sa QtDeclarative
99 */
QDeclarativeBind(QObject * parent)100 QDeclarativeBind::QDeclarativeBind(QObject *parent)
101 : QObject(*(new QDeclarativeBindPrivate), parent)
102 {
103 }
104
~QDeclarativeBind()105 QDeclarativeBind::~QDeclarativeBind()
106 {
107 }
108
109 /*!
110 \qmlproperty bool Binding::when
111
112 This property holds when the binding is active.
113 This should be set to an expression that evaluates to true when you want the binding to be active.
114
115 \code
116 Binding {
117 target: contactName; property: 'text'
118 value: name; when: list.ListView.isCurrentItem
119 }
120 \endcode
121 */
when() const122 bool QDeclarativeBind::when() const
123 {
124 Q_D(const QDeclarativeBind);
125 return d->when;
126 }
127
setWhen(bool v)128 void QDeclarativeBind::setWhen(bool v)
129 {
130 Q_D(QDeclarativeBind);
131 d->when = v;
132 eval();
133 }
134
135 /*!
136 \qmlproperty Object Binding::target
137
138 The object to be updated.
139 */
object()140 QObject *QDeclarativeBind::object()
141 {
142 Q_D(const QDeclarativeBind);
143 return d->obj;
144 }
145
setObject(QObject * obj)146 void QDeclarativeBind::setObject(QObject *obj)
147 {
148 Q_D(QDeclarativeBind);
149 d->obj = obj;
150 eval();
151 }
152
153 /*!
154 \qmlproperty string Binding::property
155
156 The property to be updated.
157 */
property() const158 QString QDeclarativeBind::property() const
159 {
160 Q_D(const QDeclarativeBind);
161 return d->prop;
162 }
163
setProperty(const QString & p)164 void QDeclarativeBind::setProperty(const QString &p)
165 {
166 Q_D(QDeclarativeBind);
167 d->prop = p;
168 eval();
169 }
170
171 /*!
172 \qmlproperty any Binding::value
173
174 The value to be set on the target object and property. This can be a
175 constant (which isn't very useful), or a bound expression.
176 */
value() const177 QVariant QDeclarativeBind::value() const
178 {
179 Q_D(const QDeclarativeBind);
180 return d->value.value;
181 }
182
setValue(const QVariant & v)183 void QDeclarativeBind::setValue(const QVariant &v)
184 {
185 Q_D(QDeclarativeBind);
186 d->value.value = v;
187 d->value.isNull = false;
188 eval();
189 }
190
classBegin()191 void QDeclarativeBind::classBegin()
192 {
193 Q_D(QDeclarativeBind);
194 d->componentComplete = false;
195 }
196
componentComplete()197 void QDeclarativeBind::componentComplete()
198 {
199 Q_D(QDeclarativeBind);
200 d->componentComplete = true;
201 eval();
202 }
203
eval()204 void QDeclarativeBind::eval()
205 {
206 Q_D(QDeclarativeBind);
207 if (!d->obj || d->value.isNull || !d->when || !d->componentComplete)
208 return;
209
210 QDeclarativeProperty prop(d->obj, d->prop);
211 prop.write(d->value.value);
212 }
213
214 QT_END_NAMESPACE
215