属性绑定与赋值

首先看下面一段示例代码：

 1 import QtQuick 2.4
 2 import QtQuick.Controls 1.3
 3 import QtQuick.Window 2.2
 4 import QtQuick.Dialogs 1.2
 5
 6 Rectangle{
 7     id: root
 8     width: 320
 9     height: 320
10     color: "red"
11     opacity: 0.3
12
13     Text {
14         id: label
15         x: 20; y: 20
16
17         property  int spacePresses: 0
18         text: "space pressed: " + spacePresses + " times"
19
20         onTextChanged: console.log("text changed to: ", text)
21
22         focus: true
23         Keys.onPressed: {
24             increment()
25         }
26
27         Keys.onEscapePressed: {
28             label.text = ‘‘
29         }
30
31         function increment() {
32             spacePresses += 1
33         }
34     }
35 }

当前应用不大适合用属性绑定来解决，使用赋值更合适：

 1 import QtQuick 2.4
 2 import QtQuick.Controls 1.3
 3 import QtQuick.Window 2.2
 4 import QtQuick.Dialogs 1.2
 5
 6 Rectangle{
 7     id: root
 8     width: 320
 9     height: 320
10     color: "red"
11     opacity: 0.3
12
13     Text {
14         id: label
15         x: 20; y: 20
16
17         property  int spacePresses: 0
18         text: "space pressed: " + spacePresses + " times"
19
20         onTextChanged: console.log("text changed to: ", text)
21
22         focus: true
23         Keys.onSpacePressed: {
24             increment()
25             text = "space pressed: " + spacePresses + " times"
26         }
27
28         Keys.onEscapePressed: {
29             text = "Release Binding: " + spacePresses
30         }
31
32         function increment() {
33             spacePresses += 1
34         }
35     }
36 }