blob: 8817f8f7761e0a909553450e9aa9f320503bd1fd (
plain)
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
|
/*
@VaadinApache2LicenseForJavaFiles@
*/
/**
*
*/
package com.vaadin.ui;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import com.vaadin.terminal.gwt.client.Paintable;
import com.vaadin.terminal.gwt.widgetsetutils.CustomWidgetMapGenerator;
import com.vaadin.terminal.gwt.widgetsetutils.EagerWidgetMapGenerator;
import com.vaadin.terminal.gwt.widgetsetutils.LazyWidgetMapGenerator;
import com.vaadin.terminal.gwt.widgetsetutils.WidgetMapGenerator;
/**
* Annotation defining the default client side counterpart in GWT terminal for
* {@link Component}.
* <p>
* With this annotation server side Vaadin component is marked to have a client
* side counterpart. The value of the annotation is the class of client side
* implementation.
* <p>
* Note, even though client side implementation is needed during development,
* one may safely remove them from the classpath of the production server.
*
* @since 6.2
*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface ClientWidget {
/**
* @return the client side counterpart for the annotated component
*/
Class<? extends Paintable> value();
/**
* Depending on the used WidgetMap generator, these optional hints may be
* used to define how the client side components are loaded by the browser.
* The default is to eagerly load all widgets
* {@link EagerWidgetMapGenerator}, but if the {@link WidgetMapGenerator} is
* used by the widgetset, these load style hints are respected.
* <p>
* Lazy loading of a widget implementation means the client side component
* is not included in the initial JavaScript application loaded when the
* application starts. Instead the implementation is loaded to the client
* when it is first needed. Lazy loaded widget can be achieved by giving
* {@link LoadStyle#LAZY} value in ClientWidget annotation.
* <p>
* Lazy loaded widgets don't stress the size and startup time of the client
* side as much as eagerly loaded widgets. On the other hand there is a
* slight latency when lazy loaded widgets are first used as the client side
* needs to visit the server to fetch the client side implementation.
* <p>
* The {@link LoadStyle#DEFERRED} will also not stress the initially loaded
* JavaScript file. If this load style is defined, the widget implementation
* is preemptively loaded to the browser after the application is started
* and the communication to server idles. This load style kind of combines
* the best of both worlds.
* <p>
* Fine tunings to widget loading can also be made by overriding
* {@link WidgetMapGenerator} in the GWT module. Tunings might be helpful if
* the end users have slow connections and especially if they have high
* latency in their network. The {@link CustomWidgetMapGenerator} is an
* abstract generator implementation for easy customization. Vaadin package
* also includes {@link LazyWidgetMapGenerator} that makes as many widgets
* lazily loaded as possible.
*
* @since 6.4
*
* @return the hint for the widget set generator how the client side
* implementation should be loaded to the browser
*/
LoadStyle loadStyle() default LoadStyle.DEFERRED;
public enum LoadStyle {
/**
* The widget is included in the initial JS sent to the client.
*/
EAGER,
/**
* Not included in the initial set of widgets, but added to queue from
* which it will be loaded when network is not busy or the
* implementation is required.
*/
DEFERRED,
/**
* Loaded to the client only if needed.
*/
LAZY
}
}
|
