<iron-list items="[[data]]" as="item">
<template>
<div tabindex$="[[tabIndex]]">
Name: [[item.name]]
</div>
</template>
</iron-list>
我可以使用Polymer.IronA11yKeysBehavior,但即使在example我也不知道如何将它添加到JavaScript到我的铁列表.
使用Vaadin Polymer GWT lib.在这个lib你有
IronList list; list.setKeyBindings(???); // don't know how to use this function list.setKeyEventTarget(????); // don't know how to use this function
当我检查键绑定的当前值时,我定义了一个打印函数来将变量记录到控制台：
public native void print(JavaScriptObject obj)/ – {
的console.log(OBJ);
} – /;
然后我打印当前值：
print(list.getKeyBindings());
结果是：
Object {up: "_didMoveUp",down: "_didMoveDown",enter: "_didEnter"}
似乎已经定义了一些关键绑定,但我不知道我在哪里找到函数_didMoveUp,_didMoveDown和_didEnter.
当我做
print(list.getKeyEventTarget());
我得到：
<iron-list class="fit x-scope iron-list-0" tabindex="1" style="overflow: auto;"> </iron-list>
如何使用Vaadin Polymer GWT lib设置捕获键盘事件的处理程序？按下Enter键时,如何收到事件？
解决方法
list.setKeyBindings(???); // don’t know how to use this function
根据com / vaadin / polymer / vaadin-gwt-polymer-elements / 1.2.3.1-SNAPSHOT / vaadin-gwt-polymer-elements-1.2.3.1-20160201.114641-2.jar！/ com / vaadin / polymer / public / bower_components /iron-list/iron-list.html:292
keyBindings应该有这样的结构的对象：
{
'up': '_didMoveUp','down': '_didMoveDown','enter': '_didEnter'
}
要构建这样的对象,可以使用以下内容：
new JSONObject() {{
put("up",new JSONString("_didMoveUp"));
put("down",new JSONString("_didMoveDown"));
put("enter",new JSONString("_didEnter"));
}}.getJavaScriptObject();
I have no idea where I find the functions _didMoveUp,_didMoveDown and
_didEnter
它们可以在这里找到：com / vaadin / polymer / vaadin-gwt-polymer-elements / 1.2.3.1-SNAPSHOT / vaadin-gwt-polymer-elements-1.2.3.1-20160201.114641-2.jar！/ com / vaadin / polymer /public/bower_components/iron-list/iron-list.html:1504
这是提取物
_didMoveUp: function() {
this._focusPhysicalItem(Math.max(0,this._focusedIndex - 1));
},_didMoveDown: function() {
this._focusPhysicalItem(Math.min(this._virtualCount,this._focusedIndex + 1));
},_didEnter: function(e) {
// focus the currently focused physical item
this._focusPhysicalItem(this._focusedIndex);
// toggle selection
this._selectionHandler(e.detail.keyboardEvent);
}
How can I set up a handler for capturing keyboard events using Vaadin
Polymer GWT lib?How can I receive an event when keys like enter are
pressed?
我可以找到这个Polymer convention：不适合外部使用的属性应该带有下划线.
这就是为什么它们不会暴露在JsType IronListElement中的原因.
您可以使用JSNI更改此功能.我认为这样的smth：
private native static void changeDidMoveUp(IronListElement ironList) /*-{
var _old = ironList._didMoveUp;
ironList._didMoveUp = function() {
console.log('tracking');
_old();
}
}-*/;
或添加一个新的
IronListElement element ...
com.vaadin.polymer.elemental.Function<Void,Event> func = event -> {
logger.debug(event.detail);
...
return null;
};
private native static void addUpdatePressed(IronListElement ironList,Function func) /*-{
ironList._updatePressed = func;
}-*/;
{
addUpdatePressed(element,func);
element.addOwnKeyBinding("a","_updatePressed");
element.addOwnKeyBinding("shift+a alt+a","_updatePressed");
element.addOwnKeyBinding("shift+tab shift+space","_updatePressed");
}
应该工作您可以从IronList#getPolymerElement()获取元素.
记住,我还没有测试这个代码:)
