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EXT GWT 2.0 BEGINNERS GUIDE PDF

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Take the user experience of your website to a new level with Ext GWT using this book and eBook. Ext GWT Beginner's Guide is a practical book that teaches you how to use .. Manual debugging is required. Smart GWT. When development of GWT-Ext. PrefaceExt GWT Beginner's Guide is a practical book that teaches you how to use the Ext GWT library to its full potential. It provides a.


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Now we define the BorderLayoutData for the central and west layout regions, the west region being collapsible and resizable. WEST, , , ; westData. Run the application and check that the screen now looks like this: [ 39 ] The Building Blocks What just happened?

We have now added Component to the Viewport using the BorderLayout. Now the application looks more like a desktop application, enabling users to collapse and expand the left panel. Loading message When building any GUI application, it is important to keep the user informed about what is going on.

Therefore, it is useful to display a loading message. When our application first starts, the JavaScript has not yet loaded, so we have to place our loading message in the application's HTML page. Time for action — adding a loading message 1. This creates a new div with the ID loading. This name is important, as it makes hiding the loading message when the application has loaded straightforward.

The div itself contains an animated gif from GXT's standard resources with a familiar AJAX loading animation together with the loading message itself. We want to make sure our loading message is displayed before the JavaScript starts loading so that our user is not looking at an empty page for any noticeable time. If we were using this technique in a conventional GWT application, we would now need to add code to our onModuleLoad method to hide or remove the loading div when the application is loaded.

However, as we are using a GXT Viewport panel, this is taken care of for us. If there is a div with ID loading, it will automatically be hidden. In fact, it will nicely fade away once the viewport is attached. If we had wanted to call our loading div something different, we would call the Viewport's setLoadingPanelId java.

Start the application. It will now have a loading indicator that will disappear when the UI has loaded: [ 42 ] Chapter 2 What just happened? We added a loading message to our application in such a way that it is automatically hidden once the UI is ready. There are two reasons to make a custom component. The first is to modify the functionality of an existing component. The second is to encapsulate one or more existing components with additional functionality to make a new component.

This is a component that wraps another in order for you to be able to create a custom component. In GXT, you might encounter some problems if you wrap components in this way. Take for example the ContentPanel we have added for navigation.

It is being added to a layout region of a Viewport that is collapsible. However, if we were to use a Composite to make a custom component based on a ContentPanel, the collapse button would mysteriously disappear.

This is because when you wrap a component in a Composite, its public API methods are hidden. GXT is designed in such a way that it needs access to those public methods in order to query the capabilities of a component. This is because the isCollapsible method is hidden and so the layout region would no longer show the collapse icon.

Therefore, to create a custom component in GXT, it is nearly always better to directly extend Component directly or indirectly using one of its subclasses such as BoxComponent, Container, or LayoutContainer.

The decision of which component to extend depends on the features your custom component requires.

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The onRender method When extending any component, there is the option of overriding the onRender method. This goes back to the idea of lazy rendering. Any code that is in the constructor of a component will get executed as soon as the component is initialized.

However, any code in the onRender method will only get executed when the component is rendered. For this reason it is good practice when defining a component to consider if the code needs to execute before the component is rendered. If not, which is often the case, it is better to put the code in the onRender method, and the code will only run if and when the component is rendered. Steps like this can improve the efficiency of your GXT applications. We could keep these as ContentPanel objects, but as the application develops, we are going to be adding more and more custom functionality to them.

For this reason, we are now going to define them as custom components that extend ContentPanel. Time for action — creating custom components 1.

In your application, create a new class named RssNavigationPanel in a new components package under the application's client package. This class should subclass ContentPanel. We now need to replace the two ContentPanels in our main code with our new custom components.

Now start the application. It should look pretty much the same as before, but now the navigation and main panels will have headings: [ 45 ] The Building Blocks What just happened? The application looks pretty much as it did before except that the navigation and main panels now have headings. However, what we have done is use custom components. By doing this now, we will make code a lot more manageable as the application develops.

First field components Two of the most basic components that are used for accepting user input as opposed to laying out other components are Buttons and TextFields. Button Let us start with buttons. In GXT, buttons have several different attributes, which can be merged to make a large number of combinations: Size Buttons come in three sizes—small, medium, or large.

They have a property named button scale, which is set using the setScale method with the parameters ButtonScale. LARGE, respectively. The text of the Button is set using the setText method. The module file always ends in gwt. In this case, it is named FirstApp. In order to use GXT, there needs to be an entry added to this file.

This can be removed. We now need to modify the host HTML file. In this project, it is named FirstApp. Edit this file, including the GXT stylesheets, by adding the following line into the head section beneath the existing stylesheet link:. Finally, we need to copy the GXT stylesheet and image resources into the project's war folder. Create a folder named gxt in the war folder, go to the location where you originally unzipped your downloaded GXT package, and open the resources folder.

Now copy both the css and images folders into the newly created gxt folder. We have configured our project so that it now has all the dependencies it needs for making use of GXT features. In the example code of this chapter, we have left in the original FirstApp class together with a FirstGxtApp class. By comparing these, you can see how, although similar, GXT controls do have some differences in how they can be used. We will now summarize the main differences. ClickEvent;import com.

ClickHandler;import com. KeyUpEvent;import com. KeyUpHandler;import com. Button;import com. DialogBox;import com. Label;import com.

TextBox;import com. ButtonEvent;import com. SelectionListener;import com. KeyListener;import com. ComponentEvent;import com. Dialog;import com. VerticalPanel;import com.

We then needed to redefine the controls. However, due to the way listeners are implemented in GXT, we lose some of the flexibility that enables this. Instead, we had to define the controls as private members as follows:.

Here are the ones we see in this example:. Another difference that is important is that while GWT now uses event handlers for events such as clicking on a button, GXT uses event listeners similar to the earlier version of GWT. However, in this case, the actual code is very similar. We now have two classes: It is also important to realize that there are some subtle differences. Over the coming chapters, we will show that there are many great features in GXT that go far beyond the basics provided by GWT.

SummaryIn this chapter, we have introduced GXT and set up the development environment. In the next chapter, we will start delving into the GXT components in more depth.

Now that we have set up our development environment, in this chapter, we are ready to take a proper look at GXT. We start by looking at the explorer demo application.

We then introduce the world of GXT components, beginning with some key concepts, and quickly move on to practically working with an example application. The following diagram shows how the components covered in this chapter fit together and it may be useful to refer back to it as the chapter goes on:.

This demo showcases all the different components available in GXT. It also provides sample code that shows you how to use them. This is an invaluable tool for understanding what is available and for giving you an idea of the code required to make use of each component. The explorer application is also hosted on the Sencha website and can be found here: If you have not done so already, it is a really good idea to go and have a good look at the Explorer application before starting this chapter, as it shows you pretty much all the components available in GXT.

Essential knowledgeAs you should have seen from looking at the Explorer applications, there are a wide range of components available to use in GXT. Some components are more complex than others, but they are all built on the same foundations. By understanding a few basic concepts, you can soon get to grips with them. GXT building block 1: Widget is the base class of all visible elements we can see in a browser such as buttons, textboxes, and tree views, for example.

In GXT, the base class for all visual elements is Component, com. All GXT's components participate in GXT's life cycle of creation, attach and detach automatically and use lazy rendering. Components inherit basic hide and show, enable and disable functionality.

Components that subclass BoxComponent inherit sizing and methods additionally.

Components that subclass Component directly are those that don't exist outside of a containing component. GXT components are different as they use lazy rendering. The HTML is only created when the render method is called on the component. This approach is understandably more efficient, as it avoids unused HTML sitting in memory. Although the HTML for a component is not created until the component is rendered, properties of components can be configured before they are rendered.

If the same Component is added to a GXT equivalent, it is the Container that calls the render method of the Component. GXT building block 2: ContainerContainers are a type of BoxComponent that can contain other components. They subclass the com. Container class, and have the ability to attach, detach, and manage their child components. Container itself does not deal with the laying out and rendering of components.

This is left to subclasses. ScrollContainer adds support for the scrolling of content to Container. LayoutContainer itself adds the ability to lay out the child components using a Layout.

Let's see how this works with the idea of lazy rendering. First of all, we will create a LayoutContainer:. Now we add a Button:. We add the Button to the LayoutContainer:. This is because the LayoutContainer itself has not been rendered. Containers use a system of cascading layout, so when the LayoutContainer is rendered, it will call the render method of each of its children, in this case the single Button.

You may think that this would make a second button appear in the LayoutContainer, but you would be wrong. In this case, we need to call the layout method of the LayoutContainer. This will call the render method for both Button components. FlowLayout adds components to the container, but does not do anything regarding the sizing and positioning of the child components. The first component is rendered in the top left corner of the container, and each subsequent component is added to the right of the previous component.

Later in the book, we will look at alternative layouts more closely. ContentPanelContentPanel subclasses LayoutContainer and is a very useful building block for user interfaces in general and the interface that we will be developing later in this chapter. It features separate header, footer, and body sections, and can display top and bottom toolbars. ContentPanel also has the built-in ability to collapse and expand and have a number of predefined tool buttons that can be shown in the header to be used for custom functions.

Here is what a ContentPanel can look like with the collapse and custom "gear" tool in the header:. GXT building block 3: EventsEvents are the concepts used for informing the program that something has happened. This can be the user interacting in some way with the application such as clicking on a button or the state of a component changing.

Each action causes an event to be fired and gives any component that is listening for the event the opportunity to respond. More formally, this is known as the observer pattern. In GXT, listeners can be added to components so that when an event is fired, any listeners are notified and can handle the event.

The base class for event is com. BaseEvent and GXT provides a wide range of events. We will cover a few of these later in this chapter and many more in later chapters. Sinking and swallowing eventsAs part of GWT's design, widgets respond to some, but not all browser events, and this also applies to GXT. The reason for this is to keep memory usage down and to avoid memory leaks.

If a widget needs to respond to a browser event, it needs to register that event by calling the sinkEvents method. For example, by default a Component may respond to an onClick event, but not to an onDoubleClick. You can extend the component to respond to a double-click by sinking the onDoubleClick event.

In a similar way, you can also swallow events to stop events being fired. For example, if you were to swallow the onClick event of a button, it would no longer fire an event when clicked on. Introducing the example applicationThe example application that we will use in the book from this point onwards is an RSS reader.

This application will give us a chance to exploit nearly all of the functions of GXT, including many of the more advanced ones. But first of all we need to put the basics in place. The requirement Our customer has a requirement for an easy-to-use RSS news feed reader that can handle multiple RSS feeds specified by the user. The application should be available on the Web, but must look and feel as much as possible the same as a conventional desktop application.

We have no control over the browser our potential users may have installed and no control over their screen resolutions, so our application must be as flexible as possible. Blank projectWe now need to create a new GXT project for our example application.

This time, however, we don't want to make use of the default GWT code, so we need to trim down the default application. Remove the greet servlet definition from the project's web. Edit the RSSReader. As we don't need this, open RSSReader. If you compile and run the application now, all you should get is a blank page with the title RSSReader in your web browser.

We removed all the GWT example code from a new project leaving us with an empty project to begin with. ViewportViewport is a subclass of LayoutContainer that fills the browser window and then monitors the window for resizing. It then triggers any child components to be resized to deal with the new window size. It is a useful component when building an application that the user expects to behave like a desktop application.

We will use a Viewport as the base panel for our application. As such, it will be added directly to GWT's root panel. The viewport lays itself out automatically when it is added to the root panel so that it is not necessary to call the layout method. Time for action adding a Viewport 1. In the RSSReader. If we started the application in the browser, it would still look blank. Now when we start the application, the browser window will initially be empty and white until the JavaScript code executes and the Viewport is rendered.

When this happens, the browser window will turn dark green:. We created a Viewport, added it to GWT's root panel, and highlighted it in green to prove that the Viewport had loaded and took up the full screen.

LayoutLayout classes define how components added to a LayoutContainer are positioned and displayed. The base class for layouts is com. We will cover more layouts as this book goes on, but for the time being, we will be working with the BorderLayout. BorderLayoutThe BorderLayout provides a very convenient way to lay out the components of a fullscreen application.

It allows us to split a layout component into a number of layout regions: It supports the resizing of regions by the user by means of split bars and allows regions to be expanded and collapsed or hidden:.

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This type of layout is very common on websites, with the north being the header, the south the footer, the center the content, and the west and or the east being the navigation.

BorderLayoutDataBefore adding a child component to a parent component that is laid out using a BorderLayout, we first need to define how that component will behave once it is added using a BorderLayoutData object. When creating a BorderLayoutData object, we have to define which layout region it applies to, and optionally its initial size and a maximum and minimum size for the region.

Once created, there are also a number of other settings that can be defined such as if the region can be collapsed or split resized by the user. When we have defined a BorderLayoutData object, we can use it to add a component to a Container that uses the BorderLayout.

Time for action using BorderLayout1. In the onModuleLoad method of the example application class, create a new. Now create BorderLayoutData for the north layout region setting it to be 20px high and neither collapsible nor resizable:. We can then create an HTML widget to use as the header and add it to the viewport in the north position using the BorderLayoutData we defined in the last step:.

Now we define the BorderLayoutData for the central and west layout regions, the west region being collapsible and resizable. We define it as being px wide initially, but also specify that it cannot be less than px or more than px wide:. WEST, , , ; westData. Finally, create two new content panels and add them to the view's west and center panels respectively:. We have now added Component to the Viewport using the BorderLayout.

Now the application looks more like a desktop application, enabling users to collapse and expand the left panel.

Loading messageWhen building any GUI application, it is important to keep the user informed about what is going on. Therefore, it is useful to display a loading message. When our application first starts, the JavaScript has not yet loaded, so we have to place our loading message in the application's HTML page.

Time for action adding a loading message1. This creates a new div with the ID loading.

This name is important, as it makes hiding the loading message when the application has loaded straightforward. The div itself contains an animated gif from GXT's standard resources with a familiar AJAX loading animation together with the loading message itself.

We want to make sure our loading message is displayed before the JavaScript starts loading so that our user is not looking at an empty page for any noticeable time. So we need to move the script tag from the head of the document to the end of the body so that the HTML file looks like this:.

If we were using this technique in a conventional GWT application, we would now need to add code to our onModuleLoad method to hide or remove the loading div when the application is loaded. However, as we are using a GXT Viewport panel, this is taken care of for us. If there is a div with ID loading, it will automatically be hidden.

In fact, it will nicely fade away once the viewport is attached. If we had wanted to call our loading div something different, we would call the Viewport's setLoadingPanelId java. Start the application. It will now have a loading indicator that will disappear when the UI has loaded:. We added a loading message to our application in such a way that it is automatically hidden once the UI is ready.

There are two reasons to make a custom component. The first is to modify the functionality of an existing component. The second is to encapsulate one or more existing components with additional functionality to make a new component.

This is a component that wraps another in order for you to be able to create a custom component. In GXT, you might encounter some problems if you wrap components in this way.

Take for example the ContentPanel we have added for navigation.

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It is being added to a layout region of a Viewport that is collapsible. However, if we were to use a Composite to make a custom component based on a ContentPanel, the collapse button would mysteriously disappear. This is because when you wrap a component in a Composite, its public API methods are hidden. GXT is designed in such a way that it needs access to those public methods in order to query the capabilities of a component.

This is because the isCollapsible method is hidden and so the layout region would no longer show the collapse icon. Therefore, to create a custom component in GXT, it is nearly always better to directly extend Component directly or indirectly using one of its subclasses such as BoxComponent, Container, or LayoutContainer.

The decision of which component to extend depends on the features your custom component requires. The onRender methodWhen extending any component, there is the option of overriding the onRender method. This goes back to the idea of lazy rendering. Any code that is in the constructor of a component will get executed as soon as the component is initialized. However, any code in the onRender method will only get executed when the component is rendered.

For this reason it is good practice when defining a component to consider if the code needs to execute before the component is rendered. If not, which is often the case, it is better to put the code in the onRender method, and the code will only run if and when the component is rendered. Steps like this can improve the efficiency of your GXT applications.

At the moment, in our example application, we have just used standard ContentPanel objects for our navigation and main panels. We could keep these as ContentPanel objects, but as the application develops, we are going to be adding more and more custom functionality to them. For this reason, we are now going to define them as custom components that extend ContentPanel.

Time for action creating custom components1. In your application, create a new class named RssNavigationPanel in a new.

This class should subclass ContentPanel. At this point, the only customizing we are doing in this custom widget is giving the panel a heading of Navigation.

Now we need to do the same for the main panel, this time naming the class RssMainPanel and setting the heading to Main:. We now need to replace the two ContentPanels in our main code with our new custom components. Now start the application. It should look pretty much the same as before, but now the navigation and main panels will have headings:. The application looks pretty much as it did before except that the navigation and main panels now have headings.

However, what we have done is use custom components. By doing this now, we will make code a lot more manageable as the application develops. First field componentsTwo of the most basic components that are used for accepting user input as opposed to laying out other components are Buttons and TextFields.

ButtonLet us start with buttons. In GXT, buttons have several different attributes, which can be merged to make a large number of combinations:.

SizeButtons come in three sizessmall, medium, or large. They have a property named button scale, which is set using the setScale method with the parameters ButtonScale. LARGE, respectively. The text of the Button is set using the setText method. IconsButtons can also have icons as well as just text. This is achieved by using the button's setIconStyle method and referencing a CSS style that specifies a background image. So if we wanted to reference an icon named "bell", we would need an entry in our CSS stylesheet like this:.

Icon positionYou can control where the icon appears on the button relative to any text by using the setIconAlign method with the parameters IconAlign.

TOP, and get the following results:. Adding a menuNormally a button performs one action when clicked on. However in GXT, you can add a menu to a button so that it displays a list of options instead. A small arrow is added to a button that has a menu. This can be added either to the bottom or the right of the button text. The position of the menu arrow can be controlled by the setArrowAlign method using the parameters ButtonArrowAlign. It maintains a pressed and un-pressed state.

You can also group toggle buttons using the toogleGroup method so that only one of the group can be pressed at a time as shown below:. SplitButtonSplitButton also subclasses Button and allows you to both click on them and display a menu. SplitButton can be clicked on in a main area to perform an action or the menu arrow can be clicked on to display a menu of further options as with a normal button with a menu button.

To use this functionality, you need to create a SplitButton component instead of a standard Button component:. The purpose of the button is to display a form that lets the user enter an URL of an existing RSS feed they would like to link to. A user may change their mind and not enter an URL after all. We could provide a cancel button for this, but as we have ToggleButton at our disposal, it would make more sense and save limited space to make the Link feed button show and hide the URL field.

As our RssNavigationPanel is based on ContentPanel, we inherit a built-in container for any buttons we add to the ContentPanel, making adding a button very simple.

Time for action adding a button1. Back in RssNavigationPanel, set the icon for the button: TooltipThe labels on buttons are concise by nature. For users who are familiar with your application or other applications that are similar, the label and icon may be enough for them to understand what the button does.

Other users, however, will appreciate a more detailed explanation and that is where tooltips come in. Tooltips can be added to buttons or other components to give the user further information when they hover their mouse over them.

We are now going to add a tooltip to our Link feed button so that a message displays when the user hovers their mouse over the button:. Time for action adding a tooltip1. In the constructor of RssNavigationPanel, add the following code to define a new. Run the application and hover your mouse over the Link feed button to display the tooltip like this:.

We created a new tooltip and associated it with the Link feed button so that when a user hovers over the button, the tooltip is displayed.

PopupPopup subclasses LayoutContainer, adding the ability for the component to be displayed over other components. We would like to take advantage of our example application to pop up a small form for entering an URL when the user clicks on the Link feed button. We will point out some of the features of Popup as we go along. Time for action creating a popup1. Create a new class in the client.

This will set the popup to be px wide and 55px high with borders and a shadow. If auto hide was not set to false, the popup would disappear if we clicked outside of that. As our popup's visibility is controlled by a toggle button, we need to disable this, or the button and the popup will become out of sync.

We defined a new component based on a popup, which we will use for displaying a TextField for the user to type in an URL. SelectionListenerIn order for our Link feed button to do anything, it needs a Listener.

A Listener registers with a component and is informed when an event occurs. It can then execute code as a result to respond to the event. In this case, our listener needs to be registered for the Link feed button to listen for selection events being selected, so we use a SelectionListener.

We will now add a SelectionListener to our Link feed button. Time for action adding a SelectionListener1. We always want the popup to stay within the Viewport. That is, we always want all of it to be visible. To do this we use the setContrainViewport method:. As the listener is for a ToggleButton, we check the button's state using isPressed.

If the button is pressed, we need to show our popup by calling the show method, otherwise we should hide it using the hide method. Run the application and check that the Link feed button now displays the Link Feed Popup when toggled on and makes it disappear again when toggled off:. We have now added a SelectionListener to our Link feed ToggleButton to enable us to hide and show a popup.

FieldField subclasses BoxComponent and provides the base class for all form fields. The Field base class provides default event handling, value handling, as well as some other functionality.

We will come back to fields in subsequent chapters, but for the time being we are just going to look at the TextField. There are a few differences, one being that when defining a text field, you define the data type that the field will store using generics. For example, a TextField that stores strings will be defined as follows:.

GXT text fields also have a number of built-in functions that allow for setting validation criteria such as making the fields required, setting a minimum and maximum length, and validating against standard regular expressions. In our example application, we need to use a TextField to allow the user to enter the URL of the news feed they want to add in our link feed popup.

Time for action adding components to the Link feed popup1. Create a Button to submit the value of the URL field and a SelectionListener to respond to the user clicking on the button:.

You may have noticed that SelectionListener is calling a method called addFeed to deal with the value the user enters. We are not going to process the value yet, but for the time being we should just create a placeholder method so that it does something.

In this case, displaying an alert box:. We now need to create a new BorderLayout like the one we used for the Viewport earlier in this chapter, but this time we are going to use it for laying out the popup, so we add it using setLayout:.

EAST, 50 ;eastData. Now start the application, click on the Link feed button and check that the popup now contains fields as shown:. Now complete the URL field, click on the add button and check that a message like this is shown:. We added fields to our Link feed popup and created a SelectionListener to respond to the add button being pressed.

Pop quiz matching the component with the descriptionIn the chapter so far, we have covered a lot of components. Try to match the following components with the descriptions:. Popup positioning and alignmentWhile our popup displays properly, it appears in the middle of the screen away from the button that made it appear.

Although we are using a ToggleButton, it is not obvious that the button would also make it disappear again. It would be a lot more user friendly if the popup appeared directly above the Link feed button.

At the moment we are simply using the show method to display the popup. What we want to do is display our popup in relation to the Link feed button. To do this, we pass the show method the following information:. A string representing how the element should align with the target element in this case the button's element.

The string is made up of the anchor point of the element to align followed by a dash, and then the anchor point of the element we want to align the element to. If the string ends with a question mark, the element will attempt to align as defined, but it means that it will reposition the popup so that it remains in the viewport.

An alignment string containing "tl-bl? This means the element would appear directly below the target. Time for action positioning the popup1. In the RssNavigationPanel, modify the action performed by the. SelectionListener so that the bottom-left corner of the linkFeedPopup will align to the top-left corner of the Link feed Button:.

Start the application and check that the popup now appears directly above the Link feed Button:. We specified that the bottom-left of our popup should be aligned with the top-left of our Link feed button, unless it would mean that it will appear outside of the viewport.

Have a go hero adding a KeyListenerAt the moment the user has to type the URL of the feed they want to add into the TextField, and then press the add button. It would be quicker if pressing the Enter key could perform the same function.

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TextField controls can take a KeyListener that responds to key presses. Try to add a KeyListener to the tfUrl field in the LinkFeedPopup class that responds to the Enter key being pressed in the same way that the SelectionListener responds to the add button being pressed.

SummaryIn this chapter, we have rapidly run through most of the basic interface building blocks of GXT. We have used them to start building a sample application. This is starting to look and feel more like a desktop application than a traditional web application. In this chapter, we explore GXT's form features.

We look at the form components that GXT provides and learn how to put them to use. We also introduce the GXT Registry and see how it can be used across the application.

Change of requirementsSo far, as our example application, we have been building an RSS reader. However, as it often happens, our customer has changed her mind and added to the requirements. She now requires that the application should not only consume RSS feeds from the Internet, but also be able to create them. This means that we need to create forms to enter data into our application.

Fortunately, GXT has comprehensive form support. The RSS 2. Now we also have to be able to support being able to create documents in this format in our example application. RSS 2. It can be found at http: Put simply, an RSS file contains a channel element that first provides a name and description of a feed and then a number of item elements containing individual news items. Some of the elements in the file are compulsory and some are optional, but for the sake of this example, we shall make use of the following channel elements:.

So we need to make two forms, one that will take channel information and another that will take item information. Let's look at what GXT provides to assist us with this. By default, it uses a layout called FormLayout. If we try to add any other component, it will be ignored and not rendered.

The main benefit FormPanel gives is the ability to act on all the fields contained within it. This includes features such as marking all fields as read-only, checking that all fields are valid, changing how labels are displayed, and ultimately submitting the form using HTTP post or GWT RPC.

FieldsIn the last chapter, we introduced TextField. This is just one of the many fields available in GXT. NumberField A TextField that only allows numbers to be entered. It also provides additional methods for validating the numbers input, such as max and min values.

This looks like a TextField, but also adds a trigger button to the right of it. This too has several subclasses. These are the important ones:. DateField A trigger field that enables the user to enter a date by clicking on the trigger button and picking a date from a date picker.

ComboBox A combobox that uses a ModelData object to provide the options. We cover ModelData in the next chapter. ComboBox componentThere are also a number of subclasses of ComboBox, which makes it more convenient to use:.

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SPR Polydor. This demo showcases all the different components available in GXT. It also provides sample. Breadcrumb Navigation. Gbs preview. Larry Mante July Hardcover.UiBinder; import com. It would be quicker if pressing the Enter key could perform the same function. The XML is not saved, and any Feed objects created will be lost when the application is restarted.

Log in to your account. Time for action adding components to the Link feed popup1. This goes back to the idea of lazy rendering. At the time of writing, Ext GWT is offered with a dual license. Stores are where the data-backed GXT components keep data. When creating a BorderLayoutData object, we have to define which layout region it applies to, and optionally its initial size and a maximum and minimum size for the region.

It supports the resizing of regions by the user by means of split bars and allows regions to be expanded and collapsed or hidden: [ 37 ] The Building Blocks This type of layout is very common on websites, with the north being the header, the south the footer, the center the content, and the west and or the east being the navigation.

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See my other articles. One of my hobbies is tang soo do. I do love upwardly.