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diff --git a/docs/html/guide/topics/views/index.jd b/docs/html/guide/topics/views/index.jd deleted file mode 100644 index a246ba1..0000000 --- a/docs/html/guide/topics/views/index.jd +++ /dev/null @@ -1,216 +0,0 @@ -page.title=Views and Layout -@jd:body - -<div id="qv-wrapper"> -<div id="qv"> - - <h2>Key classes and packages</h2> - <ol> - <li>{@link android.view.View}</li> - <li>{@link android.view.ViewGroup}</li> - <li>{@link android.widget}</li> - </ol> - - <h2>In this document</h2> - <ol> - <li><a href="#ViewHierarchy">View Hierarchy</a></li> - <li><a href="#Layout">Layout</a></li> - <li><a href="#Widgets">Widgets</a></li> - <li><a href="#Events">Events</a></li> - <li><a href="#Adapters">Adapters</a></li> - <li><a href="#StylesAndThemes">Styles and Themes</a></li> - </ol> -</div> -</div> - -<p>In an Android application, a user interface is built using {@link android.view.View} and -{@link android.view.ViewGroup} objects. There are many types of views and view groups, each of which -is a descendant of the {@link android.view.View} class.</p> - -<p>View objects are the basic units of user interface expression on the Android platform. -The View class serves as the base for subclasses called "widgets," which offer fully implemented -UI objects, like text fields and buttons. The ViewGroup class serves as the base for subclasses called "layouts," -which offer different kinds of layout architecture, like linear, tabular and relative.</p> - -<p>A View object is a data structure whose properties store the layout properties and content for a specific -rectangular area of the screen. A View object handles its own measurement, layout, drawing, focus change, -scrolling, and key/gesture interactions for the rectangular screen area it represents. </p> - - -<h2 id="ViewHierarchy">View Hierarchy</h2> - -<p>On the Android platform, you will define an Activity's UI using a hierarchy of view and view group nodes, -as shown in the diagram below. This hierarchy tree can be as simple or complex as you need it to be, and you -can build it up using Android's set of predefined widgets and layouts, or with custom view types that you -create yourself.</p> - -<img src="{@docRoot}images/viewgroup.png" alt="" width="312" height="211" align="center"/> - -<p>The Android system will notify your Activity when it becomes active and receives focus. -In order to attach the view hierarchy tree to the screen for rendering, your Activity must call its -<code>setContentView()</code> method and pass a reference to the root node object. The Android system -receives this reference so that it can invalidate, measure, and draw the tree. The root node requests -that its child nodes draw themselves — in turn, each view group node is responsible for -calling <code>Draw()</code> on each of its own child views, so that each child view can render itself. -The children may request a size and location within the parent, but the parent object has the final -decision on where how big each child can be. To learn more about how a view group and its children are measured -and drawn, read <a href="how-android-draws.html">How Android Draws Views</a>.</p> - - -<h2 id="Layout">Layout</h2> - -<p>The most common way to define your layout and express the view hierarchy is with an XML layout file. -XML offers a human-readable structure for the layout, much like HTML. Each element in XML is -(usually a descendant of) either a View or ViewGroup object. View objects are leaves in the tree, -ViewGroup objects are branches in the tree. The name of an XML element -is the respective class object name. So a <code><TextView></code> element creates -a {@link android.widget.TextView} widget in your UI, and a <code><LinearLayout></code> element creates -a {@link android.widget.LinearLayout} layout branch in the tree. To learn more about how to write your layout in XML, -read <a href="declaring-layout.html">Declaring and Querying Layout</a>. - -<div class="sidebox-wrapper"> -<div class="sidebox"> - <p><b>Tip:</b> You can also draw new views and view groups from within your code, - by adding new View and ViewGroup objects to an - existing ViewGroup (specifically, you'll use the <code>addView()</code> methods to dynamically insert new views). - To see how to add views in your code, see the {@link android.view.ViewGroup} reference.</p> -</div> -</div> - -<p>There are a variety of ways in which you can layout your views, using different view groups. -Some pre-defined view groups offered by Android (called layouts) include LinearLayout, RelativeLayout, AbsoluteLayout, -TableLayout, GridLayout and others. Each offers a different mechanisms for arranging child views -among each other. -To learn more about how to use some of these view groups for your layout, -read <a href="layout.html">Common Layout Objects</a>. - -<h3 id="IDs">IDs</h3> - -<p>Views may have an integer ID associated with them. The ID is written as a string, but once the application is -compiled, it will be referenced as an integer. -These IDs are typically assigned in the layout XML file as an attribute of the view, -and are used to uniquely identify a view within the tree. The usual syntax for an ID, inside an XML tag is:</p> -<pre>id="@+id/my_button"</pre> -<p>The at-symbol (@) at the beginning of the string indicates that the XML parser should parse and expand the rest -of the ID string and identify it as an ID resource. The plus-symbol (+) means that this is a new resource name that must -be created and added to our resources (in the <code>R.java</code> file). There are a number of other ID resources that -are offered by the Android framework. When referencing an Android resource ID, you do not need the plus-symbol, -but must add the <code>android</code> package namespace, like so:</p> -<pre>id="@android:id/empty"</pre> -<p>With the <code>android</code> package namespace in place, we're now referencing an ID from the <code>android.R</code> -resources class, rather than the local resources class.</p> - -<p>In order to create views and reference them from the application, a common pattern is to:</p> -<ol> - <li>Define a view/widget in the layout file and assign it a unique ID. E.g.: -<pre> -<Button id="@+id/my_button" - android:layout_width="wrap_content" - android:layout_height="wrap_content" - android:text="@string/my_button_text"/> -</pre> - </li> - <li>Then create an instance of the view object and capture it from the layout -(typically in the <code>onCreate()</code> method). -<pre> -Button myButton = (Button) findViewById(R.id.my_button); -</pre> - </li> -</ol> -<p>Defining IDs for view objects is important when creating a {@link android.widget.RelativeLayout}. -In a relative layout, sibling views can define their layout relative to another sibling view, -which is referenced by the unique ID.</p> -<p>An ID need not be unique throughout the entire tree, but it should be -unique within the part of the tree you are searching (which may often be the entire tree, so it's best -to be completely unique when possible).</p> - - -<h3>Layout Parameters</h3> - -<p>Every ViewGroup class implements a nested class that extends {@link -android.view.ViewGroup.LayoutParams}. This subclass -contains property types that define each child view's size and position, as -appropriate for that type of view group. As you can see in the figure below, the parent -view group defines layout parameters for each child view (including the child view group).</p> - -<img src="{@docRoot}images/layoutparams.png" alt="" height="300" align="center"/> - -<p>Note that every LayoutParams subclass has its own syntax for setting -values. Each child element must define LayoutParams that are appropriate for its parent, -though it may also define different LayoutParams for its own children. </p> - -<p>All view groups include a width and height, and each view is required to define them. -Many LayoutParams also include optional margins and -borders. You can specify width and height with exact measurements, though you probably won't want -to do this often. More often, you will tell your view to size itself either to -the dimensions required by its content, or to become as big as its parent view group -will allow (with the <var>wrap_content</var> and <var>fill_parent</var> values, respectively). -The accepted measurement types are defined in the -<a href="{@docRoot}guide/topics/resources/available-resources.html#dimension">Available Resources</a> document.</p> - -<h2 id="Widgets">Widgets</h2> - - -<p>The View class also serves as a base class for <em>widgets</em> — a set of fully implemented -View subclasses that draw interactive screen elements, so you can quickly build your UI. -Android provides a vast collection of widgets for special actions. -Some of them are basic interaction elements like buttons and text fields, while others are more complex, -like a date picker or zoom controls.</p> -<p>For a list of all built-in widgets, see the {@link android.widget widget}.</p> - -<p>You're not limited to the kinds of views, layouts and widgets provided by the Android platform. If you'd -like to do something more customized, create your own widget or layout, you can. -Read more in <a href="custom-components.html">Building Custom Components</a>. - - -<h2 id="Events">Events</h2> - -<p>Once you've designed and built your UI layout, you need to handle the user interaction with it. -Obviously, the views that you've implemented in the layout are the -receptors for such interaction events. Because the View class is built to listen for most interaction events, -receiving and handling them is pretty straigh-forward. When you want to perform an action upon an event, -you need to do one of two things:</p> -<ul> - <li>Override an existing callback method for the view you've implemented, which will be called when something -like a touch or focus event occurs.</li> - <li>Define a listener interface, like {@link android.view.View.OnClickListener} (for handling "clicks" on a View). -You must then define the listener for your view with the respective <code>set...Listener()</code> -method (such as {@link android.view.View#setOnClickListener(android.view.View.OnClickListener) setOnCLickListener()}).</li> -</ul> - -<p>To learn more about handling events and writing your own listeners, -read <a href="ui-events.html">Handling UI Events</a>.</p> - - -<h2 id="Adapters">Adapters</h2> - -<p>Sometimes you'll want to populate a view group with some information that can't be hard-coded, instead, -you want to bind your view to an external source of data. To do this, you use an AdapterView as -your view group and each child View is initialized and populated with data from the Adapter.</p> -<p>The AdapterView object is an implementation of ViewGroup that determines its child views -based on a given Adapter object. The Adapter acts like a courier between your data source (perhaps an -array of external strings) and the AdapterView, which displays it. There are several implementations -of the Adapter class, for specific tasks, such as the CursorAdapter for reading database data from a Cursor, -or an ArrayAdapter for reading from an arbitrary array.</p> -<p>To learn more about using an Adapter to populate your views, read -<a href="binding.html">Binding to Data with AdapterView</a>.</p> - - -<h2 id="StylesAndThemes">Styles and Themes</h2> - -<p>Perhaps you're not satisfied with the look of the standard widgets. To revise them, you can create some -of your own styles and themes.</p> - -<ul> - <li>A style is a set of one or more formatting attributes that you can apply as a unit to individual elements -in your layout. For example, you could define a style that specifies a certain text size and color, then -apply it to only specific View elements.</li> - <li>A theme is a set of one or more formatting attributes that you can apply as a unit to all activities in -an application, or just a single activity. For example, you could define a theme that sets specific colors for -the window frame and the panel background, and sets text sizes and colors for menus. This theme can then be -applied to specific activities or the entire application.</li> -</ul> - -<p>Styles and themes are resources. Android provides some default style and theme resources that you can use, -or you can declare your own custom style and theme resources. Learn more about using styles and themes in the -<a href="themes.html">Applying Styles and Themes</a> document.</p> |