docs/html/tools/debugging/debugging-ui.jd - LeafOS-Project/android_frameworks_base - Gitiles

 page.title=Optimizing Your UI
 parent.title=Debugging
 parent.link=index.html
 @jd:body

  <div id="qv-wrapper">
     <div id="qv">
       <h2>In this document</h2>

       <ol>
         <li>
             <a href="#HierarchyViewer">
                 Using Hierarchy Viewer
             </a>
             <ol>
                 <li><a href="#runhv">Running Hierarchy Viewer and choosing a window</a></li>
                 <li><a href="#viewhierarchy">About the View Hierarchy window</a></li>
                 <li><a href="#indiView">Working with an individual View in Tree View</a></li>
                 <li><a href="#hvdebugging">Debugging with View Hierarchy</a></li>
                 <li><a href="#hvoptimize">Optimizing with View Hierarchy</a></li>
             </ol>
         </li>
         <li>
             <a href="#pixelperfect">
                 Using Pixel Perfect
             </a>
             <ol>
                 <li><a href="#aboutpixelperfect">About the Pixel Perfect window</a></li>
                 <li><a href="#overlays">Working with Pixel Perfect overlays</a></li>
             </ol>
         </li>
         <li><a href="#lint">Using lint to optimize your UI</a></li>
       </ol>
       <h2>Related videos</h2>
           <ol>
               <li>
 <iframe title="Hierarchyviewer"
     width="210" height="160"
     src="//www.youtube.com/embed/PAgE7saQUUY?rel=0&amp;hd=1"
     frameborder="0" allowfullscreen>
 </iframe>
               </li>
               <li>
 <iframe title="Pixel Perfect"
     width="210" height="160"
     src="//www.youtube.com/embed/C45bMZGdN7Y?rel=0&amp;hd=1"
     frameborder="0"
     allowfullscreen>
 </iframe>
               </li>
           </ol>
     </div>
   </div>

   <p>
 Sometimes your application's layout can slow down your application.
   To help debug issues in your layout, the Android SDK provides the Hierarchy Viewer and
   <code>lint</code> tools.
   </p>

   <p>The Hierarchy Viewer application allows you to debug and optimize your user interface. It
   provides a visual representation of the layout's View hierarchy (the View Hierarchy window)
   with performance information for each node in the layout,
   and a magnified view of the display (the Pixel Perfect window) to closely examine the pixels
   in your layout.</p>

   <p>Android <code>lint</code> is a static code scanning tool that helps you optimize the layouts and layout
   hierarchies of your applications, as well as detect other common coding problems. You can run it against your layout files or resource
   directories to quickly check for inefficiencies or other types of problems that could be
   affecting the performance of your application.</p>

 <h2 id="HierarchyViewer">Using Hierarchy Viewer</h2>

 <h3 id="runhv">Running Hierarchy Viewer and choosing a window</h3>
 <p>
     To run Hierarchy Viewer, follow these steps:</p>
 <ol>
     <li>
         Connect your device or launch an emulator.
         <p>
             To preserve security, Hierarchy Viewer can only connect to devices running a
             developer version of the Android system.
         </p>
     </li>
     <li>
         If you have not done so already, install the application you want to work with.
     </li>
     <li>
         Run the application, and ensure that its UI is visible.
     </li>
     <li>
         From a terminal, launch <code>hierarchyviewer</code> from the
         <code>&lt;sdk&gt;/tools/</code>
         directory.
     </li>
     <li>
         The first window you see displays a list of devices and emulators. To expand the list
         of Activity objects for a device or emulator, click the arrow on the left. This displays a
         list of the Activity objects whose UI is currently visible on the device or emulator. The
         objects are listed by their Android component name. The list includes both your application
         Activity and system Activity objects. A screenshot of this window appears in
         figure 1.
     </li>
     <li>
         Select the name of your Activity from the list. You can now look at its view
         hierarchy using the View Hierarchy window, or look at a magnified image of the UI using
         the Pixel Perfect window.
     </li>
 </ol>
 <p>
     To learn how to use the View Hierarchy window, go to
     <a href="#viewhierarchy">About the View Hierarchy window</a>. To learn how to use the
     Pixel Perfect window, go to <a href="#pixelperfect">About the Pixel Perfect window</a>.
 </p>
 <img id="Fig1" src="{@docRoot}images/developing/hv_device_window.png" alt="" height="600"/>
 <p class="img-caption"><strong>Figure 1.</strong> Hierarchy Viewer device window</p>
 <h3 id="viewhierarchy">About the View Hierarchy window</h3>
 <p>
     The View Hierarchy window displays the View objects that form the UI of the
     Activity that is running on your device or emulator. You use it to look at individual
     View objects within the context of the entire View tree. For each View object, the View
     Hierarchy window also displays rendering performance data.
 </p>
 <p>
     To see the View Hierarchy window, run Hierarchy Viewer as described in
     the section <a href="#runhv">Running Hierarchy Viewer and choosing a window</a>. Next, click
     <strong>View Hierarchy</strong> at the top of the device window.
 </p>
 <p>
     You should see four panes:
 </p>
 <ul>
     <li>
         <strong>Tree View</strong>: The left-hand pane displays the Tree View,
         a diagram of the Activity object's hierarchy of views. Use Tree View to examine individual
         View objects and see the relationships between View objects in your UI.
         <p>
             To zoom in on the pane, use the slider at the bottom of the pane, or use your mouse
             scroll wheel. To move around in the pane or reveal View objects that are not currently
             visible, click and drag the pane.
         </p>
         <p>
             To highlight the nodes in the tree whose class or ID match a search string, enter the
             string in the <strong>Filter by class or id:</strong> edit box at the bottom of the
             window. The background of nodes that match the search string will change from gray to
             bright blue.
         </p>
         <p>
             To save a screenshot of Tree View to a PNG file, click <strong>Save As PNG</strong> at
             the top of the View Hierarchy window. This displays a dialog in which you can choose
             a directory and file name.
         </p>
         <p>
             To save a layered screenshot of your device or emulator to an Adobe Photoshop (PSD)
             file, click <strong>Capture Layers</strong> at the top of the View Hierarchy window.
             This displays a dialog in which you can choose a directory or file name.
             Each View in the UI is saved as a separate Photoshop layer.
         </p>
         <p>
             In Photoshop (or similar program that accepts .psd files), you can hide, show or edit a
             layer independently of others. When you save a layered screenshot, you can examine and
             modify the image of an individual View object. This helps you experiment with design
             changes.
         </p>
     </li>
     <li>
         The upper right-hand pane displays the <strong>Tree Overview</strong>, a smaller map
         representation of the entire Tree View window. Use Tree Overview to identify the part of the
         view tree that is being displayed in Tree View.
         <p>
             You can also use Tree Overview to move around in the Tree View pane. Click and drag
             the shaded rectangle over an area to reveal it in Tree View.
         </p>
     </li>
     <li>
         The middle right-hand pane displays the <strong>Properties View</strong>,
         a list of the properties for a selected View object. With Properties View, you can
         examine all the properties without having to look at your application source.
         <p>
             The properties are organized by category. To find an individual property, expand
             a category name by clicking the arrow on its left. This reveals all the properties
             in that category.
         </p>
     </li>
     <li>
         The lower right-hand pane displays the <strong>Layout View</strong>,
         a block representation of the UI. Layout View is another way to navigate through your UI.
         When you click on a View object in Tree View, its position in the UI is highlighted.
         Conversely, when you click in an area of Layout View, the View object for that area is
         highlighted in Tree View.
         <p>
             The outline colors of blocks in Layout View provide additional information:
         </p>
             <ul>
                 <li>
                     Bold red: The block represents the the View that is currently selected in
                     Tree View.
                 </li>
                 <li>
                     Light red: The block represents the parent of the block outlined in bold red.
                 </li>
                 <li>
                     White: The block represents a visible View that is not a parent or child of the
                     View that is currently selected in Tree View.
                 </li>
             </ul>
     </li>
 </ul>
 <p>
     When the UI of the current Activity changes, the View Hierarchy window is not automatically
     updated. To update it, click <strong>Load View Hierarchy</strong> at the top of the window.
 </p>
 <p>
     Also, the window is not updated if you switch to a new Activity. To update it, start by
     clicking the window selection icon in the bottom left-hand corner of the window. This
     navigates back to the Window Selection window. From this window, click the Android
     component name of the new Activity and then click <strong>Load View Hierarchy</strong>
     at the top of the window.
 </p>
 <p>
     A screenshot of the View Hierarchy window appears in figure 2.
 </p>
 <img id="Fig2" src="{@docRoot}images/developing/hv_view_hierarchy_window.png" alt="" height="600"/>
 <p class="img-caption"><strong>Figure 2.</strong> The View Hierarchy window</p>
 <h3 id="indiView">Working with an individual View in Tree View</h3>
 <p>
     Each node in Tree View represents a single View. Some information is always visible. Starting
     at the top of the node, you see the following:
 </p>
 <ol>
     <li>
         View class: The View object's class.
     </li>
     <li>
         View object address: A pointer to View object.
     </li>
     <li>
         View object ID: The value of the
         <code><a href="{@docRoot}guide/topics/resources/layout-resource.html#idvalue">android:id</a>
         </code> attribute.
     </li>
     <li>
         Performance indicators: A set of three colored dots that indicate the rendering
         speed of this View relative to other View objects in the tree. The three dots
         represent (from left to right) the measure, layout, and draw times of the rendering.
         <p>
             The colors indicate the following relative performance:
         </p>
         <ul>
             <li>
                 Green: For this part of the render time, this View is in the faster 50% of all
                 the View objects in the tree. For example, a green dot for the measure time means
                 that this View has a faster measure time than 50% of the View objects in the tree.
             </li>
             <li>
                 Yellow: For this part of the render time, this View is in the slower 50% of all
                 the View objects in the tree. For example, a yellow dot for the layout time means
                 that this View has a slower layout time than 50% of the View objects in the tree.
             </li>
             <li>
                 Red: For this part of the render time, this View is the slowest one in the tree.
                 For example, a red dot for the draw time means that this View takes the most
                 time to draw of all the View objects in the tree.
             </li>
         </ul>
     </li>
     <li>
         View index: The zero-based index of the View in its parent View. If it is the only child,
         this is 0.
     </li>
 </ol>
 <p>
     When you select a node, additional information for the View appears in a small window above
     the node. When you click one of the nodes, you see the following:
 </p>
 <ul>
     <li>
         Image: The actual image of the View, as it would appear in the emulator. If the View has
         children, these are also displayed.
     </li>
     <li>
         View count: The number of View objects represented by this node. This includes the View
         itself and a count of its children. For example, this value is 4 for a View that has 3
         children.
     </li>
     <li>
         Render times: The actual measure, layout, and draw times for the View rendering, in
         milliseconds. These represent the same values as the performance indicators mentioned in
         the preceding section.
     </li>
 </ul>
 <p>
     An annotated screenshot of an individual node in the Tree View window appears in figure 3.
 </p>
 <img id="Fig3" src="{@docRoot}images/developing/hv_treeview_screenshot.png" alt="" height="600"/>
 <p class="img-caption"><strong>Figure 3.</strong> An annotated node in Tree View</p>
 <h3 id="hvdebugging">Debugging with View Hierarchy</h3>
 <p>
     The View Hierarchy window helps you debug an application by providing a static display
     of the UI. The display starts with your application's opening screen. As you step through
     your application, the display remains unchanged until you redraw it by invalidating and
     then requesting layout for a View.
 </p>
 <p>
     To redraw a View in the display:
 </p>
     <ul>
         <li>
             Select a View in Tree View. As you move up towards the root of the tree (to the
             left in the Tree View), you see the highest-level View objects. Redrawing a high-level
             object usually forces the lower-level objects to redraw as well.
         </li>
         <li>
             Click <strong>Invalidate</strong> at the top of the window. This marks the View as
             invalid, and schedules it for a redraw at the next point that a layout is requested.
         </li>
         <li>
             Click <strong>Request Layout</strong> to request a layout. The View and its children
             are redrawn, as well as any other View objects that need to be redrawn.
         </li>
     </ul>
 <p>
     Manually redrawing a View allows you to watch the View object tree and examine the properties of
     individual View objects one step at a time as you go through breakpoints in your code.
 </p>
 <h3 id="hvoptimize">Optimizing with View Hierarchy</h3>
 <p>
     View Hierarchy also helps you identify slow render performance. You start by looking at the
     View nodes with red or yellow performance indicators to identify the slower View objects. As you
     step through your application, you can judge if a View is consistently slow or slow only in
     certain circumstances.
 </p>
 <p>
     Remember that slow performance is not necessarily evidence of a problem, especially for
     ViewGroup objects. View objects that have more children and more complex View objects render
     more slowly.
 </p>
 <p>
     The View Hierarchy window also helps you find performance issues. Just by looking at the
     performance indicators (the dots) for each View node, you can see which View objects are the
     slowest to measure, layout, and draw. From that, you can quickly identify the problems you
     should look at first.
 </p>
 <h2 id="pixelperfect">Using Pixel Perfect</h2>
 <p>
     Pixel Perfect is a tool for examining pixel properties and laying out UIs from a design drawing.
 </p>
 <h3 id="aboutpixelperfect">About the Pixel Perfect window</h3>
 <p>
     The Pixel Perfect window displays a magnified image of the screen that is currently
     visible on the emulator or device. In it, you can examine the properties
     of individual pixels in the screen image. You can also use the Pixel Perfect window
     to help you lay out your application UI based on a bitmap design.
 </p>
 <p>
     To see the Pixel Perfect window, run Hierarchy Viewer, as described in
     the section <a href="#runhv">Running Hierarchy Viewer and choosing a window</a>. Next, click
     <strong>Inspect Screenshot</strong> at the top of the device window. The Pixel Perfect window
     appears.
 </p>
 <p>
     In it, you see three panes:
 </p>
 <ul>
     <li>
         View Object pane: This is a hierarchical list of the View objects that are currently
         visible on the device or emulator screen, including both the ones in your application and
         the ones generated by the system. The objects are listed by their View class.
         To see the class names of a View object's children, expand the View by clicking the
         arrow to its left. When you click a View, its position is highlighted in the Pixel Perfect
         pane on the right.
     </li>
     <li>
         Pixel Perfect Loupe pane: This is the magnified screen image. It is overlaid by a grid in
         which each square represents one pixel. To look at the information for a pixel, click in its
         square. Its color and X,Y coordinates appear at the bottom of the pane.
         <p>
             The magenta crosshair in the pane corresponds to the positioning
             crosshair in the next pane. It only moves when you move the crosshair in the next pane.
         </p>
         <p>
             To zoom in or out on the image, use the <strong>Zoom</strong> slider at the bottom of
             the pane, or use your mouse's scroll wheel.
         </p>
         <p>
             When you select a pixel in the Loupe pane, you see the following information at the
             bottom of the pane:
         </p>
         <ul>
             <li>
                 Pixel swatch: A rectangle filled with the same color as the pixel.
             </li>
             <li>
                 HTML color code: The hexadecimal RGB code corresponding to the pixel color
             </li>
             <li>
                 RGB color values: A list of the (R), green (G), and blue (B) color values of the
                 pixel color. Each value is in the range 0-255.
             </li>
             <li>
                 X and Y coordinates: The pixel's coordinates, in device-specific pixel units.
                 The values are 0-based, with X=0 at the left of the screen and Y=0 at the top.
             </li>
         </ul>
     </li>
     <li>
         Pixel Perfect pane: This displays the currently visible screen as it would appear in the
         emulator.
         <p>
             You use the cyan crosshair to do coarse positioning. Drag the crosshair in the image,
             and the Loupe crosshair will move accordingly. You can also click on a point in the
             Pixel Perfect pane, and the crosshair will move to that point.
         </p>
         <p>
             The image corresponding to the View object selected in the View Object pane is
             outlined in a box that indicates the View object's position on the screen. For the
             selected object, the box is bold red. Sibling and parent View objects have a light
             red box. View objects that are neither parents nor siblings are in white.
         </p>
         <p>
             The layout box may have other rectangles either inside or outside it, each of which
             indicates part of the View. A purple or green rectangle indicates the View bounding box.
             A white or black box inside the layout box represents the <strong>padding</strong>, the
             defined distance between the View object's content and its bounding box. An outer white
             or black rectangle represents the <strong>margins</strong>, the distance between the
             View bounding box and adjacent View objects. The padding and margin boxes are white if
             the layout background is black, and vice versa.
         </p>
         <p>
             You can save the screen image being displayed in the Pixel Perfect pane as a PNG file.
             This produces a screenshot of the current screen. To do this, click
             <strong>Save as PNG</strong> at the top of the window. This displays a dialog,
             in which you can choose a directory and filename for the file.
         </p>
     </li>
 </ul>
 <p>
     The panes are not automatically refreshed when you change one of the View objects or go to
     another Activity. To refresh the Pixel Perfect pane and the Loupe pane, click
     <strong>Refresh Screenshot</strong> at the top of the window. This will change the panes
     to reflect the current screen image. You still may need to refresh the View Object pane;
     to do this, click <strong>Refresh Tree</strong> at the top of the window.
 </p>
 <p>
     To automatically refresh the panes while you are debugging, set
     <strong>Auto Refresh</strong> at the top of the window, and then set a refresh rate
     with the <strong>Refresh Rate</strong> slider at the bottom of the Loupe pane.
 </p>
 <h3 id="overlays">Working with Pixel Perfect overlays</h3>
 <p>
     You often construct a UI based on a design done as a bitmap image. The Pixel Perfect window
     helps you match up your View layout to a bitmap image by allowing you to load the bitmap as an
     <strong>overlay</strong> on the screen image.
 </p>
 <p>
     To use a bitmap image as an overlay:
 </p>
 <ul>
     <li>
         Start your application in a device or emulator and navigate to the Activity whose UI you
         want to work with.
     </li>
     <li>
         Start Hierarchy Viewer and navigate to the Pixel Perfect window.
     </li>
     <li>
         At the top of the window, click <strong>Load Overlay</strong>. A dialog opens, prompting
         for the image file to load. Load the image file.
     </li>
     <li>
         Pixel Perfect displays the overlay over the screen image in the Pixel Perfect pane. The
         lower left corner of the bitmap image (X=0, Y=<em>max value</em>) is anchored on the lower
         leftmost pixel (X=0, Y=<em>max screen</em>) of the screen.
         <p>
             By default, the overlay has a 50% transparency, which allows you to see the screen
             image underneath. You can adjust this with the <strong>Overlay:</strong> slider at the
             bottom of the Loupe pane.
         </p>
         <p>
             Also by default, the overlay is not displayed in the Loupe pane. To display it,
             set <strong>Show in Loupe</strong> at the top of the window.
         </p>
     </li>
 </ul>
 <p>
     The overlay is not saved as part of the screenshot when you save the screen image as a PNG
     file.
 </p>
 <p>
     A screenshot of the Pixel Perfect window appears in figure 4.
 </p>
 <img id="Fig4" src="{@docRoot}images/developing/hv_pixelperfect.png"
         alt=""
         height="600"/>
 <p class="img-caption"><strong>Figure 4.</strong> The Pixel Perfect window</p>
 <h2 id="lint">Using lint to Optimize Your UI</h2>
 <p>The Android {@code lint} tool lets you analyze the XML files that define your application's UI to find inefficiencies in the view hierarchy.</p>
 <p class="note"><strong>Note: </strong>The Android <code>layoutopt</code> tool has been replaced by the {@code lint} tool beginning in ADT and SDK Tools revision 16. The {@code lint} tool reports UI layout performance issues in a similar way as <code>layoutopt</code>, and detects additional problems.</p>
 <p>For more information about using {@code lint}, see <a href="{@docRoot}tools/debugging/improving-w-lint.html">Improving Your Code with lint</a> and the <a  href="{@docRoot}tools/help/lint.html">lint reference documentation</a>.</p>
	page.title=Optimizing Your UI
	parent.title=Debugging
	parent.link=index.html
	@jd:body

	<div id="qv-wrapper">
	<div id="qv">
	<h2>In this document</h2>

	<ol>
	<li>
	<a href="#HierarchyViewer">
	Using Hierarchy Viewer
	</a>
	<ol>
	<li><a href="#runhv">Running Hierarchy Viewer and choosing a window</a></li>
	<li><a href="#viewhierarchy">About the View Hierarchy window</a></li>
	<li><a href="#indiView">Working with an individual View in Tree View</a></li>
	<li><a href="#hvdebugging">Debugging with View Hierarchy</a></li>
	<li><a href="#hvoptimize">Optimizing with View Hierarchy</a></li>
	</ol>
	</li>
	<li>
	<a href="#pixelperfect">
	Using Pixel Perfect
	</a>
	<ol>
	<li><a href="#aboutpixelperfect">About the Pixel Perfect window</a></li>
	<li><a href="#overlays">Working with Pixel Perfect overlays</a></li>
	</ol>
	</li>
	<li><a href="#lint">Using lint to optimize your UI</a></li>
	</ol>
	<h2>Related videos</h2>
	<ol>
	<li>
	<iframe title="Hierarchyviewer"
	width="210" height="160"
	src="//www.youtube.com/embed/PAgE7saQUUY?rel=0&hd=1"
	frameborder="0" allowfullscreen>
	</iframe>
	</li>
	<li>
	<iframe title="Pixel Perfect"
	width="210" height="160"
	src="//www.youtube.com/embed/C45bMZGdN7Y?rel=0&hd=1"
	frameborder="0"
	allowfullscreen>
	</iframe>
	</li>
	</ol>
	</div>
	</div>

	<p>
	Sometimes your application's layout can slow down your application.
	To help debug issues in your layout, the Android SDK provides the Hierarchy Viewer and
	<code>lint</code> tools.
	</p>

	<p>The Hierarchy Viewer application allows you to debug and optimize your user interface. It
	provides a visual representation of the layout's View hierarchy (the View Hierarchy window)
	with performance information for each node in the layout,
	and a magnified view of the display (the Pixel Perfect window) to closely examine the pixels
	in your layout.</p>

	<p>Android <code>lint</code> is a static code scanning tool that helps you optimize the layouts and layout
	hierarchies of your applications, as well as detect other common coding problems. You can run it against your layout files or resource
	directories to quickly check for inefficiencies or other types of problems that could be
	affecting the performance of your application.</p>

	<h2 id="HierarchyViewer">Using Hierarchy Viewer</h2>

	<h3 id="runhv">Running Hierarchy Viewer and choosing a window</h3>
	<p>
	To run Hierarchy Viewer, follow these steps:</p>
	<ol>
	<li>
	Connect your device or launch an emulator.
	<p>
	To preserve security, Hierarchy Viewer can only connect to devices running a
	developer version of the Android system.
	</p>
	</li>
	<li>
	If you have not done so already, install the application you want to work with.
	</li>
	<li>
	Run the application, and ensure that its UI is visible.
	</li>
	<li>
	From a terminal, launch <code>hierarchyviewer</code> from the
	<code><sdk>/tools/</code>
	directory.
	</li>
	<li>
	The first window you see displays a list of devices and emulators. To expand the list
	of Activity objects for a device or emulator, click the arrow on the left. This displays a
	list of the Activity objects whose UI is currently visible on the device or emulator. The
	objects are listed by their Android component name. The list includes both your application
	Activity and system Activity objects. A screenshot of this window appears in
	figure 1.
	</li>
	<li>
	Select the name of your Activity from the list. You can now look at its view
	hierarchy using the View Hierarchy window, or look at a magnified image of the UI using
	the Pixel Perfect window.
	</li>
	</ol>
	<p>
	To learn how to use the View Hierarchy window, go to
	<a href="#viewhierarchy">About the View Hierarchy window</a>. To learn how to use the
	Pixel Perfect window, go to <a href="#pixelperfect">About the Pixel Perfect window</a>.
	</p>
	<img id="Fig1" src="{@docRoot}images/developing/hv_device_window.png" alt="" height="600"/>
	<p class="img-caption"><strong>Figure 1.</strong> Hierarchy Viewer device window</p>
	<h3 id="viewhierarchy">About the View Hierarchy window</h3>
	<p>
	The View Hierarchy window displays the View objects that form the UI of the
	Activity that is running on your device or emulator. You use it to look at individual
	View objects within the context of the entire View tree. For each View object, the View
	Hierarchy window also displays rendering performance data.
	</p>
	<p>
	To see the View Hierarchy window, run Hierarchy Viewer as described in
	the section <a href="#runhv">Running Hierarchy Viewer and choosing a window</a>. Next, click
	<strong>View Hierarchy</strong> at the top of the device window.
	</p>
	<p>
	You should see four panes:
	</p>
	<ul>
	<li>
	<strong>Tree View</strong>: The left-hand pane displays the Tree View,
	a diagram of the Activity object's hierarchy of views. Use Tree View to examine individual
	View objects and see the relationships between View objects in your UI.
	<p>
	To zoom in on the pane, use the slider at the bottom of the pane, or use your mouse
	scroll wheel. To move around in the pane or reveal View objects that are not currently
	visible, click and drag the pane.
	</p>
	<p>
	To highlight the nodes in the tree whose class or ID match a search string, enter the
	string in the <strong>Filter by class or id:</strong> edit box at the bottom of the
	window. The background of nodes that match the search string will change from gray to
	bright blue.
	</p>
	<p>
	To save a screenshot of Tree View to a PNG file, click <strong>Save As PNG</strong> at
	the top of the View Hierarchy window. This displays a dialog in which you can choose
	a directory and file name.
	</p>
	<p>
	To save a layered screenshot of your device or emulator to an Adobe Photoshop (PSD)
	file, click <strong>Capture Layers</strong> at the top of the View Hierarchy window.
	This displays a dialog in which you can choose a directory or file name.
	Each View in the UI is saved as a separate Photoshop layer.
	</p>
	<p>
	In Photoshop (or similar program that accepts .psd files), you can hide, show or edit a
	layer independently of others. When you save a layered screenshot, you can examine and
	modify the image of an individual View object. This helps you experiment with design
	changes.
	</p>
	</li>
	<li>
	The upper right-hand pane displays the <strong>Tree Overview</strong>, a smaller map
	representation of the entire Tree View window. Use Tree Overview to identify the part of the
	view tree that is being displayed in Tree View.
	<p>
	You can also use Tree Overview to move around in the Tree View pane. Click and drag
	the shaded rectangle over an area to reveal it in Tree View.
	</p>
	</li>
	<li>
	The middle right-hand pane displays the <strong>Properties View</strong>,
	a list of the properties for a selected View object. With Properties View, you can
	examine all the properties without having to look at your application source.
	<p>
	The properties are organized by category. To find an individual property, expand
	a category name by clicking the arrow on its left. This reveals all the properties
	in that category.
	</p>
	</li>
	<li>
	The lower right-hand pane displays the <strong>Layout View</strong>,
	a block representation of the UI. Layout View is another way to navigate through your UI.
	When you click on a View object in Tree View, its position in the UI is highlighted.
	Conversely, when you click in an area of Layout View, the View object for that area is
	highlighted in Tree View.
	<p>
	The outline colors of blocks in Layout View provide additional information:
	</p>
	<ul>
	<li>
	Bold red: The block represents the the View that is currently selected in
	Tree View.
	</li>
	<li>
	Light red: The block represents the parent of the block outlined in bold red.
	</li>
	<li>
	White: The block represents a visible View that is not a parent or child of the
	View that is currently selected in Tree View.
	</li>
	</ul>
	</li>
	</ul>
	<p>
	When the UI of the current Activity changes, the View Hierarchy window is not automatically
	updated. To update it, click <strong>Load View Hierarchy</strong> at the top of the window.
	</p>
	<p>
	Also, the window is not updated if you switch to a new Activity. To update it, start by
	clicking the window selection icon in the bottom left-hand corner of the window. This
	navigates back to the Window Selection window. From this window, click the Android
	component name of the new Activity and then click <strong>Load View Hierarchy</strong>
	at the top of the window.
	</p>
	<p>
	A screenshot of the View Hierarchy window appears in figure 2.
	</p>
	<img id="Fig2" src="{@docRoot}images/developing/hv_view_hierarchy_window.png" alt="" height="600"/>
	<p class="img-caption"><strong>Figure 2.</strong> The View Hierarchy window</p>
	<h3 id="indiView">Working with an individual View in Tree View</h3>
	<p>
	Each node in Tree View represents a single View. Some information is always visible. Starting
	at the top of the node, you see the following:
	</p>
	<ol>
	<li>
	View class: The View object's class.
	</li>
	<li>
	View object address: A pointer to View object.
	</li>
	<li>
	View object ID: The value of the
	<code><a href="{@docRoot}guide/topics/resources/layout-resource.html#idvalue">android:id</a>
	</code> attribute.
	</li>
	<li>
	Performance indicators: A set of three colored dots that indicate the rendering
	speed of this View relative to other View objects in the tree. The three dots
	represent (from left to right) the measure, layout, and draw times of the rendering.
	<p>
	The colors indicate the following relative performance:
	</p>
	<ul>
	<li>
	Green: For this part of the render time, this View is in the faster 50% of all
	the View objects in the tree. For example, a green dot for the measure time means
	that this View has a faster measure time than 50% of the View objects in the tree.
	</li>
	<li>
	Yellow: For this part of the render time, this View is in the slower 50% of all
	the View objects in the tree. For example, a yellow dot for the layout time means
	that this View has a slower layout time than 50% of the View objects in the tree.
	</li>
	<li>
	Red: For this part of the render time, this View is the slowest one in the tree.
	For example, a red dot for the draw time means that this View takes the most
	time to draw of all the View objects in the tree.
	</li>
	</ul>
	</li>
	<li>
	View index: The zero-based index of the View in its parent View. If it is the only child,
	this is 0.
	</li>
	</ol>
	<p>
	When you select a node, additional information for the View appears in a small window above
	the node. When you click one of the nodes, you see the following:
	</p>
	<ul>
	<li>
	Image: The actual image of the View, as it would appear in the emulator. If the View has
	children, these are also displayed.
	</li>
	<li>
	View count: The number of View objects represented by this node. This includes the View
	itself and a count of its children. For example, this value is 4 for a View that has 3
	children.
	</li>
	<li>
	Render times: The actual measure, layout, and draw times for the View rendering, in
	milliseconds. These represent the same values as the performance indicators mentioned in
	the preceding section.
	</li>
	</ul>
	<p>
	An annotated screenshot of an individual node in the Tree View window appears in figure 3.
	</p>
	<img id="Fig3" src="{@docRoot}images/developing/hv_treeview_screenshot.png" alt="" height="600"/>
	<p class="img-caption"><strong>Figure 3.</strong> An annotated node in Tree View</p>
	<h3 id="hvdebugging">Debugging with View Hierarchy</h3>
	<p>
	The View Hierarchy window helps you debug an application by providing a static display
	of the UI. The display starts with your application's opening screen. As you step through
	your application, the display remains unchanged until you redraw it by invalidating and
	then requesting layout for a View.
	</p>
	<p>
	To redraw a View in the display:
	</p>
	<ul>
	<li>
	Select a View in Tree View. As you move up towards the root of the tree (to the
	left in the Tree View), you see the highest-level View objects. Redrawing a high-level
	object usually forces the lower-level objects to redraw as well.
	</li>
	<li>
	Click <strong>Invalidate</strong> at the top of the window. This marks the View as
	invalid, and schedules it for a redraw at the next point that a layout is requested.
	</li>
	<li>
	Click <strong>Request Layout</strong> to request a layout. The View and its children
	are redrawn, as well as any other View objects that need to be redrawn.
	</li>
	</ul>
	<p>
	Manually redrawing a View allows you to watch the View object tree and examine the properties of
	individual View objects one step at a time as you go through breakpoints in your code.
	</p>
	<h3 id="hvoptimize">Optimizing with View Hierarchy</h3>
	<p>
	View Hierarchy also helps you identify slow render performance. You start by looking at the
	View nodes with red or yellow performance indicators to identify the slower View objects. As you
	step through your application, you can judge if a View is consistently slow or slow only in
	certain circumstances.
	</p>
	<p>
	Remember that slow performance is not necessarily evidence of a problem, especially for
	ViewGroup objects. View objects that have more children and more complex View objects render
	more slowly.
	</p>
	<p>
	The View Hierarchy window also helps you find performance issues. Just by looking at the
	performance indicators (the dots) for each View node, you can see which View objects are the
	slowest to measure, layout, and draw. From that, you can quickly identify the problems you
	should look at first.
	</p>
	<h2 id="pixelperfect">Using Pixel Perfect</h2>
	<p>
	Pixel Perfect is a tool for examining pixel properties and laying out UIs from a design drawing.
	</p>
	<h3 id="aboutpixelperfect">About the Pixel Perfect window</h3>
	<p>
	The Pixel Perfect window displays a magnified image of the screen that is currently
	visible on the emulator or device. In it, you can examine the properties
	of individual pixels in the screen image. You can also use the Pixel Perfect window
	to help you lay out your application UI based on a bitmap design.
	</p>
	<p>
	To see the Pixel Perfect window, run Hierarchy Viewer, as described in
	the section <a href="#runhv">Running Hierarchy Viewer and choosing a window</a>. Next, click
	<strong>Inspect Screenshot</strong> at the top of the device window. The Pixel Perfect window
	appears.
	</p>
	<p>
	In it, you see three panes:
	</p>
	<ul>
	<li>
	View Object pane: This is a hierarchical list of the View objects that are currently
	visible on the device or emulator screen, including both the ones in your application and
	the ones generated by the system. The objects are listed by their View class.
	To see the class names of a View object's children, expand the View by clicking the
	arrow to its left. When you click a View, its position is highlighted in the Pixel Perfect
	pane on the right.
	</li>
	<li>
	Pixel Perfect Loupe pane: This is the magnified screen image. It is overlaid by a grid in
	which each square represents one pixel. To look at the information for a pixel, click in its
	square. Its color and X,Y coordinates appear at the bottom of the pane.
	<p>
	The magenta crosshair in the pane corresponds to the positioning
	crosshair in the next pane. It only moves when you move the crosshair in the next pane.
	</p>
	<p>
	To zoom in or out on the image, use the <strong>Zoom</strong> slider at the bottom of
	the pane, or use your mouse's scroll wheel.
	</p>
	<p>
	When you select a pixel in the Loupe pane, you see the following information at the
	bottom of the pane:
	</p>
	<ul>
	<li>
	Pixel swatch: A rectangle filled with the same color as the pixel.
	</li>
	<li>
	HTML color code: The hexadecimal RGB code corresponding to the pixel color
	</li>
	<li>
	RGB color values: A list of the (R), green (G), and blue (B) color values of the
	pixel color. Each value is in the range 0-255.
	</li>
	<li>
	X and Y coordinates: The pixel's coordinates, in device-specific pixel units.
	The values are 0-based, with X=0 at the left of the screen and Y=0 at the top.
	</li>
	</ul>
	</li>
	<li>
	Pixel Perfect pane: This displays the currently visible screen as it would appear in the
	emulator.
	<p>
	You use the cyan crosshair to do coarse positioning. Drag the crosshair in the image,
	and the Loupe crosshair will move accordingly. You can also click on a point in the
	Pixel Perfect pane, and the crosshair will move to that point.
	</p>
	<p>
	The image corresponding to the View object selected in the View Object pane is
	outlined in a box that indicates the View object's position on the screen. For the
	selected object, the box is bold red. Sibling and parent View objects have a light
	red box. View objects that are neither parents nor siblings are in white.
	</p>
	<p>
	The layout box may have other rectangles either inside or outside it, each of which
	indicates part of the View. A purple or green rectangle indicates the View bounding box.
	A white or black box inside the layout box represents the <strong>padding</strong>, the
	defined distance between the View object's content and its bounding box. An outer white
	or black rectangle represents the <strong>margins</strong>, the distance between the
	View bounding box and adjacent View objects. The padding and margin boxes are white if
	the layout background is black, and vice versa.
	</p>
	<p>
	You can save the screen image being displayed in the Pixel Perfect pane as a PNG file.
	This produces a screenshot of the current screen. To do this, click
	<strong>Save as PNG</strong> at the top of the window. This displays a dialog,
	in which you can choose a directory and filename for the file.
	</p>
	</li>
	</ul>
	<p>
	The panes are not automatically refreshed when you change one of the View objects or go to
	another Activity. To refresh the Pixel Perfect pane and the Loupe pane, click
	<strong>Refresh Screenshot</strong> at the top of the window. This will change the panes
	to reflect the current screen image. You still may need to refresh the View Object pane;
	to do this, click <strong>Refresh Tree</strong> at the top of the window.
	</p>
	<p>
	To automatically refresh the panes while you are debugging, set
	<strong>Auto Refresh</strong> at the top of the window, and then set a refresh rate
	with the <strong>Refresh Rate</strong> slider at the bottom of the Loupe pane.
	</p>
	<h3 id="overlays">Working with Pixel Perfect overlays</h3>
	<p>
	You often construct a UI based on a design done as a bitmap image. The Pixel Perfect window
	helps you match up your View layout to a bitmap image by allowing you to load the bitmap as an
	<strong>overlay</strong> on the screen image.
	</p>
	<p>
	To use a bitmap image as an overlay:
	</p>
	<ul>
	<li>
	Start your application in a device or emulator and navigate to the Activity whose UI you
	want to work with.
	</li>
	<li>
	Start Hierarchy Viewer and navigate to the Pixel Perfect window.
	</li>
	<li>
	At the top of the window, click <strong>Load Overlay</strong>. A dialog opens, prompting
	for the image file to load. Load the image file.
	</li>
	<li>
	Pixel Perfect displays the overlay over the screen image in the Pixel Perfect pane. The
	lower left corner of the bitmap image (X=0, Y=<em>max value</em>) is anchored on the lower
	leftmost pixel (X=0, Y=<em>max screen</em>) of the screen.
	<p>
	By default, the overlay has a 50% transparency, which allows you to see the screen
	image underneath. You can adjust this with the <strong>Overlay:</strong> slider at the
	bottom of the Loupe pane.
	</p>
	<p>
	Also by default, the overlay is not displayed in the Loupe pane. To display it,
	set <strong>Show in Loupe</strong> at the top of the window.
	</p>
	</li>
	</ul>
	<p>
	The overlay is not saved as part of the screenshot when you save the screen image as a PNG
	file.
	</p>
	<p>
	A screenshot of the Pixel Perfect window appears in figure 4.
	</p>
	<img id="Fig4" src="{@docRoot}images/developing/hv_pixelperfect.png"
	alt=""
	height="600"/>
	<p class="img-caption"><strong>Figure 4.</strong> The Pixel Perfect window</p>
	<h2 id="lint">Using lint to Optimize Your UI</h2>
	<p>The Android {@code lint} tool lets you analyze the XML files that define your application's UI to find inefficiencies in the view hierarchy.</p>
	<p class="note"><strong>Note: </strong>The Android <code>layoutopt</code> tool has been replaced by the {@code lint} tool beginning in ADT and SDK Tools revision 16. The {@code lint} tool reports UI layout performance issues in a similar way as <code>layoutopt</code>, and detects additional problems.</p>
	<p>For more information about using {@code lint}, see <a href="{@docRoot}tools/debugging/improving-w-lint.html">Improving Your Code with lint</a> and the <a href="{@docRoot}tools/help/lint.html">lint reference documentation</a>.</p>