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+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->
+<!-- This component and the accompanying materials are made available under the terms of the License 
+"Eclipse Public License v1.0" which accompanies this distribution, 
+and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->
+<!-- Initial Contributors:
+    Nokia Corporation - initial contribution.
+Contributors: 
+-->
+<!DOCTYPE concept
+  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
+<concept id="GUID-056165A7-E8A1-4868-8051-9EC58C5A3342" xml:lang="en"><title>Usability
+considerations</title><prolog><metadata><keywords/></metadata></prolog><conbody>
+<section id="GUID-E4B60228-49E7-415D-AFF1-9E9B622D2197"> <p>All touch and
+gestural interfaces have to appear competent and safe. The interface needs
+to look as though it is not going to misuse users' personal data or break
+down. Optimizing system performance is critical here. Low screen refresh rate
+and latent images do not give the impression of a trustworthy touch UI. The
+use of touch screen and sensors may also increase battery consumption of mobile
+devices.</p><note><p>Touch screens consume most power during touch operations,
+and reducing unnecessary user interaction can help increase power efficiency.
+Specifically with resistive touch screens, avoiding excessively long touch
+and drag user actions is recommended. The continuous touch event flow keeps
+the CPU busy. The screen lock turns off the touch completely. To learn more
+about both optimizing system performance and battery life in Symbian applications,
+see the <xref href="http://www.forum.nokia.com/main/resources/user_experience/power_management/" scope="external">Power Management</xref> section at Forum Nokia.</p></note><p>The
+best products predict the needs of their users and then fulfill those needs
+in unexpectedly pleasing ways. Adaptive targets are one way to do this.  Controls
+that match the users actions well are another way devices can be clever.</p> <p><b>Interaction
+design</b></p><p>Use appropriate and simple interaction logic:</p><ul>
+<li><p>Navigation and controls should be clear and meaningful to prevent mistakes:
+strokes along the touch panel should produce a logical outcome. </p></li>
+<li><p>The coolest interaction in the world is empty unless it has clear meaning
+for the person performing it. When using indirect controls, the UI response
+should relate to the action the user is performing. </p></li>
+<li><p>Meaningful controls are easier to learn and remember. </p></li>
+</ul> <p>Touch UI can employ direct or indirect controls, or a combination
+of both:</p><ul>
+<li><p>Direct controls allow users to simply tap the item they want to manipulate
+right on the screen itself, move it, make it bigger, scroll it, and so on.
+For more information, see <xref href="GUID-CCE6DC36-625C-487C-9AD8-F1BF8E36080A.dita">UI
+components</xref> and <xref href="GUID-BB8B3A11-0BBC-4759-A7F4-A28C9E70573F.dita">Touch
+support for common UI components</xref>. </p></li>
+<li><p>Indirect controls use some other means to manipulate an object, for
+example, shaking, tilting, flipping, waving and so on. For more information,
+see <xref href="GUID-AE979B97-5610-42F3-99A7-5A3D66D3C2E6.dita">Sensor interaction</xref>.</p></li>
+<li><p>While the Symbian style provides for the use of scroll bars, it is
+common to reverse the page scrolling orientation in applications such as browser.
+In absence of scroll bars, users will flick or drag the page upwards rather
+than pull a scroller down to move the page up, that is, to scroll down. In
+this case, scroll bars are used as navigation indicators.</p></li>
+</ul><fig id="GUID-604A80CE-CB23-45A9-BC29-A01395CD6A2F">
+<image href="GUID-EE5937B6-9103-4711-B13B-06A62D56AF79_d0e47077_href.png" scale="60" placement="inline"/>
+</fig><p>Direct taps and strokes are far easier for the user to understand
+and pick up than abstract, indirect ones. A single view should always employ
+only a few indirect strokes, so that the controls do not confuse the user. </p><p><b>Visual
+design</b></p><p>On touch screens, it is important to make a clear distinction
+between touchable areas, and non-touchable areas, such as text. </p><ul>
+<li><p>Borders, glow effects, or other indicators can be used to highlight
+the interaction. </p></li>
+<li><p>Note that theme design alone is not sufficient for indicating touch
+functionality: where one theme may indicate touch, another may not.</p></li>
+</ul><p>See also:</p><ul>
+<li><p><xref href="GUID-5486EFD3-4660-4C19-A007-286DE48F6EEF.dita">Scale and positioning
+of controls</xref></p></li>
+<li><p><xref href="GUID-3CA039D8-A74D-4C9E-B4F5-6E153C7F65A1.dita">Finger vs. stylus</xref></p></li>
+<li><p><xref href="GUID-7BFEEDF7-3DB8-42FF-9D7A-F98E536F7686.dita">Sensor interaction</xref></p></li>
+</ul> </section>
+</conbody></concept>
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