Working with Multiple Android Screens

Working with Multiple Screens
Make Your Android UI Rock Everywhere

Suzanne Alexandra
Android Developer Advocate, Motorola
@suzalex
http://moto.ly/samples
© 2010 Motorola Mobility, Inc. All rights reserved except as otherwise explicitly indicated.

Why does it matter?

Make users happy Extend your reach

Size really mattersPause
&
Watch DialingWandhttp://moto.ly/dialingwand

Key Point #1Choose your target devices

Android 1.5? QVGA? Global?
As of November 2010, developer.android.com

FLIPOUT
DROID PRO
DROID X

Comparing resolution
DROID X480 x 854
Normal
DROID PRO320 x 480
Normal
FLIPOUT320 x 240
Small

Comparing resolution
DROID XHigh240 dpi
DROID PROMedium160 dpi
FLIPOUTLow120 dpi

Key Point #2Start with a fewsimple guidelines.

Pause the slides
&
watch the PhotoDemo video on YouTube

Adjust your AndroidManifestfor versions and screen sizes.

<uses-sdk android:minSdkVersion= "7"
android:targetSdkVersion= "8" />

<supports-screens
android:largeScreens= "true"
android:normalScreens="true"
android:smallScreens="true"
android:anyDensity="true" />

But be careful
Make sure minSdkVersion has the API features you need
Test thoroughly on your targetSdkVersion
Make sure you don't get size compatibility mode

Use liquid, adaptable layouts.
Try FrameLayout and RelativeLayout.

BonusScreen orientation and performance

Use adaptable measurements,like dip and sp.

Low
1 dip = 0.75 pixels
High
1 dip = 1.5 pixels
Medium
1 dip = 1 pixel
What’s a DIP?
A pixel that changes size

Pause the slides
&
Watch the RelativeLayout video on YouTube

Use one set of images andlet Android scale them, for now.
But we’ll look at this more later.

Key Point #3
Add custom resources as needed, but watch performance.

Add custom layouts, if you need them.But you might not.

Choose an image strategy
One set of images and let Android autoscale?
Custom resource sets for low, medium, and high density?
Target the most commonly used density?
Retrieve images dynamically at runtime and handle?

150% for high
100% for normal
75% for low

Memory vs file size
PhotoOne 32 MBmemory
324 KB size
PhotoThree 23 MBmemory
728 KB size

In other words
Autoscaling uses memory.Custom image sets increase file size.

What happens if you load a really big image
into a small view?

You might get
No image
Or a memory error

Your application UI can behave differently across devicesor in different conditionsdue to memory

Pause the slides
&
Watch the handling images video on YouTube

private Bitmap loadBitmap() {
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
int screenDensity = metrics.densityDpi;
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = false;
options.inSampleSize = 4;
options.inScaled = true;
options.inTargetDensity = screenDensity;
Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
R.drawable.clover, options);
return bitmap;
}

If you need to detect density at runtimeandroid.util.DisplayMetricsis cool

Pause the slides
&Watch the detecting device density video on YouTube

240 and 1.5
120 and 0.75
160 and 1.0

public void checkDensity() {
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
String logical_density = Float.toString(metrics.density);
Log.e (TAG, "Logical density is " + logical_density);
// for API level 4 (Android 1.6) and forward
String screen_density = Integer.toString(metrics.densityDpi);
Log.e (TAG, "Screen density is " + screen_density);
}

Key Point #4
Touch and gesture are key.
Make sure they’re density independent too.

Pause the slides
&Watch the buttons video on YouTube

16 pixels
3.3 mm
1.7 mm
2.5 mm

private static final float DISTANCE_DIP = 16.0f;
private static final float PATH_DIP = 40.0f;
// convert dip measurements to pixels
final float scale = getResources().getDisplayMetrics().density;
scaledDistance = (int) ( DISTANCE_DIP * scale + 0.5f );
scaledPath = (int) ( PATH_DIP * scale + 0.5f );

Okay ..
Remember the key points?

Once again …
Choose your target devices.
Start with a few simple guidelines.
Add custom resources as needed, but watch performance.
Make sure touch and gesture are density independent too.

Thank youGraciasObrigada谢谢
@suzalex@motodev
http://moto.ly/samples

LICENSE AND TRADEMARK NOTICES
Except where noted, sample source code written by Motorola Mobility Inc. and provided to you is licensed as described below.
Copyright © 2010, Motorola, Inc. All rights reserved except as otherwise explicitly indicated.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
Neither the name of the Motorola, Inc. nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Other source code displayed in this presentation may be licensed under Apache License, Version 2 
Copyright © 2010, Android Open Source Project. All rights reserved unless otherwise explicitly indicated. 
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0.
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
DROID is a trademark of Lucasfilm Ltd. and its related companies. Used under license.

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Working with Multiple Android Screens

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Working with Multiple Android Screens Webinar Transcript