Exercise: style

A style is a set of one or more formatting attributes that you can apply as a unit to single elements in your layout XML file(s). For example, you could define a style that specifies a certain text size and color, then apply it to instances of a certain type of View element.

details>>

Create a dummy Android Application, AndroidStyle. Create style.xml in the folder res > values

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <style name="StyleText1">
     <item name="android:textSize">20sp</item>
     <item name="android:textColor">#EC9200</item>
     <item name="android:gravity">center_horizontal</item>
 
 </style>
 <style name="StyleText2">
     <item name="android:textSize">30sp</item>
     <item name="android:textColor">#990000</item>
     <item name="android:gravity">right</item>
 </style>
 <style name="StyleButton1">
     <item name="android:layout_width">wrap_content</item>
     <item name="android:layout_height">wrap_content</item>
 </style>
 <style name="StyleButton2">
     <item name="android:layout_width">fill_parent</item>
     <item name="android:layout_height">fill_parent</item>
 </style>    
</resources>

Modify main.xml to apply the styles.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 >
<TextView
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:text="@string/hello"
 />
<TextView
 style="@style/StyleText1"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:text="It's StyleText1"
 />
<TextView
 style="@style/StyleText2"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:text="It's StyleText2"
 />
<Button
 style="@style/StyleButton1"
 android:text="It's StyleButton1"
 />
<Button
 style="@style/StyleButton2"
 android:text="It's StyleButton2"
 /> 
</LinearLayout>

Exercise: Get screen resolution using android.util.DisplayMetrics

android.util.DisplayMetrics is a structure describing general information about a display, such as its size, density, and font scaling.

To use android.util.DisplayMetrics to get resolution:

Create a dummy Android Application, add a TextView in main.xml to display the result.

<TextView
android:id="@+id/strScreenSize"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text=""
/>

Modify the .java file to read DisplayMetrics

package com.exercise.AndroidScreen;

import android.app.Activity;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.widget.TextView;

public class AndroidScreenActivity extends Activity {
 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.main);
 
        DisplayMetrics dm = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dm);
        String str_ScreenSize = "The Android Screen is: "
                    + dm.widthPixels
                    + " x "
                    + dm.heightPixels;

        TextView mScreenSize = (TextView) findViewById(R.id.strScreenSize);
        mScreenSize.setText(str_ScreenSize);
 }
}

Related Post:
- Get screen size in DPI

Exercise: Apply Theme in AndroidManifest.xml

Android provide some predefine themes in the base package, you can change the theme by adding a code in the file AndroidManifest.xml.

Inside Application tag to take effect on whole Application.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
 package="com.exercise.AndroidTheme"
 android:versionCode="1"
 android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name"
 android:theme="@android:style/Theme.Black"
 >
   <activity android:name=".AndroidThemeActivity"
             android:label="@string/app_name">
       <intent-filter>
           <action android:name="android.intent.action.MAIN" />
           <category android:name="android.intent.category.LAUNCHER" />
       </intent-filter>
   </activity>
</application>
<uses-sdk android:minSdkVersion="2" />
</manifest>

Or,
Inside Activity tag to take effect on individual Activity.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="com.exercise.AndroidTheme"
  android:versionCode="1"
  android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name"
 >
    <activity android:name=".AndroidThemeActivity"
              android:label="@string/app_name"
              android:theme="@android:style/Theme.Light"
              >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>
<uses-sdk android:minSdkVersion="2" />
</manifest>

@android:style/Theme.Black



@android:style/Theme.Light



@android:style/Theme.Translucent

Hitler Not Pleased with FriendFeed Acquisition

Check out this post on TechCrunch. Someone took an old Hitler movie and redid the subtitles to comment on the Facebook acquisition of FriendFeed. Too funny!

An early alpha release of e4, the next generation of the Eclipse platform, is now available.

An early alpha release of e4, the next generation of the Eclipse platform, is now available.

The mission of the e4 project is to build a next generation platform for pervasive, component-based applications and tools. See the about page as well as the original project proposal for more details.

I tried to install, with ADT and Android SDK. And also tried Hello Android. It seem to be compatible. The install procedure is same as Install Android SDK on Eclipse 3.5 Galileo.

Simple steps to change the drawable icon with Transparency background using GIMP

In the Exercise: Add a icon on Dialog, the background of android icon is in white. It can be removed to be transparency using GIMP.

Open the android.png in GIMP.

Select Fuzzy Select Tool.

Click on the background of the icon.

Click Select > Invert to select the foreground image.

Click Edit > Copy to copy the select image to clipboard.

Close the original file.

Click File > New to create a new image

Expend the Advanced Options in the Create a New Image dialog.
Select Transparency in the Fill with option, and click OK.

Click Edit > Paste to paste the copied image as the foreground.

Run the Android Application again, the background have been changed to transparency now.

Exercise: Add a icon on Dialog

Extends from the previous exercise, Exercise: Menu and Dialog. A icon will be added on the About me Dialog, as shown:



Save the icon, , in the folder res/drawable.

Add one line in the openOptionsDialog() class:

private void openOptionsDialog()
{
new AlertDialog.Builder(this)
.setTitle(R.string.app_about)
.setIcon(R.drawable.android)
.setMessage(R.string.app_about_message)
.setPositiveButton(R.string.str_ok,
new DialogInterface.OnClickListener()
{
public void onClick(DialogInterface dialoginterface, int i)
{
}
})
.show();
}

Next: Simple steps to change the drawable icon with Transparency background using GIMP