Developing an Android Homescreen

How can I create a custom home-screen replacement application for Android?

Writing your own home screen application is possible. It is called the Launcher.

You can get the source code of the default Android Launcher via Git.

The project URL is:

https://android.googlesource.com/platform/packages/apps/Launcher2.git

You can get the source code like this:

git clone https://android.googlesource.com/platform/packages/apps/Launcher2.git

That will create a directory called Launcher2 for you. Now you can get cracking and create your custom launcher.

_{If you need help with using Git then checkout Git's documentation section.}

Developing an Android Homescreen

EDIT (July 3rd, 2012):

Since there seem to be still quite a few views and comments about this answer, I thought I should add a note, that with the newer SDK, you should now use ViewPager instead to have the same functionality. That class is also included in the Android Support library so you can also use it to run on earlier Android devices.

EDIT (March 4th, 2013):

Since there are still people coming here, just wanted to also say I put together a ViewPager with the background moving at slower speed to give a parallax effect. The code is here.

If you really want to do it all manually, the original answer is here below...

I think you can find what you are looking for here : http://www.anddev.org/why_do_not_these_codes_work-t4012.html

I used that in a different project to also create a home screen with different views. This is straight from the Android Launcher, it works quite well after following that thread.

Here is my code... first the source code

package com.matthieu.launcher;

import android.content.Context;
import android.util.Log;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewConfiguration;
import android.widget.Scroller;

public class DragableSpace extends ViewGroup {
    private Scroller mScroller;
    private VelocityTracker mVelocityTracker;

    private int mScrollX = 0;
    private int mCurrentScreen = 0;

    private float mLastMotionX;

    private static final String LOG_TAG = "DragableSpace";

    private static final int SNAP_VELOCITY = 1000;

    private final static int TOUCH_STATE_REST = 0;
    private final static int TOUCH_STATE_SCROLLING = 1;

    private int mTouchState = TOUCH_STATE_REST;

    private int mTouchSlop = 0;

    public DragableSpace(Context context) {
        super(context);
        mScroller = new Scroller(context);

        mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();

        this.setLayoutParams(new ViewGroup.LayoutParams(
                    ViewGroup.LayoutParams.WRAP_CONTENT,
                    ViewGroup.LayoutParams.FILL_PARENT));
    }

    public DragableSpace(Context context, AttributeSet attrs) {
        super(context, attrs);
        mScroller = new Scroller(context);

        mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();

        this.setLayoutParams(new ViewGroup.LayoutParams(
                    ViewGroup.LayoutParams.WRAP_CONTENT ,
                    ViewGroup.LayoutParams.FILL_PARENT));

        TypedArray a=getContext().obtainStyledAttributes(attrs,R.styleable.DragableSpace);
        mCurrentScreen = a.getInteger(R.styleable.DragableSpace_default_screen, 0);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        /*
         * This method JUST determines whether we want to intercept the motion.
         * If we return true, onTouchEvent will be called and we do the actual
         * scrolling there.
         */

        /*
         * Shortcut the most recurring case: the user is in the dragging state
         * and he is moving his finger. We want to intercept this motion.
         */
        final int action = ev.getAction();
        if ((action == MotionEvent.ACTION_MOVE)
                && (mTouchState != TOUCH_STATE_REST)) {
            return true;
                }

        final float x = ev.getX();

        switch (action) {
            case MotionEvent.ACTION_MOVE:
                /*
                 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check
                 * whether the user has moved far enough from his original down touch.
                 */

                /*
                 * Locally do absolute value. mLastMotionX is set to the y value
                 * of the down event.
                 */
                final int xDiff = (int) Math.abs(x - mLastMotionX);

                boolean xMoved = xDiff > mTouchSlop;

                if (xMoved) {
                    // Scroll if the user moved far enough along the X axis
                    mTouchState = TOUCH_STATE_SCROLLING;
                }
                break;

            case MotionEvent.ACTION_DOWN:
                // Remember location of down touch
                mLastMotionX = x;

                /*
                 * If being flinged and user touches the screen, initiate drag;
                 * otherwise don't.  mScroller.isFinished should be false when
                 * being flinged.
                 */
                mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING;
                break;

            case MotionEvent.ACTION_CANCEL:
            case MotionEvent.ACTION_UP:
                // Release the drag
                mTouchState = TOUCH_STATE_REST;
                break;
        }

        /*
         * The only time we want to intercept motion events is if we are in the
         * drag mode.
         */
        return mTouchState != TOUCH_STATE_REST;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {

        if (mVelocityTracker == null) {
            mVelocityTracker = VelocityTracker.obtain();
        }
        mVelocityTracker.addMovement(event);

        final int action = event.getAction();
        final float x = event.getX();

        switch (action) {
            case MotionEvent.ACTION_DOWN:
                Log.i(LOG_TAG, "event : down");
                /*
                 * If being flinged and user touches, stop the fling. isFinished
                 * will be false if being flinged.
                 */
                if (!mScroller.isFinished()) {
                    mScroller.abortAnimation();
                }

                // Remember where the motion event started
                mLastMotionX = x;
                break;
            case MotionEvent.ACTION_MOVE:
                // Log.i(LOG_TAG,"event : move");
                // if (mTouchState == TOUCH_STATE_SCROLLING) {
                // Scroll to follow the motion event
                final int deltaX = (int) (mLastMotionX - x);
                mLastMotionX = x;

                //Log.i(LOG_TAG, "event : move, deltaX " + deltaX + ", mScrollX " + mScrollX);

                if (deltaX < 0) {
                    if (mScrollX > 0) {
                        scrollBy(Math.max(-mScrollX, deltaX), 0);
                    }
                } else if (deltaX > 0) {
                    final int availableToScroll = getChildAt(getChildCount() - 1)
                        .getRight()
                        - mScrollX - getWidth();
                    if (availableToScroll > 0) {
                        scrollBy(Math.min(availableToScroll, deltaX), 0);
                    }
                }
                // }
                break;
            case MotionEvent.ACTION_UP:
                Log.i(LOG_TAG, "event : up");
                // if (mTouchState == TOUCH_STATE_SCROLLING) {
                final VelocityTracker velocityTracker = mVelocityTracker;
                velocityTracker.computeCurrentVelocity(1000);
                int velocityX = (int) velocityTracker.getXVelocity();

                if (velocityX > SNAP_VELOCITY && mCurrentScreen > 0) {
                    // Fling hard enough to move left
                    snapToScreen(mCurrentScreen - 1);
                } else if (velocityX < -SNAP_VELOCITY
                        && mCurrentScreen < getChildCount() - 1) {
                    // Fling hard enough to move right
                    snapToScreen(mCurrentScreen + 1);
                } else {
                    snapToDestination();
                }

                if (mVelocityTracker != null) {
                    mVelocityTracker.recycle();
                    mVelocityTracker = null;
                }
                // }
                mTouchState = TOUCH_STATE_REST;
                break;
            case MotionEvent.ACTION_CANCEL:
                Log.i(LOG_TAG, "event : cancel");
                mTouchState = TOUCH_STATE_REST;
        }
        mScrollX = this.getScrollX();

        return true;
    }

    private void snapToDestination() {
        final int screenWidth = getWidth();
        final int whichScreen = (mScrollX + (screenWidth / 2)) / screenWidth;
        Log.i(LOG_TAG, "from des");
        snapToScreen(whichScreen);
    }

    public void snapToScreen(int whichScreen) {         
        Log.i(LOG_TAG, "snap To Screen " + whichScreen);
        mCurrentScreen = whichScreen;
        final int newX = whichScreen * getWidth();
        final int delta = newX - mScrollX;
        mScroller.startScroll(mScrollX, 0, delta, 0, Math.abs(delta) * 2);             
        invalidate();
    }

    public void setToScreen(int whichScreen) {
        Log.i(LOG_TAG, "set To Screen " + whichScreen);
        mCurrentScreen = whichScreen;
        final int newX = whichScreen * getWidth();
        mScroller.startScroll(newX, 0, 0, 0, 10);             
        invalidate();
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int childLeft = 0;

        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            if (child.getVisibility() != View.GONE) {
                final int childWidth = child.getMeasuredWidth();
                child.layout(childLeft, 0, childLeft + childWidth, child
                        .getMeasuredHeight());
                childLeft += childWidth;
            }
        }

    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        final int width = MeasureSpec.getSize(widthMeasureSpec);
        final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        if (widthMode != MeasureSpec.EXACTLY) {
            throw new IllegalStateException("error mode.");
        }

        final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        if (heightMode != MeasureSpec.EXACTLY) {
            throw new IllegalStateException("error mode.");
        }

        // The children are given the same width and height as the workspace
        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
        }
        Log.i(LOG_TAG, "moving to screen "+mCurrentScreen);
        scrollTo(mCurrentScreen * width, 0);      
    }  

    @Override
    public void computeScroll() {
        if (mScroller.computeScrollOffset()) {
            mScrollX = mScroller.getCurrX();
            scrollTo(mScrollX, 0);
            postInvalidate();
        }
    }
}

And the layout file :

<?xml version="1.0" encoding="utf-8"?>
<com.matthieu.launcher.DragableSpace xmlns:app="http://schemas.android.com/apk/res/com.matthieu.launcher"
    xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/space"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
app:default_screen="1"
>
<include android:id="@+id/left"  layout="@layout/left_screen" />
<include android:id="@+id/center"  layout="@layout/initial_screen" />
<include android:id="@+id/right"  layout="@layout/right_screen" />
</com.matthieu.launcher.DragableSpace>

To be able to have the extra attribute in the xml file, you want to save this in res/values/attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="DragableSpace">
        <attr name="default_screen" format="integer"/>
    </declare-styleable>
</resources>

creating android app shortcut on the home screen

Do like This:

Step 1:

Update your manifest.xml :

  <uses-permission
    android:name="com.android.launcher.permission.INSTALL_SHORTCUT" />

Step 2:

in your MainActivity.java create addShortcut() method and in it`s block put this code :

private void addShourcut(){
  Intent shortCutIntent = new Intent(getApplicationContext() ,MainActivity.class);

  shortCutIntent.setAction(Intent.ACTION_MAIN);

  Intent addIntent = new Intent();

  addIntent.putExtra(Intent.EXTRA_SHORTCUT_INTENT , shortCutIntent);
  addIntent.putExtra(Intent.EXTRA_SHORTCUT_NAME , "Convertor");
  addIntent.putExtra(Intent.EXTRA_SHORTCUT_ICON_RESOURCE ,
    Intent.ShortcutIconResource.fromContext(getApplicationContext() , R.mipmap.ic_launcher));
  addIntent.setAction("com.android.launcher.action.INSTALL_SHORTCUT");
  addIntent.putExtra("duplicate" , false);
  getApplicationContext().sendBroadcast(addIntent);

}

Step3:

set onClickListener for your view that be create shortcut :

img_pin = (ImageView) findViewById(R.id.img_pin);
img_pin.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {

    addShourcut();
    Toast.makeText(MainActivity.this, "shortcut created !", Toast.LENGTH_SHORT).show();

  }
});

This is worked for me ...
happy codinngggg...:)

Developing Material Design homescreen-widgets in Android

you might want to have a look at the source of the google i/o app : https://github.com/google/iosched/blob/master/android/src/main/res/layout/widget.xml

Modify android home screen

Yes, you can definitely create a home screen replacement. To do that, your app must have an activity with android.intent.category.HOME in its filters (in AndroidManifest.xml). That's how the system knows which application will display the home screen... For more info:

http://developer.android.com/guide/topics/intents/intents-filters.html

(Search for android.intent.category.HOME to go straight to the point)

Android - creating custom launcher

Well, firstly you need to listen to the android.intent.category.HOME intent. Here are some links with full source code which you can have a look at:

• Old launcher source code
• New launcher source code

Or take a look at launcher plus.

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