Question

I am using linear layout to get the message with image from .net server.

when the new message is come the position of the layout is increased and the new message is added to the top of the layout one by one.

the problem is when the new message will come,the new message is added to layout suddenly.

I want to apply animation to the layout and make my app like when the new message is come the message is added to the layout slowly. means the previous messages move down slowly and new message is added top of the layout.

Answer 1

Use android:animateLayoutChanges on the LinearLayout that shall hold the data. This will trigger an animation when adding new content. It starts by moving the old data down making room for more content. Then follows a second step where the new data will fade into the free space.

Example code

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/baseLL"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
>

    <!-- button used to add data -->
    <Button
        android:layout_width="192dip"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:text="Add Content"
        android:onClick="onAddContentClick" />

    <!-- button used to remove data -->
    <Button
        android:layout_width="192dip"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:text="Remove Content"
        android:onClick="onRemoveContentClick" />

    <!-- data will be added to this LinearLayout at run time -->
    <LinearLayout
        android:id="@+id/dataLL"
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:animateLayoutChanges="true"
    >

    </LinearLayout>

</LinearLayout>

basicanimation.java

package com.test.animation.basic;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.LinearLayout.LayoutParams;
import android.widget.TextView;

public class BasicAnimationActivity extends Activity {

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }

    public void onAddContentClick(View v) {
        LinearLayout dataLL = (LinearLayout) findViewById(R.id.dataLL);
        int dataCount = dataLL.getChildCount();
        TextView newDataTV = generateData(dataCount);
        dataLL.addView(newDataTV, 0);
    }

    public void onRemoveContentClick(View v) {
        LinearLayout dataLL = (LinearLayout) findViewById(R.id.dataLL);
        if (dataLL.getChildCount() > 0) {
            dataLL.removeViewAt(0);
        }
    }

    private TextView generateData(int dataCount) {
        TextView TV = new TextView(this);
        TV.setText("Data " + dataCount);
        TV.setLayoutParams(new LayoutParams(android.view.ViewGroup.LayoutParams.FILL_PARENT,
                android.view.ViewGroup.LayoutParams.WRAP_CONTENT));
        return TV;
    }
}