Develop Reference

In root LinearLayout android:gravity="center" shows padding

when I remove gravity attribute then the image will set on top corner right but when it used it leave padding at the top why gravity leaves space ????
enter image description here

android:gravity="center" ---> center_horizontal+center_vertical
The center_vertical attribute leaves the padding at the top. Changing it to center_horizontal will make the view/views just align center horizontally so use
android:gravity="center_horizontal"

I think why should you use layout_marginTop in imageview?it's not necessory to set.you can set layout_gravity at imageview and remove gravity at top linear layout.
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/black">
<ImageView
android:layout_width="wrap_content"
android:layout_height="200dp"
android:src="#drawable/android_ic"
android:layout_gravity="center"
/>
</LinearLayout>

When you have added android:gravity="center" your entire layout will be at center of the screen.Since you have added multiple views below the imageView, it has been managed to be at the top with some space.Change it to android:gravity="center_horizontal" and also if the image is small set the height as "wrap_content" instead of 200dp ,it may also have additional space.
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_horizontal"
>
<ImageView
android:layout_width="wrap_content"
android:layout_height="200dp"
android:src="#drawable/coffee"
/></LinearLayout>

how to make imageView take match parent of relativelayout

i'm trying to make ImageView take match_parent of RelativeLayout
like this picture :
when i run my app ImageView looks like that :
this my xml :
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/linealL"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/khdar">
<RelativeLayout
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:layout_margin="10dp"
android:id="#+id/RelativeLayout02"
android:layout_width="wrap_content"
android:background="#color/colorGriviewBorder"
android:layout_height="wrap_content" >
<LinearLayout
android:layout_margin="5dp"
android:id="#+id/LinearLayout01"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#drawable/gradient"
android:orientation="vertical" >
<TextView
android:text="GIF"
android:textSize="16sp"
android:layout_gravity="center"
android:textColor="#color/colorGriviewBorder"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/dev"/>
</LinearLayout>
<ImageView
android:padding="8dp"
android:layout_below="#+id/LinearLayout01"
android:contentDescription="#string/app_name"
android:id="#+id/imageSelectTo"
android:scaleType="fitXY"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:layout_height="wrap_content"
android:layout_width="wrap_content"/>
</RelativeLayout>
</RelativeLayout>

Change layout_width of ImageView to match_parent and add one new attribute to it: android:adjustViewBounds="true".

If you want to fit the ImageView width then You have to ignore height. And by default will not strech for you to keep aspect ratio, so you need to add another attributes for adjust view bounds. So lastly you will have your code chages as follows for an ImageView:
android:layout_width="match_parent"
android:adjustViewBounds="true"
The adjust View bounds will adjust to a particular height while keeping the aspect ratio.
More
Also to avoid future mistakes again in your code you have nested two RelativeLayout's which I guess is due backgrounds. If there is no need for that If do not care about space. The inner RelativeLayout View height and width should be set to match_parent!. Happy Coding!

Your ImageView's layout_width and layout_height are set to wrap_content instead of match_parent.

Aligning View with ImageView that has adjustViewBounds="true" does not work

Did anybody encounter the situation when you have an ImageView with adjustViewBounds="true" and you need to align another view with it? My layout is working unpredictably:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<ImageView
android:id="#+id/thumb"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:scaleType="centerInside"
android:src="#drawable/thumbnail"
android:layout_centerInParent="true"
android:adjustViewBounds="true"/>
<LinearLayout
android:id="#+id/selection"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_alignTop="#id/thumb"
android:layout_alignBottom="#id/thumb">
</LinearLayout>
</RelativeLayout>
It would be great to not code that aligning.

I changed RelativeLayout width and height to match_parent, and work for me. By the way what is the point to align center the ImageView if it limited its size? It don't understand. What's the aim? Can you post a wireframe?

ImageView increases and decreases dynamically after the size of a textfield

I have a layout like this one:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/tabBar"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#272727"
android:orientation="horizontal" >
<ImageButton
android:id="#+id/BtnSlide"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:background="#null"
android:src="#drawable/lin" />
<TextView
android:id="#+id/textView1"
android:layout_width="275dp"
android:layout_height="50dp"
android:gravity="center"
android:paddingLeft="20dp"
android:paddingRight="100dp"
android:text="HEADER"
android:textAppearance="?android:attr/textAppearanceMedium" />
<ImageView
android:id="#+id/imageView1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingTop="2.2dp"
android:src="#drawable/logo" />
The ImageView is placed to the right of the screen. But I'm facing an issue, the ImageView increases and decreases in height and width depending on the length of the TextView, how can I make this work properly, without the ImageView changing size?

The problem here is that your ImageView matches the size of your parent, that is your LinearLayout (with id tabBar).
That LinearLayout wraps the content on his height, so, it sums all "heights" of his contents. The LinearLayout will take the height of TextView + the height of the ImageButton. Then, the ImageView will match that height.
A solution depends on what you are trying to do, but you can try to:
Set a predefined height in your ImageView
Use a RelativeLayout instead of a LinearLayout and align all your views depending on each other

My suggestion is to set layout_weight to all the components so that their size is fixed regardless of their contents:) See here for more details

centerHorizontal does not centre the image correctly

Here is the XML:
<?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"
android:background="#drawable/bg"
>
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="4"
android:orientation="vertical"
>
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center_horizontal" //CENTER 01
>
<!--center button-->
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/img"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true" //CENTER 02
/>
//...
</RelativeLayout>
</LinearLayout>
<include android:id="#+id/banner" layout="#layout/banner"
android:layout_weight="1"
android:layout_gravity="bottom"/>
</LinearLayout>
The center button is centered, but not in the real center of the screen, but rather approx 50px to the right of the center. If I remove centerHorizontal CENTER01, then this does not happen.
Does anyone know why is this happening?

Please try for //CENTER 02:
android:layout_centerInParent="true"

This issue may be due to using of both Relative Layout and Linear Layout inside a xml file.
Change all Linear Layout to Relative Layouts so that Image View will be centered as you expected.
I too mingled both Linear Layout and Relative Layout in single XML and faces this kind of issue. Once i replaces all Linear Layout to Relative Layout my problem Resolved.
Try it.Thanks.Venky

Its because in Relative Layout center_horizontal isn't the command. that works for views wrapped in linear Layout. for RelativeLayout you need to use
android:layout_centerInParent="true";
as the center gravity command in linear
or
android:layout_centerHorizontal="true"
as the gravity center_horizontal in linear.

When you set android:gravity="center_horizontal" on a parent, it influences the behaviour of its children. Hence, your ImageView gets effected, creating the effect you see after already being placed in the center by other properties.
You can see this effect for yourself by placing a TextView in there with android:layout_width="fill_parent".