Develop Reference

Custom Square Layout not working as expected

I stumbled across this problem when working with custom Square Layout : by extending the Layout and overriding its onMeasure() method to make the dimensions = smaller of the two (height or width).
Following is the custom Layout code :
public class CustomSquareLayout extends RelativeLayout{
public CustomSquareLayout(Context context) {
super(context);
}
public CustomSquareLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
public CustomSquareLayout(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
#RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
public CustomSquareLayout(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
//Width is smaller
if(widthMeasureSpec < heightMeasureSpec)
super.onMeasure(widthMeasureSpec, widthMeasureSpec);
//Height is smaller
else
super.onMeasure(heightMeasureSpec, heightMeasureSpec);
}
}
The custom Square Layout works fine, until in cases where the custom layout goes out of bound of the screen. What should have automatically adjusted to screen dimensions though, doesn't happen. As seen below, the CustomSquareLayout actually extends below the screen (invisible). What I expect is for the onMeasure to handle this, and give appropriate measurements. But that is not the case. Note of interest here is that even thought the CustomSquareLayout behaves weirdly, its child layouts all fall under a Square shaped layout that is always placed on the Left hand side.
<!-- XML for above image -->
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="300dp"
android:text="Below is the Square Layout"
android:gravity="center"
android:id="#+id/text"
/>
<com.app.application.CustomSquareLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="#id/text"
android:background="#color/colorAccent" #PINK
android:layout_centerInParent="true"
android:id="#+id/square"
android:padding="16dp"
>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true" #Note this
android:background="#color/colorPrimaryDark" #BLUE
>
</RelativeLayout>
</com.app.application.CustomSquareLayout>
</RelativeLayout>
Normal case : (Textview is in Top)
Following are few links I referenced:
Custom Square LinearLayout. How?
Simple way to do dynamic but square layout
Hope to find a solution to this, using onMeasure or any other function when extending the layout (so that even if some extends the Custom Layout, the Square property remains)
Edit 1 : For further clarification, the expected result for 1st case is shown
Edit 2 : I gave a preference to onMeasure() or such functions as the need is for the layout specs (dimensions) to be decided earlier (before rendering). Otherwise changing the dimensions after the component loads is simple, but is not requested.

You can force a square view by checking for "squareness" after layout. Add the following code to onCreate().
final View squareView = findViewById(R.id.square);
squareView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
squareView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
if (squareView.getWidth() != squareView.getHeight()) {
int squareSize = Math.min(squareView.getWidth(), squareView.getHeight());
RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams) squareView.getLayoutParams();
lp.width = squareSize;
lp.height = squareSize;
squareView.requestLayout();
}
}
});
This will force a remeasurement and layout of the square view with a specified size that replaces MATCH_PARENT. Not incredibly elegant, but it works.
You can also add a PreDraw listener to your custom view.
onPreDraw
boolean onPreDraw ()
Callback method to be invoked when the view tree is about to be drawn. At this point, all views in the tree have been measured and given a frame. Clients can use this to adjust their scroll bounds or even to request a new layout before drawing occurs.
Return true to proceed with the current drawing pass, or false to cancel.
Add a call to an initialization method in each constructor in the custom view:
private void init() {
this.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
#Override
public boolean onPreDraw() {
if (getWidth() != getHeight()) {
int squareSize = Math.min(getWidth(), getHeight());
RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams) getLayoutParams();
lp.width = squareSize;
lp.height = squareSize;
requestLayout();
return false;
}
return true;
}
});
}
The XML can look like the following:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="300dp"
android:gravity="center"
android:text="Below is the Square Layout" />
<com.example.squareview.CustomSquareLayout
android:id="#+id/square"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="#id/text"
android:background="#color/colorAccent"
android:padding="16dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true"
android:background="#color/colorPrimaryDark" />
</com.example.squareview.CustomSquareLayout>
</RelativeLayout>

There is a difference between the view's measured width and the view's width (same for height). onMeasure is only setting the view's measured dimensions. There is still a different part of the drawing process that constrains the view's actual dimensions so that they don't go outside the parent.
If I add this code:
final View square = findViewById(R.id.square);
square.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
System.out.println("measured width: " + square.getMeasuredWidth());
System.out.println("measured height: " + square.getMeasuredHeight());
System.out.println("actual width: " + square.getWidth());
System.out.println("actual height: " + square.getHeight());
}
});
I see this in the logs:
09-05 10:19:25.768 4591 4591 I System.out: measured width: 579
09-05 10:19:25.768 4591 4591 I System.out: measured height: 579
09-05 10:19:25.768 4591 4591 I System.out: actual width: 768
09-05 10:19:25.768 4591 4591 I System.out: actual height: 579
How to solve it by creating a custom view? I don't know; I never learned. But I do know how to solve it without having to write any Java code at all: use ConstraintLayout.
ConstraintLayout supports the idea that children should be able to set their dimensions using an aspect ratio, so you can simply use a ratio of 1 and get a square child. Here's my updated layout (the key piece is the app:layout_constraintDimensionRatio attr):
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="300dp"
android:gravity="center"
android:text="Below is the Square Layout"
app:layout_constraintTop_toTopOf="parent"/>
<RelativeLayout
android:id="#+id/square"
android:layout_width="match_parent"
android:layout_height="0dp"
android:padding="16dp"
android:background="#color/colorAccent"
app:layout_constraintTop_toBottomOf="#+id/text"
app:layout_constraintDimensionRatio="1">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true"
android:background="#color/colorPrimaryDark">
</RelativeLayout>
</RelativeLayout>
</android.support.constraint.ConstraintLayout>
And screenshots:

You cannot compare the two measure specs, as they are not simply a size. You can see a very good explanation in this answer. This answer is for a custom view, but measure specs are the same. You need to get the mode and the size to compute final sizes, and compare the end results for both dimensions.
In the second example you shared, the right question is this one (third answer). Is written for Xamarin in C#, but is easy to understand.
The case that is failing for you is because you're finding an AT_MOST mode (when the view is hitting the bottom of the screen), that's why comparisons are failing in this case.
That should be the final method (can contain typos, I have been unable to test it:
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
int width, height;
switch (widthMode) {
case MeasureSpec.EXACTLY:
width = widthSize;
break;
case MeasureSpec.AT_MOST:
width = Math.min(widthSize, heightSize);
break;
default:
width = 100;
break;
}
switch (heightMode) {
case MeasureSpec.EXACTLY:
height = heightSize;
break;
case MeasureSpec.AT_MOST:
height = Math.min(widthSize, heightSize);
break;
default:
height = 100;
break;
}
var size = Math.min(width, height);
var newMeasureSpec = MeasureSpec.makeMeasureSpec(size, MeasureSpec.EXACTLY);
super.onMeasure(newMeasureSpec, newMeasureSpec);
}
I expect the end result to be roughly like this (maybe centered, but this dimensions):
Notice that this is a made up image done with Gimp.

try this. You can use on measure method to make a custom view. Check the link below for more details.
http://codecops.blogspot.in/2017/06/how-to-make-responsive-imageview-in.html

Get width of CardView in Adapter.onBindViewHolder

I have a list of posts and most of them are pictures (simply put it is posts just like G+ or FB apps). Each post entry has an image aspect ratio, so I can set image height based on it's width even before image was loaded from server, so card layout wouldn't change on load.
The problem is layout_width="match_parent" set for both card and post image. When I get width of cardview it is zero. So i can't calculate height.
For now the only solution I see is to take width of parent container (RecyclerView) and deduct all paddings, but it doesn't look like a good solution.
Is there any other way to do it?
Here is an example of adapter code
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
....
int width = holder.itemView.getWidth();
....
//do some calculations
}
Layouts (without irrelevant parts)
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:id="#+id/card"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:descendantFocusability="blocksDescendants"
android:foreground="?android:attr/selectableItemBackground"
card_view:cardBackgroundColor="#ffffff"
card_view:cardCornerRadius="3dp">
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<include
android:id="#+id/includedPost"
layout="#layout/post_details" />
</RelativeLayout>
</android.support.v7.widget.CardView>
includedPost:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:id="#+id/postImage"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#+id/commenterImage"
android:minHeight="120dp"
android:scaleType="centerCrop" />
</RelativeLayout>

when onBind or onViewAttachedToWindow is called, the child is not measured yet so you cannot get the width. Even if these calls were made after child is measured, what you are trying to do would not be a good practice because changing height will require a new measurement.
If you are using LinearLayoutManager, it will give the full width to the child (expect RecyclerView padding and child's margins). It is not great but OK to derive your height from there.
Another (more flexible) approach here is to create a custom ImageView that keeps your aspect ratio. When onBind is called, you'll set the desired aspect ratio of your custom ImageView.
When on measure is called, it will measure depending on your aspect ratio.
class MyImageView extends ImageVIew {
....
private float mScale = 1f;
public void setScale(int scale) {
mScale = scale;
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int width = getMeasuredWidth();
setMeasuredDimension(width, width * mScale);
}
}
So in your onBind method, you call setScale on the ImageView depending on your w/h ratio.
I have not tested but this approach should work as desired.

You can use Picasso Transformation to achieve this.
FitToTargetViewTransformation class:
import android.graphics.Bitmap;
import android.view.View;
import com.squareup.picasso.Transformation;
/**
* Picasso Transformation class to fit image to target View size
*/
public class FitToTargetViewTransformation implements Transformation {
private View view;
public FitToTargetViewTransformation(View view) {
this.view = view;
}
#Override
public Bitmap transform(Bitmap source) {
int targetWidth = view.getWidth();
double aspectRatio = (double) source.getHeight() / (double) source.getWidth();
int targetHeight = (int) (targetWidth * aspectRatio);
if (source.getHeight() >= source.getWidth()) {
return source;
}
Bitmap result = Bitmap.createScaledBitmap(source, targetWidth, targetHeight, false);
if (result != source) {
// Same bitmap is returned if sizes are the same
source.recycle();
}
return result;
}
#Override
public String key() {
return "transformation" + " desiredWidth";
}
}
And somewhere in onBindViewHolder you do something like this:
Picasso.with(context)
.load(AVATAR_ENDPOINT)
.transform(new FitToTargetViewTransformation(feedViewHolder.icAvatar))
.into(feedViewHolder.icAvatar);

Android: Rotate whole layout

I need to be able to rotate whole layouts on the fly (on the click of a button).
I am able to rotate the layouts using, eg. layout.setRotation(270.0f). The problem is, after the rotation, the layout height and width are not matching its parent's.
I have tried inverting height and width like so,
RelativeLayout layout = (RelativeLayout)findViewById(R.id.rootLayout);
LayoutParams layoutParams = layout.getLayoutParams();
int height = layout.getHeight();
int width = layout.getWidth();
layoutParams.height = width;
layoutParams.width = height;
Which does nothing at all.
I am working with sdk 14.
The first image below is the app as it starts. The second one, after a rotation. I wish to fill the black "space". Any help would be appreciated.
The images below show only a button in the layout. However, in reality, the layout are a lot more complex. What I am trying to achieve is "faking" a landscape view.
Edit: Changed images and added descriptions.

Not sure why this is useful, but it's a nice puzzle. Here is something that works for me:
On rotate click, do this:
RelativeLayout mainLayout = (RelativeLayout) findViewById(R.id.main);
int w = mainLayout.getWidth();
int h = mainLayout.getHeight();
mainLayout.setRotation(270.0f);
mainLayout.setTranslationX((w - h) / 2);
mainLayout.setTranslationY((h - w) / 2);
ViewGroup.LayoutParams lp = (ViewGroup.LayoutParams) mainLayout.getLayoutParams();
lp.height = w;
lp.width = h;
mainLayout.requestLayout();
And the layout:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:id="#+id/main"
android:layout_height="match_parent"
android:background="#ffcc88"
tools:context=".TestRotateActivity" >
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Test"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
/>
<Button
android:id="#+id/rotate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Rotate"
android:layout_centerInParent="true"
/>
</RelativeLayout>

Try this code:
btnRotate.setOnClickListener(new OnClickListener()
{
#SuppressLint("NewApi")
#Override
public void onClick(View v)
{
int orientation = getResources().getConfiguration().orientation;
switch(orientation)
{
case Configuration.ORIENTATION_LANDSCAPE:
llparent.setRotation(270.0f);
RelativeLayout.LayoutParams layoutParams_LandsScape =
new RelativeLayout.LayoutParams(
rlRoot.getHeight(), rlRoot.getWidth());
layoutParams_LandsScape.setMargins(
rlRoot.getTop(), rlRoot.getRight(),
rlRoot.getBottom(), rlRoot.getLeft());
layoutParams_LandsScape.addRule(RelativeLayout.CENTER_IN_PARENT);
llparent.setLayoutParams(layoutParams_LandsScape);
break;
case Configuration.ORIENTATION_PORTRAIT:
llparent.setRotation(270.0f);
RelativeLayout.LayoutParams layoutParams_Portrait =
new RelativeLayout.LayoutParams(
rlRoot.getHeight(), rlRoot.getWidth());
layoutParams_Portrait.setMargins(
0, 0, rlRoot.getBottom(), rlRoot.getLeft());
layoutParams_Portrait.addRule(RelativeLayout.CENTER_IN_PARENT);
llparent.setLayoutParams(layoutParams_Portrait);
break;
}
}
});
}
And XML:
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".RotateAnim">
<RelativeLayout
android:id="#+id/rlroot"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#090">
<LinearLayout
android:id="#+id/llParent"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#900"
android:gravity="center"
android:orientation="vertical">
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="center"
android:text="Button"/>
</LinearLayout>
</RelativeLayout>
</RelativeLayout>

Simple and tricky way to make screen orientation along the button click.. with an example..
Here,I'm using the sharedPreference(Im setting an boolean value based on orientation )
Method for button onClick.
public void rotate(View v) {
edt = prefs.edit();
if (!prefs.getBoolean("screen_protrait", true)) {
edt.putBoolean("screen_protrait", true);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
} else {
edt.putBoolean("screen_protrait", false);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
}
edt.commit();
}
In xml, set an onClick method for rotate button
<Button
android:id="#+id/bt_rotate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:onClick="rotate"
android:text="Rotate" />
Last one, is in onCreate of Activity you want to set the Prefernce from Application..as
prefs = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
Keep coding.. You can achieve your goal...Let me know,if it's working with your scenario.

If you want to literally rotate the screen, you can force a screen orientation.
Otherwise there's no easy way to do what you are trying to do as View.setRotation(float) will always render the View in its "real" bounds and then rotate it! What I suggest is careful consideration of what elements of the layout should be rotated and then to rotate those specifically.
The only true "automatic" way of achieving it would be to create a custom layout that essentially measures, layouts and draws children rotated... Honestly I would only go there if I really, really needed to and it's probably more trouble than it's worth!

// get root layout from activity's XML
LinearLayout mParentLayout = (LinearLayout) findViewById(R.id.activity_main);
// get screen size from DisplayMetrics if you need to rotate before the screen is shown
DisplayMetrics displayMetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
int height = displayMetrics.heightPixels;
int width = displayMetrics.widthPixels;
// if you are rotating after the view was shown
// acquire width and height from the layout's parent's LayoutParams
// calculate offset to move the view into correct position
int offset = (width - height) / 2;
// rotate the layout
FrameLayout.LayoutParams lp = new FrameLayout.LayoutParams(height, width);
mParentLayout.setLayoutParams(lp);
// 90° clockwise
mParentLayout.setRotation(90.0f);
mParentLayout.setTranslationX(offset);
mParentLayout.setTranslationY(-offset);
It may look like the suggested answer, but this displays how to get dimensions from DisplayMetrics and the calculating the offset for the translation is a little different because that's the only way it worked properly.

i'll suggest you rotate only button rather than rotating the whole layout like
btn_rotate.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v)
{
rotation = AnimationUtils.loadAnimation(MainActivity.this, R.anim.rotate);
rotation.setFillAfter(true);
btn_rotate.startAnimation(rotation);
}
});
rotate.xml
<set>
<rotate
xmlns:android="http://schemas.android.com/apk/res/android"
android:duration="0"
android:fromDegrees="270"
android:pivotX="50%"
android:pivotY="50%"
android:startOffset="0"
android:toDegrees="270" />
</set>

try set your layout params to match_parent after rotation:
layout.setRotation(270.0f)
and then
RelativeLayout layout = (RelativeLayout) findViewById(R.id.rootLayout);
layout.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
EDIT: get the parentView View parent = layout.getParent(); and set the width and height of the parent view to your layout as you need - in width to height and vice versa.

Android: alternate layout xml for landscape mode
As I can remember, you should define a new layout for the horizontal view. I think this link can help you

Try this code:
(RelativeLayoutOuterFrame) it is the name of your layout.which you want to rotate.
Actually, we are not rotate the layout.we just change height an width value.
int w = RelativeLayoutOuterFrame.getWidth();
int h = RelativeLayoutOuterFrame.getHeight();
ViewGroup.LayoutParams lp = (ViewGroup.LayoutParams) RelativeLayoutOuterFrame.getLayoutParams();
lp.height = w;
lp.width = h;
RelativeLayoutOuterFrame.setGravity(RelativeLayout.CENTER_IN_PARENT);
RelativeLayoutOuterFrame.setGravity(RelativeLayout.CENTER_HORIZONTAL);
RelativeLayoutOuterFrame.requestLayout();

android: buttons on top of imageview in multiple screen sizes

Hi I'm developing an app on android and I have some layouts where I would like to have an image that fills the screen-width in landscape mode. On top of that, i want some buttons on specific places.
I used a scrollview (because the image doesn't fit in height if it fills the width of the screen), with a relative layout within.
In that relative layout, I put the imageview and the buttons. The image fills the width and wraps the content for the height. The buttons are placed through setting the left and top margins within the relative layout.
Everything is looking good on the phone i tested it with, but when i test on a different device (other screen size and density) all buttons are on the wrong place and aren't big enough anymore.
How can i change this, so that all proportions stay the same? The buttons have to be in the exact same position and have to be the same size, in comparison with the image.
My code:
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/svCentralAmerica"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fillViewport="true" >
<RelativeLayout
android:id="#+id/rlCentralAmerica"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<ImageView
android:id="#+id/ivCentralAmerica"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:adjustViewBounds="true"
android:src="#drawable/mapcentralamerica" />
<Button
android:id="#+id/mexu"
android:layout_width="36dp"
android:layout_height="36dp"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="16dp"
android:layout_marginTop="33dp"
android:background="#drawable/usa_y"
android:onClick="onCountryClick"
android:paddingTop="3dp"
android:scaleType="fitCenter"
android:tag="1;U"
android:text="2"
android:textColor="#color/Black"
android:textSize="15sp"
android:textStyle="bold" />
<Button
android:id="#+id/mexr"
android:layout_width="36dp"
android:layout_height="36dp"
android:layout_alignTop="#id/mexu"
android:layout_marginLeft="4dp"
android:layout_toRightOf="#id/mexu"
android:background="#drawable/russia_n"
android:onClick="onCountryClick"
android:paddingTop="18dp"
android:scaleType="fitCenter"
android:tag="1;R"
android:text="3"
android:textColor="#color/Red"
android:textSize="15sp"
android:textStyle="bold" />
</RelativeLayout>
</ScrollView>

I have actually done what you're thinking of. Unfortunately, if you want exact control of the positioning on any screen size, and an exact aspect ratio, then you're going to have to position resources programmatically. If you use xml, you can come pretty close, but won't have precise positioning control. For a beginner, positioning programmatically can be tedious. Since you're only positioning a couple of buttons here and there, it shouldn't be too much of a hassle.
How I did it: get the screenwidth and screenheight programmatically. Then calculate the aspect ratio of your button. Next, calculate the position of the button in relation to the screenwidth and screenheight (this would be in %). With all this info, you should be able to position buttons exactly where you want it on any screen size with a particular orientation. I would recommend positioning everything else on xml and do only the buttons programmatically. On orientation change, you will need to recalculate everything again, which can be annoying. I would recommend that you stick with 1 orientation and maybe support multiple orientations later.

I use these helper functions to move my buttons around based on the percentage of the screen height and width. First I layout the screen for a 320 x 480 screen in graphical layout to create the xml, then move the buttons in my onCreate method.
Here are the imports I used:
import android.app.Activity;
import android.os.Bundle;
import android.view.Display;
import android.view.View;
import android.view.WindowManager;
import android.widget.AbsoluteLayout;
import android.widget.Button;
import android.content.Context;
import android.util.Log;
Here are the calls to move the buttons in onCreate:
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
moveBtn(0.1843,0.1187,0.128,0.7375,R.id.credits_button);
moveBtn(0.1843,0.1187,0.3125,0.7375,R.id.website_button);
moveBtn(0.1843,0.1187,0.5,0.7375,R.id.facebook_button);
moveBtn(0.1843,0.1187,0.6906,0.7375,R.id.support_button);
}
Here are the helper functions:
//----------------------------------------------------------------------------------------------
// public void moveBtn(double percent_width, double percent_height, double percent_x, double percent_y, int myObject)
//----------------------------------------------------------------------------------------------
public void moveBtn(double percent_width, double percent_height, double percent_x, double percent_y, int myObject) {
int width = (int)Math.round((ScWth(this) * percent_width));
int height = (int)Math.round((ScHgt(this) * percent_height));
int x = (int)Math.round((ScWth(this) * percent_x));
int y = (int)Math.round((ScHgt(this) * percent_y));
Log.d(TAG, "Object: " + myObject + "/Width: " + width + "/Height: "+ height + "/x: "+ x + "/y: "+ y);
AbsoluteLayout.LayoutParams myParam = new AbsoluteLayout.LayoutParams(width, height, x, y);
Button thisButton = (Button)findViewById(myObject);
thisButton.setLayoutParams(myParam);
}
//----------------------------------------------------------------------------------------------
// public static double ScWth(Context context)
//----------------------------------------------------------------------------------------------
//return the screen width of the device
public static double ScWth(Context context){
WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
Display display = windowManager.getDefaultDisplay();
return display.getWidth();
}
//----------------------------------------------------------------------------------------------
// public static double ScHgt(Context context)
//----------------------------------------------------------------------------------------------
//return the screen height of the device
public static double ScHgt(Context context){
WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
Display display = windowManager.getDefaultDisplay();
return display.getHeight();
}
I hope it helps someone.

Dynamically setting relative dimension of a linearlayout

I want to resize my LinearLayout (or a view) to a dimension which is relative to the parent or itself. For example, I want the width to be 1/3 of the parent's width. Or, the height should be same as its own width. I don't want to use any constants , so that it works for all devices.
adding code:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
>
<LinearLayout android:id="#+id/ll_board"
android:gravity="center_horizontal"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</LinearLayout>
...
</LinearLayout>
code:
public class GMActivity extends Activity {
public void onCreate(Bundle savedInstanceState) {
LinearLayout board_layout = (LinearLayout)findViewById(R.id.ll_board);
// I wanted to resize board_layout here ..
// getParent().getWidth() returns 0
Log.d("gm", "layout: " + ((LinearLayout) board_layout.getParent()).getWidth());
// ..
}
}
getWidth() is giving 0. Is it too early to call this? If yes, what is the correct place to call this?
Basically my intention is to make the width of the layout a fraction of the screen size width, and, height same as its own width.

Considering layout your LinearLayout and that its parent it's another LinearLayout:
Get the parent's width:
int parentWidth = ((LinearLayout) layout.getParent()).getWidth();
Get the view's width:
int viewWidth = ((LinearLayout) layout).getWidth();
set the
view.setHeight(viewWidth );
view.setWidth(parentWidth / 3);

I found height=width solution (square shaped layout) in LinearLayout in Square Form