Develop Reference

Incorrect image size on different screen size

I have a screen on which I need to display a number of images inside a horizontal LinearLayout.
I designed it for an xhdpi. I set the sizes of each ImageView to 100dp, and on an emulator (xhdpi 768x1280 4.7" screen) it looks something like
this while on a tablet emulator (xhdpi 1534x2048 9" screen) it looks like this.
In the latter, the images aren't scaled properly to look like it does on the smaller screen.
Is there a way to make it look the same on both screen sizes?

to make your layout adjust on different screen you need to design it to be responsive. Yes like what G.Dator said, you can use weight attribute. Here's the example :
<LinearLayout
android:layout_height="200dp"
android:layout_width="match_parent"
android:orientation="horizontal">
<ImageView
android:layout_width="0dp"
android:layout_height="200dp"
android:layout_weight="25"/>
<ImageView
android:layout_width="0dp"
android:layout_height="200dp"
android:layout_weight="25"/>
<ImageView
android:layout_width="0dp"
android:layout_height="200dp"
android:layout_weight="25"/>
<ImageView
android:layout_width="0dp"
android:layout_height="200dp"
android:layout_weight="25"/>
</LinearLayout>
Please let me know if you have further question.

Actually, the image is the same size in 2 devices. The problem is the difference between your dp width of your phone (384dp) and your tablet (767dp). There're few ways to resolve it:
using multiple layout files for sw360 and sw720. You can check this Google Guide
Using the same weight for all your ImageView with adjustViewBound=true to keep your image ratios.
Using code to set your ImageView size programmatically.

In addition to implementing a responsive layout structure (like what #Bhimbim mentioned), there is a library (https://github.com/intuit/sdp) which can be useful when you want to code once and use it on multiple different devices, it offers you sdp unit instead of dp which helps your view to scale better.
Example:
layout_width="#dimen/_30sdp"
layout_height="#dimen/_30sdp"
(Sorry i couldn't comment as i have registered recently).

Too much padding around Button's Text

I have a fragment that takes up the whole screen, with Buttons and a SeekBar which scale to fit it, as well as fixed size TextViews. I use linear horizontal and vertical layouts with weights to achieve this.
The problem is I can't get the button text large enough without it making the buttons expand in size. For some reason, any text size greater than about 35sp makes the button expand, no matter how big the button is. This screen shot shows the button sizes have plenty of space for the text:
Ideally I would like the "<" and ">" characters to fill the buttons. (I was going to programmatically change the font size according to the button size, e.g. for different screen sizes) but haven't tried since I can't even get the static layout to work.
Edit: I would like to avoid images, since if I had 15 buttons, and 8 buckets, that would be 120 images I need!
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/VerticalLinearLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="0dp"
android:paddingLeft="0dp"
android:paddingRight="0dp"
android:paddingTop="0dp" >
<!-- ........ -->
<TextView
android:id="#+id/trackTextView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="2" >
<Button
android:id="#+id/trackPreviousButton"
style="android:buttonBarStyle"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:text="#string/button_track_previous"
android:textSize="35sp" />
<Button
android:id="#+id/trackNextButton"
style="android:buttonBarStyle"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:text="#string/button_track_next"
android:textSize="35sp" />
</LinearLayout>
<SeekBar
android:id="#+id/seekBar"
style="#style/tallerBarStyle"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />
<!-- ........ -->
</LinearLayout>
I have tried adding the following line to Buttons, but it only makes a small difference, if any:
android:padding="0dp"
Advice on getting the font height to fill the buttons without padding is my primary question. (But if the problem of dynamically sizing the text to fill the buttons for different screen sizes can be solved at the same time, that would be brilliant).
Edit: it turns out that using larger font sizes affects the effect of weighting for the height of the linear layouts, which is why there seemed to be padding - larger font size increased the button size, not because of the padding (which was 0) but because of the weighting

Button is not the right widget for your purpose. Use an ImageButton (or even an ImageView) instead.
I was going to programmatically change the font size according to the button size, e.g. for different screen sizes
Your current approach will land you in a lot of problems regarding proper sizing of your UI components. Given the plethora of android devices out there, screen size is just one aspect of the problem. You will also be dealing with varying screen densities. Best approach would be to put size/density buckets (drawable-mdpi/hdpi/xhdpi) to use. Help android in working for you.
Use drawables to indicate next and previous. If you're worried about the drawables being too small for tablet screens, create appropriate drawable resources/folders:
// Phones - 4 to 7 in
drawable-ldpi
drawable-mdpi
drawable-hdpi
drawable-xhdpi
drawable-xxhdpi
// Tablets - 7 to 10 in
drawable-large-mdpi
drawable-large-hdpi
// Tablets - 10 in
drawable-xlarge-mdpi
This list may not be exhaustive. Consider doing some research before finalizing your size/density buckets.
Output:
# drawable size 32dp:
# drawable size 64dp
Now it becomes quite straightforward - finalize drawable size by visual inspection on a phone, on a 7 inch tablet, and on a 10 inch tablet. Then use density scales to create and store appropriately sized drawable in the folders I mentioned above. Let android deal with what bucket to pick from.

The problem is by default buttons include a minHeight attribute. I had the same problem and solved it with just a single line of code in my XML file:
android:minHeight="0dp"

There is a quick and easy solution to your problem!
Auto-sizing text in Android is fiendishly difficult in my experience, especially when padding is involved. I would advise that instead of using an angle bracket character, you use a drawable - there are plenty of arrow icons available online - and an ImageButton. For example:
<ImageButton
android:id="#+id/trackNextButton"
style="android:buttonBarStyle"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:src="#drawable/left_arrow"
android:scaleType="fitXY"
android:padding="0dp"
android:textSize="35sp" />
By using different ScaleTypes you can alter the stretching of the image. Even better, the screen sizes problem is solved because you can add different drawables for different densities.

Use minWidth="0" or "1" to reduce the horizontal padding on a text Button.

What is the scaleType I have to use here

I have an Image of resolution 1600 x 2400. I want it to be displayed in an ImageView as follow:
<ImageView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:scaleType="centerInside" />
I want the image to:
Take full width
Maintain Aspect ratio
Hence the imageview height must be as per the ratio
Eg: on a 320 x 600 screen, an image of size 1600 x 2400 must be shown as 320 x 480
What I currently get is an imageview with dimensions 320 x 2400 with image centered and space on top and bottom.

save the image in hdmi folder and use
android:src="#drawable/imagename"
or you can use
android:background="#drawable/imagename"
and you can set the heigth and width with
instead of fill parent or wrap or match use sizes in dp like 100dp or whatever you like.
android:layout_width="fill_parent"
android:layout_height="wrap_content"
example
android:layout_width="100dp"
1.Please go through the Developers guide first. Supporting Multiple Screens provides a pretty good overview of what you are trying to achieve. It's a challenging task being honest. Most of the iPhone devs enjoy the fixed screen size but we Android devs have to go through this problem. I can recomend few practices that I'm following
2.Try not to use Fixed height and weight as much as you can
Stick to Linear Layout if the layout is not complex. Go to relative layout only when its really mandatory.
Use Wrap and fill parent than giving fixed sizes..
These are the few I can think of.
3.Typically you just provide different layouts and resources for different screen densities and orientations as described in Android documentation
try using
android:scaleType="fitXY"
or
android:scaleType="fitCenter"

Assuming you have calculated how high your view should be: set it's layout parameters through code.
imageView.setLayoutParams(new LayoutParams(320, height));

Stretching an image relative to screen size

I have a layout that features six buttons. All of them have the size of 72x72dip, so they appear to be larger on small screens and vice versa.
How can I tackle this problem? I want the buttons to be relatively the same size (eg 10% of the screen's width), but I don't know how to do it.
This is how my layout looks:
The layout's sourcecode can be found here.

1 - Did you fix all you 'image views' to layout_width & height of 72dip ?
2 - Normally 72dip is the same thing on every screen size... But you still can have 3(or 4 if you support XHDPI) resolution of your images...
2 - Add 4 différent fonder for you Drawable :
2.1 drawable
2.2 drawable-ldpi
2.3 drawable-mdpi
2.4 drawable-hdpi
Consider the following ratio for your images :
ldpi is 3
mdpi is 4
hdpi is 6
So make sure to make HDPI images first, so you can isealy resize other images applying ration 1.5 and 2 (just divide by 2 for LDPI for example).
3.By the way, why did you just did it all by yourself ? Seems you are on android 4.0, why don't you just use the new "DashBoard" class from Android ?

I usually do this by setting the width and height to wrap_content and then tweaking the layout_weight on the ImageButton widgets so that each button takes up the same amount of space. I usually do scaleType="center_inside" to make them line up nicely. Then pad around the edges of the TableView with margins as necessary.

Few quick observations:
a. You do not need TableLayout, just use LinearLayout
b. You do not need separate ImageView and TextView, you can use Button and image to it using
android:drawableTop="#drawable/"
c. Never use absolute values in width/height of any views, so use wrap_content.
Sample Layout should be like this:
<LinearLayout
android:layout_height="fill_parent"
android:layout_width="fill_parent"
android:orientation="vertical">
<!-- Row 1 -->
<LinearLayout
android:layout_height="0dp"
android:layout_width="fill_parent"
android:layout_weight="1.0"
android:orientation="horizontal">
<Button
android:layout_height="wrap_content"
android:layout_width="0"
android:layout_weight="1.0"
android:text="Preferences"
android:drawableTop="#drawable/Preferences" />
<Button
android:layout_height="wrap_content"
android:layout_width="0"
android:layout_weight="1.0"
android:text="Preferences"
android:drawableTop="#drawable/Preferences" />
</LinearLayout>
.
.
.
</LinearLayout>
</LinearLayout>

Single Layout for all screen sizes

I have read many documentation on supporting multiple screen sizes but still confused.
I have read like if specified in dp it will get automatically scaled.
In my sample i just have a single layout. there i have placed an edit text.
and given width , suppose 170 dp. suppose width wise it is half the screen in a 5 inch phone emulator.
What i was expecting is, if i show it on an tablet 7inch or 10 inch , there also it will be half the width of the screen (i.e it will get automatically scaled). But it didnt. in a 10 inch tablet it is only very small size.
what should i do to achieve this only through layout xml ( only single xml )

Dont set a Static width for the Textview as android will automatically scale it the the correct size using
android:layout_width="fill_parent"
android:layout_height="wrap_content"
Basically what this does is makes the TextView the full size of the width of the device, and wraps the Height only to the needed height of the text.
YOu could also do warp_content for width to if you wanted. This is the best way. If you set it statically, you will need to create different layouts using XML.

Learn to use layout weights, you can use them like a percentage of 100.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<TextView
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_weight="50"
android:text="aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" />
<View
android:layout_width="0dip"
android:layout_height="0dip"
android:layout_weight="50" />
</LinearLayout>
Here the textview takes up 50% of the screen width and the other view is a kind of invisible spacer taking up the other 50% of the screen width.
Which looks something like this (Eclipse XML preview):
As you can see the textview wraps when it gets to 50% of the screen. Working on all sizes of screen.