Develop Reference

Make ImageView to look the same on different devices

I have a RelativeLayout with an ImageView that has the following properties,
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginRight="100dp"
android:layout_marginLeft="100dp"
android:layout_marginTop="100dp"
android:layout_marginBottom="300dp"
So, aparently 100dp doesn't look the same on different devices.
How can I make the ImageView to look the same on tablet as it looks on phone? using just 1 layout
phone
tablet

You could use a ConstraintLayout's layout_constraintGuide_percent attribute so that the size is always relative to the screen width and height.
See the example in the docs of the (deprecated) PercentRelativeLayout on how to use a ConstraintLayout to reach your goal.

The problem is that you've defined your ImageView to be the size of the screen, minus some margins. So on small screens it will be really small, and on large screens it will be really large.
You'd be better off simply defining how large you want it to be directly. Your "phone" screenshot looks like you're probably working with a 320dp wide screen, so you could just write this instead:
<ImageView
android:layout_width="120dp"
android:layout_height="120dp"
android:layout_centerHorizontal="true"
android:layout_marginTop="100dp"/>
Now your image view will always be ~2.5cm wide/tall on every screen, centered horizontally, and ~2cm from the top edge of the screen.

Android - ImageView - Multiple Screen Support - Set height/width as dp or match_parent/wrap_content?

I am currently trying to adjust my Android App so it will look and feel similar on multiple screens/devices.
I know by now that a major part in this is to provide multiple image sizes for every image file according to the x1, x1.5, x2, x3, x4 ratios for mdpi, hdpi, xhpi, xxhdpi and xxxhdpi respectively, and I have finished doing so today.
After doing this, I have defined Density independent Pixel dimensions in the #dimen.xml values resource that correspond with the actual image sizes in pixels of the MDPI resources. Subsequently, i have set the imageviews in question's layout_width and layout_height to this dimension.
I am currently at a loss, however, as to why my application still looks significantly different on an MDPI emulator than it does on an HDPI emulator. To highlight what I mean, I'll provide the following screenshot showing the HDPI and MPDI emulator next to one another (left is HDPI (4" WVGA Nexus S) and right is MDPI (5.4" FWVGA)). I want both of them to look like the MPDI version, but what I've done so far apparently isn't working.
I have three theories of my own as to why this is not working the way I intend it to:
1. I am not supposed to set ImageView layout_width and layout_height to a dp value, but rather match_parent or wrap_content (?) (and change the structure of my .xml layouts in the process).
2. I am not only supposed to define multiple drawable resources, but also multiple layout resources for different screen sizes (?).
3. I have misunderstood the entire idea behind how this is supposed to work (?).
I will also give you an example of one of the list items that can be seen in the first screenshot (#drawable/phone_speed_icon is a 64 x64 pixel resource in MPDI and a 96x96 resource in HDPI, and #dimen/icon_attribute_size is 64dp):
<LinearLayout
android:id="#+id/llSpeed_PreSession"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:paddingBottom="10dp"
android:paddingEnd="20dp"
android:paddingStart="20dp"
android:weightSum="100">
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="#dimen/icon_attribute_size"
android:layout_weight="20"
android:weightSum="100">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="70"
android:gravity="center"
android:orientation="vertical">
<ImageView
android:layout_width="#dimen/icon_attribute_size"
android:layout_height="#dimen/icon_attribute_size"
android:src="#drawable/phone_speed_icon" />
</LinearLayout>
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="30"
android:gravity="center_vertical"
android:paddingStart="10dp"
android:text="Speed"
android:textAppearance="#android:style/TextAppearance.Large"
android:textColor="#878787"
android:textStyle="bold" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="80"
android:gravity="center">
<android.support.v7.widget.SwitchCompat
android:id="#+id/swSpeed_PreSession"
android:layout_width="wrap_content"
android:layout_height="match_parent" />
</LinearLayout>
</LinearLayout>
In the end, I have four questions that I'd like answered:
1. How do I make the list items in screenshot 1 look the same on MDPI devices as HDPI devices? Does this have anything to do with one of the three theories I mentioned earlier?
2. Why is the header text ("What do you want to measure?") wrapped on one device, but not on the other? They use the sp unit (via android:style/TextApperance.TextApperance.Large)?
3. Shouldn't everything be more spaced out on an HDPI device (if anything) rather than less spaced out? The HDPI emulator looks as if it "has got way less pixels available", if you can understand what I'm saying even a little.
4. How do I make the Fragments on the second screenshot look the same? Or should i not even want this, because the HDPI is (for some reason) physically smaller, which is why the layout is less spread out?
Anyway, I have been at this all day and the more I read the more thouroughly confused I get, so any help is greatly appreciated!

You have the option to create multiple dimens.xml files depending on a variety of factors. Here you'll see what my current project looks like with the various dimens.xml files in Android Studio based on screen width.
However, you can have different requirements for each dimens file you want. For example, you can create dimens files for each density:

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.

Android: Supporting multiple screen sizes within the same screen size type

The problem I am running into related to supporting multiple screen sizes - a fairly common one I believe. I have searched a lot, but have not found something helpful.
I have my project laid out traditionally, with folders to support the various sizes called layout, layout-small, layout-large, layout-xlarge.
So as I have found out, even within each of these size regimes, there screens are not all the same size. For example, my 320x480 screen qualifies for the normal size layout, but so does someone's 480x800. As you can imagine, the content of my app will not fill up the whole screen of a 480x800 device because there is more area. Here are examples of what it looks like:
On 320x480 (what I designed for):
On 480x800 (notice the extra space at the bottom):
Now, I have done a lot of research and applied lots of techniques in an effort to make my app look nice on all screen, but I feel like I am missing something fundamental. I have taken all the basic steps to use dp instead of px, use RelativeLayout everywhere, stuff like that. But I need some way for my app to re-size itself to better fit the larger screens. For example, the margins between the various components could increase a little to occupy more of the empty vertical space.
Any advice, or help? In the worst case, is there a way to design a layout which would fire up specifically for 480x800 screens (because they seem to be most common)? Thanks.

If I were you I'd use a layout like this:
<LinearLayout android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:layout_weight="1">
<!-- Your first form line -->
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:layout_weight="1">
<!-- Your second form line -->
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:layout_weight="1">
<!-- Your third form line -->
</LinearLayout>
<!-- .... -->
</LinearLayout>
This layout will produce this (without colors, of course :) ). The ratio of the lines (colored boxes) is fix, but it's size is dinamically fit to the screen height. The fill_parent and layout_weight do the trick.
If you want to use RelativeLayout, you have to set the whitespaces and heights programatically from JAVA (some explanation here)

320 : 480 has a different ratio than 480 : 800. So the latter simply has more vertical space in relation to the horizontal space than the former. So there is nothing wrong with your layout.

You need to design screens so that you always think about how the Views you define behave when the screen's size shrinks or grows. As you saw, screens may be varying greatly even in the same size-category.
In the case of the screen that you showed, you need to give the width of the EditText components by using weights, not exact dp amounts. You can find many articles on how you might do this, here's one for a start.

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>