Develop Reference

Supporting 9.6 inch and 10.1 inch android tablet

I have to support android devices with screen resolution 1280*800(in dp)(KitKat) and 1280 * 752(dp)(Lollipop). The first one is a 10.1 inch tablet and second one is 9.6 inch tablet.
I am using same layout for all device and using externalized dimension to adjust layout for different screen.
But I am not able to separate the device using "values-sw720dp" and "values-sw800dp". If I use sw800dp both of them use the dimen value from sw800dp dimen folder.
How can I give separate dimension for the two devices?

Get your device's screnn inches programmatically and appy dimension
public static double getDeviceInches(Activity activity) {
DisplayMetrics metrics = getMetrics(activity);
int widthPixels = metrics.widthPixels;
int heightPixels = metrics.heightPixels;
float widthDpi = metrics.xdpi;
float heightDpi = metrics.ydpi;
float widthInches = widthPixels / widthDpi;
float heightInches = heightPixels / heightDpi;
return getDiagonalInches(widthInches, heightInches);
}
private static double getDiagonalInches(float widthInches, float heightInches) {
double diagonalInches = Math.sqrt((widthInches * widthInches) + (heightInches * heightInches));
float roundedValue = (float) Math.round(diagonalInches);
return (double)roundedValue;
}
//From this, we can get the information required to size the display:
private static DisplayMetrics getMetrics(Activity activity) {
DisplayMetrics metrics = new DisplayMetrics();
activity.getWindowManager().getDefaultDisplay().getMetrics(metrics);
return metrics;
}
public static int convertDpToPx(Context context, int value) {
// Get the screen's density scale
final float scale = context.getResources().getDisplayMetrics().density;
// Convert the dps to pixels, based on density scale(0.5f is for rounding up value) (arrowWidth is 50dp)
int pxValue= (int) (value * scale + 0.5f);
return pxValue;
}
Put your above code in utility class and call getDeviceInches method from your acitivty or fragment class

How can I specify the dip-pixels in a code?

I read that there is two kinds of referent pixels - w3c reference pixel and dip pixel. I do not understand how can I use the dip pixels. Do I have to write, for example, "width:100dip" or something like that. How can I specify this dip-pixels in my html+css+javascript code?

In XML:
android:layout_width="100dp"
In Java:
int width = dpToPx(100);
public static int dpToPx(int dpWidth) {
DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
float screenDpWidth = displayMetrics.widthPixels / displayMetrics.density;
int screenPxWidth = Math.round((screenDpWidth) * displayMetrics.density);
int dpPxWidth = Math.round(screenPxWidth / screenDPWidth);
return dpPxWidth * dpWidth;
}

Strange behavior of setTextSize (or maybe something else!)

I want to set the text size of my TextView to be proportional to screen width. I'm getting screen width using this code:
public static int getScreenWidth(Context context) {
if (SCREEN_WIDTH == 0) {
WindowManager wm = (WindowManager) context
.getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
DisplayMetrics outMetrics = new DisplayMetrics();
display.getMetrics(outMetrics);
SCREEN_WIDTH = outMetrics.widthPixels;
}
return SCREEN_WIDTH;
}
When I set the font size to be a proportion of screen width
textView.setTextSize(screenWidth / something);
I get different results on different devices, particularly Samsung GT-I9000 (android 2.3.3) and Nexus 7 (android 4.3).
However I managed to get it right by doing it this way:
textView.setTextSize(TypedValue.COMPLEX_UNIT_DIP,
Utils.pixelsToDip(context, screenWidth / something));
It's weird because basically it's like multiplying and dividing by same value.
Here is pixelsToDip method:
public static float pixelsToDip(Context context, float px) {
Resources resources = context.getResources();
DisplayMetrics metrics = resources.getDisplayMetrics();
float dp = px / (metrics.densityDpi / 160f);
return dp;
}
Does anyone knows what is the problem here? Maybe there is some faults in pixelToDip method, or I have a misunderstanding of size units?

How to determine the screen width in terms of dp or dip at runtime in Android?

I need to code the layout of the android widgets using dip/dp (in java files). At runtime if I code,
int pixel=this.getWindowManager().getDefaultDisplay().getWidth();
this return the screen width in pixels (px). To convert this to dp, I coded:
int dp =pixel/(int)getResources().getDisplayMetrics().density ;
This does not seem to be returning correct answer. I made the emulator of WVGA800 whose screen resolution is 480 by 800. When the run the emulator and let the code print the values of pixel and dp, it came to 320 in both. This emulator is 240 dpi whose scale factor would be 0.75.

As #Tomáš Hubálek mentioned;
Try something like:
DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
float dpHeight = displayMetrics.heightPixels / displayMetrics.density;
float dpWidth = displayMetrics.widthPixels / displayMetrics.density;
OR
Try old answer:
Display display = getWindowManager().getDefaultDisplay();
DisplayMetrics outMetrics = new DisplayMetrics ();
display.getMetrics(outMetrics);
float density = getResources().getDisplayMetrics().density;
float dpHeight = outMetrics.heightPixels / density;
float dpWidth = outMetrics.widthPixels / density;

I stumbled upon this question from Google, and later on I found an easy solution valid for API >= 13.
For future references:
Configuration configuration = yourActivity.getResources().getConfiguration();
int screenWidthDp = configuration.screenWidthDp; //The current width of the available screen space, in dp units, corresponding to screen width resource qualifier.
int smallestScreenWidthDp = configuration.smallestScreenWidthDp; //The smallest screen size an application will see in normal operation, corresponding to smallest screen width resource qualifier.
See Configuration class reference
Edit: As noted by Nick Baicoianu, this returns the usable width/height of the screen (which should be the interesting ones in most uses). If you need the actual display dimensions stick to the top answer.

2023 Answer simplified for Kotlin:
val widthDp = resources.displayMetrics.run { widthPixels / density }
val heightDp = resources.displayMetrics.run { heightPixels / density }
As one-liner:
val (height, width) = resources.displayMetrics.run { heightPixels/density to widthPixels/density }
For Jetpack Compose:
val (height, width) = LocalConfiguration.current.run { screenHeightDp.dp to screenWidthDp.dp }

How about using this instead ?
final DisplayMetrics displayMetrics=getResources().getDisplayMetrics();
final float screenWidthInDp=displayMetrics.widthPixels/displayMetrics.density;
final float screenHeightInDp=displayMetrics.heightPixels/displayMetrics.density;

You are missing default density value of 160.
2 px = 3 dip if dpi == 80(ldpi), 320x240 screen
1 px = 1 dip if dpi == 160(mdpi), 480x320 screen
3 px = 2 dip if dpi == 240(hdpi), 840x480 screen
In other words, if you design you layout with width equal to 160dip in portrait mode, it will be half of the screen on all ldpi/mdpi/hdpi devices(except tablets, I think)

DisplayMetrics displayMetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
int width_px = Resources.getSystem().getDisplayMetrics().widthPixels;
int height_px =Resources.getSystem().getDisplayMetrics().heightPixels;
int pixeldpi = Resources.getSystem().getDisplayMetrics().densityDpi;
int width_dp = (width_px/pixeldpi)*160;
int height_dp = (height_px/pixeldpi)*160;

Answer in kotlin:
context?.let {
val displayMetrics = it.resources.displayMetrics
val dpHeight = displayMetrics.heightPixels / displayMetrics.density
val dpWidth = displayMetrics.widthPixels / displayMetrics.density
}

In the new world of Compose on one line
val (height, width) = LocalConfiguration.current.run { screenHeightDp.dp to screenWidthDp.dp }

Get Screen Width and Height in terms of DP with some good decoration:
Step 1: Create interface
public interface ScreenInterface {
float getWidth();
float getHeight();
}
Step 2: Create implementer class
public class Screen implements ScreenInterface {
private Activity activity;
public Screen(Activity activity) {
this.activity = activity;
}
private DisplayMetrics getScreenDimension(Activity activity) {
DisplayMetrics displayMetrics = new DisplayMetrics();
activity.getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
return displayMetrics;
}
private float getScreenDensity(Activity activity) {
return activity.getResources().getDisplayMetrics().density;
}
#Override
public float getWidth() {
DisplayMetrics displayMetrics = getScreenDimension(activity);
return displayMetrics.widthPixels / getScreenDensity(activity);
}
#Override
public float getHeight() {
DisplayMetrics displayMetrics = getScreenDimension(activity);
return displayMetrics.heightPixels / getScreenDensity(activity);
}
}
Step 3: Get width and height in activity:
Screen screen = new Screen(this); // Setting Screen
screen.getWidth();
screen.getHeight();

This is a copy/pastable function to be used based on the previous responses.
/**
* #param context
* #return the Screen height in DP
*/
public static float getHeightDp(Context context) {
DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
float dpHeight = displayMetrics.heightPixels / displayMetrics.density;
return dpHeight;
}
/**
* #param context
* #return the screnn width in dp
*/
public static float getWidthDp(Context context) {
DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
float dpWidth = displayMetrics.widthPixels / displayMetrics.density;
return dpWidth;
}

If you just want to know about your screen width, you can just search for "smallest screen width" in your developer options. You can even edit it.

Your problem is with casting the float to an int, losing precision. You should also multiply with the factor and not divide.
Do this:
int dp = (int)(pixel*getResources().getDisplayMetrics().density);

Programmatically set height on LayoutParams as density-independent pixels

Is there any way to set the height/width of a LayoutParams as density-independent pixels (dp)? It looks like the height/width, when set programmatically, are in pixels and not dp.

You need to convert your dip value into pixels:
int height = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, <HEIGHT>, getResources().getDisplayMetrics());
For me this does the trick.

public static int getDPI(int size, DisplayMetrics metrics){
return (size * metrics.densityDpi) / DisplayMetrics.DENSITY_DEFAULT;
}
Call the function like this,
DisplayMetrics metrics;
metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
int heigh = getDPI(height or width, metrics);

Since it may be used multiple times:
public static int convDpToPx(Context context, float dp) {
DisplayMetrics metrics = context.getResources().getDisplayMetrics();
return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, metrics);
}
I found it more practical to use the conversion rate, as usally more than one value has to be converted. Since the conversion rate does not change, it saves a bit of processing time.
/**
* Get conversion rate from dp into px.<br>
* E.g. to convert 100dp: px = (int) (100 * convRate);
* #param context e.g. activity
* #return conversion rate
*/
public static float convRateDpToPx(Context context) {
return context.getResources().getDisplayMetrics().densityDpi / 160f;
}

Here is my snippet:
public class DpiUtils {
public static int toPixels(int dp, DisplayMetrics metrics) {
return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, metrics);
}
}
where DisplayMetrics metrics = getResources().getDisplayMetrics()

The answered solution didn't work for me, the height of the view was still off. I ended up with this, which works well:
protected int dp2px(int dp){
final float scale = getResources().getDisplayMetrics().density;
return (int) (dp * scale + 0.5f);
}
And if you want the other way round, pixels to dp ...
protected float px2dp(float px){
DisplayMetrics metrics = Resources.getSystem().getDisplayMetrics();
float dp = px / (metrics.densityDpi / 160f);
return Math.round(dp);
}