Change the system display size programatically Android N

问题

Background: Android N comes with a feature to change system Display Size from settings, in addition to the previously present feature of changing Font Size.

Change Display Size:

Image Source: pcmag.com

Question:

If an app has android.permission.WRITE_SETTINGS permission to change the settings, there are ways to change the system font size programatically as mentioned in How to programmatically change font settings of Device: font style and font size?. However I couldn't find a way to change the display size programatically. Is it possible?

What I've tried?

I've checked the possible options in the list of Settings.System convenience functions provided for changing settings programatically.

Update:

I've opened a feature request for the same here: https://code.google.com/p/android/issues/detail?id=214124 . If you feel it would be useful please star it.

Thanks for your help in advance!

回答1:

While referring Settings.System , there is a [putConfiguration(ContentResolver cr, Configuration config)](https://developer.android.com/reference/android/provider/Settings.System.html#putConfiguration(android.content.ContentResolver, android.content.res.Configuration)) method. Use of this method is:

Convenience function to write a batch of configuration-related settings from a Configuration object.

In Configuration

This includes both user-specified configuration options (locale list and scaling) as well as device configurations (such as input modes, screen size and screen orientation).

Set configuration with SCREENLAYOUT_SIZE_MASK values for screen size. It is:

The SCREENLAYOUT_SIZE_MASK bits define the overall size of the screen. They may be one of SCREENLAYOUT_SIZE_SMALL, SCREENLAYOUT_SIZE_NORMAL, SCREENLAYOUT_SIZE_LARGE, or SCREENLAYOUT_SIZE_XLARGE.

I hope its helps you.

回答2:

In manifest, under application: android:configChanges="density"

In an activity/application:

public void adjustDisplayScale(Configuration configuration) {
    if (configuration != null) {
        Log.d("TAG", "adjustDisplayScale: " + configuration.densityDpi);
        if(configuration.densityDpi >= 485) //for 6 inch device OR for 538 ppi
            configuration.densityDpi = 500; //decrease "display size" by ~30
        else if(configuration.densityDpi >= 300) //for 5.5 inch device OR for 432 ppi
            configuration.densityDpi = 400; //decrease "display size" by ~30
        else if(configuration.densityDpi >= 100) //for 4 inch device OR for 233 ppi
            configuration.densityDpi = 200; //decrease "display size" by ~30
        DisplayMetrics metrics = getResources().getDisplayMetrics();
        WindowManager wm = (WindowManager) getSystemService(WINDOW_SERVICE);
        wm.getDefaultDisplay().getMetrics(metrics);
        metrics.scaledDensity = configuration.densityDpi * metrics.density;
        this.getResources().updateConfiguration(configuration, metrics);
    }
}

Call it just after super.onCreate(..):

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    adjustDisplayScale( getResources().getConfiguration());

This will set the Display Size in-between the "Smaller" and "Small" settings of "Display Size" overriding any Display Size settings set by user. It self-adjusts correctly for 4in, 5.5in, 6in etc devices.. but I'm sure there would a better way than using those if statements.

来源：https://stackoverflow.com/questions/37996601/change-the-system-display-size-programatically-android-n

标签

android

android-settings

android-7.0-nougat