Dotted line is actually not dotted when app is running on real Android device

Question

in my app I use XML defined vertical dotted line.

<?xml version="1.0" encoding="utf-8"?>
<rotate xmlns:android="http://schemas.android.com/apk/res/android"
    android:fromDegrees="90"
    android:toDegrees="90">
<shape

    android:shape="line">
    <stroke

        android:width="1dp"
        android:color="@color/light_gray"
        android:dashWidth="2dp"
        android:dashGap="4dp"
        />
</shape>

When I am nitpicking my layout in Android Studio, the line is rendered properly dotted, as it should, but problem comes out when I run the app on real device. The line is just solid with no gaps..Do you know where could be the problem? I tried many different devices including those running latest 4.3 Android..It look everywhere the same:/

Answer 1

This is most likely related to hardware acceleration: Dashed lines are not supported in GL mode.

Its documented here: https://code.google.com/p/android/issues/detail?id=29944

Turn off your HW-acceleration in your AndroidManifest.xml like this:

android:hardwareAccelerated="false"

or:

myView.setLayerType(View.LAYER_TYPE_SOFTWARE, null) 

For more information how to use first solution: http://developer.android.com/guide/topics/graphics/hardware-accel.html

Answer 2

Controlling Hardware Acceleration

You can control hardware acceleration at the following levels:

• Application

• Activity

• Window

• View

Application level

<application android:hardwareAccelerated="true" ...>

Activity level

<application android:hardwareAccelerated="true">
    <activity ... />
    <activity android:hardwareAccelerated="false" />
</application>

Window level

getWindow().setFlags(
    WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED,
    WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED);

View level

myView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);

Reference

Answer 3

I found a same solution but in View attributes (xml):

        <View
        android:layout_width="wrap_content"
        android:layout_height="4dp"
        ...
        android:layerType="software"/>

I suppose it's a View level as said above. Other variants for attribute ("none" and of course "hardware") didn't work for me.