Android development scratch pad

AndroidDeveloperCheetSheet.kt

// Load image from assets folder
val tile = BitmapFactory.decodeStream(resources.assets.open("filename.png"), null, options)

// The amount canvas is scaling resource images (res/drawables) 
var metrics = DisplayMetrics()
windowManager.defaultDisplay.getMetrics(metrics)
val logicalDensity = metrics.density

// These options will scale bitmaps to fit your screen pixel density
var options = BitmapFactory.Options()
options.inDensity = DisplayMetrics.DENSITY_DEFAULT
options.inTargetDensity = DisplayMetrics.DENSITY_DEVICE_STABLE;
options.inScaled = true

// Multidirectional scrollview

class MDScrollView @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0) : HorizontalScrollView(context, attrs, defStyleAttr)
{
    var scrollView : ScrollView? = null
    override fun onTouchEvent(event: MotionEvent?): Boolean {
        super.onTouchEvent(event)
        scrollView!!.onTouchEvent(event)
        return true
    }
    override fun onInterceptTouchEvent(ev: MotionEvent?): Boolean {
        super.onInterceptTouchEvent(ev)
        scrollView!!.onInterceptTouchEvent(ev)
        return true
    }
}

// Activity
override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
  val hv = MDScrollView(this)
  val sv = ScrollView(this)
  hv.scrollView = sv  
  addView(hv,ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT))
  hv.addView(sv, ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT))
}

//load json file as string
fun loadJSONAsset(file: String, context: Context): String? {
  var json: String? = null
  try {
      val stream = context.getAssets().open(file)
      val size = stream.available()
      val buffer = ByteArray(size)
      stream.read(buffer)
      stream.close()
      json = String(buffer, Charset.defaultCharset())
  } catch (ex: IOException) {
      ex.printStackTrace()
      return null
  }
  return json
}