Mobile App Development 2021W Lecture 18

Video

Video from the lecture given on March 22, 2021 is now available.

Code

MainActivity.kt

<syntaxhighlight lang="kotlin" line>

package carleton.comp1601.mar22

import androidx.appcompat.app.AppCompatActivity import android.os.Bundle import android.text.Editable import android.text.TextWatcher import android.widget.EditText import android.widget.ImageView

class MainActivity : AppCompatActivity() {

   private lateinit var p: ImageView
   private var r = 0F
   private var scale = 1F
   private lateinit var rotationInput: EditText
   private lateinit var scaleInput: EditText

   override fun onCreate(savedInstanceState: Bundle?) {
       super.onCreate(savedInstanceState)
       setContentView(R.layout.activity_main)
       if (savedInstanceState != null) {
           // do something
       }

       p = findViewById(R.id.mypic)
       rotationInput = findViewById(R.id.rotation)
       scaleInput = findViewById(R.id.scale)

       p.setImageResource(R.drawable.roshi)
       rotationInput.addTextChangedListener(rotationWatcher)
       scaleInput.addTextChangedListener(scaleWatcher)
       updateImage()
   }

   fun updateImage() {
       p.setX(0F)
       p.setY(0F)
       p.setRotation(r)
       p.setScaleX(scale)
       p.setScaleY(scale)
   }

   private val rotationWatcher = object : TextWatcher {
       override fun afterTextChanged(s: Editable) {
           val new_rS = rotationInput.getText().toString()
           val new_r = new_rS.toFloatOrNull()

           if (new_r != null) {
               r = new_r
               updateImage()
           }
       }

       override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
       }

       override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
       }
   }
   private val scaleWatcher = object : TextWatcher {
       override fun afterTextChanged(s: Editable) {
           val new_scaleS = rotationInput.getText().toString()
           val new_scale = new_scaleS.toFloatOrNull()

           if (new_scale != null) {
               if (new_scale > 1.5F) {
                   scale = 1.5F
               } else {
                   scale = new_scale
               }
               updateImage()
           }
       }

       override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
       }

       override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
       }
   }

} <syntaxhighlight>

activity_main.xml

<syntaxhighlight lang="xml" line> <?xml version="1.0" encoding="utf-8"?> <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"

   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".MainActivity">

   <LinearLayout
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       android:orientation="vertical">

       <EditText
           android:id="@+id/rotation"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:ems="10"
           android:inputType="numberDecimal" />

       <EditText
           android:id="@+id/scale"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:ems="10"
           android:inputType="numberDecimal" />

       <ImageView
           android:id="@+id/mypic"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           app:srcCompat="@drawable/kittens" />
   </LinearLayout>

</androidx.constraintlayout.widget.ConstraintLayout> <syntaxhighlight>