View source for Mobile App Development 2021W Lecture 18

==Video==

Video from the lecture given on March 22, 2021 [https://homeostasis.scs.carleton.ca/~soma/mad-2021w/lectures/comp1601-2021w-lec18-20210322.m4v 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>