I am trying to set up a canvas to redraw whenever the user clicks a button. Whenever I trigger the redraw via invalidate() the app freezes and crashes. I am very new to android development so I am struggling to see what I neglecting. Any insight would be appriciated.
The relevent classes are included below.
Thanks,
mainactivity
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
fun submit(view: View) {
val text = findViewById<View>(R.id.editTextNumberDecimal) as EditText
val canvas = findViewById<View>(R.id.customCanvas) as CustomCanvas
val value = text.text.toString()
val t = findViewById<View>(R.id.textView) as TextView
t.text = value
canvas.setWeightandRedraw(value.toFloat())
}
}
canvas
class CustomCanvas : View {
constructor(context: Context) : this(context, null)
constructor(context: Context, attrs: AttributeSet?) : this(context, attrs, 0)
constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr) {
}
var weight: Float = 0.0f;
override fun onDraw(canvas: Canvas?) {
drawBar(canvas);
drawWeightKg(canvas, this.weight)
}
fun setWeightandRedraw(_weight: Float) {
weight = _weight;
invalidate();
}
fun drawBar(canvas: Canvas?) {
.........
}
fun drawWeightKg(canvas: Canvas?, weight: Float) {
.........
}
}
Moving invalidate() to onDraw() appeard to fix this.
override fun onDraw(canvas: Canvas?) {
drawBar(canvas);
drawWeightKg(canvas, this.weight)
invalidate();
}
Related
I assume I'm missing something simple, but I can't seem to get joystick actions (X,Y,Z,RZ) from a game pad using View.OnGenericMotionListener in Android API 30. I followed an example (I thought) but joystick motions are undetected. If I replace OnGenericMotionListener and my onGenericMotion functions with OnTouchListener and onTouch I see exactly what I would expect from touches of the touchpad. In the code below I have reduced to a minimum to see the issue. With joystick = BasicMotion I do not get my debug log messages- I only get
I/ViewRootImpl#cc64931[MainActivity]: ViewPostIme key 1
If I change to joystick = BasicTouch I get my debug log.
What am I missing to get input from a game pad? main_activity and BasicMotion/BasicTouch classes below. Also note if I add the onGenericMotionEvent function to MainActivity, then I see joystick inputs there, so I know the game pad is working. Code is in Kotlin, but I'd be happy with a java solution.
class MainActivity : AppCompatActivity(){
override fun onCreate(savedInstanceState: Bundle?) {
// val joystick = BasicMotion(this)
val joystick = BasicTouch(this)
setContentView(joystick)
super.onCreate(savedInstanceState)
}
}
BasicMotion class:
class BasicMotion : SurfaceView, SurfaceHolder.Callback, View.OnGenericMotionListener {
constructor(context: Context?) : super(context) {
holder.addCallback(this)
setOnGenericMotionListener(this)
}
constructor(context: Context?, attributes: AttributeSet?) : super(context, attributes) {
holder.addCallback(this)
setOnGenericMotionListener(this)
}
constructor(context: Context?, attributes: AttributeSet?, style: Int) : super(
context, attributes, style
) {
holder.addCallback(this)
setOnGenericMotionListener(this)
}
override fun surfaceCreated(holder: SurfaceHolder) {}
override fun surfaceChanged(holder: SurfaceHolder, format: Int, width: Int, height: Int) {}
override fun surfaceDestroyed(holder: SurfaceHolder) {}
override fun onGenericMotion(v: View, event: MotionEvent): Boolean {
Log.d("Debug Motion", "detected")
return true
}
}
Equivalent BasicTouch class:
class BasicTouch : SurfaceView, SurfaceHolder.Callback, View.OnTouchListener {
constructor(context: Context?) : super(context) {
holder.addCallback(this)
setOnTouchListener(this)
}
constructor(context: Context?, attributes: AttributeSet?) : super(context, attributes) {
holder.addCallback(this)
setOnTouchListener(this)
}
constructor(context: Context?, attributes: AttributeSet?, style: Int) : super(
context, attributes, style
) {
holder.addCallback(this)
setOnTouchListener(this)
}
override fun surfaceCreated(holder: SurfaceHolder) {}
override fun surfaceChanged(holder: SurfaceHolder, format: Int, width: Int, height: Int) {}
override fun surfaceDestroyed(holder: SurfaceHolder) {}
override fun onTouch(v: View, event: MotionEvent): Boolean {
Log.d("Debug Touch", "detected")
return true
}
}
In Android UI, we can create a custom view by overloading View as shown below.
class CustomView #JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0)
: View(context, attrs, defStyleAttr) {
override fun onDraw(canvas: Canvas) {
super.onDraw(canvas)
// Perform the needing drawing
if (isAttachedToWindow) invalidate()
}
override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec)
val desiredWidth = suggestedMinimumWidth + paddingLeft + paddingRight
val desiredHeight = suggestedMinimumHeight + paddingTop + paddingBottom
setMeasuredDimension(View.resolveSize(desiredWidth, widthMeasureSpec),
View.resolveSize(desiredHeight, heightMeasureSpec))
}
}
Can we wrap JetpackCompose in this CustomView, so that the underlying Drawing it using JetpackCompose instead?
I check https://developer.android.com/jetpack/compose/interop/interop-apis, don't seems to have it stated.
To get it to work, we can have
class CustomComposeView #JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) : AbstractComposeView(context, attrs, defStyleAttr) {
#Composable
override fun Content() {
// JetpacCompose code here
}
}
In the XML, we can have something like this
<com.package.CustomComposeView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="700dp" />
I have a Custom EditTextClass that Im using for all EditTexts on my App -
Class CustomEditText : EditText {
...
}
I want to change the background image, so that it should be reflected in all the usages of this CustomEditText.
I tried this -
override fun onDraw(canvas: Canvas ? ) {
val d = AppCompatResources.getDrawable(mContext!!, R.drawable.new_drawable)
d?.draw(canvas!!)
super.onDraw(canvas)
}
and this -
fun init(context: Context ? , attrs : AttributeSet ? ) {
background = ResourcesCompat.getDrawable(context!!.getResources(), R.drawable.new_drawable, null)
setBackground(background)
}
Both the ways, don't work. Can anyone tell me what is the correct solution ?
You need to setBounds to drawable when draw drawable.
So you should make your draw method like this.
override fun onDraw(canvas: Canvas? ) {
val d = AppCompatResources.getDrawable(context!!, R.drawable.new_drawable)
d?.setBounds(0, 0, width, height)
d?.draw(canvas!!)
super.onDraw(canvas)
}
First draw to canvas and pass the canvas to parent meaning super.onDraw should be at bottom
override fun onDraw(canvas: Canvas ? ) {
val d = AppCompatResources.getDrawable(mContext!!, R.drawable.new_drawable)
d?.draw(canvas!!)
super.onDraw(canvas)
}
In my opinion, you should not override onDraw method as this could cause issues when super.onDraw(canvas) is called before your operations (your drawable could cover the text, hits, drawable elements, etc.).
I've made a demo, which worked for me:
class CustomEditText : AppCompatEditText {
constructor(context: Context) : super(context) {
init()
}
constructor(context: Context, attrs: AttributeSet?) : super(context, attrs) {
init()
}
constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(context,
attrs,
defStyleAttr) {
init()
}
private fun init() {
setBackgroundResource(R.drawable.new_drawable)
}
}
How to save scroll state of scrollview properly.In my code, I'm using :
scroll_x = scrollView.getScrollX();
scroll_y = scrollView.getScrollY();
when activity pause,i'm stored x and y as you can see here, and when activity start, i'm scroll scrollView to x and y.
But crux is (main problem) is, scrollview not scrollview to x and y properly, it scroll up or down a little bit automatically. How to fix it?
You can manage the instance state by using this class:
class SaveScrollNestedScrollViewer : NestedScrollView {
constructor(context: Context) : super(context)
constructor(context: Context, attributes: AttributeSet) : super(context, attributes)
constructor(context: Context, attributes: AttributeSet, defStyleAttr: Int) : super(context, attributes, defStyleAttr)
public override fun onSaveInstanceState(): Parcelable? {
return super.onSaveInstanceState()
}
public override fun onRestoreInstanceState(state: Parcelable?) {
super.onRestoreInstanceState(state)
}
}
use on your xml:
<yourClassNamePlace.SaveScrollNestedScrollViewer
android:id="#+id/my_scroll_viewer"
android:layout_width="match_parent"
android:layout_height="match_parent">
</yourClassNamePlace.SaveScrollNestedScrollViewer>
and then use in activity like this:
class MyActivity : AppCompatActivity() {
companion object {
var myScrollViewerInstanceState: Parcelable? = null
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.my_activity)
if (myScrollViewerInstanceState != null) {
my_scroll_viewer.onRestoreInstanceState(myScrollViewerInstanceState)
}
}
public override fun onPause() {
super.onPause()
myScrollViewerInstanceState = my_scroll_viewer.onSaveInstanceState()
}
}
I want to use a centered spinner where the width of the spinner is only as wide as the selected item text. From my research it seems that this is not natively supported out of the box with an attribute so I found another StackOverflow question/answer and tried implementing that but ran into some issues with it.
So I took option 1 from this SO response and implemented it in Kotlin and It's not working for me
class DynamicWidthSpinner #JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) : AppCompatSpinner(context, attrs, defStyleAttr) {
override fun setAdapter(adapter: SpinnerAdapter?) {
super.setAdapter(if (adapter != null) WrapperSpinnerAdapter(adapter) else null)
}
inner class WrapperSpinnerAdapter(val baseAdapter: SpinnerAdapter) : SpinnerAdapter {
override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
return baseAdapter.getView(selectedItemPosition, convertView, parent)
}
override fun getDropDownView(position: Int, convertView: View?, parent: ViewGroup): View {
return baseAdapter.getDropDownView(position, convertView, parent)
}
override fun getCount(): Int = baseAdapter.count
override fun getItem(position: Int): Any = baseAdapter.getItem(position)
override fun getItemId(position: Int): Long = baseAdapter.getItemId(position)
override fun getItemViewType(position: Int): Int = baseAdapter.getItemViewType(position)
override fun getViewTypeCount(): Int = baseAdapter.viewTypeCount
override fun hasStableIds(): Boolean = baseAdapter.hasStableIds()
override fun isEmpty(): Boolean = baseAdapter.isEmpty
override fun registerDataSetObserver(observer: DataSetObserver) {
baseAdapter.registerDataSetObserver(observer)
}
override fun unregisterDataSetObserver(observer: DataSetObserver) {
baseAdapter.unregisterDataSetObserver(observer)
}
}
}
and in my MainActivity I'm doing this from onCreate
val spinner: DynamicWidthSpinner = findViewById(R.id.global_toolbar_location_spinner)
val tempLocationList = ArrayList<String>()
tempLocationList.add("Test1")
tempLocationList.add("Much longer test string 2")
spinner.adapter = ArrayAdapter(
this,
R.layout.global_toolbar_spinner_item,
tempLocationList
)
spinner.onItemSelectedListener = object : OnItemSelectedListener {
override fun onItemSelected(parent: AdapterView<*>, view: View, position: Int, arg3: Long) {
// TODO: do stuff on selection here
}
override fun onNothingSelected(arg0: AdapterView<*>) {
// TODO: do nothing... yet
}
}
spinner.setSelection(0)
and I am using my custom Spinner in the layout xml (ommitting everything else that is not necessary because I am able to get it work just fine using the native <Spinner> or androidx compat Spinner
<com.blablabla.app.ui.DynamicWidthSpinner
android:id="#+id/global_toolbar_location_spinner"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:spinnerMode="dialog"
/>
What I see is just the first item "Test1" and nothing happens when I tap on it and arrow seems to have disappeared now as well
I figured out the issue. Turns out that this is one of those cases where the #JvmOverloads doesn't work. Once I converted it to the multiple constructor kotlin syntax it worked without a problem
class DynamicWidthSpinner : AppCompatSpinner {
constructor(context: Context) : super(context)
constructor(context: Context, attrs: AttributeSet?) : super(context, attrs)
constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr)
...
}