How to simply create a custom view without duplicate LinearLayout?

How to simply create a custom view without duplicate LinearLayout? - android

The simplest way I found to create a custom view, so I don't have to handle annoying things like to override the onLayout() method, is to make it inherit from a LinearLayout. I also have a LinearLayout at the root of the associated XML file that I inflate, so there is 2 of them at the root.
How can I optimise this, by removing one of this extra LinearLayout, but keep it simple to create custom views ?
MyToolbar.kt:
class MyToolbar #JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) :
LinearLayoutCompat(context, attrs, defStyleAttr) {
private val binding = MyToolbarBinding.inflate(LayoutInflater.from(context), this, true)
init {
// [...] Initialization of my view ...
}
}
my_toolbar.xml:
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_vertical"
android:orientation="horizontal">
<!-- Actual content of my view -->
</LinearLayout>

What I have right now after #Pawel and #Cata suggestion. This doesn't work, the LinearLayout use the whole height of the parent, but it should only wrap its content.
MyToolbar.kt:
class MyToolbar #JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) :
LinearLayoutCompat(context, attrs, defStyleAttr) {
private val binding
init {
// Tried to add the attributes here as they seems ignored on the `merge` tag
gravity = Gravity.CENTER_VERTICAL
orientation = HORIZONTAL
layoutParams = LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT)
binding = MyToolbarBinding.inflate(LayoutInflater.from(context), this)
// [...] Initialization of the view ...
}
}
my_toolbar.xml:
<merge
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_vertical"
android:orientation="horizontal">
<!-- Actual content of the view -->
</merge>

As Pawel suggested you could use merge to do that.
This is a sample from the developer website:
<merge xmlns:android="http://schemas.android.com/apk/res/android">
<!-- Here you can add your custom content views.. -->
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="#string/add"/>
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="#string/delete"/>
</merge>

Related

How to fill item width children in reyclerview android

Hey I am working in android. I want to fit children in whole view of recyclerview android. I have horizontal recylerview. I will show what I want in diagram.
Scenario 1
when I have more item in recyclerview, I want to show children like this in my recycler view.
Expected Output
Scenario 2
when I have three item I want to show like this. It will fill whole view in reyclerview.
Expected Output
Scenario 3
When I have Two item in reyclerview, I need to look like this
Expected Output
The problem I am getting that I have 3 item, the view is not filling fully. Actually I want to stretch whole view to full width like Scenario 2.
Actual output
item_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="10dp"
android:orientation="vertical">
<LinearLayout
android:id="#+id/container"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:background="#drawable/drawable_selector"
android:orientation="vertical">
<TextView
android:id="#+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="10dp" />
<TextView
android:id="#+id/subText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginEnd="10dp"
android:layout_marginBottom="10dp" />
</LinearLayout>
<RelativeLayout
android:id="#+id/tagContainer"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:visibility="gone">
<TextView
android:id="#+id/tagText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:paddingStart="10dp"
android:paddingEnd="10dp" />
</RelativeLayout>
</FrameLayout>
UPDATE
after #Cheticamp suggestion I did this code
companion object {
fun bindView(parent: ViewGroup): XYZViewHolder {
val view = XyzLayoutBinding.inflate(
LayoutInflater.from(parent.context),
parent,
false
)
val lp = view.container.layoutParams
lp.width = parent.measuredWidth / 3
return OptionsViewHolder(
view
)
}
}
As you can see my last item is cut from the end.
I think in my framelayout i Used marginEnd 10 dp is it causing issue? please refer my layout if you need more. And one more thing I didn't divide framelayout instead I take linear layout as container. I am adding my github link.

You can change the width of the RecyclerView item views in onCreateViewHolder(). The ViewGroup parent is the RecyclerView.
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
val view = LayoutInflater.from(parent.context).inflate(R.layout.item_view, parent, false)
val lp = view.layoutParams
// Change the width of the item view here
lp.width = parent.measuredWidth / 3 // width is 1/3 of the width of the RecyclerView
return ItemViewHolder(view)
}

Customize frameLayout class
make a class inherit FrameLayout or another layout you use.
public class SquareFrameLayout extends FrameLayout {
public SquareFrameLayout(#NonNull Context context) {
super(context);
}
public SquareFrameLayout(#NonNull Context context, #Nullable AttributeSet attrs) {
super(context, attrs);
}
public SquareFrameLayout(#NonNull Context context, #Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
public SquareFrameLayout(#NonNull Context context, #Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, widthMeasureSpec);
}
}
onMeasure method is important.
then change root layout item recyclerView to SquareFrameLayout (The class built now)
like this:
<com.example.app.SquareFrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#drawable/background_rv_item"
android:orientation="vertical"
android:padding="16dp"
android:layout_margin="4dp"
xmlns:tools="http://schemas.android.com/tools">
//your items
</com.example.app.SquareFrameLayout>

You can use flexbox-layout library provided by Google.
You can adjust the items according to your need.
Download the app and see this demo working for you or not. https://github.com/google/flexbox-layout

TextView in a custom view is not switching text color in night mode

Using:
com.google.android.material:material:1.4.0
If I have a layout xml file in a fragment/activity with a TextView:
<TextView
style="#style/TextAppearance.MaterialComponents.Body1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
If I go between light/dark mode the text color switches appropriately.
However if I create a custom view:
class MyView #JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyle: Int = 0,
defStyleRes: Int = 0
) : LinearLayout(context, attrs, defStyle, defStyleRes) { ... }
And that view contains the same textview, the text color does not change in night mode.
I initialize the view from a fragment:
new MyView(this.getActivity().getBaseContext());
I have also tried to directly apply the base theme:
new MyView(this.getActivity().getBaseContext(), null, R.id.AppTheme);
In addition for some strange reason I can work around this issue by creating my own text colors in the appropriate light/dark folders and that picks up the change between light/dark:
<TextView
style="#style/TextAppearance.MaterialComponents.Body1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#color/my_text_color" />

Turns out I was passing the wrong context.
When creating the view:
new MyView(this.getActivity().getBaseContext());
Should be:
new MyView(this.getActivity());

How to decorate the camer preview during barcode scanning?

I want to create a barcode scanner activity, I found this nice tutorial:
http://www.devexchanges.info/2016/10/reading-barcodeqr-code-using-mobile.html
How can I decorate the preview image with detected area (with dots or rectangle).

Put another transparent view on top of your SurfaceView and draw on that. B oth views will loosely coupled, so there is some math involved in getting it right to match the decoration with the camera output.
So in your activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="16dp">
<SurfaceView
android:id="#+id/surface_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true" />
<com.yourApp.YourDecoratorView
android:id="#+id/decorator_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true" />
...
</RelativeLayout>
And then, create a custom view:
class YourDecoratorView #JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) : View(context, attrs, defStyleAttr) {
... initializing code
override fun onDraw(canvas: Canvas?) {
super.onDraw(canvas)
// your code
canvas?.drawLine(0f, 0f, 0f, paint)
}
}
If it is just static visuals you want to show, use an ImageView instead of a custom view and create the drawable you want.

Kotlin Custom View referencing textview returns null

I have a Custom view:
class CustomerView(context: Context, attrs: AttributeSet) : LinearLayout(context, attrs) {
private var txtName: TextView
private var txtAge: TextView
init {
View.inflate(context, R.layout.view_customer, null)
txtName = findViewById(R.id.txtTestName)
txtAge = findViewById(R.id.txtTestAge)
txtName.text = "Person"
txtAge.text = "61"
}
}
My Layout view_customer looks like this:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="#+id/txtTestName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="name" />
<TextView
android:id="#+id/txtTestAge"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="age" />
</LinearLayout>
however when I call it in my other page, the app crashes saying
Caused by: java.lang.IllegalStateException:
findViewById(R.id.txtTestName) must not be null
at com.helcim.helcimcommercemobile.customviews.CustomerView.(CustomerView.kt:19)
which is when I am trying to assign txtName
I don't really understand how it is null when I have it in the layout view. and it is named the same.
Am I creating a custom view incorrectly?

You have to add parent layout as parameter to 'inflate' method.
class CustomerView(context: Context, attrs: AttributeSet) : LinearLayout(context, attrs) {
private var txtName: TextView
private var txtAge: TextView
init {
View.inflate(context, R.layout.view_customer, this)
txtName = findViewById(R.id.txtTestName)
txtAge = findViewById(R.id.txtTestAge)
txtName.text = "Derek"
txtAge.text = "23"
}
}

Create a custom View by inflating a layout?

I am trying to create a custom View that would replace a certain layout that I use at multiple places, but I am struggling to do so.
Basically, I want to replace this:
<RelativeLayout
android:id="#+id/dolphinLine"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:background="#drawable/background_box_light_blue"
android:padding="10dip"
android:layout_margin="10dip">
<TextView
android:id="#+id/dolphinTitle"
android:layout_width="200dip"
android:layout_height="100dip"
android:layout_alignParentLeft="true"
android:layout_marginLeft="10dip"
android:text="#string/my_title"
android:textSize="30dip"
android:textStyle="bold"
android:textColor="#2E4C71"
android:gravity="center"/>
<Button
android:id="#+id/dolphinMinusButton"
android:layout_width="100dip"
android:layout_height="100dip"
android:layout_toRightOf="#+id/dolphinTitle"
android:layout_marginLeft="30dip"
android:text="#string/minus_button"
android:textSize="70dip"
android:textStyle="bold"
android:gravity="center"
android:layout_marginTop="1dip"
android:background="#drawable/button_blue_square_selector"
android:textColor="#FFFFFF"
android:onClick="onClick"/>
<TextView
android:id="#+id/dolphinValue"
android:layout_width="100dip"
android:layout_height="100dip"
android:layout_marginLeft="15dip"
android:background="#android:drawable/editbox_background"
android:layout_toRightOf="#+id/dolphinMinusButton"
android:text="0"
android:textColor="#2E4C71"
android:textSize="50dip"
android:gravity="center"
android:textStyle="bold"
android:inputType="none"/>
<Button
android:id="#+id/dolphinPlusButton"
android:layout_width="100dip"
android:layout_height="100dip"
android:layout_toRightOf="#+id/dolphinValue"
android:layout_marginLeft="15dip"
android:text="#string/plus_button"
android:textSize="70dip"
android:textStyle="bold"
android:gravity="center"
android:layout_marginTop="1dip"
android:background="#drawable/button_blue_square_selector"
android:textColor="#FFFFFF"
android:onClick="onClick"/>
</RelativeLayout>
By this:
<view class="com.example.MyQuantityBox"
android:id="#+id/dolphinBox"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:myCustomAttribute="#string/my_title"/>
So, I do not want a custom layout, I want a custom View (it should not be possible for this view to have child).
The only thing that could change from one instance of a MyQuantityBox to another is the title. I would very much like to be able to specify this in the XML (as I do on the last XML line)
How can I do this? Should I put the RelativeLayout in a XML file in /res/layout and inflate it in my MyBoxQuantity class? If yes how do I do so?
Thanks!

A bit old, but I thought sharing how I'd do it, based on chubbsondubs' answer:
I use FrameLayout (see Documentation), since it is used to contain a single view, and inflate into it the view from the xml.
Code following:
public class MyView extends FrameLayout {
public MyView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initView();
}
public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
initView();
}
public MyView(Context context) {
super(context);
initView();
}
private void initView() {
inflate(getContext(), R.layout.my_view_layout, this);
}
}

Here is a simple demo to create customview (compoundview) by inflating from xml
attrs.xml
<resources>
<declare-styleable name="CustomView">
<attr format="string" name="text"/>
<attr format="reference" name="image"/>
</declare-styleable>
</resources>
CustomView.kt
class CustomView #JvmOverloads constructor(context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0) :
ConstraintLayout(context, attrs, defStyleAttr) {
init {
init(attrs)
}
private fun init(attrs: AttributeSet?) {
View.inflate(context, R.layout.custom_layout, this)
val image_thumb = findViewById<ImageView>(R.id.image_thumb)
val text_title = findViewById<TextView>(R.id.text_title)
val ta = context.obtainStyledAttributes(attrs, R.styleable.CustomView)
try {
val text = ta.getString(R.styleable.CustomView_text)
val drawableId = ta.getResourceId(R.styleable.CustomView_image, 0)
if (drawableId != 0) {
val drawable = AppCompatResources.getDrawable(context, drawableId)
image_thumb.setImageDrawable(drawable)
}
text_title.text = text
} finally {
ta.recycle()
}
}
}
custom_layout.xml
We should use merge here instead of ConstraintLayout because
If we use ConstraintLayout here, layout hierarchy will be ConstraintLayout->ConstraintLayout -> ImageView + TextView => we have 1 redundant ConstraintLayout => not very good for performance
<?xml version="1.0" encoding="utf-8"?>
<merge 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"
tools:parentTag="android.support.constraint.ConstraintLayout">
<ImageView
android:id="#+id/image_thumb"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
tools:ignore="ContentDescription"
tools:src="#mipmap/ic_launcher" />
<TextView
android:id="#+id/text_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="#id/image_thumb"
app:layout_constraintStart_toStartOf="#id/image_thumb"
app:layout_constraintTop_toBottomOf="#id/image_thumb"
tools:text="Text" />
</merge>
Using
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<your_package.CustomView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#f00"
app:image="#drawable/ic_android"
app:text="Android" />
<your_package.CustomView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#0f0"
app:image="#drawable/ic_adb"
app:text="ADB" />
</LinearLayout>
Result
See full code on:
Github

Yes you can do this. RelativeLayout, LinearLayout, etc are Views so a custom layout is a custom view. Just something to consider because if you wanted to create a custom layout you could.
What you want to do is create a Compound Control. You'll create a subclass of RelativeLayout, add all our your components in code (TextView, etc), and in your constructor you can read the attributes passed in from the XML. You can then pass that attribute to your title TextView.
http://developer.android.com/guide/topics/ui/custom-components.html

Use the LayoutInflater as I shown below.
public View myView() {
View v; // Creating an instance for View Object
LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = inflater.inflate(R.layout.myview, null);
TextView text1 = v.findViewById(R.id.dolphinTitle);
Button btn1 = v.findViewById(R.id.dolphinMinusButton);
TextView text2 = v.findViewById(R.id.dolphinValue);
Button btn2 = v.findViewById(R.id.dolphinPlusButton);
return v;
}

In practice, I have found that you need to be a bit careful, especially if you are using a bit of xml repeatedly. Suppose, for example, that you have a table that you wish to create a table row for each entry in a list. You've set up some xml:
In my_table_row.xml:
<?xml version="1.0" encoding="utf-8"?>
<TableRow xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent" android:id="#+id/myTableRow">
<ImageButton android:src="#android:drawable/ic_menu_delete" android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="#+id/rowButton"/>
<TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:textAppearance="?android:attr/textAppearanceMedium" android:text="TextView" android:id="#+id/rowText"></TextView>
</TableRow>
Then you want to create it once per row with some code. It assume that you have defined a parent TableLayout myTable to attach the Rows to.
for (int i=0; i<numRows; i++) {
/*
* 1. Make the row and attach it to myTable. For some reason this doesn't seem
* to return the TableRow as you might expect from the xml, so you need to
* receive the View it returns and then find the TableRow and other items, as
* per step 2.
*/
LayoutInflater inflater = (LayoutInflater)getBaseContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View v = inflater.inflate(R.layout.my_table_row, myTable, true);
// 2. Get all the things that we need to refer to to alter in any way.
TableRow tr = (TableRow) v.findViewById(R.id.profileTableRow);
ImageButton rowButton = (ImageButton) v.findViewById(R.id.rowButton);
TextView rowText = (TextView) v.findViewById(R.id.rowText);
// 3. Configure them out as you need to
rowText.setText("Text for this row");
rowButton.setId(i); // So that when it is clicked we know which one has been clicked!
rowButton.setOnClickListener(this); // See note below ...
/*
* To ensure that when finding views by id on the next time round this
* loop (or later) gie lots of spurious, unique, ids.
*/
rowText.setId(1000+i);
tr.setId(3000+i);
}
For a clear simple example on handling rowButton.setOnClickListener(this), see Onclicklistener for a programmatically created button.

There are multiple answers which point the same way in different approaches, I believe the below is the simplest approach without using any third-party libraries, even you can use it using Java.
In Kotlin;
Create values/attr.xml
<resources>
<declare-styleable name="DetailsView">
<attr format="string" name="text"/>
<attr format="string" name="value"/>
</declare-styleable>
</resources>
Create layout/details_view.xml file for your view
<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="#+id/text_label"
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_weight="0.5"
tools:text="Label" />
<TextView
android:id="#+id/text_value"
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_weight="0.5"
tools:text="Value" />
</LinearLayout>
</merge>
Create the custom view widget DetailsView.kt
import android.content.Context
import android.content.res.TypedArray
import android.util.AttributeSet
import android.view.View
import android.widget.LinearLayout
import android.widget.TextView
import com.payable.taponphone.R
class DetailsView #JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) : LinearLayout(context, attrs, defStyleAttr) {
private val attributes: TypedArray = context.obtainStyledAttributes(attrs, R.styleable.DetailsView)
private val view: View = View.inflate(context, R.layout.details_view, this)
init {
view.findViewById<TextView>(R.id.text_label).text = attributes.getString(R.styleable.DetailsView_text)
view.findViewById<TextView>(R.id.text_value).text = attributes.getString(R.styleable.DetailsView_value)
}
}
That's it now you can call the widget anywhere in your app as below
<com.yourapp.widget.DetailsView
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:text="Welcome"
app:value="Feb" />

A simple Custom View using Kotlin
Replace FrameLayout with whatever view you Like to extend
/**
* Simple Custom view
*/
class CustomView#JvmOverloads
constructor(context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0)
: FrameLayout(context, attrs, defStyleAttr) {
init {
// Init View
val rootView = (getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater)
.inflate(R.layout.custom_layout, this, true)
val titleView= rootView.findViewById(id.txtTitle)
// Load Values from XML
val attrsArray = getContext().obtainStyledAttributes(attrs, R.styleable.CutsomView, defStyleAttr, 0)
val titleString = attrsArray.getString(R.styleable.cutomAttrsText)
attrsArray.recycle()
}
}

Develop Reference

The Android operating system is a mobile operating system that was developed by Google (GOOGL?) to be primarily used for touchscreen devices, cell phones, and tablets.

How to simply create a custom view without duplicate LinearLayout? - android

Related

How to fill item width children in reyclerview android

TextView in a custom view is not switching text color in night mode

How to decorate the camer preview during barcode scanning?

Kotlin Custom View referencing textview returns null

Create a custom View by inflating a layout?

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