Develop Reference

Android custom attributes with data binding

I have a big library of custom components that I want to use in my Android app.
All components use custom attributes to customize its content.
This is a sample component declared in a XML file:
<myapp.CustomTextView
android:id="#+id/text_view_1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="25dp"
android:layout_marginRight="25dp"
android:layout_marginBottom="8dp"
custom:textContent="This is my text" />
This is the custom attributed declared:
<declare-styleable name="CustomTextView">
<attr name="textContent" format="string" />
</declare-styleable>
And this is the implementation of the custom component:
public class CustomTextView extends TextView {
private Context context;
public CustomTextView(Context context) {
this(context, null);
}
public CustomTextView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public CustomTextView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
readAttrs(context, attrs);
}
private void readAttrs(Context context, AttributeSet attrs) {
TypedArray array = context.getTheme().obtainStyledAttributes(attrs, R.styleable.CustomTextView,0, 0);
try {
String content = array.getString(R.styleable.CustomTextView_textContent);
initContent(context, content);
} finally {
array.recycle();
}
}
private void initContent(Context context, String content) {
...
}
}
The problem is that I'm using data binding in my app, so if I do this, the app doesn't compile:
<myapp.CustomTextView
android:id="#+id/text_view_1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="25dp"
android:layout_marginRight="25dp"
android:layout_marginBottom="8dp"
custom:textContent="#{mainView.content}" />
After reading a lot, the solution seems to be to create a bindingadapter for that custom attribute, but in my case, create a binding adapter for every custom attribute would be a huge work because there are tons of components and attributes.
Is there a way to reduce this amount of work or to adapt data binding to these custom attributes?

Android studio: change textSize on Custom extends activity

I extended the TextView class to "CustomTextView" that's why I needed to set a custom font. So it's the result:
public class CustomTextView extends TextView {
public CustomTextView(Context context, AttributeSet attrs) {
super(context, attrs);
this.setTypeface(Typeface.createFromAsset(context.getAssets(), "fonts/nn.otf"));
this.setTextSize(30);
}
}
You can see that I setted a default textSize that it's 30:
When I want this CustomTextView, I use this code:
<com.calendar.CustomTextView
android:id="#+id/edData"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="DOM 21 GIU"
android:textSize="45dp"/>
If you notice, I setted the textSize value to 45dp, but the it remains 30 (from the custom class).
How do I set a different textSize? Also, for bold style?

you should remove the this.setTextSize(30); from the constructor, because the xml layout do the resize in during the super(context, attrs) call, and the bold font should be included in the otf file (usually are different otf files for different styles)

This is my solution: (I made tests with textColor and not textSize, but it's the same).
I edited the res/values/atrs.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="CustomTextView">
<attr name="textColor" format="string" />
</declare-styleable>
</resources>
Then, I edited my class like:
public class CustomTextView extends TextView {
public CustomTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(attrs);
}
public CustomTextView(Context context, AttributeSet attrs) {
super(context, attrs);
init(attrs);
}
public CustomTextView(Context context) {
super(context);
init(null);
}
private void init(AttributeSet attrs) {
if (attrs != null) {
TypedArray a = getContext().obtainStyledAttributes(attrs, R.styleable.CustomTextView);
String fontName = a.getString(R.styleable.CustomTextView_fontName);
if (textColor != null) {
this.setTextColor(Color.parseColor(textColor));
} else {
this.setTextColor(Color.parseColor("#000000"));
}
a.recycle();
}
}
}
So this work:
<com.imgspa.listviewadapter.CustomTextView
android:id="#+id/ed"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
listviewadapter:textColor="#FF0000"/>
<com.imgspa.listviewadapter.CustomTextView
android:id="#+id/edRis"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="35dp" />
The first custom textview text is red, the second one is black

To set the style just use android:textStyle="bold". For your other problem, you can check the textSize from the attributes I believe using attrs.getAttribute(NAME OF ATTRIBUTE) method and then you can set it to that value or set it to 30 depending on what you want.

Android: best way to control view that added dynamically?

As the title, i want to know if there is a the best way to control a view that added dynamically. (we have to keep reference to the view that was added)
Some time, for a complex request we have to add view in runtime. The is some ways to do that. In my case:
Some time i use a listview/recyclerview and control view via the list/recycleview adapter.
Other way is use a hashmap.
Do you have any other ideas? and how it work?

I prefer way, when I define View both by Java and XML file. View created like this, gives you ability to call your own Java methods, but you don`t need to create whole layout dynamically in Java. Little example:
MyView.java:
public class MyView extends LinearLayout {
TextView textView;
public MyView(Context context) {
super(context);
init();
}
public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public MyView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
public void init() {
inflate(getContext(), R.layout.my_view, this);
setOrientation(VERTICAL);
textView = (TextView) findViewById(R.id.text_view);
}
public MyView setContent(String value) {
textView.setText(value);
return this;
}
}
my_view.xml:
<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android">
<TextView
android:id="#+id/text_view"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</merge>
After that, you can simply add it in you layout through Java:
cont.addView(new MyView(this).setContent("Value"));
or xml:
<com.path.to.your.view.MyView
android:id="#+id/my_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>

BitmapDrawable cannot be cast to RoundRectDrawableWithShadow

I am trying to extend a cardview to set the background image. I know that this can not be done with normal cardview. I have searched net and found plenty of solutions for setting a background color to the card view but none for image.
My code to do so:
public class CCView extends CardView {
public CCView (Context context) {
super(context);
init();
}
public CCView (Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public CCView (Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init() {
setBackground(getResources().getDrawable(R.drawable.cc_background));
}
}
I get this exception when I populate the code from XML
android.graphics.drawable.BitmapDrawable cannot be cast to android.support.v7.widget.RoundRectDrawableWithShadow
Any solution?

As CardView extends FrameLayout you can layer layouts on top of it. To get around the problem you're having, I'd try adding a blank view "underneath" all the other elements in your view, and then set that view to inherit the state of its parent. Something like this:
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_height="match_parent"
android:layout_width="match_parent"
card_view:cardBackgroundColor="#DDFFFFFF"
card_view:cardElevation="#dimen/card_elevation">
<View
android:layout_width="match_parent"
android:layout_height="match_parent"
android:duplicateParentState="true"
android:background="#drawable/card_background"/>
<LinearLayout
....
....
....
/LinearLayout>
</android.support.v7.widget.CardView>

how to put a custom view inside of a custom viewGroup / Layout

custom view inside of a custom viewGroup not visible, how can I get it to show up?
or is there a better way to do this that would work?
no compile or runtime errors but the view does not show up in the viewGroup, it is supposed to fill the area with color like the other views but it is white and the color for the view is not showing up inside of the CustomLayout
xml code, the first 2 views show up with no problems but the 3rd view that is nested inside of the CustomLayout does not show up, just white color area, the view inside not visible
CustomViewOne is a separate class file, CustomViewTwo and CustomViewThree are both nested inside the MainActivity class as static inner classes, and CustomLayout is a separate file
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity" >
<com.example.customviewexample.CustomViewOne
android:layout_width="100dp"
android:layout_height="50dp" />
<view
class="com.example.customviewexample.MainActivity$CustomViewTwo"
android:layout_width="100dp"
android:layout_height="50dp" />
<com.example.customviewexample.CustomLayout
android:layout_width="100dp"
android:layout_height="50dp">
<view
class="com.example.customviewexample.MainActivity$CustomViewThree"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</com.example.customviewexample.CustomLayout>
</LinearLayout>
here is the code for the CustomViewThree, vary simple like the other custom Views it just fills the area with color, it is nested inside of the MainActivity so you have to use MainActivity$CustomViewThree to access it.
public static class CustomViewThree extends View {
public CustomViewThree(Context context) {
super(context);
}
public CustomViewThree(Context context, AttributeSet attrs) {
super(context, attrs);
}
public CustomViewThree(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawColor(Color.GREEN);
}
}
and here is the code for the CustomLayout class
public class CustomLayout extends FrameLayout {
public CustomLayout(Context context) {
super(context);
init(context);
}
public CustomLayout(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public CustomLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}
public void init(Context context) {
}
#Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
}
}

custom view inside of a custom viewGroup not visible, how can I get it
to show up?
Your parent CustomLayout which wraps the child has a empty onLayout() method which makes the child to not appear. This method is important in a ViewGroup because it's used by the widget to place its children in it. So, you need to provide an implementation for this method to place the children(by calling the layout() method on each of them with the proper positions). As CustomLayout extends FrameLayout you could just call the super method to use FrameLayout's implementation or even better remove the overridden method(is there a reason for implementing it?).