Develop Reference

How to Bind the Wikitude aar file in xamarin

Hi I am trying to bind wikitude .aar fine in xamarin...I am having some issues
Com.Wikitude.Tracker.IObjectTrackerListener.cs(47,47): Error CS0102: The type 'TargetsLoadedEventArgs' already contains a definition for 'p0' (CS0102) (AarBinding)
Com.Wikitude.Tracker.IObjectTrackerListener.cs(14,14): Error CS0102: The type 'ErrorLoadingTargetsEventArgs' already contains a definition for 'P1' (CS0102) (AarBinding)
I tried to use the Metadata.xml as
<attr path="/api/package[#name='Com.Wikitude.Tracker']/class[#name='ErrorLoadingTargetsEventArgs']/field[#name='p0']" name="managedName">p0_2</attr>
But it is now working any suggestions Please ?

Hi I was as able to fix this issue..It may be helpful for others
<?xml version="1.0" encoding="UTF-8"?>
<metadata>
<attr path="/api/package[#name='com.wikitude.tracker']/interface[#name='ObjectTrackerListener']/method[#name='onTargetsLoaded']/parameter[1]" name="managedName">tracker</attr>
<attr path="/api/package[#name='com.wikitude.tracker']/interface[#name='ObjectTrackerListener']/method[#name='onErrorLoadingTargets']/parameter[1]" name="managedName">tracker</attr>
<attr path="/api/package[#name='com.wikitude.tracker']/interface[#name='ObjectTrackerListener']/method[#name='onErrorLoadingTargets']/parameter[2]" name="managedName">errorCode</attr>
<attr path="/api/package[#name='com.wikitude.tracker']/interface[#name='ObjectTrackerListener']/method[#name='onErrorLoadingTargets']/parameter[3]" name="managedName">errorMessage</attr>
<attr path="/api/package[#name='com.pbar.samples']/class[#name='StartActivity']"
name="visibility">public</attr>
</metadata>

I can't get styleable array of attrs

I am declaring a styleable view with attrs, and I created the file myview_attrs.xml this simple way:
<resources>
<declare-styleable name="TestStyleable">
<attr name="testAttr" format="integer"/>
</declare-styleable>
</resources>
Then, I want to load this attr in my code:
void loadAttributes(AttributeSet attrs) {
TypedArray typedArray = getContext().obtainStyledAttributes(attrs, R.styleable.);
}
After R.styleable. , with ctrl-SPACE, these are the options I am given:
That is obviously wrong. Indeed, I can't select R.styleable.TestStyleable, because it's not proposed in the menu, but only R.styleable.TestStyleable_testAttr, that does not make sense.
Of course, if I choose the second one it gives me error, because a int[] is expected and I put an int. On the other side, if I manually write R.styleable.TestStyleable fails with "Cannot resolve symbol".
What am I missing here??
Update: this ended to be an Android Studio bug.

As #Yurii Tsap stated, this is an Android Studio bug, and it finally got fixed by making
File -> Invalidate Caches / Restart

Understanding the xmlns attribute in an Android layout

I have only recently had to set the xmlns attribute in an Android layout file. Initially when I was adding a third-party control, certain attributes in the control's XML didn't have a prefix to identify the namespace. When I ran my app, the control was displayed but those attributes that didn't have the namespace prefix were ignored. Only after adding the xmlns to the top of my file and adding the prefix to the attributes did those attributes get recognized at run time. Here is what the corrected code looks like:
xmlns:fab="http://schemas.android.com/apk/res-auto"
<com.getbase.floatingactionbutton.FloatingActionButton
android:id="#+id/ivFAB"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
fab:fab_icon="#drawable/ic_fab_star"
fab:fab_colorNormal="#color/pink_500"
fab:fab_colorPressed="#color/pink_100"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_marginRight="15dp"
android:layout_marginBottom="15dp"
android:visibility="visible"
/>
The xmlns prefix her is 'fab'. What I don't understand is that without the namespace and prefix, the app compiles without any errors. Why doesn't Android Studio complain that it cannot find fab_icon? Why does it just ignore these attributes? I have seen a number of posts throughout stackoverflow on different topics where someone has indicated to leave out the prefix and then the code worked. So I'm at a loss to understand what's going on. In some problems (like mine) having the prefix is required but in others it isn't? Is this an issue with different versions of Android Studio or the SDK versions?

Yes. Even you can define your own custom layout attributes.
Step 1: Create a subclass of a view.
class PieChart extends View {
public PieChart(Context context, AttributeSet attrs) {
super(context, attrs);
}
}
Step 2: Define Custom Attributes with <declare-styleable> in res/values/attrs.xml .
<resources>
<declare-styleable name="PieChart">
<attr name="showText" format="boolean" />
<attr name="labelPosition" format="enum">
<enum name="left" value="0"/>
<enum name="right" value="1"/>
</attr>
</declare-styleable>
</resources>
Step 3: Using those attributes inside your layout xml.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:custom="http://schemas.android.com/apk/res/com.example.customviews">
<com.example.customviews.charting.PieChart
custom:showText="true"
custom:labelPosition="left" />
</LinearLayout>
Step 4: Applying custom attributes to your view.
public PieChart(Context context, AttributeSet attrs) {
super(context, attrs);
TypedArray a = context.getTheme().obtainStyledAttributes(
attrs,
R.styleable.PieChart,
0, 0);
try {
mShowText = a.getBoolean(R.styleable.PieChart_showText, false);
mTextPos = a.getInteger(R.styleable.PieChart_labelPosition, 0);
} finally {
a.recycle();
}
}
Step 5: Adding properties and events
Attributes are a powerful way of controlling the behavior and appearance of views, but they can only be read when the view is initialized. To provide dynamic behavior, expose a property getter and setter pair for each custom attribute. The following snippet shows how PieChart exposes a property called showText
public boolean isShowText() {
return mShowText;
}
public void setShowText(boolean showText) {
mShowText = showText;
invalidate();
requestLayout();
}
For more information and details, read this link.

Create Custom Compound View in Android with Attributes

I have created a custom compound view inside a library application and everything was OK. When I add custom attributes to view, I always get default values. I followed this steps with only one difference: my view is in a library project.
/res/values/attrs.xml
<resources>
<declare-styleable name="DatePickerView">
<attr name="showToday" format="boolean" />
<attr name="calendar" format="enum">
<enum name="jalali" value="0" />
<enum name="gregorian" value="1" />
</attr>
</declare-styleable>
</resources>
Layout file that contains view:
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:farayan="http://schemas.android.com/apk/lib/net.farayan.android.view"
...
<net.farayan.android.view.datepicker.DatePickerView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
farayan:showToday="false"
farayan:calendar="gregorian"/>
...
Component's code:
int calendar;
boolean showToday;
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.DatePickerView, 0, 0);
try {
calendar = a.getInteger(R.styleable.DatePickerView_calendar, 0);
showToday = a.getBoolean(R.styleable.DatePickerView_showToday, true);
} finally {
a.recycle();
}
calendar and showToday are always 0 and true respectively. Any idea?

It looks like something is not right here:
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:farayan="http://schemas.android.com/apk/lib/net.farayan.android.view"
What about change to:
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:farayan="http://schemas.android.com/apk/res/net.farayan.android.view"
net.farayan.android.view is your app root namespace.
update1
xmlns:farayan="http://schemas.android.com/apk/res/your_main_app_package"
Here is am example. It use a view defined in the library project.

If we add new compound view code and its attributesinside project, we should add this at the beginning of layout:
xmlns:custom="http://schemas.android.com/apk/res/your_main_app_package
and if new compound view is inside a library project linked to our peoject, we should add this:
xmlns:custom="http://schemas.android.com/apk/res-auto
Link: https://stackoverflow.com/a/10217752/1152549

Android Custom Control namespace issue

I've been working on a Custom Control for Android and although I tried to do what's suggested here there seems to be something I'm doing wrong.
Here's my code to see if anyone can spot the problem:
MyComponent.java
public MyComponent(Context context, AttributeSet attrs)
{
super(context);
TypedArray arr = context.obtainStyledAttributes(attrs, R.styleable.MyComponent);
CharSequence myId = arr.getString(R.styleable.MyComponent_identifier);
if (myId != null)
{
this.setIdentifier(myId.toString());
}
Integer cds = arr.getInteger(R.styleable.MyComponent_cd_number, 0);
if(cds != null)
{
this.setCds(cds);
}
arr.recycle();
}
attrs.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="MyComponent">
<attr name="cd_number" format="integer" />
<attr name="identifier" format="string" />
</declare-styleable>
</resources>
main.xml
<TableLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:bgl="http://schemas.android.com/apk/res/my.test.package.components"
android:id="#+id/table"
android:layout_width="match_parent"
android:layout_height="match_parent">
...
<my.test.package.MyComponent
android:id="#+id/hand"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_span="2"
bgl:cd_number="4"
bgl:identifier="plr"/>
...
</TableLayout>
When I put this I get the following errors:
error: No resource identifier found for attribute 'cd_number' in package 'my.test.package'
error: No resource identifier found for attribute 'identifier' in package 'my.test.package'
If I change my namespace to something like:
xmlns:bgl="http://schemas.mywhatever.com/apk/res/my.test.package"
...the errors go way and the thing runs but myId is null and cds is 0 (the default value!) back on the MyComponent.java constructor.
I'd say it's some very basic mistake but I not being able to spot it and since there's not much documentation on this I decided to ask here.
Thanks in advance!

Ok. I got it solved!
On the original post I had:
xmlns:bgl="http://schemas.android.com/apk/res/my.test.package
...but in my source I had:
xmlns:bgl="http://schemas.android.com/apk/res/my.test.package.components
...because I thought one should put the URI to the components package.
THIS IS WRONG!
On the xmlns it should be the application name as is declared on the Manifest!
When I removed the "components" part of the xmlns it "matched" the application name in the Manifest and the errors went away and when I ran the thing in debug I could actually see the values I was passing to the parameters in the XML!
Hope this helps someone else! :-)
UPDATE
Later on I had the need to move the control into a library and faced the problem again. It seems that when you put the component in a library and use it on a client app you must declare the xmlns as below:
xmlns:myns="http://schemas.android.com/apk/res-auto"
If you do so (and have the library declared as an Android dependency) Eclipse (or is it Android?) will search the dependencies for the appropriate attribute bindings.

I had a problem similar to this, turned out it was calling a different constructor
Try with the constructor that takes in the defStyle parameter
public MyComponent(Context context, AttributeSet attrs, int defStyle)