Develop Reference

How to read a TextAppearance attribute programmatically [duplicate]

Currently I'm using either a WebView or a TextView to show some dynamic data coming from a webservice in one of my apps.
If the data contains pure text, it uses the TextView and applies a style from styles.xml.
If the data contains HTML (mostly text and images) it uses the WebView.
However, this WebView is unstyled. Therefor it looks a lot different from the usual TextView.
I've read that it's possible to style the text in a WebView simply by inserting some HTML directly into the data. This sounds easy enough, but I would like to use the data from my Styles.xml as the values required in this HTML so I won't need to change the colors et cetera on two locations if I change my styles.
So, how would I be able to do this? I've done some extensive searching but I have found no way of actually retrieving the different style attributes from your styles.xml. Am I missing something here or is it really not possible to retrieve these values?
The style I'm trying to get the data from is the following:
<style name="font4">
<item name="android:layout_width">fill_parent</item>
<item name="android:layout_height">wrap_content</item>
<item name="android:textSize">14sp</item>
<item name="android:textColor">#E3691B</item>
<item name="android:paddingLeft">5dp</item>
<item name="android:paddingRight">10dp</item>
<item name="android:layout_marginTop">10dp</item>
<item name="android:textStyle">bold</item>
</style>
I'm mainly interested in the textSize and textColor.

It is possible to retrieve custom styles from styles.xml programmatically.
Define some arbitrary style in styles.xml:
<style name="MyCustomStyle">
<item name="android:textColor">#efefef</item>
<item name="android:background">#ffffff</item>
<item name="android:text">This is my text</item>
</style>
Now, retrieve the styles like this
// The attributes you want retrieved
int[] attrs = {android.R.attr.textColor, android.R.attr.background, android.R.attr.text};
// Parse MyCustomStyle, using Context.obtainStyledAttributes()
TypedArray ta = obtainStyledAttributes(R.style.MyCustomStyle, attrs);
// Fetch the text from your style like this.
String text = ta.getString(2);
// Fetching the colors defined in your style
int textColor = ta.getColor(0, Color.BLACK);
int backgroundColor = ta.getColor(1, Color.BLACK);
// Do some logging to see if we have retrieved correct values
Log.i("Retrieved text:", text);
Log.i("Retrieved textColor as hex:", Integer.toHexString(textColor));
Log.i("Retrieved background as hex:", Integer.toHexString(backgroundColor));
// OH, and don't forget to recycle the TypedArray
ta.recycle()

The answer #Ole has given seems to break when using certain attributes, such as shadowColor, shadowDx, shadowDy, shadowRadius (these are only a few I found, there might be more)
I have no idea as to why this issue occurs, which I am asking about here, but #AntoineMarques coding style seems to solve the issue.
To make this work with any attribute it would be something like this
First, define a stylable to contain the resource ids like so
attrs.xml
<resources>
<declare-styleable name="MyStyle" >
<attr name="android:textColor" />
<attr name="android:background" />
<attr name="android:text" />
</declare-styleable>
</resources>
Then in code you would do this to get the text.
TypedArray ta = obtainStyledAttributes(R.style.MyCustomStyle, R.styleable.MyStyle);
String text = ta.getString(R.styleable.MyStyle_android_text);
The advantage of using this method is, you are retrieving the value by name and not an index.

The answers from Ole and PrivatMamtora didn't work well for me, but this did.
Let's say I wanted to read this style programmatically:
<style name="Footnote">
<item name="android:fontFamily">#font/some_font</item>
<item name="android:textSize">14sp</item>
<item name="android:textColor">#color/black</item>
</style>
I could do it like this:
fun getTextColorSizeAndFontFromStyle(
context: Context,
textAppearanceResource: Int // Can be any style in styles.xml like R.style.Footnote
) {
val typedArray = context.obtainStyledAttributes(
textAppearanceResource,
R.styleable.TextAppearance // These are added to your project automatically.
)
val textColor = typedArray.getColorStateList(
R.styleable.TextAppearance_android_textColor
)
val textSize = typedArray.getDimensionPixelSize(
R.styleable.TextAppearance_android_textSize
)
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
val typeface = typedArray.getFont(R.styleable.TextAppearance_android_fontFamily)
// Do something with the typeface...
} else {
val fontFamily = typedArray.getString(R.styleable.TextAppearance_fontFamily)
?: when (typedArray.getInt(R.styleable.TextAppearance_android_typeface, 0)) {
1 -> "sans"
2 -> "serif"
3 -> "monospace"
else -> null
}
// Do something with the fontFamily...
}
typedArray.recycle()
}
I took some inspiration from Android's TextAppearanceSpan class, you can find it here: https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/text/style/TextAppearanceSpan.java

I was not able to get the earlier solutions to work.
My style is:
<style name="Widget.TextView.NumPadKey.Klondike" parent="Widget.TextView.NumPadKey">
<item name="android:textSize">12sp</item>
<item name="android:fontFamily">sans-serif</item>
<item name="android:textColor">?attr/wallpaperTextColorSecondary</item>
<item name="android:paddingBottom">0dp</item>
</style>
The obtainStyledAttributes() for android.R.attr.textSize gives String results of "12sp" which I then have to parse. For android.R.attr.textColor it gave a resource file XML name. This was much too cumbersome.
Instead, I found an easy way using ContextThemeWrapper.
TextView sample = new TextView(new ContextThemeWrapper(getContext(), R.style.Widget_TextView_NumPadKey_Klondike), null, 0);
This gave me a fully-styled TextView to query for anything I want. For example:
float textSize = sample.getTextSize();

With Kotlin, if you include the androidx.core:core-ktx library in your app/library...
implementation("androidx.core:core-ktx:1.6.0") // Note the -ktx
...you can have either of the following (no need for you to recycle the TypedArray):
// Your desired attribute IDs
val attributes = intArrayOf(R.attr.myAttr1, R.attr.myAttr2, android.R.attr.text)
context.withStyledAttributes(R.style.MyStyle, attributes) {
val intExample = getInt(R.styleable.MyIntAttrName, 0)
val floatExample = getFloat(R.styleable.MyFloatAttrName, 0f)
val enumExample = R.styleable.MyEnumAttrName, MyEnum.ENUM_1 // See Note 1 below
// Similarly, getColor(), getBoolean(), etc.
}
context.withStyledAttributes(R.style.MyStyle, R.styleable.MyStyleable) {
// Like above
}
// attributeSet is provided to you like in the constructor of a custom view
context.withStyledAttributes(attributeSet, R.styleable.MyStyleable) {
// Like above
}
Note 1 (thanks to this answer)
For getting an enum value you can define this extension function:
internal inline fun <reified T : Enum<T>> TypedArray.getEnum(index: Int, default: T) =
getInt(index, -1).let { if (it >= 0) enumValues<T>()[it] else default }
Note 2
The difference between -ktx dependencies like androidx.core:core and androidx.core:core-ktx is that the -ktx variant includes useful extension functions for Kotlin.
Otherwise, they are the same.
Also, thanks to the answer by Ole.

If accepted solution not working for try to rename attr.xml to attrs.xml (worked for me)

Resources$NotFoundException in Graphical Layout ADT preview (but app actually Works)

My problem is that loading an array of strings defined in XML works in the app but will result in an error in the ADT Graphical Layout preview.
Now I can't see any graphics in the Graphical Layout because of this error, and it's difficult to work with other graphics.
But the view is loading and displaying the strings fine if I build and run my app.
So I suppose my code is correct but either:
I am missing some limitations of the Graphical Layout preview and some workaround
or perhaps I'm missing something obvious and doing things wrong even if it seems to work in the app
I have a custom view where I get an array defined by me in an array.xml file.
public class ScoreTable extends View {
[...]
#Override
protected void onDraw(Canvas canvas) {
[...]
int score_vals[] = getResources().getIntArray(R.array.score_vals);
[...]
}
[...]
}
My array is defined in res/values/array.xml:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<array name="score_vals">
<item >10</item>
<item >20</item>
<item >50</item>
</array>
</resources>
Graphical Layout is blank and says:
Int array resource ID #0x7f050000
Exception details are logged in Window > Show View > Error Log
But of course I have "public static final int score_vals=0x7f050000;" in R.java!
The details of this error are in a 50-deep stack, but resumes to this:
android.content.res.Resources$NotFoundException: Int array resource ID #0x7f050000
at android.content.res.Resources.getIntArray(Resources.java:405)
at com.threecats.poker.ScoreTable.onDraw(ScoreTable.java:53)
at android.view.View.draw(View.java:6740)
[...]
So, should getResources().getXXXArray() work in the context of a ADT Graphical Layout preview?
I would like to mention that I tried with both "array" and "array-integer" in the XML, and both work in the app but not in the preview.
Also I tried to save the Context from the constructor of the view in a private Context member... didn't help either.

Your code is alright but unfortunately there are still some bugs in ADT plugin and there is one of them. Layout Editor has troubles with rendering custom views. I had the same issue and the only workout I have found is checking View.isInEditMode and initializing int array in some other way but not from resources. So your code will look like this:
int score_vals[];
if (isInEditMode()) {
score_vals = { 10, 20, 50 };
} else {
score_vals = getResources().getIntArray(R.array.score_vals);
}
And by the way don't create or load any resources in your onDraw methods. I suppose getResources().getIntArray uses some sort of caching but anyway your perfomance may suffer.

I found a kind of a workaround whereby you have to hijack android's own attributes to get access to resources in the designer.
The following should provide the idea, but you would have to find a native android property of type int[]
This custom view XML should render in the graphical layout preview while using resources
<!-- Could override individual attributes here too rather than using a style -->
<com.github.espiandev.showcaseview.ShowcaseView
style="#style/ShowcaseView"/>
styles.xml - Style specifying some of the resources to use
<style name="ShowcaseView" parent="match_fill">
<!--# Cling drawable -->
<item name="android:src">#drawable/cling</item>
<!--# Title #-->
<item name="android:contentDescription">#string/showcase_title</item>
<!--# Description #-->
<item name="android:description">#string/showcase_description</item>
<!--# Button Text #-->
<item name="android:text">#string/ok</item>
<item name="sv_titleTextColor">#33B5E5</item>
<item name="sv_detailTextColor">#FFFFFF</item>
<item name="sv_backgroundColor">#3333B5E5</item>
<item name="sv_buttonBackgroundColor">#3333B5E5</item>
<item name="sv_buttonForegroundColor">#33B5E5</item>
</style>
attrs.xml - Custom attribute definition compatible with design-time preview
<!-- The android attrs assume the corresponding android format / data type -->
<declare-styleable name="ShowcaseView">
<!--# Cling drawable -->
<attr name="android:src"/>
<!--# Title #-->
<attr name="android:contentDescription"/>
<!--# Description #-->
<attr name="android:description"/>
<!--# Button Text #-->
<attr name="android:text"/>
<attr name="sv_backgroundColor" format="color|reference" />
<attr name="sv_detailTextColor" format="color|reference" />
<attr name="sv_titleTextColor" format="color|reference" />
<attr name="sv_buttonBackgroundColor" format="color|reference" />
<attr name="sv_buttonForegroundColor" format="color|reference" />
</declare-styleable>
ShowcaseView.java - Using the custom attributes in the custom view
public ShowcaseView(Context context) {
this(context, null, R.styleable.CustomTheme_showcaseViewStyle);
}
public ShowcaseView(Context context, AttributeSet attrs) {
this(context, attrs, R.styleable.CustomTheme_showcaseViewStyle);
}
public ShowcaseView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// Get the attributes for the ShowcaseView
final TypedArray styled = context.getTheme().obtainStyledAttributes(attrs, R.styleable.ShowcaseView, 0, 0);
showcase = styled.getDrawable(R.styleable.ShowcaseView_android_src);
titleText = styled.getString(R.styleable.ShowcaseView_android_contentDescription);
subText = styled.getString(R.styleable.ShowcaseView_android_description);
buttonText = styled.getString(R.styleable.ShowcaseView_android_text);
backColor = styled.getInt(R.styleable.ShowcaseView_sv_backgroundColor, Color.argb(128, 80, 80, 80));
detailTextColor = styled.getColor(R.styleable.ShowcaseView_sv_detailTextColor, Color.WHITE);
titleTextColor = styled.getColor(R.styleable.ShowcaseView_sv_titleTextColor, Color.parseColor("#49C0EC"));
styled.recycle();
// Now make use of the fields / do further initialization ..
}

Read Newer Theme Attributes On Older Platform

I am trying to read attribute values from themes and styles which were designed for platforms that are newer than I am running my application on.
Please don't ask why. If you know anything about the libraries I write then you should already know that I like to push the capabilities of the platform :)
I am operating under the presumption that when Android styles are compiled the attribute constants are what is used for the keys and therefore should theoretically be able to be read on any platform somehow. This is what I have observed to be happening with layout XMLs in my other libraries with no trouble.
Here is a base test case which shows the problem. This should be compiled using Android 3.0+.
<resources>
<style name="Theme.BreakMe">
<item name="android:actionBarStyle">#style/Widget.BreakMe</item>
</style>
<style name="Widget.BreakMe" parent="android:Widget">
<item name="android:padding">20dp</item>
</style>
</resources>
The fact that this uses android:actionBarStyle specifically is irreleveant. All that should be understood is that its an attribute which was only available starting with Android 3.0.
Here are the way that I have tried to access these values thus far on platforms prior to Android 3.0.
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Break Me"
style="?android:attr/actionBarStyle"
/>
and
<declare-styleable name="Whatever">
<item name="datStyle" format="reference" />
</declare-styleable>
<style name="Theme.BreakMe.Take2">
<item name="datStyle">?android:attr/actionBarSize</item>
</style>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Break Me"
style="?attr/datStyle"
/>
and
TypedValue outValue = new TypedValue();
context.getTheme().resolveAttribute(android.R.attr.actionBarStyle, outValue, true);
and
int[] Theme = new int[] { android.R.attr.actionBarSize };
int Theme_actionBarSize = 0;
TypedArray a = context.obtainStyledAttributes(attrs, Theme);
int ref = a.getResourceId(Theme_actionBarSize, 0);
and
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ActionBar, android.R.attr.actionBarStyle, 0);
All of them result in this error in LogCat:
E/ResourceType(5618): Style contains key with bad entry: 0x010102ce
The 0x010102ce constant is the attribute value of android.R.attr.actionBarStyle which seems to indicate the platform is rejecting the attribute before I can even get a chance to access its value.
I am looking for any other way to read attributes like this from the Theme. I'm fairly sure that once I've obtained the style reference I won't have trouble reading its attributes.
Is there any possible way to do this?

I am operating under the presumption that when Android styles are compiled the attribute constants are what is used for the keys and therefore should theoretically be able to be read on any platform somehow.
Possibly, though that is not how I am interpreting the C++ source code that raises the error you are seeing. Check out ResTable::Theme::applyStyle() in frameworks/base/libs/utils/ResourceTypes.cpp.
My interpretation is that Android has what amounts to an in-memory table of packages->types->possible entries:
numEntries = curPI->types[t].numEntries;
Your entry index is higher than the highest known entry:
if (e >= numEntries) {
LOGE("Style contains key with bad entry: 0x%08x\n", attrRes);
bag++;
continue;
}
It is possible that they handle this different for android versus other packages -- android uses known values at firmware build time (and your generated entry index is higher, because it is from a newer platform), non-android ones assume anything's valid.
If my guesswork is correct, what you want to do will not work. That being said, my C++ days are seriously in my rear-view mirror, so I may be misinterpreting what I'm seeing.

Perhaps I'm missing the end goal here, but I put together the following example that was able to read out all the attributes without issue on any 2.x device. The example was compiled against a 3.0 targetSdk.
styles.xml (Declare the styles and themes)
<resources>
<style name="Theme.NewFeatures" parent="android:Theme">
<item name="android:actionBarStyle">#style/Widget.MyActionBar</item>
</style>
<style name="Widget.MyActionBar" parent="android:Widget">
<item name="android:padding">20dp</item>
</style>
</resources>
attrs.xml (Declare the attribute groups you wish to obtain at runtime)
<resources>
<declare-styleable name="ActionBarNewFeatures">
<attr name="android:actionBarStyle" />
</declare-styleable>
<declare-styleable name="MyWidgetNewFeatures">
<attr name="android:padding" />
</declare-styleable>
</resources>
AndroidManifest.xml (Apply the custom theme)
<application
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/Theme.NewFeatures" >
<activity
android:name=".SomeActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
SomeActivity.java (Go digging for attributes)
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
TypedArray a = obtainStyledAttributes(R.styleable.ActionBarNewFeatures);
//Get the style ID for the widget
int resid = a.getResourceId(R.styleable.ActionBarNewFeatures_android_actionBarStyle, -1);
a.recycle();
a = obtainStyledAttributes(resid, R.styleable.MyWidgetNewFeatures);
int padding = a.getDimensionPixelSize(R.styleable.MyWidgetNewFeatures_android_padding, -1);
a.recycle();
TextView tv = new TextView(this);
tv.setText(String.format("Padding will be %d px", padding));
setContentView(tv);
}
As long as I compile the example against 3.0 so it can resolved all the attribute names; on every 2.X device/emulator I have this will correctly read into the theme and then into the widget style to get the scaled padding dimension I had set.
Hope I didn't miss something big.

Probably, You must define a few themes. For old devices use folder res/values-v11/themes.xml. See section "Using Holo while supporting Android 2.x" in the http://android-developers.blogspot.com/2012/01/holo-everywhere.html

How to add a custom button state

For instance, the default button has the following dependencies between its states and background images:
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_window_focused="false" android:state_enabled="true"
android:drawable="#drawable/btn_default_normal" />
<item android:state_window_focused="false" android:state_enabled="false"
android:drawable="#drawable/btn_default_normal_disable" />
<item android:state_pressed="true"
android:drawable="#drawable/btn_default_pressed" />
<item android:state_focused="true" android:state_enabled="true"
android:drawable="#drawable/btn_default_selected" />
<item android:state_enabled="true"
android:drawable="#drawable/btn_default_normal" />
<item android:state_focused="true"
android:drawable="#drawable/btn_default_normal_disable_focused" />
<item
android:drawable="#drawable/btn_default_normal_disable" />
</selector>
How can I define my own custom state (smth like android:state_custom), so then I could use it to dynamically change my button visual appearance?

The solution indicated by #(Ted Hopp) works, but needs a little correction: in the selector, the item states need an "app:" prefix, otherwise the inflater won't recognise the namespace correctly, and will fail silently; at least this is what happens to me.
Allow me to report here the whole solution, with some more details:
First, create file "res/values/attrs.xml":
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="food">
<attr name="state_fried" format="boolean" />
<attr name="state_baked" format="boolean" />
</declare-styleable>
</resources>
Then define your custom class. For instance, it may be a class "FoodButton", derived from class "Button". You will have to implement a constructor; implement this one, which seems to be the one used by the inflater:
public FoodButton(Context context, AttributeSet attrs) {
super(context, attrs);
}
On top of the derived class:
private static final int[] STATE_FRIED = {R.attr.state_fried};
private static final int[] STATE_BAKED = {R.attr.state_baked};
Also, your state variables:
private boolean mIsFried = false;
private boolean mIsBaked = false;
And a couple of setters:
public void setFried(boolean isFried) {mIsFried = isFried;}
public void setBaked(boolean isBaked) {mIsBaked = isBaked;}
Then override function "onCreateDrawableState":
#Override
protected int[] onCreateDrawableState(int extraSpace) {
final int[] drawableState = super.onCreateDrawableState(extraSpace + 2);
if (mIsFried) {
mergeDrawableStates(drawableState, STATE_FRIED);
}
if (mIsBaked) {
mergeDrawableStates(drawableState, STATE_BAKED);
}
return drawableState;
}
Finally, the most delicate piece of this puzzle; the selector defining the StateListDrawable that you will use as a background for your widget. This is file "res/drawable/food_button.xml":
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res/com.mydomain.mypackage">
<item
app:state_baked="true"
app:state_fried="false"
android:drawable="#drawable/item_baked" />
<item
app:state_baked="false"
app:state_fried="true"
android:drawable="#drawable/item_fried" />
<item
app:state_baked="true"
app:state_fried="true"
android:drawable="#drawable/item_overcooked" />
<item
app:state_baked="false"
app:state_fried="false"
android:drawable="#drawable/item_raw" />
</selector>
Notice the "app:" prefix, whereas with standard android states you would have used prefix "android:". The XML namespace is crucial for a correct interpretation by the inflater and depends on the type of project in which you are adding attributes. If it is an application, replace com.mydomain.mypackage with the actual package name of your application (application name excluded). If it is a library you must use "http://schemas.android.com/apk/res-auto" (and be using Tools R17 or later) or you will get runtime errors.
A couple of notes:
It seems you don't need to call the "refreshDrawableState" function, at least the solution works well as is, in my case
In order to use your custom class in a layout xml file, you will have to specify the fully qualified name (e.g. com.mydomain.mypackage.FoodButton)
You can as weel mix-up standard states (e.g. android:pressed, android:enabled, android:selected) with custom states, in order to represent more complicated state combinations

This thread shows how to add custom states to buttons and the like. (If you can't see the new Google groups in your browser, there's a copy of the thread here.)

Please do not forget to call refreshDrawableState within UI thread:
mHandler.post(new Runnable() {
#Override
public void run() {
refreshDrawableState();
}
});
It took lot of my time to figure out why my button is not changing its state even though everything looks right.

How can I use a resource within a custom Xml resource file?

I have an XML resource file:
<resources>
<section>
<category value="1" resourceId="#xml/categoryData1" />
<category value="2" resourceId="#xml/categoryData2" />
<category value="3" resourceId="#xml/categoryData3" />
</section>
</resources>
Using XmlPullParser, on the START_TAG, I can use:
int value = parser.getAttributeIntValue(null, "value", 0);
to get values 1, 2, 3...however:
int resourceId = parser.getAttributeIntValue(null, "resourceId", 0);
doesn't work...it just yields the default value 0, or whatever I change the default value (3rd parameter) to be...
Does anyone know what I am doing wrong or if this is possible?

well, if you look in your resourceId attribute, it does not seem to contain an int, does it? Or am I misreading you?
you should instead use getAttributeValue and cast it in the right Type.