How to display dynamic text on a button and auto adjust their size in Android?
Take a look at this question Auto Scale TextView Text to Fit within Bounds. The same technique should apply to a button.
(yes, it is much more complicated than it seems like it should be.)
Style.xml:
<style name="Widget.Button.CustomStyle" parent="Widget.MaterialComponents.Button">
<item name="android:minHeight">50dp</item>
<item name="android:maxWidth">300dp</item>
<item name="android:textStyle">bold</item>
<item name="android:textSize">16sp</item>
<item name="backgroundTint">@color/white</item>
<item name="cornerRadius">25dp</item>
<item name="autoSizeTextType">uniform</item>
<item name="autoSizeMinTextSize">10sp</item>
<item name="autoSizeMaxTextSize">16sp</item>
<item name="autoSizeStepGranularity">2sp</item>
<item name="android:maxLines">1</item>
<item name="android:textColor">@color/colorPrimary</item>
<item name="android:insetTop">0dp</item>
<item name="android:insetBottom">0dp</item>
<item name="android:lineSpacingExtra">4sp</item>
<item name="android:gravity">center</item>
</style>
Usage:
<com.google.android.material.button.MaterialButton
android:id="@+id/blah"
style="@style/Widget.Button.CustomStyle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginEnd="16dp"
android:text="Your long text, to the infinity and beyond!!! Why not :)" />
Result:
[Source: https://stackoverflow.com/a/59302886/421467 ]
Android 8.0 supports Autosizing TextViews so you just have to specify android:autoSizeTextType="uniform". For older versions, you can use android.support.v7.widget.AppCompatTextView with app:autoSizeTextType="uniform".
By chance, it also works for buttons and for older versions just use android.support.v7.widget.AppCompatButton instead.
Hope this helped.
I know this question is a few years old, but I want to add a full solution for future reference.
This code is based on AutoFitTextView and has been adapted for Buttons. Specifically it also considers the text width to avoid word-breaks when resizing.
For all licensing information visit the above link.
You'll need at least to java files:
AutoSizeTextButton.java
public class AutoSizeTextButton extends android.support.v7.widget.AppCompatButton implements AutofitHelper.OnTextSizeChangeListener{
private AutofitHelper mHelper;
public AutoSizeTextButton(Context context) {
this(context, null, 0);
}
public AutoSizeTextButton(Context context, AttributeSet attrs) {
super(context, attrs, 0);
}
public AutoSizeTextButton(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(attrs, defStyleAttr);
}
private void init(AttributeSet attrs, int defStyleAttr) {
mHelper = AutofitHelper.create(this, attrs, defStyleAttr)
.addOnTextSizeChangeListener(this);
}
// Getters and Setters
/**
* {@inheritDoc}
*/
@Override
public void setTextSize(int unit, float size) {
super.setTextSize(unit, size);
if (mHelper != null) {
mHelper.setTextSize(unit, size);
}
}
/**
* {@inheritDoc}
*/
@Override
public void setLines(int lines) {
super.setLines(lines);
if (mHelper != null) {
mHelper.setMaxLines(lines);
}
}
/**
* {@inheritDoc}
*/
@Override
public void setMaxLines(int maxLines) {
super.setMaxLines(maxLines);
if (mHelper != null) {
mHelper.setMaxLines(maxLines);
}
}
/**
* Returns the {@link AutofitHelper} for this View.
*/
public AutofitHelper getAutofitHelper() {
return mHelper;
}
/**
* Returns whether or not the text will be automatically re-sized to fit its constraints.
*/
public boolean isSizeToFit() {
return mHelper.isEnabled();
}
/**
* Sets the property of this field (sizeToFit), to automatically resize the text to fit its
* constraints.
*/
public void setSizeToFit() {
setSizeToFit(true);
}
/**
* If true, the text will automatically be re-sized to fit its constraints; if false, it will
* act like a normal View.
*
* @param sizeToFit
*/
public void setSizeToFit(boolean sizeToFit) {
mHelper.setEnabled(sizeToFit);
}
/**
* Returns the maximum size (in pixels) of the text in this View.
*/
public float getMaxTextSize() {
return mHelper.getMaxTextSize();
}
/**
* Set the maximum text size to the given value, interpreted as "scaled pixel" units. This size
* is adjusted based on the current density and user font size preference.
*
* @param size The scaled pixel size.
*
* @attr ref android.R.styleable#TextView_textSize
*/
public void setMaxTextSize(float size) {
mHelper.setMaxTextSize(size);
}
/**
* Set the maximum text size to a given unit and value. See TypedValue for the possible
* dimension units.
*
* @param unit The desired dimension unit.
* @param size The desired size in the given units.
*
* @attr ref android.R.styleable#TextView_textSize
*/
public void setMaxTextSize(int unit, float size) {
mHelper.setMaxTextSize(unit, size);
}
/**
* Returns the minimum size (in pixels) of the text in this View.
*/
public float getMinTextSize() {
return mHelper.getMinTextSize();
}
/**
* Set the minimum text size to the given value, interpreted as "scaled pixel" units. This size
* is adjusted based on the current density and user font size preference.
*
* @param minSize The scaled pixel size.
*
* @attr ref R.styleable#AutofitButton_minTextSize
*/
public void setMinTextSize(int minSize) {
mHelper.setMinTextSize(TypedValue.COMPLEX_UNIT_SP, minSize);
}
/**
* Set the minimum text size to a given unit and value. See TypedValue for the possible
* dimension units.
*
* @param unit The desired dimension unit.
* @param minSize The desired size in the given units.
*
* @attr ref R.styleable#AutofitButton_minTextSize
*/
public void setMinTextSize(int unit, float minSize) {
mHelper.setMinTextSize(unit, minSize);
}
/**
* Returns the amount of precision used to calculate the correct text size to fit within its
* bounds.
*/
public float getPrecision() {
return mHelper.getPrecision();
}
/**
* Set the amount of precision used to calculate the correct text size to fit within its
* bounds. Lower precision is more precise and takes more time.
*
* @param precision The amount of precision.
*/
public void setPrecision(float precision) {
mHelper.setPrecision(precision);
}
@Override
public void onTextSizeChange(float textSize, float oldTextSize) {
// do nothing
}
}
AutofitHelper.java
/**
* A helper class to enable automatically resizing a {@link android.widget.Button}`s {@code textSize} to fit
* within its bounds.
*
* @attr ref R.styleable.AutofitButton_sizeToFit
* @attr ref R.styleable.AutofitButton_minTextSize
* @attr ref R.styleable.AutofitButton_precision
*/
public class AutofitHelper {
private static final String TAG = "AutoFitTextHelper";
private static final boolean SPEW = false;
// Minimum size of the text in pixels
private static final int DEFAULT_MIN_TEXT_SIZE = 8; //sp
// How precise we want to be when reaching the target textWidth size
private static final float DEFAULT_PRECISION = 0.5f;
/**
* Creates a new instance of {@code AutofitHelper} that wraps a {@link android.widget.Button} and enables
* automatically sizing the text to fit.
*/
public static AutofitHelper create(Button view) {
return create(view, null, 0);
}
/**
* Creates a new instance of {@code AutofitHelper} that wraps a {@link android.widget.Button} and enables
* automatically sizing the text to fit.
*/
public static AutofitHelper create(Button view, AttributeSet attrs) {
return create(view, attrs, 0);
}
/**
* Creates a new instance of {@code AutofitHelper} that wraps a {@link android.widget.Button} and enables
* automatically sizing the text to fit.
*/
public static AutofitHelper create(Button view, AttributeSet attrs, int defStyle) {
AutofitHelper helper = new AutofitHelper(view);
boolean sizeToFit = true;
if (attrs != null) {
Context context = view.getContext();
int minTextSize = (int) helper.getMinTextSize();
float precision = helper.getPrecision();
TypedArray ta = context.obtainStyledAttributes(
attrs,
R.styleable.AutofitButton,
defStyle,
0);
sizeToFit = ta.getBoolean(R.styleable.AutofitButton_sizeToFit, sizeToFit);
minTextSize = ta.getDimensionPixelSize(R.styleable.AutofitButton_minTextSize,
minTextSize);
precision = ta.getFloat(R.styleable.AutofitButton_precision, precision);
ta.recycle();
helper.setMinTextSize(TypedValue.COMPLEX_UNIT_PX, minTextSize)
.setPrecision(precision);
}
helper.setEnabled(sizeToFit);
return helper;
}
/**
* Re-sizes the textSize of the TextView so that the text fits within the bounds of the View.
*/
private static void autofit(Button view, TextPaint paint, float minTextSize, float maxTextSize,
int maxLines, float precision) {
if (maxLines <= 0 || maxLines == Integer.MAX_VALUE) {
// Don't auto-size since there's no limit on lines.
return;
}
int targetWidth = view.getWidth() - view.getPaddingLeft() - view.getPaddingRight();
if (targetWidth <= 0) {
return;
}
CharSequence text = view.getText();
TransformationMethod method = view.getTransformationMethod();
if (method != null) {
text = method.getTransformation(text, view);
}
Context context = view.getContext();
Resources r = Resources.getSystem();
DisplayMetrics displayMetrics;
float size = maxTextSize;
float high = size;
float low = 0;
if (context != null) {
r = context.getResources();
}
displayMetrics = r.getDisplayMetrics();
paint.set(view.getPaint());
paint.setTextSize(size);
if ((maxLines == 1 && paint.measureText(text, 0, text.length()) > targetWidth)
|| getLineCount(text, paint, size, targetWidth, displayMetrics) > maxLines
|| getMaxWordWidth(text, paint, size, displayMetrics) > targetWidth) {
size = getAutofitTextSize(text, getMaxWord(text, paint), paint, targetWidth, maxLines, low, high, precision,
displayMetrics);
}
if (size < minTextSize) {
size = minTextSize;
}
view.setTextSize(TypedValue.COMPLEX_UNIT_PX, size);
}
/**
* Recursive binary search to find the best size for the text.
*/
private static float getAutofitTextSize(CharSequence text, String widestWord, TextPaint paint,
float targetWidth, int maxLines, float low, float high, float precision,
DisplayMetrics displayMetrics) {
float mid = (low + high) / 2.0f;
int lineCount = 1;
StaticLayout layout = null;
paint.setTextSize(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_PX, mid,
displayMetrics));
if (maxLines != 1) {
layout = new StaticLayout(text, paint, (int)targetWidth, Layout.Alignment.ALIGN_NORMAL,
1.0f, 0.0f, true);
lineCount = layout.getLineCount();
}
if (SPEW) Log.d(TAG, "low=" + low + " high=" + high + " mid=" + mid +
" target=" + targetWidth + " maxLines=" + maxLines + " lineCount=" + lineCount);
if (lineCount > maxLines) {
// For the case that `text` has more newline characters than `maxLines`.
if ((high - low) < precision) {
return low;
}
return getAutofitTextSize(text, widestWord, paint, targetWidth, maxLines, low, mid, precision,
displayMetrics);
}
else if (lineCount < maxLines) {
return getAutofitTextSize(text, widestWord, paint, targetWidth, maxLines, mid, high, precision,
displayMetrics);
}
else {
float maxLineWidth = 0;
if (maxLines == 1) {
maxLineWidth = paint.measureText(text, 0, text.length());
} else {
for (int i = 0; i < lineCount; i++) {
if (layout.getLineWidth(i) > maxLineWidth) {
maxLineWidth = layout.getLineWidth(i);
}
}
}
float maxWordWidth = paint.measureText(widestWord, 0, widestWord.length());
if(maxWordWidth > maxLineWidth){
maxLineWidth = maxWordWidth;
}
if ((high - low) < precision) {
return low;
} else if (maxLineWidth > targetWidth) {
return getAutofitTextSize(text, widestWord, paint, targetWidth, maxLines, low, mid, precision,
displayMetrics);
} else if (maxLineWidth < targetWidth) {
return getAutofitTextSize(text, widestWord, paint, targetWidth, maxLines, mid, high, precision,
displayMetrics);
} else {
return mid;
}
}
}
private static int getLineCount(CharSequence text, TextPaint paint, float size, float width,
DisplayMetrics displayMetrics) {
paint.setTextSize(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_PX, size,
displayMetrics));
StaticLayout layout = new StaticLayout(text, paint, (int)width,
Layout.Alignment.ALIGN_NORMAL, 1.0f, 0.0f, true);
return layout.getLineCount();
}
private static int getMaxLines(Button view) {
int maxLines = -1; // No limit (Integer.MAX_VALUE also means no limit)
TransformationMethod method = view.getTransformationMethod();
if (method != null && method instanceof SingleLineTransformationMethod) {
maxLines = 1;
}
else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
// setMaxLines() and getMaxLines() are only available on android-16+
maxLines = view.getMaxLines();
}
return maxLines;
}
private static float getMaxWordWidth(CharSequence text, TextPaint paint, float size,
DisplayMetrics displayMetrics) {
paint.setTextSize(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_PX, size,
displayMetrics));
String maxWord = getMaxWord(text, paint);
return paint.measureText(maxWord, 0, maxWord.length());
}
private static String getMaxWord(CharSequence text, TextPaint paint) {
String textStr = text.toString();
textStr = textStr.replace("-", "- ");
String[] words = textStr.split("[ \u00AD\u200B]");
String maxWord = "";
float maxWordWidth = 0;
for (String word : words) {
float wordWidth = paint.measureText(word, 0, word.length());
if (wordWidth > maxWordWidth){
maxWordWidth = wordWidth;
maxWord = word;
}
}
return maxWord;
}
// Attributes
private Button mButton;
private TextPaint mPaint;
/**
* Original textSize of the TextView.
*/
private float mTextSize;
private int mMaxLines;
private float mMinTextSize;
private float mMaxTextSize;
private float mPrecision;
private boolean mEnabled;
private boolean mIsAutofitting;
private ArrayList<OnTextSizeChangeListener> mListeners;
private TextWatcher mTextWatcher = new AutofitTextWatcher();
private View.OnLayoutChangeListener mOnLayoutChangeListener =
new AutofitOnLayoutChangeListener();
private AutofitHelper(Button view) {
final Context context = view.getContext();
float scaledDensity = context.getResources().getDisplayMetrics().scaledDensity;
mButton = view;
mPaint = new TextPaint();
setRawTextSize(view.getTextSize());
mMaxLines = getMaxLines(view);
mMinTextSize = scaledDensity * DEFAULT_MIN_TEXT_SIZE;
mMaxTextSize = mTextSize;
mPrecision = DEFAULT_PRECISION;
}
/**
* Adds an {@link OnTextSizeChangeListener} to the list of those whose methods are called
* whenever the {@link android.widget.Button}'s {@code textSize} changes.
*/
public AutofitHelper addOnTextSizeChangeListener(OnTextSizeChangeListener listener) {
if (mListeners == null) {
mListeners = new ArrayList<OnTextSizeChangeListener>();
}
mListeners.add(listener);
return this;
}
/**
* Removes the specified {@link OnTextSizeChangeListener} from the list of those whose methods
* are called whenever the {@link android.widget.Button}'s {@code textSize} changes.
*/
public AutofitHelper removeOnTextSizeChangeListener(OnTextSizeChangeListener listener) {
if (mListeners != null) {
mListeners.remove(listener);
}
return this;
}
/**
* Returns the amount of precision used to calculate the correct text size to fit within its
* bounds.
*/
public float getPrecision() {
return mPrecision;
}
/**
* Set the amount of precision used to calculate the correct text size to fit within its
* bounds. Lower precision is more precise and takes more time.
*
* @param precision The amount of precision.
*/
public AutofitHelper setPrecision(float precision) {
if (mPrecision != precision) {
mPrecision = precision;
autofit();
}
return this;
}
/**
* Returns the minimum size (in pixels) of the text.
*/
public float getMinTextSize() {
return mMinTextSize;
}
/**
* Set the minimum text size to the given value, interpreted as "scaled pixel" units. This size
* is adjusted based on the current density and user font size preference.
*
* @param size The scaled pixel size.
*
* @attr ref me.grantland.R.styleable#AutofitTextView_minTextSize
*/
public AutofitHelper setMinTextSize(float size) {
return setMinTextSize(TypedValue.COMPLEX_UNIT_SP, size);
}
/**
* Set the minimum text size to a given unit and value. See TypedValue for the possible
* dimension units.
*
* @param unit The desired dimension unit.
* @param size The desired size in the given units.
*
* @attr ref me.grantland.R.styleable#AutofitTextView_minTextSize
*/
public AutofitHelper setMinTextSize(int unit, float size) {
Context context = mButton.getContext();
Resources r = Resources.getSystem();
if (context != null) {
r = context.getResources();
}
setRawMinTextSize(TypedValue.applyDimension(unit, size, r.getDisplayMetrics()));
return this;
}
private void setRawMinTextSize(float size) {
if (size != mMinTextSize) {
mMinTextSize = size;
autofit();
}
}
/**
* Returns the maximum size (in pixels) of the text.
*/
public float getMaxTextSize() {
return mMaxTextSize;
}
/**
* Set the maximum text size to the given value, interpreted as "scaled pixel" units. This size
* is adjusted based on the current density and user font size preference.
*
* @param size The scaled pixel size.
*
* @attr ref android.R.styleable#TextView_textSize
*/
public AutofitHelper setMaxTextSize(float size) {
return setMaxTextSize(TypedValue.COMPLEX_UNIT_SP, size);
}
/**
* Set the maximum text size to a given unit and value. See TypedValue for the possible
* dimension units.
*
* @param unit The desired dimension unit.
* @param size The desired size in the given units.
*
* @attr ref android.R.styleable#TextView_textSize
*/
public AutofitHelper setMaxTextSize(int unit, float size) {
Context context = mButton.getContext();
Resources r = Resources.getSystem();
if (context != null) {
r = context.getResources();
}
setRawMaxTextSize(TypedValue.applyDimension(unit, size, r.getDisplayMetrics()));
return this;
}
private void setRawMaxTextSize(float size) {
if (size != mMaxTextSize) {
mMaxTextSize = size;
autofit();
}
}
/**
* @see TextView#getMaxLines()
*/
public int getMaxLines() {
return mMaxLines;
}
/**
* @see TextView#setMaxLines(int)
*/
public AutofitHelper setMaxLines(int lines) {
if (mMaxLines != lines) {
mMaxLines = lines;
autofit();
}
return this;
}
/**
* Returns whether or not automatically resizing text is enabled.
*/
public boolean isEnabled() {
return mEnabled;
}
/**
* Set the enabled state of automatically resizing text.
*/
public AutofitHelper setEnabled(boolean enabled) {
if (mEnabled != enabled) {
mEnabled = enabled;
if (enabled) {
mButton.addTextChangedListener(mTextWatcher);
mButton.addOnLayoutChangeListener(mOnLayoutChangeListener);
autofit();
} else {
mButton.removeTextChangedListener(mTextWatcher);
mButton.removeOnLayoutChangeListener(mOnLayoutChangeListener);
mButton.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize);
}
}
return this;
}
/**
* Returns the original text size of the View.
*
* @see TextView#getTextSize()
*/
public float getTextSize() {
return mTextSize;
}
/**
* Set the original text size of the View.
*
* @see TextView#setTextSize(float)
*/
public void setTextSize(float size) {
setTextSize(TypedValue.COMPLEX_UNIT_SP, size);
}
/**
* Set the original text size of the View.
*
* @see TextView#setTextSize(int, float)
*/
public void setTextSize(int unit, float size) {
if (mIsAutofitting) {
// We don't want to update the TextView's actual textSize while we're autofitting
// since it'd get set to the autofitTextSize
return;
}
Context context = mButton.getContext();
Resources r = Resources.getSystem();
if (context != null) {
r = context.getResources();
}
setRawTextSize(TypedValue.applyDimension(unit, size, r.getDisplayMetrics()));
}
private void setRawTextSize(float size) {
if (mTextSize != size) {
mTextSize = size;
}
}
private void autofit() {
float oldTextSize = mButton.getTextSize();
float textSize;
mIsAutofitting = true;
autofit(mButton, mPaint, mMinTextSize, mMaxTextSize, mMaxLines, mPrecision);
mIsAutofitting = false;
textSize = mButton.getTextSize();
if (textSize != oldTextSize) {
sendTextSizeChange(textSize, oldTextSize);
}
}
private void sendTextSizeChange(float textSize, float oldTextSize) {
if (mListeners == null) {
return;
}
for (OnTextSizeChangeListener listener : mListeners) {
listener.onTextSizeChange(textSize, oldTextSize);
}
}
private class AutofitTextWatcher implements TextWatcher {
@Override
public void beforeTextChanged(CharSequence charSequence, int start, int count, int after) {
// do nothing
}
@Override
public void onTextChanged(CharSequence charSequence, int start, int before, int count) {
autofit();
}
@Override
public void afterTextChanged(Editable editable) {
// do nothing
}
}
private class AutofitOnLayoutChangeListener implements View.OnLayoutChangeListener {
@Override
public void onLayoutChange(View view, int left, int top, int right, int bottom,
int oldLeft, int oldTop, int oldRight, int oldBottom) {
autofit();
}
}
/**
* When an object of a type is attached to an {@code AutofitHelper}, its methods will be called
* when the {@code textSize} is changed.
*/
public interface OnTextSizeChangeListener {
/**
* This method is called to notify you that the size of the text has changed to
* {@code textSize} from {@code oldTextSize}.
*/
public void onTextSizeChange(float textSize, float oldTextSize);
}
}
Then add the needed attributes in values/attrs.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="AutofitButton">
<!-- Minimum size of the text. -->
<attr name="minTextSize" format="dimension" />
<!-- Amount of precision used to calculate the correct text size to fit within its
bounds. Lower precision is more precise and takes more time. -->
<attr name="precision" format="float" />
<!-- Defines whether to automatically resize text to fit to the view's bounds. -->
<attr name="sizeToFit" format="boolean" />
</declare-styleable>
<!-- Your other attributes -->
</resources>
And you're done! You can now use the AutoSizeTextButton class.
<your.package.name.AutoSizeTextButton
android:layout_width="..."
android:layout_height="..."
android:maxLines="2" />
And be sure to add the android:maxLines attribute with a value larger than 0, otherwise it won't do anything!
Additional Notes:
The text is shrunken until the longest word fits into the button without wrapping (or the minimum size is reached). The words have to be seperated by either a normal space, or a hyphen. This algorithm also considers a SOFT HYPHEN or a ZERO WIDTH SPACE a word seperator, however I would strongly advise to test them before using them, because the Android Text Engine used in buttons ignores these characters (at least in API 19), which could lead to weird word-wraps.