下面是添加了自定义字体功能的 avalancha TextView。
用法：
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:foo="http://schemas.android.com/apk/res-auto"
android:layout_width="wrap_content"
android:layout_height="match_parent" >
<de.meinprospekt.androidhd.view.AutoFitText
android:layout_width="wrap_content"
android:layout_height="10dp"
android:text="Small Text"
android:textColor="#FFFFFF"
android:textSize="100sp"
foo:customFont="fonts/Roboto-Light.ttf" />
</FrameLayout>
不要忘记添加：xmlns:foo="http://schemas.android.com/apk/res-auto"。字体应该在资产中
import java.util.ArrayList;
import java.util.List;
import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Paint;
import android.graphics.Typeface;
import android.os.Build;
import android.util.AttributeSet;
import android.util.Log;
import android.util.TypedValue;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.view.ViewTreeObserver;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.widget.TextView;
import de.meinprospekt.androidhd.R;
import de.meinprospekt.androidhd.adapter.BrochuresHorizontalAdapter;
import de.meinprospekt.androidhd.util.LOG;
/**
* https://stackoverflow.com/a/16174468/2075875 This class builds a new android Widget named AutoFitText which can be used instead of a TextView to
* have the text font size in it automatically fit to match the screen width. Credits go largely to Dunni, gjpc, gregm and speedplane from
* Stackoverflow, method has been (style-) optimized and rewritten to match android coding standards and our MBC. This version upgrades the original
* "AutoFitTextView" to now also be adaptable to height and to accept the different TextView types (Button, TextClock etc.)
*
* @author pheuschk
* @createDate: 18.04.2013
*
* combined with: https://stackoverflow.com/a/7197867/2075875
*/
@SuppressWarnings("unused")
public class AutoFitText extends TextView {
private static final String TAG = AutoFitText.class.getSimpleName();
/** Global min and max for text size. Remember: values are in pixels! */
private final int MIN_TEXT_SIZE = 10;
private final int MAX_TEXT_SIZE = 400;
/** Flag for singleLine */
private boolean mSingleLine = false;
/**
* A dummy {@link TextView} to test the text size without actually showing anything to the user
*/
private TextView mTestView;
/**
* A dummy {@link Paint} to test the text size without actually showing anything to the user
*/
private Paint mTestPaint;
/**
* Scaling factor for fonts. It's a method of calculating independently (!) from the actual density of the screen that is used so users have the
* same experience on different devices. We will use DisplayMetrics in the Constructor to get the value of the factor and then calculate SP from
* pixel values
*/
private float mScaledDensityFactor;
/**
* Defines how close we want to be to the factual size of the Text-field. Lower values mean higher precision but also exponentially higher
* computing cost (more loop runs)
*/
private final float mThreshold = 0.5f;
/**
* Constructor for call without attributes --> invoke constructor with AttributeSet null
*
* @param context
*/
public AutoFitText(Context context) {
this(context, null);
}
public AutoFitText(Context context, AttributeSet attrs) {
super(context, attrs);
init(context, attrs);
}
public AutoFitText(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context, attrs);
}
private void init(Context context, AttributeSet attrs) {
//TextViewPlus part https://stackoverflow.com/a/7197867/2075875
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.AutoFitText);
String customFont = a.getString(R.styleable.AutoFitText_customFont);
setCustomFont(context, customFont);
a.recycle();
// AutoFitText part
mScaledDensityFactor = context.getResources().getDisplayMetrics().scaledDensity;
mTestView = new TextView(context);
mTestPaint = new Paint();
mTestPaint.set(this.getPaint());
this.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
// make an initial call to onSizeChanged to make sure that refitText is triggered
onSizeChanged(AutoFitText.this.getWidth(), AutoFitText.this.getHeight(), 0, 0);
// Remove the LayoutListener immediately so we don't run into an infinite loop
//AutoFitText.this.getViewTreeObserver().removeOnGlobalLayoutListener(this);
removeOnGlobalLayoutListener(AutoFitText.this, this);
}
});
}
public boolean setCustomFont(Context ctx, String asset) {
Typeface tf = null;
try {
tf = Typeface.createFromAsset(ctx.getAssets(), asset);
} catch (Exception e) {
LOG.e(TAG, "Could not get typeface: "+e.getMessage());
return false;
}
setTypeface(tf);
return true;
}
@SuppressLint("NewApi")
public static void removeOnGlobalLayoutListener(View v, ViewTreeObserver.OnGlobalLayoutListener listener){
if (Build.VERSION.SDK_INT < 16) {
v.getViewTreeObserver().removeGlobalOnLayoutListener(listener);
} else {
v.getViewTreeObserver().removeOnGlobalLayoutListener(listener);
}
}
/**
* Main method of this widget. Resizes the font so the specified text fits in the text box assuming the text box has the specified width. This is
* done via a dummy text view that is refit until it matches the real target width and height up to a certain threshold factor
*
* @param targetFieldWidth The width that the TextView currently has and wants filled
* @param targetFieldHeight The width that the TextView currently has and wants filled
*/
private void refitText(String text, int targetFieldWidth, int targetFieldHeight) {
// Variables need to be visible outside the loops for later use. Remember size is in pixels
float lowerTextSize = MIN_TEXT_SIZE;
float upperTextSize = MAX_TEXT_SIZE;
// Force the text to wrap. In principle this is not necessary since the dummy TextView
// already does this for us but in rare cases adding this line can prevent flickering
this.setMaxWidth(targetFieldWidth);
// Padding should not be an issue since we never define it programmatically in this app
// but just to to be sure we cut it off here
targetFieldWidth = targetFieldWidth - this.getPaddingLeft() - this.getPaddingRight();
targetFieldHeight = targetFieldHeight - this.getPaddingTop() - this.getPaddingBottom();
// Initialize the dummy with some params (that are largely ignored anyway, but this is
// mandatory to not get a NullPointerException)
mTestView.setLayoutParams(new LayoutParams(targetFieldWidth, targetFieldHeight));
// maxWidth is crucial! Otherwise the text would never line wrap but blow up the width
mTestView.setMaxWidth(targetFieldWidth);
if (mSingleLine) {
// the user requested a single line. This is very easy to do since we primarily need to
// respect the width, don't have to break, don't have to measure...
/*************************** Converging algorithm 1 ***********************************/
for (float testSize; (upperTextSize - lowerTextSize) > mThreshold;) {
// Go to the mean value...
testSize = (upperTextSize + lowerTextSize) / 2;
mTestView.setTextSize(TypedValue.COMPLEX_UNIT_SP, testSize / mScaledDensityFactor);
mTestView.setText(text);
mTestView.measure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
if (mTestView.getMeasuredWidth() >= targetFieldWidth) {
upperTextSize = testSize; // Font is too big, decrease upperSize
} else {
lowerTextSize = testSize; // Font is too small, increase lowerSize
}
}
/**************************************************************************************/
// In rare cases with very little letters and width > height we have vertical overlap!
mTestView.measure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
if (mTestView.getMeasuredHeight() > targetFieldHeight) {
upperTextSize = lowerTextSize;
lowerTextSize = MIN_TEXT_SIZE;
/*************************** Converging algorithm 1.5 *****************************/
for (float testSize; (upperTextSize - lowerTextSize) > mThreshold;) {
// Go to the mean value...
testSize = (upperTextSize + lowerTextSize) / 2;
mTestView.setTextSize(TypedValue.COMPLEX_UNIT_SP, testSize / mScaledDensityFactor);
mTestView.setText(text);
mTestView.measure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
if (mTestView.getMeasuredHeight() >= targetFieldHeight) {
upperTextSize = testSize; // Font is too big, decrease upperSize
} else {
lowerTextSize = testSize; // Font is too small, increase lowerSize
}
}
/**********************************************************************************/
}
} else {
/*********************** Converging algorithm 2 ***************************************/
// Upper and lower size converge over time. As soon as they're close enough the loop
// stops
// TODO probe the algorithm for cost (ATM possibly O(n^2)) and optimize if possible
for (float testSize; (upperTextSize - lowerTextSize) > mThreshold;) {
// Go to the mean value...
testSize = (upperTextSize + lowerTextSize) / 2;
// ... inflate the dummy TextView by setting a scaled textSize and the text...
mTestView.setTextSize(TypedValue.COMPLEX_UNIT_SP, testSize / mScaledDensityFactor);
mTestView.setText(text);
// ... call measure to find the current values that the text WANTS to occupy
mTestView.measure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
int tempHeight = mTestView.getMeasuredHeight();
// int tempWidth = mTestView.getMeasuredWidth();
// LOG.debug("Measured: " + tempWidth + "x" + tempHeight);
// LOG.debug("TextSize: " + testSize / mScaledDensityFactor);
// ... decide whether those values are appropriate.
if (tempHeight >= targetFieldHeight) {
upperTextSize = testSize; // Font is too big, decrease upperSize
} else {
lowerTextSize = testSize; // Font is too small, increase lowerSize
}
}
/**************************************************************************************/
// It is possible that a single word is wider than the box. The Android system would
// wrap this for us. But if you want to decide fo yourself where exactly to break or to
// add a hyphen or something than you're going to want to implement something like this:
mTestPaint.setTextSize(lowerTextSize);
List<String> words = new ArrayList<String>();
for (String s : text.split(" ")) {
Log.i("tag", "Word: " + s);
words.add(s);
}
for (String word : words) {
if (mTestPaint.measureText(word) >= targetFieldWidth) {
List<String> pieces = new ArrayList<String>();
// pieces = breakWord(word, mTestPaint.measureText(word), targetFieldWidth);
// Add code to handle the pieces here...
}
}
}
/**
* We are now at most the value of threshold away from the actual size. To rather undershoot than overshoot use the lower value. To match
* different screens convert to SP first. See {@link http://developer.android.com/guide/topics/resources/more-resources.html#Dimension} for
* more details
*/
this.setTextSize(TypedValue.COMPLEX_UNIT_SP, lowerTextSize / mScaledDensityFactor);
return;
}
/**
* This method receives a call upon a change in text content of the TextView. Unfortunately it is also called - among others - upon text size
* change which means that we MUST NEVER CALL {@link #refitText(String)} from this method! Doing so would result in an endless loop that would
* ultimately result in a stack overflow and termination of the application
*
* So for the time being this method does absolutely nothing. If you want to notify the view of a changed text call {@link #setText(CharSequence)}
*/
@Override
protected void onTextChanged(CharSequence text, int start, int lengthBefore, int lengthAfter) {
// Super implementation is also intentionally empty so for now we do absolutely nothing here
super.onTextChanged(text, start, lengthBefore, lengthAfter);
}
@Override
protected void onSizeChanged(int width, int height, int oldWidth, int oldHeight) {
if (width != oldWidth && height != oldHeight) {
refitText(this.getText().toString(), width, height);
}
}
/**
* This method is guaranteed to be called by {@link TextView#setText(CharSequence)} immediately. Therefore we can safely add our modifications
* here and then have the parent class resume its work. So if text has changed you should always call {@link TextView#setText(CharSequence)} or
* {@link TextView#setText(CharSequence, BufferType)} if you know whether the {@link BufferType} is normal, editable or spannable. Note: the
* method will default to {@link BufferType#NORMAL} if you don't pass an argument.
*/
@Override
public void setText(CharSequence text, BufferType type) {
int targetFieldWidth = this.getWidth();
int targetFieldHeight = this.getHeight();
if (targetFieldWidth <= 0 || targetFieldHeight <= 0 || text.equals("")) {
// Log.v("tag", "Some values are empty, AutoFitText was not able to construct properly");
} else {
refitText(text.toString(), targetFieldWidth, targetFieldHeight);
}
super.setText(text, type);
}
/**
* TODO add sensibility for {@link #setMaxLines(int)} invocations
*/
@Override
public void setMaxLines(int maxLines) {
// TODO Implement support for this. This could be relatively easy. The idea would probably
// be to manipulate the targetHeight in the refitText-method and then have the algorithm do
// its job business as usual. Nonetheless, remember the height will have to be lowered
// dynamically as the font size shrinks so it won't be a walk in the park still
if (maxLines == 1) {
this.setSingleLine(true);
} else {
throw new UnsupportedOperationException("MaxLines != 1 are not implemented in AutoFitText yet, use TextView instead");
}
}
@Override
public void setSingleLine(boolean singleLine) {
// save the requested value in an instance variable to be able to decide later
mSingleLine = singleLine;
super.setSingleLine(singleLine);
}
}
已知错误：不适用于 Android 4.03 - 字体不可见或非常小（原始 avalancha 也不起作用）下面是该错误的解决方法：https ://stackoverflow.com/a/21851239/2075875
