Created
February 9, 2015 13:45
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TextView that gets its text size refined to fit the available space
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import android.annotation.TargetApi; | |
import android.content.Context; | |
import android.content.res.Resources; | |
import android.graphics.RectF; | |
import android.os.Build; | |
import android.text.Layout.Alignment; | |
import android.text.StaticLayout; | |
import android.text.TextPaint; | |
import android.util.AttributeSet; | |
import android.util.SparseIntArray; | |
import android.util.TypedValue; | |
import android.widget.TextView; | |
public class AutoResizeTextView extends TextView { | |
private interface SizeTester { | |
/** | |
* @param suggestedSize Size of text to be tested | |
* @param availableSpace available space in which text must fit | |
* @return an integer < 0 if after applying {@code suggestedSize} to | |
* text, it takes less space than {@code availableSpace}, > 0 | |
* otherwise | |
*/ | |
public int onTestSize(int suggestedSize, RectF availableSpace); | |
} | |
private RectF mTextRect = new RectF(); | |
private RectF mAvailableSpaceRect; | |
private SparseIntArray mTextCachedSizes; | |
private TextPaint mPaint; | |
private float mMaxTextSize; | |
private float mSpacingMult = 1.0f; | |
private float mSpacingAdd = 0.0f; | |
private float mMinTextSize = 20; | |
private int mWidthLimit; | |
private static final int NO_LINE_LIMIT = -1; | |
private int mMaxLines; | |
private boolean mEnableSizeCache = true; | |
private boolean mInitiallized; | |
public AutoResizeTextView(Context context) { | |
super(context); | |
initialize(); | |
} | |
public AutoResizeTextView(Context context, AttributeSet attrs) { | |
super(context, attrs); | |
initialize(); | |
} | |
public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) { | |
super(context, attrs, defStyle); | |
initialize(); | |
} | |
private void initialize() { | |
mPaint = new TextPaint(getPaint()); | |
mMaxTextSize = getTextSize(); | |
mAvailableSpaceRect = new RectF(); | |
mTextCachedSizes = new SparseIntArray(); | |
if (mMaxLines == 0) { | |
// no value was assigned during construction | |
mMaxLines = NO_LINE_LIMIT; | |
} | |
mInitiallized = true; | |
} | |
@Override | |
public void setText(final CharSequence text, BufferType type) { | |
super.setText(text, type); | |
adjustTextSize(text.toString()); | |
} | |
@Override | |
public void setTextSize(float size) { | |
mMaxTextSize = size; | |
mTextCachedSizes.clear(); | |
adjustTextSize(getText().toString()); | |
} | |
@Override | |
public void setMaxLines(int maxlines) { | |
super.setMaxLines(maxlines); | |
mMaxLines = maxlines; | |
reAdjust(); | |
} | |
public int getMaxLines() { | |
return mMaxLines; | |
} | |
@Override | |
public void setSingleLine() { | |
super.setSingleLine(); | |
mMaxLines = 1; | |
reAdjust(); | |
} | |
@Override | |
public void setSingleLine(boolean singleLine) { | |
super.setSingleLine(singleLine); | |
if (singleLine) { | |
mMaxLines = 1; | |
} else { | |
mMaxLines = NO_LINE_LIMIT; | |
} | |
reAdjust(); | |
} | |
@Override | |
public void setLines(int lines) { | |
super.setLines(lines); | |
mMaxLines = lines; | |
reAdjust(); | |
} | |
@Override | |
public void setTextSize(int unit, float size) { | |
Context c = getContext(); | |
Resources r; | |
if (c == null) | |
r = Resources.getSystem(); | |
else | |
r = c.getResources(); | |
mMaxTextSize = TypedValue.applyDimension(unit, size, | |
r.getDisplayMetrics()); | |
mTextCachedSizes.clear(); | |
adjustTextSize(getText().toString()); | |
} | |
@Override | |
public void setLineSpacing(float add, float mult) { | |
super.setLineSpacing(add, mult); | |
mSpacingMult = mult; | |
mSpacingAdd = add; | |
} | |
/** | |
* Set the lower text size limit and invalidate the view | |
* | |
* @param minTextSize | |
*/ | |
public void setMinTextSize(float minTextSize) { | |
mMinTextSize = minTextSize; | |
reAdjust(); | |
} | |
private void reAdjust() { | |
adjustTextSize(getText().toString()); | |
} | |
private void adjustTextSize(String string) { | |
if (!mInitiallized) { | |
return; | |
} | |
int startSize = (int) mMinTextSize; | |
int heightLimit = getMeasuredHeight() - getCompoundPaddingBottom() | |
- getCompoundPaddingTop(); | |
mWidthLimit = getMeasuredWidth() - getCompoundPaddingLeft() | |
- getCompoundPaddingRight(); | |
mAvailableSpaceRect.right = mWidthLimit; | |
mAvailableSpaceRect.bottom = heightLimit; | |
super.setTextSize( | |
TypedValue.COMPLEX_UNIT_PX, | |
efficientTextSizeSearch(startSize, (int) mMaxTextSize, | |
mSizeTester, mAvailableSpaceRect)); | |
} | |
private final SizeTester mSizeTester = new SizeTester() { | |
@TargetApi(Build.VERSION_CODES.JELLY_BEAN) | |
@Override | |
public int onTestSize(int suggestedSize, RectF availableSPace) { | |
mPaint.setTextSize(suggestedSize); | |
String text = getText().toString(); | |
boolean singleline = getMaxLines() == 1; | |
if (singleline) { | |
mTextRect.bottom = mPaint.getFontSpacing(); | |
mTextRect.right = mPaint.measureText(text); | |
} else { | |
StaticLayout layout = new StaticLayout(text, mPaint, | |
mWidthLimit, Alignment.ALIGN_NORMAL, mSpacingMult, | |
mSpacingAdd, true); | |
// return early if we have more lines | |
if (getMaxLines() != NO_LINE_LIMIT | |
&& layout.getLineCount() > getMaxLines()) { | |
return 1; | |
} | |
mTextRect.bottom = layout.getHeight(); | |
int maxWidth = -1; | |
for (int i = 0; i < layout.getLineCount(); i++) { | |
if (maxWidth < layout.getLineWidth(i)) { | |
maxWidth = (int) layout.getLineWidth(i); | |
} | |
} | |
mTextRect.right = maxWidth; | |
} | |
mTextRect.offsetTo(0, 0); | |
if (availableSPace.contains(mTextRect)) { | |
// may be too small, don't worry we will find the best match | |
return -1; | |
} else { | |
// too big | |
return 1; | |
} | |
} | |
}; | |
/** | |
* Enables or disables size caching, enabling it will improve performance | |
* where you are animating a value inside TextView. This stores the font | |
* size against getText().length() Be careful though while enabling it as 0 | |
* takes more space than 1 on some fonts and so on. | |
* | |
* @param enable enable font size caching | |
*/ | |
public void enableSizeCache(boolean enable) { | |
mEnableSizeCache = enable; | |
mTextCachedSizes.clear(); | |
adjustTextSize(getText().toString()); | |
} | |
private int efficientTextSizeSearch(int start, int end, | |
SizeTester sizeTester, RectF availableSpace) { | |
if (!mEnableSizeCache) { | |
return binarySearch(start, end, sizeTester, availableSpace); | |
} | |
String text = getText().toString(); | |
int key = text == null ? 0 : text.length(); | |
int size = mTextCachedSizes.get(key); | |
if (size != 0) { | |
return size; | |
} | |
size = binarySearch(start, end, sizeTester, availableSpace); | |
mTextCachedSizes.put(key, size); | |
return size; | |
} | |
private static int binarySearch(int start, int end, SizeTester sizeTester, | |
RectF availableSpace) { | |
int lastBest = start; | |
int lo = start; | |
int hi = end - 1; | |
int mid = 0; | |
while (lo <= hi) { | |
mid = (lo + hi) >>> 1; | |
int midValCmp = sizeTester.onTestSize(mid, availableSpace); | |
if (midValCmp < 0) { | |
lastBest = lo; | |
lo = mid + 1; | |
} else if (midValCmp > 0) { | |
hi = mid - 1; | |
lastBest = hi; | |
} else { | |
return mid; | |
} | |
} | |
// make sure to return last best | |
// this is what should always be returned | |
return lastBest; | |
} | |
@Override | |
protected void onTextChanged(final CharSequence text, final int start, | |
final int before, final int after) { | |
super.onTextChanged(text, start, before, after); | |
reAdjust(); | |
} | |
@Override | |
protected void onSizeChanged(int width, int height, int oldwidth, | |
int oldheight) { | |
mTextCachedSizes.clear(); | |
super.onSizeChanged(width, height, oldwidth, oldheight); | |
if (width != oldwidth || height != oldheight) { | |
reAdjust(); | |
} | |
} | |
} |
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