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public class FillTextView extends TextView {
/** Our ellipsis string. */
private static final String mEllipsis = "\u2026";
/**
* Upper bounds for text size.
* This acts as a starting point for resizing.
*/
private int mMaxTextSizePixels;
/** Lower bounds for text size. */
private int mMinTextSizePixels;
/** TextView line spacing multiplier. */
private float mLineSpacingMultiplier = 1.0f;
/** TextView additional line spacing. */
private float mLineSpacingExtra = 0.0f;
/**
* Default constructor override.
*
* @param context
*/
public FillTextView(Context context) {
this(context, null);
initialise();
}
/**
* Default constructor when inflating from XML file.
*
* @param context
* @param attrs
*/
public FillTextView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
initialise();
}
/**
* Default constructor override.
*
* @param context
* @param attrs
* @param defStyle
*/
public FillTextView(
Context context,
AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
initialise();
}
@Override
protected void onLayout (
boolean changed,
int left,
int top,
int right,
int bottom) {
super.onLayout(changed, left, top, right, bottom);
resizeText();
}
@Override
protected void onTextChanged(
CharSequence text,
int start,
int lengthBefore,
int lengthAfter) {
super.onTextChanged(text, start, lengthBefore, lengthAfter);
requestLayout();
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
if (w != oldw || h != oldh) {
requestLayout();
}
}
@Override
public void setTextSize(float size) {
setTextSize(TypedValue.COMPLEX_UNIT_SP, size);
}
@Override
public void setTextSize(int unit, float size) {
super.setTextSize(unit, size);
mMaxTextSizePixels = (int) getTextSize();
requestLayout();
}
@Override
public void setLineSpacing(float add, float mult) {
super.setLineSpacing(add, mult);
mLineSpacingMultiplier = mult;
mLineSpacingExtra = add;
requestLayout();
}
@Override
public void setEllipsize(TextUtils.TruncateAt where) {
super.setEllipsize(where);
requestLayout();
}
/**
* Sets the lower text size limit and invalidates the view.
*
* @param minTextSizeScaledPixels the minimum size to use for text in this view,
* in scaled pixels.
*/
public void setMinTextSize(int minTextSizeScaledPixels) {
mMinTextSizePixels = convertScaledPixelsToPixels(minTextSizeScaledPixels);
requestLayout();
}
/**
* @return lower text size limit, in pixels.
*/
public float getMinTextSizePixels() {
return mMinTextSizePixels;
}
private void initialise() {
mMaxTextSizePixels = (int) getTextSize();
}
/**
* Resizes this view's text size with respect to its width and height
* (minus padding).
*/
private void resizeText() {
final int availableHeightPixels = getHeight()
- getCompoundPaddingBottom() - getCompoundPaddingTop();
final int availableWidthPixels = getWidth()
- getCompoundPaddingLeft() - getCompoundPaddingRight();
final CharSequence text = getText();
// Safety check
// (Do not resize if the view does not have dimensions or if there is no text)
if (text == null
|| text.length() == 0
|| availableHeightPixels <= 0
|| availableWidthPixels <= 0
|| mMaxTextSizePixels == 0) {
return;
}
int targetTextSizePixels = mMaxTextSizePixels;
int targetTextHeightPixels = getTextHeightPixels(
text,
availableWidthPixels,
targetTextSizePixels);
// Until we either fit within our TextView
// or we have reached our minimum text size,
// incrementally try smaller sizes
while (targetTextHeightPixels > availableHeightPixels
&& targetTextSizePixels > mMinTextSizePixels) {
targetTextSizePixels = Math.max(
targetTextSizePixels - 2,
mMinTextSizePixels);
targetTextHeightPixels = getTextHeightPixels(
text,
availableWidthPixels,
targetTextSizePixels);
}
// If we have reached our minimum text size and the text still doesn't fit,
// append an ellipsis
// (NOTE: Auto-ellipsize doesn't work hence why we have to do it here)
// (TODO: put ellipsis at the beginning, middle or end
// depending on the value of getEllipsize())
if (getEllipsize() != null
&& targetTextSizePixels == mMinTextSizePixels
&& targetTextHeightPixels > availableHeightPixels) {
// Make a copy of the original TextPaint object for measuring
TextPaint textPaintCopy = new TextPaint(getPaint());
textPaintCopy.setTextSize(targetTextSizePixels);
// Measure using a StaticLayout instance
StaticLayout staticLayout = new StaticLayout(
text,
textPaintCopy,
availableWidthPixels,
Layout.Alignment.ALIGN_NORMAL,
mLineSpacingMultiplier,
mLineSpacingExtra,
false);
// Check that we have a least one line of rendered text
if (staticLayout.getLineCount() > 0) {
// Since the line at the specific vertical position would be cut off,
// we must trim up to the previous line and add an ellipsis
int lastLine = staticLayout.getLineForVertical(availableHeightPixels) - 1;
if (lastLine >= 0) {
int startOffset = staticLayout.getLineStart(lastLine);
int endOffset = staticLayout.getLineEnd(lastLine);
float lineWidthPixels = staticLayout.getLineWidth(lastLine);
float ellipseWidth = textPaintCopy.measureText(mEllipsis);
// Trim characters off until we have enough room to draw the ellipsis
while (availableWidthPixels < lineWidthPixels + ellipseWidth) {
endOffset--;
lineWidthPixels = textPaintCopy.measureText(
text.subSequence(startOffset, endOffset + 1).toString());
}
setText(text.subSequence(0, endOffset) + mEllipsis);
}
}
}
super.setTextSize(TypedValue.COMPLEX_UNIT_PX, targetTextSizePixels);
// Some devices try to auto adjust line spacing, so force default line spacing
super.setLineSpacing(mLineSpacingExtra, mLineSpacingMultiplier);
}
/**
* Sets the text size of a clone of the view's {@link TextPaint} object
* and uses a {@link StaticLayout} instance to measure the height of the text.
*
* @param source
* @param availableWidthPixels
* @param textSizePixels
* @return the height of the text when placed in a view
* with the specified width
* and when the text has the specified size.
*/
private int getTextHeightPixels(
CharSequence source,
int availableWidthPixels,
float textSizePixels) {
// Make a copy of the original TextPaint object
// since the object gets modified while measuring
// (see also the docs for TextView.getPaint()
// which states to access it read-only)
TextPaint textPaintCopy = new TextPaint(getPaint());
textPaintCopy.setTextSize(textSizePixels);
// Measure using a StaticLayout instance
StaticLayout staticLayout = new StaticLayout(
source,
textPaintCopy,
availableWidthPixels,
Layout.Alignment.ALIGN_NORMAL,
mLineSpacingMultiplier,
mLineSpacingExtra,
true);
return staticLayout.getHeight();
}
/**
* @param scaledPixels
* @return the number of pixels which
scaledPixels
corresponds to on the device.
*/
private int convertScaledPixelsToPixels(int scaledPixels) {
float pixels = scaledPixels * getContext().getResources().getDisplayMetrics().scaledDensity;
return (int) pixels;
}
}