学习戚继光，一边儿读别人的源码，一边儿做笔记
代码来源：https://gist.github.com/stepango/1dcf6055a80f840f9185
/**
* A {@link android.widget.TextView} that ellipsizes more intelligently.
* This class supports ellipsizing multiline text through setting {@code android:ellipsize}
* and {@code android:maxLines}.
*
* Note: {@link android.text.TextUtils.TruncateAt#MARQUEE} ellipsizing type is not supported.
*
*/
public class EllipsizingTextView extends AppCompatTextView {
public static final int ELLIPSIZE_ALPHA = 0x88;
private SpannableString ELLIPSIS = new SpannableString("\u2026");
//能力不够，看不懂
private static final Pattern DEFAULT_END_PUNCTUATION
= Pattern.compile("[\\.!?,;:\u2026]*$", Pattern.DOTALL);
//监听器
private final List mEllipsizeListeners = new ArrayList<>();
//非常漂亮的策略模式
private EllipsizeStrategy mEllipsizeStrategy;
//配合监听器服务的
private boolean isEllipsized;
//为了是的reset方法只需要调用一次
private boolean isStale;
//用来判断调用setText()的入口是 是resetText还是其它地方调用的，这种做法很酷。
private boolean programmaticChange;
//文本
private CharSequence mFullText;
private int mMaxLines;
//行间距，这点儿都考虑到了，了不起。
private float mLineSpacingMult = 1.0f;
private float mLineAddVertPad = 0.0f;
/**
* The end punctuation which will be removed when appending {@link #ELLIPSIS}.
*/
private Pattern mEndPunctPattern;
public EllipsizingTextView(Context context) {
this(context, null);
}
public EllipsizingTextView(Context context, AttributeSet attrs) {
this(context, attrs, android.R.attr.textViewStyle);
}
public EllipsizingTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
TypedArray a = context.obtainStyledAttributes(attrs,
new int[]{android.R.attr.maxLines, android.R.attr.ellipsize}, defStyle, 0);
setMaxLines(a.getInt(0, Integer.MAX_VALUE));
a.recycle();
setEndPunctuationPattern(DEFAULT_END_PUNCTUATION);
final int currentTextColor = getCurrentTextColor();
final int ellipsizeColor = Color.argb(ELLIPSIZE_ALPHA, Color.red(currentTextColor), Color.green(currentTextColor), Color.blue(currentTextColor));
ELLIPSIS.setSpan(new ForegroundColorSpan(ellipsizeColor), 0, ELLIPSIS.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}
public void setEndPunctuationPattern(Pattern pattern) {
mEndPunctPattern = pattern;
}
@SuppressWarnings("unused")
public void addEllipsizeListener(@NonNull EllipsizeListener listener) {
mEllipsizeListeners.add(listener);
}
@SuppressWarnings("unused")
public void removeEllipsizeListener(@NonNull EllipsizeListener listener) {
mEllipsizeListeners.remove(listener);
}
@SuppressWarnings("unused")
public boolean isEllipsized() {
return isEllipsized;
}
/**
* @return The maximum number of lines displayed in this {@link android.widget.TextView}.
*/
public int getMaxLines() {
return mMaxLines;
}
@Override
public void setMaxLines(int maxLines) {
super.setMaxLines(maxLines);
mMaxLines = maxLines;
isStale = true;
}
/**
* Determines if the last fully visible line is being ellipsized.
*
* @return {@code true} if the last fully visible line is being ellipsized;
* otherwise, returns {@code false}.
*/
public boolean ellipsizingLastFullyVisibleLine() {
return mMaxLines == Integer.MAX_VALUE;
}
@Override
public void setLineSpacing(float add, float mult) {
mLineAddVertPad = add;
mLineSpacingMult = mult;
super.setLineSpacing(add, mult);
}
@Override
public void setText(CharSequence text, BufferType type) {
if (!programmaticChange) {//区分调用来源
mFullText = text instanceof Spanned ? (Spanned) text : text;
isStale = true;
}
super.setText(text, type);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
if (ellipsizingLastFullyVisibleLine()) {//严谨，学习
isStale = true;
}
}
@Override
public void setPadding(int left, int top, int right, int bottom) {
super.setPadding(left, top, right, bottom);
if (ellipsizingLastFullyVisibleLine()) {//严谨，学习
isStale = true;
}
}
@Override
protected void onDraw(@NonNull Canvas canvas) {
if (isStale) {
resetText();
}
super.onDraw(canvas);
}
/**
* Sets the ellipsized text if appropriate.
*/
private void resetText() {
int maxLines = getMaxLines();
CharSequence workingText = mFullText;
boolean ellipsized = false;
if (maxLines != -1) {
if (mEllipsizeStrategy == null) setEllipsize(null);
workingText = mEllipsizeStrategy.processText(mFullText);
ellipsized = !mEllipsizeStrategy.isInLayout(mFullText);
}
if (!workingText.equals(getText())) {//避免无用的操作
programmaticChange = true;
try {
setText(workingText);
} finally {
programmaticChange = false;
}
}
isStale = false;//切换状态
//通知监听器
if (ellipsized != isEllipsized) {
isEllipsized = ellipsized;
for (EllipsizeListener listener : mEllipsizeListeners) {
listener.ellipsizeStateChanged(ellipsized);
}
}
}
/**
* Causes words in the text that are longer than the view is wide to be ellipsized
* instead of broken in the middle. Use {@code null} to turn off ellipsizing.
*
* Note: Method does nothing for {@link android.text.TextUtils.TruncateAt#MARQUEE}
* ellipsizing type.
*
* @param where part of text to ellipsize
*/
@Override
public void setEllipsize(TruncateAt where) {
if (where == null) {
mEllipsizeStrategy = new EllipsizeNoneStrategy();
return;
}
switch (where) {
case END:
mEllipsizeStrategy = new EllipsizeEndStrategy();
break;
case START:
mEllipsizeStrategy = new EllipsizeStartStrategy();
break;
case MIDDLE:
mEllipsizeStrategy = new EllipsizeMiddleStrategy();
break;
case MARQUEE:
default:
mEllipsizeStrategy = new EllipsizeNoneStrategy();
break;
}
}
/**
* A listener that notifies when the ellipsize state has changed.
*/
public interface EllipsizeListener {
void ellipsizeStateChanged(boolean ellipsized);
}
/**
* A base class for an ellipsize strategy.
*/
private abstract class EllipsizeStrategy {
/**
* Returns ellipsized text if the text does not fit inside of the layout;
* otherwise, returns the full text.
*
* @param text text to process
* @return Ellipsized text if the text does not fit inside of the layout;
* otherwise, returns the full text.
*/
public CharSequence processText(CharSequence text) {
return !isInLayout(text) ? createEllipsizedText(text) : text;
}
/**
* Determines if the text fits inside of the layout.
*
* @param text text to fit
* @return {@code true} if the text fits inside of the layout;
* otherwise, returns {@code false}.
*/
public boolean isInLayout(CharSequence text) {
Layout layout = createWorkingLayout(text);
return layout.getLineCount() <= getLinesCount();
}
/**
* Creates a working layout with the given text.
*
* @param workingText text to create layout with
* @return {@link android.text.Layout} with the given text.
*/
protected Layout createWorkingLayout(CharSequence workingText) {
return new StaticLayout(workingText, getPaint(),
getWidth() - getCompoundPaddingLeft() - getCompoundPaddingRight(),
Alignment.ALIGN_NORMAL, mLineSpacingMult,
mLineAddVertPad, false /* includepad */);
}
/**
* Get how many lines of text we are allowed to display.
*/
protected int getLinesCount() {
if (ellipsizingLastFullyVisibleLine()) {
int fullyVisibleLinesCount = getFullyVisibleLinesCount();
return fullyVisibleLinesCount == -1 ? 1 : fullyVisibleLinesCount;
} else {
return mMaxLines;
}
}
/**
* Get how many lines of text we can display so their full height is visible.
*/
protected int getFullyVisibleLinesCount() {
Layout layout = createWorkingLayout("");
int height = getHeight() - getCompoundPaddingTop() - getCompoundPaddingBottom();
int lineHeight = layout.getLineBottom(0);
return height / lineHeight;
}
/**
* Creates ellipsized text from the given text.
*
* @param fullText text to ellipsize
* @return Ellipsized text
*/
protected abstract CharSequence createEllipsizedText(CharSequence fullText);
}
/**
* An {@link EllipsizingTextView.EllipsizeStrategy} that
* does not ellipsize text.
*/
private class EllipsizeNoneStrategy extends EllipsizeStrategy {
@Override
protected CharSequence createEllipsizedText(CharSequence fullText) {
return fullText;
}
}
/**
* An {@link EllipsizingTextView.EllipsizeStrategy} that
* ellipsizes text at the end.
*/
private class EllipsizeEndStrategy extends EllipsizeStrategy {
@Override
protected CharSequence createEllipsizedText(CharSequence fullText) {
Layout layout = createWorkingLayout(fullText);
int cutOffIndex = layout.getLineEnd(mMaxLines - 1);
int textLength = fullText.length();
int cutOffLength = textLength - cutOffIndex;
if (cutOffLength < ELLIPSIS.length()) cutOffLength = ELLIPSIS.length();
//真正要显示的文本
CharSequence workingText = TextUtils.substring(fullText, 0, textLength - cutOffLength).trim();
t("ELLIPSIS.length()", ELLIPSIS.length());
t("workingText 1", workingText);
final int lastLineStart = layout.getLineStart(mMaxLines - 1);
final CharSequence remainder = TextUtils.ellipsize(fullText.subSequence(lastLineStart,
fullText.length()), getPaint(), getWidth(), TextUtils.TruncateAt.END);
t("remainder", remainder);
//看不懂，可能是为了提出一些不好的边角吧
while (!isInLayout(TextUtils.concat(stripEndPunctuation(workingText), ELLIPSIS))) {
workingText = workingText.subSequence(0, workingText.length() - 1);
/*
int lastSpace = TextUtils.lastIndexOf(workingText, ' ');
if (lastSpace == -1) {
break;
}
workingText = TextUtils.substring(workingText, 0, lastSpace).trim();
*/
}
//链接...
workingText = TextUtils.concat(stripEndPunctuation(workingText), ELLIPSIS);
SpannableStringBuilder dest = new SpannableStringBuilder(workingText);
t("workingText 2", workingText);
//神操作
if (fullText instanceof Spanned) {
TextUtils.copySpansFrom((Spanned) fullText, 0, workingText.length(), null, dest, 0);
}
return dest;
}
/**
* Strips the end punctuation from a given text according to {@link #mEndPunctPattern}.
*
* @param workingText text to strip end punctuation from
* @return Text without end punctuation.
*/
public String stripEndPunctuation(CharSequence workingText) {
return mEndPunctPattern.matcher(workingText).replaceFirst("");
}
}
/**
* An {@link EllipsizingTextView.EllipsizeStrategy} that
* ellipsizes text at the start.
*/
private class EllipsizeStartStrategy extends EllipsizeStrategy {
@Override
protected CharSequence createEllipsizedText(CharSequence fullText) {
Layout layout = createWorkingLayout(fullText);
int cutOffIndex = layout.getLineEnd(mMaxLines - 1);
int textLength = fullText.length();
int cutOffLength = textLength - cutOffIndex;
if (cutOffLength < ELLIPSIS.length()) cutOffLength = ELLIPSIS.length();
CharSequence workingText = TextUtils.substring(fullText, cutOffLength, textLength).trim();
while (!isInLayout(TextUtils.concat(ELLIPSIS, workingText))) {
int firstSpace = TextUtils.indexOf(workingText, ' ');
if (firstSpace == -1) {
break;
}
workingText = TextUtils.substring(workingText, firstSpace, workingText.length()).trim();
}
workingText = TextUtils.concat(ELLIPSIS, workingText);
SpannableStringBuilder dest = new SpannableStringBuilder(workingText);
if (fullText instanceof Spanned) {
TextUtils.copySpansFrom((Spanned) fullText, textLength - workingText.length(),
textLength, null, dest, 0);
}
return dest;
}
}
/**
* An {@link EllipsizingTextView.EllipsizeStrategy} that
* ellipsizes text in the middle.
*/
private class EllipsizeMiddleStrategy extends EllipsizeStrategy {
@Override
protected CharSequence createEllipsizedText(CharSequence fullText) {
Layout layout = createWorkingLayout(fullText);
int cutOffIndex = layout.getLineEnd(mMaxLines - 1);
int textLength = fullText.length();
int cutOffLength = textLength - cutOffIndex;
if (cutOffLength < ELLIPSIS.length()) cutOffLength = ELLIPSIS.length();
cutOffLength += cutOffIndex % 2; // Make it even.
String firstPart = TextUtils.substring(
fullText, 0, textLength / 2 - cutOffLength / 2).trim();
String secondPart = TextUtils.substring(
fullText, textLength / 2 + cutOffLength / 2, textLength).trim();
while (!isInLayout(TextUtils.concat(firstPart, ELLIPSIS, secondPart))) {
int lastSpaceFirstPart = firstPart.lastIndexOf(' ');
int firstSpaceSecondPart = secondPart.indexOf(' ');
if (lastSpaceFirstPart == -1 || firstSpaceSecondPart == -1) break;
firstPart = firstPart.substring(0, lastSpaceFirstPart).trim();
secondPart = secondPart.substring(firstSpaceSecondPart, secondPart.length()).trim();
}
SpannableStringBuilder firstDest = new SpannableStringBuilder(firstPart);
SpannableStringBuilder secondDest = new SpannableStringBuilder(secondPart);
if (fullText instanceof Spanned) {
TextUtils.copySpansFrom((Spanned) fullText, 0, firstPart.length(),
null, firstDest, 0);
TextUtils.copySpansFrom((Spanned) fullText, textLength - secondPart.length(),
textLength, null, secondDest, 0);
}
return TextUtils.concat(firstDest, ELLIPSIS, secondDest);
}
}
public static void t(Object... msgs) {
StringBuilder text = new StringBuilder();
for (Object o : msgs) {
if (o == null) {
text.append("null");
} else {
text.append(o.toString());
}
text.append(" ");
}
Log.e("AJAX", "########## " + text);
}
}
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