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}.* <p/>* Note: {@link android.text.TextUtils.TruncateAt#MARQUEE} ellipsizing type is not supported.* <p>*/
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<EllipsizeListener> 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;}@Overridepublic 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;}@Overridepublic void setLineSpacing(float add, float mult) {mLineAddVertPad = add;mLineSpacingMult = mult;super.setLineSpacing(add, mult);}@Overridepublic 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);}@Overrideprotected void onSizeChanged(int w, int h, int oldw, int oldh) {super.onSizeChanged(w, h, oldw, oldh);if (ellipsizingLastFullyVisibleLine()) {//严谨，学习isStale = true;}}@Overridepublic void setPadding(int left, int top, int right, int bottom) {super.setPadding(left, top, right, bottom);if (ellipsizingLastFullyVisibleLine()) {//严谨，学习isStale = true;}}@Overrideprotected 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.* <p/>* Note: Method does nothing for {@link android.text.TextUtils.TruncateAt#MARQUEE}* ellipsizing type.** @param where part of text to ellipsize*/@Overridepublic 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 {@Overrideprotected CharSequence createEllipsizedText(CharSequence fullText) {return fullText;}}/*** An {@link EllipsizingTextView.EllipsizeStrategy} that* ellipsizes text at the end.*/private class EllipsizeEndStrategy extends EllipsizeStrategy {@Overrideprotected 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 {@Overrideprotected 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 {@Overrideprotected 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);}}
复制代码