Refactor Styled utility functions into reusable objects.

This takes utility functions from Styled and a few other classes and
incorporates them into two new utility classes, TextLine and
MeasuredText.  The main point of this is to support shaping by skia,
to experiment with how this will look, this also introduces
character-based Arabic shaping.

MeasuredText is used by code that determines line breaks by generating
and examining character widths in logical order.  Factoring the code
in this way makes it usable by the ellipsize functions in TextUtils as
well as by StaticLayout.  This class takes over the caching of widths
and chars arrays that was previously performed by StyledText.  A small
number of MeasuredText objects are themselves cached by the class and
accesed using static obtain and recycle methods.  Generally only these
few cached instances are ever created.

TextLine is used by code that draws or measures text on a line.  This
unifies the line measuring and rendering code, and pushes assumptions
about how rtl text is treated closer to the points where skia code is
invoked.  TextLine implements the functions that were previously
provided by Styled, working on member arrays rather than
explicitly-passed arguments.  It implements the same kind of static
cache as MeasuredText.

TextLine and MeasureText simulate arabic glyph generation and shaping
by using ArabicShaping, ported with very minor changes from ICU4J's
ArabicShaping.  This class generates shaped Arabic glyphs and Lam-Alef
ligatures using Unicode presentation forms.  ArabicShaping is not
intended to be permanent, but to be replaced by real shaping from the
skia layer. It is introduced in order to emulate the behavior of real
shaping so that higher level code dealing with rendering shaped text
and cursor movement over ligatures can be developed and tested; it
also provides basic-level support for Arabic.

Since cursor movement depends on conjuncts whose formation is
font-dependent, cursor movement code that was formerly in Layout and
StaticLayout was moved into TextLine so that it can work on the shaped
text.

Other than these changes, the other major change is a rework of the
ellipsize utility functions to combine multiple branches into fewer
branches with additional state.

Updated copyright notices on new files.

Change-Id: I492cb58b51f5aaf6f14cb1419bdbed49eac5ba29

1 files changed, 149 insertions, 293 deletions

diff --git a/core/java/android/text/TextUtils.java b/core/java/android/text/TextUtils.java
index 9589bf3..2d6c7b6 100644
--- a/core/java/android/text/TextUtils.java
+++ b/core/java/android/text/TextUtils.java
@@ -17,12 +17,11 @@
 package android.text;
 
 import com.android.internal.R;
+import com.android.internal.util.ArrayUtils;
 
-import android.content.res.ColorStateList;
 import android.content.res.Resources;
 import android.os.Parcel;
 import android.os.Parcelable;
-import android.text.method.TextKeyListener.Capitalize;
 import android.text.style.AbsoluteSizeSpan;
 import android.text.style.AlignmentSpan;
 import android.text.style.BackgroundColorSpan;
@@ -45,10 +44,8 @@ import android.text.style.URLSpan;
 import android.text.style.UnderlineSpan;
 import android.util.Printer;
 
-import com.android.internal.util.ArrayUtils;
-
-import java.util.regex.Pattern;
 import java.util.Iterator;
+import java.util.regex.Pattern;
 
 public class TextUtils {
     private TextUtils() { /* cannot be instantiated */ }
@@ -983,7 +980,7 @@ public class TextUtils {
     /**
      * Returns the original text if it fits in the specified width
      * given the properties of the specified Paint,
-     * or, if it does not fit, a copy with ellipsis character added 
+     * or, if it does not fit, a copy with ellipsis character added
      * at the specified edge or center.
      * If <code>preserveLength</code> is specified, the returned copy
      * will be padded with zero-width spaces to preserve the original
@@ -992,7 +989,7 @@ public class TextUtils {
      * report the start and end of the ellipsized range.
      */
     public static CharSequence ellipsize(CharSequence text,
-                                         TextPaint p,
+                                         TextPaint paint,
                                          float avail, TruncateAt where,
                                          boolean preserveLength,
                                          EllipsizeCallback callback) {
@@ -1003,13 +1000,12 @@ public class TextUtils {
 
         int len = text.length();
 
-        // Use Paint.breakText() for the non-Spanned case to avoid having
-        // to allocate memory and accumulate the character widths ourselves.
-
-        if (!(text instanceof Spanned)) {
-            float wid = p.measureText(text, 0, len);
+        MeasuredText mt = MeasuredText.obtain();
+        try {
+            float width = setPara(mt, paint, text, 0, text.length(),
+                    Layout.DIR_REQUEST_DEFAULT_LTR);
 
-            if (wid <= avail) {
+            if (width <= avail) {
                 if (callback != null) {
                     callback.ellipsized(0, 0);
                 }
@@ -1017,252 +1013,71 @@ public class TextUtils {
                 return text;
             }
 
-            float ellipsiswid = p.measureText(sEllipsis);
-
-            if (ellipsiswid > avail) {
-                if (callback != null) {
-                    callback.ellipsized(0, len);
-                }
-
-                if (preserveLength) {
-                    char[] buf = obtain(len);
-                    for (int i = 0; i < len; i++) {
-                        buf[i] = '\uFEFF';
-                    }
-                    String ret = new String(buf, 0, len);
-                    recycle(buf);
-                    return ret;
-                } else {
-                    return "";
-                }
-            }
-
-            if (where == TruncateAt.START) {
-                int fit = p.breakText(text, 0, len, false,
-                                      avail - ellipsiswid, null);
-
-                if (callback != null) {
-                    callback.ellipsized(0, len - fit);
-                }
-
-                if (preserveLength) {
-                    return blank(text, 0, len - fit);
-                } else {
-                    return sEllipsis + text.toString().substring(len - fit, len);
-                }
+            // XXX assumes ellipsis string does not require shaping and
+            // is unaffected by style
+            float ellipsiswid = paint.measureText(sEllipsis);
+            avail -= ellipsiswid;
+
+            int left = 0;
+            int right = len;
+            if (avail < 0) {
+                // it all goes
+            } else if (where == TruncateAt.START) {
+                right = len - mt.breakText(0, len, false, avail);
             } else if (where == TruncateAt.END) {
-                int fit = p.breakText(text, 0, len, true,
-                                      avail - ellipsiswid, null);
-
-                if (callback != null) {
-                    callback.ellipsized(fit, len);
-                }
-
-                if (preserveLength) {
-                    return blank(text, fit, len);
-                } else {
-                    return text.toString().substring(0, fit) + sEllipsis;
-                } 
-            } else /* where == TruncateAt.MIDDLE */ {
-                int right = p.breakText(text, 0, len, false,
-                                        (avail - ellipsiswid) / 2, null);
-                float used = p.measureText(text, len - right, len);
-                int left = p.breakText(text, 0, len - right, true,
-                                       avail - ellipsiswid - used, null);
-
-                if (callback != null) {
-                    callback.ellipsized(left, len - right);
-                }
-
-                if (preserveLength) {
-                    return blank(text, left, len - right);
-                } else {
-                    String s = text.toString();
-                    return s.substring(0, left) + sEllipsis +
-                           s.substring(len - right, len);
-                }
+                left = mt.breakText(0, len, true, avail);
+            } else {
+                right = len - mt.breakText(0, len, false, avail / 2);
+                avail -= mt.measure(right, len);
+                left = mt.breakText(0, right, true, avail);
             }
-        }
-
-        // But do the Spanned cases by hand, because it's such a pain
-        // to iterate the span transitions backwards and getTextWidths()
-        // will give us the information we need.
-
-        // getTextWidths() always writes into the start of the array,
-        // so measure each span into the first half and then copy the
-        // results into the second half to use later.
-
-        float[] wid = new float[len * 2];
-        TextPaint temppaint = new TextPaint();
-        Spanned sp = (Spanned) text;
-
-        int next;
-        for (int i = 0; i < len; i = next) {
-            next = sp.nextSpanTransition(i, len, MetricAffectingSpan.class);
-
-            Styled.getTextWidths(p, temppaint, sp, i, next, wid, null);
-            System.arraycopy(wid, 0, wid, len + i, next - i);
-        }
-
-        float sum = 0;
-        for (int i = 0; i < len; i++) {
-            sum += wid[len + i];
-        }
 
-        if (sum <= avail) {
             if (callback != null) {
-                callback.ellipsized(0, 0);
+                callback.ellipsized(left, right);
             }
 
-            return text;
-        }
-
-        float ellipsiswid = p.measureText(sEllipsis);
-
-        if (ellipsiswid > avail) {
-            if (callback != null) {
-                callback.ellipsized(0, len);
-            }
+            char[] buf = mt.mChars;
+            Spanned sp = text instanceof Spanned ? (Spanned) text : null;
 
+            int remaining = len - (right - left);
             if (preserveLength) {
-                char[] buf = obtain(len);
-                for (int i = 0; i < len; i++) {
+                if (remaining > 0) { // else eliminate the ellipsis too
+                    buf[left++] = '\u2026';
+                }
+                for (int i = left; i < right; i++) {
                     buf[i] = '\uFEFF';
                 }
-                SpannableString ss = new SpannableString(new String(buf, 0, len));
-                recycle(buf);
-                copySpansFrom(sp, 0, len, Object.class, ss, 0);
-                return ss;
-            } else {
-                return "";
-            }
-        }
-
-        if (where == TruncateAt.START) {
-            sum = 0;
-            int i;
-
-            for (i = len; i >= 0; i--) {
-                float w = wid[len + i - 1];
-
-                if (w + sum + ellipsiswid > avail) {
-                    break;
+                String s = new String(buf, 0, len);
+                if (sp == null) {
+                    return s;
                 }
-
-                sum += w;
-            }
-
-            if (callback != null) {
-                callback.ellipsized(0, i);
-            }
-
-            if (preserveLength) {
-                SpannableString ss = new SpannableString(blank(text, 0, i));
-                copySpansFrom(sp, 0, len, Object.class, ss, 0);
-                return ss;
-            } else {
-                SpannableStringBuilder out = new SpannableStringBuilder(sEllipsis);
-                out.insert(1, text, i, len);
-
-                return out;
-            }
-        } else if (where == TruncateAt.END) {
-            sum = 0;
-            int i;
-
-            for (i = 0; i < len; i++) {
-                float w = wid[len + i];
-
-                if (w + sum + ellipsiswid > avail) {
-                    break;
-                }
-
-                sum += w;
-            }
-
-            if (callback != null) {
-                callback.ellipsized(i, len);
-            }
-
-            if (preserveLength) {
-                SpannableString ss = new SpannableString(blank(text, i, len));
+                SpannableString ss = new SpannableString(s);
                 copySpansFrom(sp, 0, len, Object.class, ss, 0);
                 return ss;
-            } else {
-                SpannableStringBuilder out = new SpannableStringBuilder(sEllipsis);
-                out.insert(0, text, 0, i);
-
-                return out;
-            }
-        } else /* where = TruncateAt.MIDDLE */ {
-            float lsum = 0, rsum = 0;
-            int left = 0, right = len;
-
-            float ravail = (avail - ellipsiswid) / 2;
-            for (right = len; right >= 0; right--) {
-                float w = wid[len + right - 1];
-
-                if (w + rsum > ravail) {
-                    break;
-                }
-
-                rsum += w;
             }
 
-            float lavail = avail - ellipsiswid - rsum;
-            for (left = 0; left < right; left++) {
-                float w = wid[len + left];
-
-                if (w + lsum > lavail) {
-                    break;
-                }
-
-                lsum += w;
+            if (remaining == 0) {
+                return "";
             }
 
-            if (callback != null) {
-                callback.ellipsized(left, right);
+            if (sp == null) {
+                StringBuilder sb = new StringBuilder(remaining + sEllipsis.length());
+                sb.append(buf, 0, left);
+                sb.append(sEllipsis);
+                sb.append(buf, right, len - right);
+                return sb.toString();
             }
 
-            if (preserveLength) {
-                SpannableString ss = new SpannableString(blank(text, left, right));
-                copySpansFrom(sp, 0, len, Object.class, ss, 0);
-                return ss;
-            } else {
-                SpannableStringBuilder out = new SpannableStringBuilder(sEllipsis);
-                out.insert(0, text, 0, left);
-                out.insert(out.length(), text, right, len);
-
-                return out;
-            }
+            SpannableStringBuilder ssb = new SpannableStringBuilder();
+            ssb.append(text, 0, left);
+            ssb.append(sEllipsis);
+            ssb.append(text, right, len);
+            return ssb;
+        } finally {
+            MeasuredText.recycle(mt);
         }
     }
 
-    private static String blank(CharSequence source, int start, int end) {
-        int len = source.length();
-        char[] buf = obtain(len);
-
-        if (start != 0) {
-            getChars(source, 0, start, buf, 0);
-        }
-        if (end != len) {
-            getChars(source, end, len, buf, end);
-        }
-
-        if (start != end) {
-            buf[start] = '\u2026';
-
-            for (int i = start + 1; i < end; i++) {
-                buf[i] = '\uFEFF';
-            }
-        }
-    
-        String ret = new String(buf, 0, len);
-        recycle(buf);
-
-        return ret;
-    }
-
     /**
      * Converts a CharSequence of the comma-separated form "Andy, Bob,
      * Charles, David" that is too wide to fit into the specified width
@@ -1278,80 +1093,121 @@ public class TextUtils {
                                               TextPaint p, float avail,
                                               String oneMore,
                                               String more) {
-        int len = text.length();
-        char[] buf = new char[len];
-        TextUtils.getChars(text, 0, len, buf, 0);
 
-        int commaCount = 0;
-        for (int i = 0; i < len; i++) {
-            if (buf[i] == ',') {
-                commaCount++;
+        MeasuredText mt = MeasuredText.obtain();
+        try {
+            int len = text.length();
+            float width = setPara(mt, p, text, 0, len, Layout.DIR_REQUEST_DEFAULT_LTR);
+            if (width <= avail) {
+                return text;
             }
-        }
-
-        float[] wid;
 
-        if (text instanceof Spanned) {
-            Spanned sp = (Spanned) text;
-            TextPaint temppaint = new TextPaint();
-            wid = new float[len * 2];
+            char[] buf = mt.mChars;
 
-            int next;
-            for (int i = 0; i < len; i = next) {
-                next = sp.nextSpanTransition(i, len, MetricAffectingSpan.class);
-
-                Styled.getTextWidths(p, temppaint, sp, i, next, wid, null);
-                System.arraycopy(wid, 0, wid, len + i, next - i);
+            int commaCount = 0;
+            for (int i = 0; i < len; i++) {
+                if (buf[i] == ',') {
+                    commaCount++;
+                }
             }
 
-            System.arraycopy(wid, len, wid, 0, len);
-        } else {
-            wid = new float[len];
-            p.getTextWidths(text, 0, len, wid);
-        }
+            int remaining = commaCount + 1;
 
-        int ok = 0;
-        int okRemaining = commaCount + 1;
-        String okFormat = "";
+            int ok = 0;
+            int okRemaining = remaining;
+            String okFormat = "";
 
-        int w = 0;
-        int count = 0;
+            int w = 0;
+            int count = 0;
+            float[] widths = mt.mWidths;
 
-        for (int i = 0; i < len; i++) {
-            w += wid[i];
+            int request = mt.mDir == 1 ? Layout.DIR_REQUEST_LTR :
+                Layout.DIR_REQUEST_RTL;
 
-            if (buf[i] == ',') {
-                count++;
+            MeasuredText tempMt = MeasuredText.obtain();
+            for (int i = 0; i < len; i++) {
+                w += widths[i];
 
-                int remaining = commaCount - count + 1;
-                float moreWid;
-                String format;
+                if (buf[i] == ',') {
+                    count++;
 
-                if (remaining == 1) {
-                    format = " " + oneMore;
-                } else {
-                    format = " " + String.format(more, remaining);
-                }
+                    String format;
+                    // XXX should not insert spaces, should be part of string
+                    // XXX should use plural rules and not assume English plurals
+                    if (--remaining == 1) {
+                        format = " " + oneMore;
+                    } else {
+                        format = " " + String.format(more, remaining);
+                    }
 
-                moreWid = p.measureText(format);
+                    // XXX this is probably ok, but need to look at it more
+                    tempMt.setPara(format, 0, format.length(), request);
+                    float moreWid = mt.addStyleRun(p, mt.mLen, null);
 
-                if (w + moreWid <= avail) {
-                    ok = i + 1;
-                    okRemaining = remaining;
-                    okFormat = format;
+                    if (w + moreWid <= avail) {
+                        ok = i + 1;
+                        okRemaining = remaining;
+                        okFormat = format;
+                    }
                 }
             }
-        }
+            MeasuredText.recycle(tempMt);
 
-        if (w <= avail) {
-            return text;
-        } else {
             SpannableStringBuilder out = new SpannableStringBuilder(okFormat);
             out.insert(0, text, 0, ok);
             return out;
+        } finally {
+            MeasuredText.recycle(mt);
         }
     }
 
+    private static float setPara(MeasuredText mt, TextPaint paint,
+            CharSequence text, int start, int end, int bidiRequest) {
+
+        mt.setPara(text, start, end, bidiRequest);
+
+        float width;
+        Spanned sp = text instanceof Spanned ? (Spanned) text : null;
+        int len = end - start;
+        if (sp == null) {
+            width = mt.addStyleRun(paint, len, null);
+        } else {
+            width = 0;
+            int spanEnd;
+            for (int spanStart = 0; spanStart < len; spanStart = spanEnd) {
+                spanEnd = sp.nextSpanTransition(spanStart, len,
+                        MetricAffectingSpan.class);
+                MetricAffectingSpan[] spans = sp.getSpans(
+                        spanStart, spanEnd, MetricAffectingSpan.class);
+                width += mt.addStyleRun(paint, spans, spanEnd - spanStart, null);
+            }
+        }
+
+        return width;
+    }
+
+    private static final char FIRST_RIGHT_TO_LEFT = '\u0590';
+
+    /* package */
+    static boolean doesNotNeedBidi(CharSequence s, int start, int end) {
+        for (int i = start; i < end; i++) {
+            if (s.charAt(i) >= FIRST_RIGHT_TO_LEFT) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /* package */
+    static boolean doesNotNeedBidi(char[] text, int start, int len) {
+        for (int i = start, e = i + len; i < e; i++) {
+            if (text[i] >= FIRST_RIGHT_TO_LEFT) {
+                return false;
+            }
+        }
+        return true;
+    }
+
     /* package */ static char[] obtain(int len) {
         char[] buf;
 
@@ -1529,7 +1385,7 @@ public class TextUtils {
      */
     public static final int CAP_MODE_CHARACTERS
             = InputType.TYPE_TEXT_FLAG_CAP_CHARACTERS;
-    
+
     /**
      * Capitalization mode for {@link #getCapsMode}: capitalize the first
      * character of all words.  This value is explicitly defined to be the same as
@@ -1537,7 +1393,7 @@ public class TextUtils {
      */
     public static final int CAP_MODE_WORDS
             = InputType.TYPE_TEXT_FLAG_CAP_WORDS;
-    
+
     /**
      * Capitalization mode for {@link #getCapsMode}: capitalize the first
      * character of each sentence.  This value is explicitly defined to be the same as
@@ -1545,13 +1401,13 @@ public class TextUtils {
      */
     public static final int CAP_MODE_SENTENCES
             = InputType.TYPE_TEXT_FLAG_CAP_SENTENCES;
-    
+
     /**
      * Determine what caps mode should be in effect at the current offset in
      * the text.  Only the mode bits set in <var>reqModes</var> will be
      * checked.  Note that the caps mode flags here are explicitly defined
      * to match those in {@link InputType}.
-     * 
+     *
      * @param cs The text that should be checked for caps modes.
      * @param off Location in the text at which to check.
      * @param reqModes The modes to be checked: may be any combination of
@@ -1651,7 +1507,7 @@ public class TextUtils {
 
         return mode;
     }
-    
+
     private static Object sLock = new Object();
     private static char[] sTemp = null;
 }