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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.text;
     18 
     19 import android.graphics.Canvas;
     20 import android.graphics.Paint;
     21 import android.text.style.MetricAffectingSpan;
     22 import android.text.style.ReplacementSpan;
     23 import android.util.Log;
     24 
     25 import com.android.internal.util.ArrayUtils;
     26 
     27 /**
     28  * @hide
     29  */
     30 class MeasuredText {
     31     private static final boolean localLOGV = false;
     32     CharSequence mText;
     33     int mTextStart;
     34     float[] mWidths;
     35     char[] mChars;
     36     byte[] mLevels;
     37     int mDir;
     38     boolean mEasy;
     39     int mLen;
     40 
     41     private int mPos;
     42     private TextPaint mWorkPaint;
     43 
     44     private MeasuredText() {
     45         mWorkPaint = new TextPaint();
     46     }
     47 
     48     private static final Object[] sLock = new Object[0];
     49     private static MeasuredText[] sCached = new MeasuredText[3];
     50 
     51     static MeasuredText obtain() {
     52         MeasuredText mt;
     53         synchronized (sLock) {
     54             for (int i = sCached.length; --i >= 0;) {
     55                 if (sCached[i] != null) {
     56                     mt = sCached[i];
     57                     sCached[i] = null;
     58                     return mt;
     59                 }
     60             }
     61         }
     62         mt = new MeasuredText();
     63         if (localLOGV) {
     64             Log.v("MEAS", "new: " + mt);
     65         }
     66         return mt;
     67     }
     68 
     69     static MeasuredText recycle(MeasuredText mt) {
     70         mt.mText = null;
     71         if (mt.mLen < 1000) {
     72             synchronized(sLock) {
     73                 for (int i = 0; i < sCached.length; ++i) {
     74                     if (sCached[i] == null) {
     75                         sCached[i] = mt;
     76                         mt.mText = null;
     77                         break;
     78                     }
     79                 }
     80             }
     81         }
     82         return null;
     83     }
     84 
     85     void setPos(int pos) {
     86         mPos = pos - mTextStart;
     87     }
     88 
     89     /**
     90      * Analyzes text for bidirectional runs.  Allocates working buffers.
     91      */
     92     void setPara(CharSequence text, int start, int end, TextDirectionHeuristic textDir) {
     93         mText = text;
     94         mTextStart = start;
     95 
     96         int len = end - start;
     97         mLen = len;
     98         mPos = 0;
     99 
    100         if (mWidths == null || mWidths.length < len) {
    101             mWidths = new float[ArrayUtils.idealFloatArraySize(len)];
    102         }
    103         if (mChars == null || mChars.length < len) {
    104             mChars = new char[ArrayUtils.idealCharArraySize(len)];
    105         }
    106         TextUtils.getChars(text, start, end, mChars, 0);
    107 
    108         if (text instanceof Spanned) {
    109             Spanned spanned = (Spanned) text;
    110             ReplacementSpan[] spans = spanned.getSpans(start, end,
    111                     ReplacementSpan.class);
    112 
    113             for (int i = 0; i < spans.length; i++) {
    114                 int startInPara = spanned.getSpanStart(spans[i]) - start;
    115                 int endInPara = spanned.getSpanEnd(spans[i]) - start;
    116                 // The span interval may be larger and must be restricted to [start, end[
    117                 if (startInPara < 0) startInPara = 0;
    118                 if (endInPara > len) endInPara = len;
    119                 for (int j = startInPara; j < endInPara; j++) {
    120                     mChars[j] = '\uFFFC'; // object replacement character
    121                 }
    122             }
    123         }
    124 
    125         if ((textDir == TextDirectionHeuristics.LTR ||
    126                 textDir == TextDirectionHeuristics.FIRSTSTRONG_LTR ||
    127                 textDir == TextDirectionHeuristics.ANYRTL_LTR) &&
    128                 TextUtils.doesNotNeedBidi(mChars, 0, len)) {
    129             mDir = Layout.DIR_LEFT_TO_RIGHT;
    130             mEasy = true;
    131         } else {
    132             if (mLevels == null || mLevels.length < len) {
    133                 mLevels = new byte[ArrayUtils.idealByteArraySize(len)];
    134             }
    135             int bidiRequest;
    136             if (textDir == TextDirectionHeuristics.LTR) {
    137                 bidiRequest = Layout.DIR_REQUEST_LTR;
    138             } else if (textDir == TextDirectionHeuristics.RTL) {
    139                 bidiRequest = Layout.DIR_REQUEST_RTL;
    140             } else if (textDir == TextDirectionHeuristics.FIRSTSTRONG_LTR) {
    141                 bidiRequest = Layout.DIR_REQUEST_DEFAULT_LTR;
    142             } else if (textDir == TextDirectionHeuristics.FIRSTSTRONG_RTL) {
    143                 bidiRequest = Layout.DIR_REQUEST_DEFAULT_RTL;
    144             } else {
    145                 boolean isRtl = textDir.isRtl(mChars, 0, len);
    146                 bidiRequest = isRtl ? Layout.DIR_REQUEST_RTL : Layout.DIR_REQUEST_LTR;
    147             }
    148             mDir = AndroidBidi.bidi(bidiRequest, mChars, mLevels, len, false);
    149             mEasy = false;
    150         }
    151     }
    152 
    153     float addStyleRun(TextPaint paint, int len, Paint.FontMetricsInt fm) {
    154         if (fm != null) {
    155             paint.getFontMetricsInt(fm);
    156         }
    157 
    158         int p = mPos;
    159         mPos = p + len;
    160 
    161         if (mEasy) {
    162             int flags = mDir == Layout.DIR_LEFT_TO_RIGHT
    163                 ? Canvas.DIRECTION_LTR : Canvas.DIRECTION_RTL;
    164             return paint.getTextRunAdvances(mChars, p, len, p, len, flags, mWidths, p);
    165         }
    166 
    167         float totalAdvance = 0;
    168         int level = mLevels[p];
    169         for (int q = p, i = p + 1, e = p + len;; ++i) {
    170             if (i == e || mLevels[i] != level) {
    171                 int flags = (level & 0x1) == 0 ? Canvas.DIRECTION_LTR : Canvas.DIRECTION_RTL;
    172                 totalAdvance +=
    173                         paint.getTextRunAdvances(mChars, q, i - q, q, i - q, flags, mWidths, q);
    174                 if (i == e) {
    175                     break;
    176                 }
    177                 q = i;
    178                 level = mLevels[i];
    179             }
    180         }
    181         return totalAdvance;
    182     }
    183 
    184     float addStyleRun(TextPaint paint, MetricAffectingSpan[] spans, int len,
    185             Paint.FontMetricsInt fm) {
    186 
    187         TextPaint workPaint = mWorkPaint;
    188         workPaint.set(paint);
    189         // XXX paint should not have a baseline shift, but...
    190         workPaint.baselineShift = 0;
    191 
    192         ReplacementSpan replacement = null;
    193         for (int i = 0; i < spans.length; i++) {
    194             MetricAffectingSpan span = spans[i];
    195             if (span instanceof ReplacementSpan) {
    196                 replacement = (ReplacementSpan)span;
    197             } else {
    198                 span.updateMeasureState(workPaint);
    199             }
    200         }
    201 
    202         float wid;
    203         if (replacement == null) {
    204             wid = addStyleRun(workPaint, len, fm);
    205         } else {
    206             // Use original text.  Shouldn't matter.
    207             wid = replacement.getSize(workPaint, mText, mTextStart + mPos,
    208                     mTextStart + mPos + len, fm);
    209             float[] w = mWidths;
    210             w[mPos] = wid;
    211             for (int i = mPos + 1, e = mPos + len; i < e; i++)
    212                 w[i] = 0;
    213             mPos += len;
    214         }
    215 
    216         if (fm != null) {
    217             if (workPaint.baselineShift < 0) {
    218                 fm.ascent += workPaint.baselineShift;
    219                 fm.top += workPaint.baselineShift;
    220             } else {
    221                 fm.descent += workPaint.baselineShift;
    222                 fm.bottom += workPaint.baselineShift;
    223             }
    224         }
    225 
    226         return wid;
    227     }
    228 
    229     int breakText(int limit, boolean forwards, float width) {
    230         float[] w = mWidths;
    231         if (forwards) {
    232             int i = 0;
    233             while (i < limit) {
    234                 width -= w[i];
    235                 if (width < 0.0f) break;
    236                 i++;
    237             }
    238             while (i > 0 && mChars[i - 1] == ' ') i--;
    239             return i;
    240         } else {
    241             int i = limit - 1;
    242             while (i >= 0) {
    243                 width -= w[i];
    244                 if (width < 0.0f) break;
    245                 i--;
    246             }
    247             while (i < limit - 1 && mChars[i + 1] == ' ') i++;
    248             return limit - i - 1;
    249         }
    250     }
    251 
    252     float measure(int start, int limit) {
    253         float width = 0;
    254         float[] w = mWidths;
    255         for (int i = start; i < limit; ++i) {
    256             width += w[i];
    257         }
    258         return width;
    259     }
    260 }
    261