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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 final 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 = ArrayUtils.newUnpaddedFloatArray(len);
    102         }
    103         if (mChars == null || mChars.length < len) {
    104             mChars = ArrayUtils.newUnpaddedCharArray(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 = ArrayUtils.newUnpaddedByteArray(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             boolean isRtl = mDir != Layout.DIR_LEFT_TO_RIGHT;
    163             return paint.getTextRunAdvances(mChars, p, len, p, len, isRtl, mWidths, p);
    164         }
    165 
    166         float totalAdvance = 0;
    167         int level = mLevels[p];
    168         for (int q = p, i = p + 1, e = p + len;; ++i) {
    169             if (i == e || mLevels[i] != level) {
    170                 boolean isRtl = (level & 0x1) != 0;
    171                 totalAdvance +=
    172                         paint.getTextRunAdvances(mChars, q, i - q, q, i - q, isRtl, mWidths, q);
    173                 if (i == e) {
    174                     break;
    175                 }
    176                 q = i;
    177                 level = mLevels[i];
    178             }
    179         }
    180         return totalAdvance;
    181     }
    182 
    183     float addStyleRun(TextPaint paint, MetricAffectingSpan[] spans, int len,
    184             Paint.FontMetricsInt fm) {
    185 
    186         TextPaint workPaint = mWorkPaint;
    187         workPaint.set(paint);
    188         // XXX paint should not have a baseline shift, but...
    189         workPaint.baselineShift = 0;
    190 
    191         ReplacementSpan replacement = null;
    192         for (int i = 0; i < spans.length; i++) {
    193             MetricAffectingSpan span = spans[i];
    194             if (span instanceof ReplacementSpan) {
    195                 replacement = (ReplacementSpan)span;
    196             } else {
    197                 span.updateMeasureState(workPaint);
    198             }
    199         }
    200 
    201         float wid;
    202         if (replacement == null) {
    203             wid = addStyleRun(workPaint, len, fm);
    204         } else {
    205             // Use original text.  Shouldn't matter.
    206             wid = replacement.getSize(workPaint, mText, mTextStart + mPos,
    207                     mTextStart + mPos + len, fm);
    208             float[] w = mWidths;
    209             w[mPos] = wid;
    210             for (int i = mPos + 1, e = mPos + len; i < e; i++)
    211                 w[i] = 0;
    212             mPos += len;
    213         }
    214 
    215         if (fm != null) {
    216             if (workPaint.baselineShift < 0) {
    217                 fm.ascent += workPaint.baselineShift;
    218                 fm.top += workPaint.baselineShift;
    219             } else {
    220                 fm.descent += workPaint.baselineShift;
    221                 fm.bottom += workPaint.baselineShift;
    222             }
    223         }
    224 
    225         return wid;
    226     }
    227 
    228     int breakText(int limit, boolean forwards, float width) {
    229         float[] w = mWidths;
    230         if (forwards) {
    231             int i = 0;
    232             while (i < limit) {
    233                 width -= w[i];
    234                 if (width < 0.0f) break;
    235                 i++;
    236             }
    237             while (i > 0 && mChars[i - 1] == ' ') i--;
    238             return i;
    239         } else {
    240             int i = limit - 1;
    241             while (i >= 0) {
    242                 width -= w[i];
    243                 if (width < 0.0f) break;
    244                 i--;
    245             }
    246             while (i < limit - 1 && mChars[i + 1] == ' ') i++;
    247             return limit - i - 1;
    248         }
    249     }
    250 
    251     float measure(int start, int limit) {
    252         float width = 0;
    253         float[] w = mWidths;
    254         for (int i = start; i < limit; ++i) {
    255             width += w[i];
    256         }
    257         return width;
    258     }
    259 }
    260