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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 #define LOG_TAG "TextLayout"
     18 
     19 #include "TextLayout.h"
     20 #include "TextLayoutCache.h"
     21 
     22 #include <android_runtime/AndroidRuntime.h>
     23 
     24 #include "SkTemplates.h"
     25 #include "unicode/ubidi.h"
     26 #include "unicode/ushape.h"
     27 #include <utils/Log.h>
     28 
     29 namespace android {
     30 
     31 // Returns true if we might need layout.  If bidiFlags force LTR, assume no layout, if
     32 // bidiFlags indicate there probably is RTL, assume we do, otherwise scan the text
     33 // looking for a character >= the first RTL character in unicode and assume we do if
     34 // we find one.
     35 bool TextLayout::needsLayout(const jchar* text, jint len, jint bidiFlags) {
     36     if (bidiFlags == kBidi_Force_LTR) {
     37         return false;
     38     }
     39     if ((bidiFlags == kBidi_RTL) || (bidiFlags == kBidi_Default_RTL) ||
     40             bidiFlags == kBidi_Force_RTL) {
     41         return true;
     42     }
     43     for (int i = 0; i < len; ++i) {
     44         if (text[i] >= UNICODE_FIRST_RTL_CHAR) {
     45             return true;
     46         }
     47     }
     48     return false;
     49 }
     50 
     51 // Draws or gets the path of a paragraph of text on a single line, running bidi and shaping.
     52 // This will draw if canvas is not null, otherwise path must be non-null and it will create
     53 // a path representing the text that would have been drawn.
     54 void TextLayout::handleText(SkPaint *paint, const jchar* text, jsize len,
     55                             jint bidiFlags, jfloat x, jfloat y, SkPath *path) {
     56     sp<TextLayoutValue> value = TextLayoutEngine::getInstance().getValue(paint,
     57             text, 0, len, len, bidiFlags);
     58     if (value == NULL) {
     59         return ;
     60     }
     61     SkScalar x_ = SkFloatToScalar(x);
     62     SkScalar y_ = SkFloatToScalar(y);
     63     // Beware: this needs Glyph encoding (already done on the Paint constructor)
     64     paint->getTextPath(value->getGlyphs(), value->getGlyphsCount() * 2, x_, y_, path);
     65 }
     66 
     67 void TextLayout::getTextRunAdvances(SkPaint* paint, const jchar* chars, jint start,
     68                                     jint count, jint contextCount, jint dirFlags,
     69                                     jfloat* resultAdvances, jfloat* resultTotalAdvance) {
     70     sp<TextLayoutValue> value = TextLayoutEngine::getInstance().getValue(paint,
     71             chars, start, count, contextCount, dirFlags);
     72     if (value == NULL) {
     73         return ;
     74     }
     75     if (resultAdvances) {
     76         memcpy(resultAdvances, value->getAdvances(), value->getAdvancesCount() * sizeof(jfloat));
     77     }
     78     if (resultTotalAdvance) {
     79         *resultTotalAdvance = value->getTotalAdvance();
     80     }
     81 }
     82 
     83 void TextLayout::getTextPath(SkPaint *paint, const jchar *text, jsize len,
     84                              jint bidiFlags, jfloat x, jfloat y, SkPath *path) {
     85     handleText(paint, text, len, bidiFlags, x, y, path);
     86 }
     87 
     88 
     89 void TextLayout::drawTextOnPath(SkPaint* paint, const jchar* text, int count,
     90                                 int bidiFlags, jfloat hOffset, jfloat vOffset,
     91                                 SkPath* path, SkCanvas* canvas) {
     92 
     93     SkScalar h_ = SkFloatToScalar(hOffset);
     94     SkScalar v_ = SkFloatToScalar(vOffset);
     95 
     96     sp<TextLayoutValue> value = TextLayoutEngine::getInstance().getValue(paint,
     97             text, 0, count, count, bidiFlags);
     98     if (value == NULL) {
     99         return;
    100     }
    101 
    102     // Beware: this needs Glyph encoding (already done on the Paint constructor)
    103     canvas->drawTextOnPathHV(value->getGlyphs(), value->getGlyphsCount() * 2, *path, h_, v_, *paint);
    104 }
    105 
    106 }
    107