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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "TextLayout"
#include "TextLayout.h"
#include "TextLayoutCache.h"
#include <android_runtime/AndroidRuntime.h>
#include "SkTemplates.h"
#include "unicode/ubidi.h"
#include "unicode/ushape.h"
#include <utils/Log.h>
namespace android {
// Returns true if we might need layout. If bidiFlags force LTR, assume no layout, if
// bidiFlags indicate there probably is RTL, assume we do, otherwise scan the text
// looking for a character >= the first RTL character in unicode and assume we do if
// we find one.
bool TextLayout::needsLayout(const jchar* text, jint len, jint bidiFlags) {
if (bidiFlags == kBidi_Force_LTR) {
return false;
}
if ((bidiFlags == kBidi_RTL) || (bidiFlags == kBidi_Default_RTL) ||
bidiFlags == kBidi_Force_RTL) {
return true;
}
for (int i = 0; i < len; ++i) {
if (text[i] >= UNICODE_FIRST_RTL_CHAR) {
return true;
}
}
return false;
}
// Draws or gets the path of a paragraph of text on a single line, running bidi and shaping.
// This will draw if canvas is not null, otherwise path must be non-null and it will create
// a path representing the text that would have been drawn.
void TextLayout::handleText(SkPaint *paint, const jchar* text, jsize len,
jint bidiFlags, jfloat x, jfloat y, SkPath *path) {
sp<TextLayoutValue> value = TextLayoutEngine::getInstance().getValue(paint,
text, 0, len, len, bidiFlags);
if (value == NULL) {
return ;
}
SkScalar x_ = SkFloatToScalar(x);
SkScalar y_ = SkFloatToScalar(y);
// Beware: this needs Glyph encoding (already done on the Paint constructor)
paint->getTextPath(value->getGlyphs(), value->getGlyphsCount() * 2, x_, y_, path);
}
void TextLayout::getTextRunAdvances(SkPaint* paint, const jchar* chars, jint start,
jint count, jint contextCount, jint dirFlags,
jfloat* resultAdvances, jfloat* resultTotalAdvance) {
sp<TextLayoutValue> value = TextLayoutEngine::getInstance().getValue(paint,
chars, start, count, contextCount, dirFlags);
if (value == NULL) {
return ;
}
if (resultAdvances) {
memcpy(resultAdvances, value->getAdvances(), value->getAdvancesCount() * sizeof(jfloat));
}
if (resultTotalAdvance) {
*resultTotalAdvance = value->getTotalAdvance();
}
}
void TextLayout::getTextRunAdvancesICU(SkPaint* paint, const jchar* chars, jint start,
jint count, jint contextCount, jint dirFlags,
jfloat* resultAdvances, jfloat& resultTotalAdvance) {
// Compute advances and return them
computeAdvancesWithICU(paint, chars, start, count, contextCount, dirFlags,
resultAdvances, &resultTotalAdvance);
}
void TextLayout::getTextPath(SkPaint *paint, const jchar *text, jsize len,
jint bidiFlags, jfloat x, jfloat y, SkPath *path) {
handleText(paint, text, len, bidiFlags, x, y, path);
}
void TextLayout::drawTextOnPath(SkPaint* paint, const jchar* text, int count,
int bidiFlags, jfloat hOffset, jfloat vOffset,
SkPath* path, SkCanvas* canvas) {
SkScalar h_ = SkFloatToScalar(hOffset);
SkScalar v_ = SkFloatToScalar(vOffset);
sp<TextLayoutValue> value = TextLayoutEngine::getInstance().getValue(paint,
text, 0, count, count, bidiFlags);
if (value == NULL) {
return;
}
// Beware: this needs Glyph encoding (already done on the Paint constructor)
canvas->drawTextOnPathHV(value->getGlyphs(), value->getGlyphsCount() * 2, *path, h_, v_, *paint);
}
void TextLayout::computeAdvancesWithICU(SkPaint* paint, const UChar* chars,
size_t start, size_t count, size_t contextCount, int dirFlags,
jfloat* outAdvances, jfloat* outTotalAdvance) {
SkAutoSTMalloc<CHAR_BUFFER_SIZE, jchar> tempBuffer(contextCount);
jchar* buffer = tempBuffer.get();
SkScalar* scalarArray = (SkScalar*)outAdvances;
// this is where we'd call harfbuzz
// for now we just use ushape.c
size_t widths;
const jchar* text;
if (dirFlags & 0x1) { // rtl, call arabic shaping in case
UErrorCode status = U_ZERO_ERROR;
// Use fixed length since we need to keep start and count valid
u_shapeArabic(chars, contextCount, buffer, contextCount,
U_SHAPE_LENGTH_FIXED_SPACES_NEAR |
U_SHAPE_TEXT_DIRECTION_LOGICAL | U_SHAPE_LETTERS_SHAPE |
U_SHAPE_X_LAMALEF_SUB_ALTERNATE, &status);
// we shouldn't fail unless there's an out of memory condition,
// in which case we're hosed anyway
for (int i = start, e = i + count; i < e; ++i) {
if (buffer[i] == UNICODE_NOT_A_CHAR) {
buffer[i] = UNICODE_ZWSP; // zero-width-space for skia
}
}
text = buffer + start;
widths = paint->getTextWidths(text, count << 1, scalarArray);
} else {
text = chars + start;
widths = paint->getTextWidths(text, count << 1, scalarArray);
}
jfloat totalAdvance = 0;
if (widths < count) {
#if DEBUG_ADVANCES
ALOGD("ICU -- count=%d", widths);
#endif
// Skia operates on code points, not code units, so surrogate pairs return only
// one value. Expand the result so we have one value per UTF-16 code unit.
// Note, skia's getTextWidth gets confused if it encounters a surrogate pair,
// leaving the remaining widths zero. Not nice.
for (size_t i = 0, p = 0; i < widths; ++i) {
totalAdvance += outAdvances[p++] = SkScalarToFloat(scalarArray[i]);
if (p < count &&
text[p] >= UNICODE_FIRST_LOW_SURROGATE &&
text[p] < UNICODE_FIRST_PRIVATE_USE &&
text[p-1] >= UNICODE_FIRST_HIGH_SURROGATE &&
text[p-1] < UNICODE_FIRST_LOW_SURROGATE) {
outAdvances[p++] = 0;
}
#if DEBUG_ADVANCES
ALOGD("icu-adv = %f - total = %f", outAdvances[i], totalAdvance);
#endif
}
} else {
#if DEBUG_ADVANCES
ALOGD("ICU -- count=%d", count);
#endif
for (size_t i = 0; i < count; i++) {
totalAdvance += outAdvances[i] = SkScalarToFloat(scalarArray[i]);
#if DEBUG_ADVANCES
ALOGD("icu-adv = %f - total = %f", outAdvances[i], totalAdvance);
#endif
}
}
*outTotalAdvance = totalAdvance;
}
}
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