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Commit 902a5b31 authored by Fabrice Di Meglio's avatar Fabrice Di Meglio
Browse files

TextLayoutCache - fix diacritics composition 

- normalize (with ICU) each BiDi run before shaping them

We are normalizing by "chuncks" and starting from the end of the string. Each "chunck"
is composed of the main code point and its associated diacritics.

Fix bug #5738435 TextLayoutCache should be able to take care about diacritics during shaping

Change-Id: I7288027a7fa8eafb8b9f38d449625be60214548a
parent 09bd7978

core/jni/android/graphics/TextLayoutCache.cpp

+76 −8
Original line number Diff line number Diff line
@@ -19,6 +19,8 @@ 
#include "TextLayoutCache.h"

#include "TextLayout.h"

#include "SkFontHost.h"

#include <unicode/unistr.h>

#include <unicode/normlzr.h>



extern "C" {

  #include "harfbuzz-unicode.h"
@@ -503,7 +505,8 @@ void TextLayoutEngine::computeValues(SkPaint* paint, const UChar* chars, 
static void logGlyphs(HB_ShaperItem shaperItem) {

    LOGD("         -- glyphs count=%d", shaperItem.num_glyphs);

    for (size_t i = 0; i < shaperItem.num_glyphs; i++) {

        LOGD("         -- glyph[%d] = %d, offset.x = %f, offset.y = %f", i, shaperItem.glyphs[i],

        LOGD("         -- glyph[%d] = %d, offset.x = %0.2f, offset.y = %0.2f", i,

                shaperItem.glyphs[i],

                HBFixedToFloat(shaperItem.offsets[i].x),

                HBFixedToFloat(shaperItem.offsets[i].y));

    }
@@ -519,8 +522,73 @@ void TextLayoutEngine::computeRunValues(SkPaint* paint, const UChar* chars, 
        return;

    }



    UErrorCode error = U_ZERO_ERROR;

    bool useNormalizedString = false;

    for (ssize_t i = count - 1; i >= 0; --i) {

        UChar ch1 = chars[i];

        if (::ublock_getCode(ch1) == UBLOCK_COMBINING_DIACRITICAL_MARKS) {

            // So we have found a diacritic, let's get now the main code point which is paired

            // with it. As we can have several diacritics in a row, we need to iterate back again

#if DEBUG_GLYPHS

            LOGD("The BiDi run '%s' is containing a Diacritic at position %d",

                    String8(chars, count).string(), int(i));

#endif

            ssize_t j = i - 1;

            for (; j >= 0;  --j) {

                UChar ch2 = chars[j];

                if (::ublock_getCode(ch2) != UBLOCK_COMBINING_DIACRITICAL_MARKS) {

                    break;

                }

            }



            // We could not found the main code point, so we will just use the initial chars

            if (j < 0) {

                break;

            }



#if DEBUG_GLYPHS

            LOGD("Found main code point at index %d", int(j));

#endif

            // We found the main code point, so we can normalize the "chunck" and fill

            // the remaining with ZWSP so that the Paint.getTextWidth() APIs will still be able

            // to get one advance per char

            mBuffer.remove();

            Normalizer::normalize(UnicodeString(chars + j, i - j + 1),

                    UNORM_NFC, 0 /* no options */, mBuffer, error);

            if (U_SUCCESS(error)) {

                if (!useNormalizedString) {

                    useNormalizedString = true;

                    mNormalizedString.setTo(false /* not terminated*/, chars, count);

                }

                // Set the normalized chars

                for (ssize_t k = j; k < j + mBuffer.length(); ++k) {

                    mNormalizedString.setCharAt(k, mBuffer.charAt(k - j));

                }

                // Fill the remain part with ZWSP (ZWNJ and ZWJ would lead to weird results

                // because some fonts are missing those glyphs)

                for (ssize_t k = j + mBuffer.length(); k <= i; ++k) {

                    mNormalizedString.setCharAt(k, UNICODE_ZWSP);

                }

            }

            i = j - 1;

        }

    }



#if DEBUG_GLYPHS

    if (useNormalizedString) {

        LOGD("Will use normalized string '%s', length = %d",

                    String8(mNormalizedString.getTerminatedBuffer(),

                            mNormalizedString.length()).string(),

                    mNormalizedString.length());

    } else {

        LOGD("Normalization cannot be done, using initial string");

    }

#endif



    assert(mNormalizedString.length() == count);



    // Set the string properties

    mShaperItem.string = chars;

    mShaperItem.string = useNormalizedString ? mNormalizedString.getTerminatedBuffer() : chars;

    mShaperItem.stringLength = count;



    // Define shaping paint properties
@@ -532,14 +600,14 @@ void TextLayoutEngine::computeRunValues(SkPaint* paint, const UChar* chars, 


    // Split the BiDi run into Script runs. Harfbuzz will populate the pos, length and script

    // into the shaperItem

    ssize_t indexFontRun = isRTL ? count - 1 : 0;

    ssize_t indexFontRun = isRTL ? mShaperItem.stringLength - 1 : 0;

    unsigned numCodePoints = 0;

    jfloat totalAdvance = 0;

    while ((isRTL) ?

            hb_utf16_script_run_prev(&numCodePoints, &mShaperItem.item, chars,

                    count, &indexFontRun):

            hb_utf16_script_run_next(&numCodePoints, &mShaperItem.item, chars,

                    count, &indexFontRun)) {

            hb_utf16_script_run_prev(&numCodePoints, &mShaperItem.item, mShaperItem.string,

                    mShaperItem.stringLength, &indexFontRun):

            hb_utf16_script_run_next(&numCodePoints, &mShaperItem.item, mShaperItem.string,

                    mShaperItem.stringLength, &indexFontRun)) {



        ssize_t startScriptRun = mShaperItem.item.pos;

        size_t countScriptRun = mShaperItem.item.length;
@@ -611,7 +679,7 @@ void TextLayoutEngine::computeRunValues(SkPaint* paint, const UChar* chars, 
#if DEBUG_ADVANCES

        LOGD("Returned advances");

        for (size_t i = 0; i < countScriptRun; i++) {

            LOGD("         -- hb-adv[%d] = %f, log_clusters = %d, total = %f", i,

            LOGD("         -- hb-adv[%d] = %0.2f, log_clusters = %d, total = %0.2f", i,

                    (*outAdvances)[i], mShaperItem.log_clusters[i], totalFontRunAdvance);

        }

#endif

core/jni/android/graphics/TextLayoutCache.h

+18 −0
Original line number Diff line number Diff line
@@ -35,6 +35,8 @@ 


#include <unicode/ubidi.h>

#include <unicode/ushape.h>

#include <unicode/unistr.h>



#include "HarfbuzzSkia.h"

#include "harfbuzz-shaper.h"
@@ -249,10 +251,26 @@ private: 
    SkTypeface* mHebrewRegularTypeface;

    SkTypeface* mHebrewBoldTypeface;



    /**

     * Cache of Harfbuzz faces

     */

    KeyedVector<SkFontID, HB_Face> mCachedHBFaces;



    /**

     * Cache of glyph array size

     */

    size_t mShaperItemGlyphArraySize;



    /**

     * Buffer for containing the ICU normalized form of a run

     */

    UnicodeString mNormalizedString;



    /**

     * Buffer for normalizing a piece of a run with ICU

     */

    UnicodeString mBuffer;



    size_t shapeFontRun(SkPaint* paint, bool isRTL);



    void computeValues(SkPaint* paint, const UChar* chars,