core/jni/android/graphics/Paint.cpp

/* libs/android_runtime/android/graphics/Paint.cpp
**
** Copyright 2006, 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.
*/

#include "jni.h"
#include "GraphicsJNI.h"
#include <android_runtime/AndroidRuntime.h>

#include "SkBlurDrawLooper.h"
#include "SkColorFilter.h"
#include "SkMaskFilter.h"
#include "SkRasterizer.h"
#include "SkShader.h"
#include "SkTypeface.h"
#include "SkXfermode.h"
#include "unicode/ushape.h"
#include "TextLayout.h"

// temporary for debugging
#include <Caches.h>
#include <utils/Log.h>

namespace android {

struct JMetricsID {
    jfieldID    top;
    jfieldID    ascent;
    jfieldID    descent;
    jfieldID    bottom;
    jfieldID    leading;
};

static jclass   gFontMetrics_class;
static JMetricsID gFontMetrics_fieldID;

static jclass   gFontMetricsInt_class;
static JMetricsID gFontMetricsInt_fieldID;

static void defaultSettingsForAndroid(SkPaint* paint) {
    // looks best we decided
    paint->setHinting(SkPaint::kSlight_Hinting);
    // utf16 is required for java
    paint->setTextEncoding(SkPaint::kUTF16_TextEncoding);
}

class SkPaintGlue {
public:
    enum MoveOpt {
        AFTER, AT_OR_AFTER, BEFORE, AT_OR_BEFORE, AT
    };

    static void finalizer(JNIEnv* env, jobject clazz, SkPaint* obj) {
        delete obj;
    }

    static SkPaint* init(JNIEnv* env, jobject clazz) {
        SkPaint* obj = new SkPaint();
        defaultSettingsForAndroid(obj);
        return obj;
    }

    static SkPaint* intiWithPaint(JNIEnv* env, jobject clazz, SkPaint* paint) {
        SkPaint* obj = new SkPaint(*paint);
        return obj;
    }

    static void reset(JNIEnv* env, jobject clazz, SkPaint* obj) {
        obj->reset();
        defaultSettingsForAndroid(obj);
    }

    static void assign(JNIEnv* env, jobject clazz, SkPaint* dst, const SkPaint* src) {
        *dst = *src;
    }

    static jint getFlags(JNIEnv* env, jobject paint) {
        NPE_CHECK_RETURN_ZERO(env, paint);
        return GraphicsJNI::getNativePaint(env, paint)->getFlags();
    }

    static void setFlags(JNIEnv* env, jobject paint, jint flags) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setFlags(flags);
    }

    static void setAntiAlias(JNIEnv* env, jobject paint, jboolean aa) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setAntiAlias(aa);
    }

    static void setLinearText(JNIEnv* env, jobject paint, jboolean linearText) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setLinearText(linearText);
    }

    static void setSubpixelText(JNIEnv* env, jobject paint, jboolean subpixelText) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setSubpixelText(subpixelText);
    }

    static void setUnderlineText(JNIEnv* env, jobject paint, jboolean underlineText) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setUnderlineText(underlineText);
    }

    static void setStrikeThruText(JNIEnv* env, jobject paint, jboolean strikeThruText) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setStrikeThruText(strikeThruText);
    }

    static void setFakeBoldText(JNIEnv* env, jobject paint, jboolean fakeBoldText) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setFakeBoldText(fakeBoldText);
    }

    static void setFilterBitmap(JNIEnv* env, jobject paint, jboolean filterBitmap) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setFilterBitmap(filterBitmap);
    }

    static void setDither(JNIEnv* env, jobject paint, jboolean dither) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setDither(dither);
    }

    static jint getStyle(JNIEnv* env, jobject clazz, SkPaint* obj) {
        return obj->getStyle();
    }

    static void setStyle(JNIEnv* env, jobject clazz, SkPaint* obj, SkPaint::Style style) {
        obj->setStyle(style);
    }

    static jint getColor(JNIEnv* env, jobject paint) {
        NPE_CHECK_RETURN_ZERO(env, paint);
        return GraphicsJNI::getNativePaint(env, paint)->getColor();
    }

    static jint getAlpha(JNIEnv* env, jobject paint) {
        NPE_CHECK_RETURN_ZERO(env, paint);
        return GraphicsJNI::getNativePaint(env, paint)->getAlpha();
    }

    static void setColor(JNIEnv* env, jobject paint, jint color) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setColor(color);
    }

    static void setAlpha(JNIEnv* env, jobject paint, jint a) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setAlpha(a);
    }

    static jfloat getStrokeWidth(JNIEnv* env, jobject paint) {
        NPE_CHECK_RETURN_ZERO(env, paint);
        return SkScalarToFloat(GraphicsJNI::getNativePaint(env, paint)->getStrokeWidth());
    }

    static void setStrokeWidth(JNIEnv* env, jobject paint, jfloat width) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setStrokeWidth(SkFloatToScalar(width));
    }

    static jfloat getStrokeMiter(JNIEnv* env, jobject paint) {
        NPE_CHECK_RETURN_ZERO(env, paint);
        return SkScalarToFloat(GraphicsJNI::getNativePaint(env, paint)->getStrokeMiter());
    }

    static void setStrokeMiter(JNIEnv* env, jobject paint, jfloat miter) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setStrokeMiter(SkFloatToScalar(miter));
    }

    static jint getStrokeCap(JNIEnv* env, jobject clazz, SkPaint* obj) {
        return obj->getStrokeCap();
    }

    static void setStrokeCap(JNIEnv* env, jobject clazz, SkPaint* obj, SkPaint::Cap cap) {
        obj->setStrokeCap(cap);
    }

    static jint getStrokeJoin(JNIEnv* env, jobject clazz, SkPaint* obj) {
        return obj->getStrokeJoin();
    }

    static void setStrokeJoin(JNIEnv* env, jobject clazz, SkPaint* obj, SkPaint::Join join) {
        obj->setStrokeJoin(join);
    }

    static jboolean getFillPath(JNIEnv* env, jobject clazz, SkPaint* obj, SkPath* src, SkPath* dst) {
        return obj->getFillPath(*src, dst);
    }

    static SkShader* setShader(JNIEnv* env, jobject clazz, SkPaint* obj, SkShader* shader) {
        return obj->setShader(shader);
    }

    static SkColorFilter* setColorFilter(JNIEnv* env, jobject clazz, SkPaint* obj, SkColorFilter* filter) {
        return obj->setColorFilter(filter);
    }

    static SkXfermode* setXfermode(JNIEnv* env, jobject clazz, SkPaint* obj, SkXfermode* xfermode) {
        return obj->setXfermode(xfermode);
    }

    static SkPathEffect* setPathEffect(JNIEnv* env, jobject clazz, SkPaint* obj, SkPathEffect* effect) {
        return obj->setPathEffect(effect);
    }

    static SkMaskFilter* setMaskFilter(JNIEnv* env, jobject clazz, SkPaint* obj, SkMaskFilter* maskfilter) {
        return obj->setMaskFilter(maskfilter);
    }

    static SkTypeface* setTypeface(JNIEnv* env, jobject clazz, SkPaint* obj, SkTypeface* typeface) {
        return obj->setTypeface(typeface);
    }

    static SkRasterizer* setRasterizer(JNIEnv* env, jobject clazz, SkPaint* obj, SkRasterizer* rasterizer) {
        return obj->setRasterizer(rasterizer);
    }

    static jint getTextAlign(JNIEnv* env, jobject clazz, SkPaint* obj) {
        return obj->getTextAlign();
    }

    static void setTextAlign(JNIEnv* env, jobject clazz, SkPaint* obj, SkPaint::Align align) {
        obj->setTextAlign(align);
    }

    static jfloat getTextSize(JNIEnv* env, jobject paint) {
        NPE_CHECK_RETURN_ZERO(env, paint);
        return SkScalarToFloat(GraphicsJNI::getNativePaint(env, paint)->getTextSize());
    }

    static void setTextSize(JNIEnv* env, jobject paint, jfloat textSize) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setTextSize(SkFloatToScalar(textSize));
    }

    static jfloat getTextScaleX(JNIEnv* env, jobject paint) {
        NPE_CHECK_RETURN_ZERO(env, paint);
        return SkScalarToFloat(GraphicsJNI::getNativePaint(env, paint)->getTextScaleX());
    }

    static void setTextScaleX(JNIEnv* env, jobject paint, jfloat scaleX) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setTextScaleX(SkFloatToScalar(scaleX));
    }

    static jfloat getTextSkewX(JNIEnv* env, jobject paint) {
        NPE_CHECK_RETURN_ZERO(env, paint);
        return SkScalarToFloat(GraphicsJNI::getNativePaint(env, paint)->getTextSkewX());
    }

    static void setTextSkewX(JNIEnv* env, jobject paint, jfloat skewX) {
        NPE_CHECK_RETURN_VOID(env, paint);
        GraphicsJNI::getNativePaint(env, paint)->setTextSkewX(SkFloatToScalar(skewX));
    }

    static jfloat ascent(JNIEnv* env, jobject paint) {
        NPE_CHECK_RETURN_ZERO(env, paint);
        SkPaint::FontMetrics    metrics;
        (void)GraphicsJNI::getNativePaint(env, paint)->getFontMetrics(&metrics);
        return SkScalarToFloat(metrics.fAscent);
    }

    static jfloat descent(JNIEnv* env, jobject paint) {
        NPE_CHECK_RETURN_ZERO(env, paint);
        SkPaint::FontMetrics    metrics;
        (void)GraphicsJNI::getNativePaint(env, paint)->getFontMetrics(&metrics);
        return SkScalarToFloat(metrics.fDescent);
    }

    static jfloat getFontMetrics(JNIEnv* env, jobject paint, jobject metricsObj) {
        NPE_CHECK_RETURN_ZERO(env, paint);
        SkPaint::FontMetrics metrics;
        SkScalar             spacing = GraphicsJNI::getNativePaint(env, paint)->getFontMetrics(&metrics);

        if (metricsObj) {
            SkASSERT(env->IsInstanceOf(metricsObj, gFontMetrics_class));
            env->SetFloatField(metricsObj, gFontMetrics_fieldID.top, SkScalarToFloat(metrics.fTop));
            env->SetFloatField(metricsObj, gFontMetrics_fieldID.ascent, SkScalarToFloat(metrics.fAscent));
            env->SetFloatField(metricsObj, gFontMetrics_fieldID.descent, SkScalarToFloat(metrics.fDescent));
            env->SetFloatField(metricsObj, gFontMetrics_fieldID.bottom, SkScalarToFloat(metrics.fBottom));
            env->SetFloatField(metricsObj, gFontMetrics_fieldID.leading, SkScalarToFloat(metrics.fLeading));
        }
        return SkScalarToFloat(spacing);
    }

    static jint getFontMetricsInt(JNIEnv* env, jobject paint, jobject metricsObj) {
        NPE_CHECK_RETURN_ZERO(env, paint);
        SkPaint::FontMetrics metrics;

        GraphicsJNI::getNativePaint(env, paint)->getFontMetrics(&metrics);
        int ascent = SkScalarRound(metrics.fAscent);
        int descent = SkScalarRound(metrics.fDescent);
        int leading = SkScalarRound(metrics.fLeading);

        if (metricsObj) {
            SkASSERT(env->IsInstanceOf(metricsObj, gFontMetricsInt_class));
            env->SetIntField(metricsObj, gFontMetricsInt_fieldID.top, SkScalarFloor(metrics.fTop));
            env->SetIntField(metricsObj, gFontMetricsInt_fieldID.ascent, ascent);
            env->SetIntField(metricsObj, gFontMetricsInt_fieldID.descent, descent);
            env->SetIntField(metricsObj, gFontMetricsInt_fieldID.bottom, SkScalarCeil(metrics.fBottom));
            env->SetIntField(metricsObj, gFontMetricsInt_fieldID.leading, leading);
        }
        return descent - ascent + leading;
    }

    static jfloat measureText_CII(JNIEnv* env, jobject jpaint, jcharArray text, int index, int count) {
        NPE_CHECK_RETURN_ZERO(env, jpaint);
        NPE_CHECK_RETURN_ZERO(env, text);

        size_t textLength = env->GetArrayLength(text);

        if ((index | count) < 0 || (size_t)(index + count) > textLength) {
            doThrowAIOOBE(env);
            return 0;
        }

        SkPaint* paint = GraphicsJNI::getNativePaint(env, jpaint);
        const jchar* textArray = env->GetCharArrayElements(text, NULL);
        jfloat result = 0;
#if RTL_USE_HARFBUZZ
        TextLayout::getTextRunAdvances(paint, textArray, index, count, count, paint->getFlags(),
                NULL /* dont need all advances */, result);
#else
        // we double count, since measureText wants a byteLength
        SkScalar width = paint->measureText(textArray + index, count << 1);
        result = SkScalarToFloat(width);
#endif
        env->ReleaseCharArrayElements(text, const_cast<jchar*>(textArray), JNI_ABORT);
        return result;
    }

    static jfloat measureText_StringII(JNIEnv* env, jobject jpaint, jstring text, int start, int end) {
        NPE_CHECK_RETURN_ZERO(env, jpaint);
        NPE_CHECK_RETURN_ZERO(env, text);

        SkPaint* paint = GraphicsJNI::getNativePaint(env, jpaint);
        const jchar* textArray = env->GetStringChars(text, NULL);

        int count = end - start;
        size_t textLength = env->GetStringLength(text);
        if ((start | count) < 0 || (size_t)count > textLength) {
            doThrowAIOOBE(env);
            return 0;
        }
        jfloat width = 0;

#if RTL_USE_HARFBUZZ
        TextLayout::getTextRunAdvances(paint, textArray, 0, count, count, paint->getFlags(),
                NULL /* dont need all advances */, width);
#else

        width = SkScalarToFloat(paint->measureText(textArray + start, count << 1));
#endif
        env->ReleaseStringChars(text, textArray);
        return width;
    }

    static jfloat measureText_String(JNIEnv* env, jobject jpaint, jstring text) {
        NPE_CHECK_RETURN_ZERO(env, jpaint);
        NPE_CHECK_RETURN_ZERO(env, text);

        SkPaint* paint = GraphicsJNI::getNativePaint(env, jpaint);
        const jchar* textArray = env->GetStringChars(text, NULL);
        size_t textLength = env->GetStringLength(text);
        jfloat width = 0;
#if RTL_USE_HARFBUZZ
        TextLayout::getTextRunAdvances(paint, textArray, 0, textLength, textLength, paint->getFlags(),
                NULL /* dont need all advances */, width);
#else
        width = SkScalarToFloat(paint->measureText(textArray, textLength << 1));
#endif
        env->ReleaseStringChars(text, textArray);
        return width;
    }

    static int dotextwidths(JNIEnv* env, SkPaint* paint, const jchar text[], int count, jfloatArray widths) {
        AutoJavaFloatArray autoWidths(env, widths, count);
        jfloat* widthsArray = autoWidths.ptr();
#if RTL_USE_HARFBUZZ
        jfloat totalAdvance;

        TextLayout::getTextRunAdvances(paint, text, 0, count, count, paint->getFlags(),
                widthsArray, totalAdvance);
#else
        SkScalar* scalarArray = (SkScalar*)widthsArray;

        count = paint->getTextWidths(text, count << 1, scalarArray);
        for (int i = 0; i < count; i++) {
            widthsArray[i] = SkScalarToFloat(scalarArray[i]);
        }
#endif
        return count;
    }

    static int getTextWidths___CII_F(JNIEnv* env, jobject clazz, SkPaint* paint, jcharArray text, int index, int count, jfloatArray widths) {
        const jchar* textArray = env->GetCharArrayElements(text, NULL);
        count = dotextwidths(env, paint, textArray + index, count, widths);
        env->ReleaseCharArrayElements(text, const_cast<jchar*>(textArray),
                                      JNI_ABORT);
        return count;
    }

    static int getTextWidths__StringII_F(JNIEnv* env, jobject clazz, SkPaint* paint, jstring text,
            int start, int end, jfloatArray widths) {
        const jchar* textArray = env->GetStringChars(text, NULL);
        int count = dotextwidths(env, paint, textArray + start, end - start, widths);
        env->ReleaseStringChars(text, textArray);
        return count;
    }

    static int doTextGlyphs(JNIEnv* env, SkPaint* paint, const jchar* text, jint start, jint count,
            jint contextCount, jint flags, jcharArray glyphs) {
        jchar* glyphsArray = env->GetCharArrayElements(glyphs, NULL);
        HB_ShaperItem shaperItem;
        HB_FontRec font;
        FontData fontData;
        TextLayoutCacheValue::shapeWithHarfbuzz(&shaperItem, &font, &fontData, paint, text,
                start, count, contextCount, flags);

        int glyphCount = shaperItem.num_glyphs;
        for (int i = 0; i < glyphCount; i++) {
            glyphsArray[i] = (jchar) shaperItem.glyphs[i];
        }
        env->ReleaseCharArrayElements(glyphs, glyphsArray, JNI_ABORT);
        return glyphCount;
    }

    static int getTextGlyphs__StringIIIII_C(JNIEnv* env, jobject clazz, SkPaint* paint,
            jstring text, jint start, jint end, jint contextStart, jint contextEnd, jint flags,
            jcharArray glyphs) {
        const jchar* textArray = env->GetStringChars(text, NULL);
        int count = doTextGlyphs(env, paint, textArray + contextStart, start - contextStart,
                end - start, contextEnd - contextStart, flags, glyphs);
        env->ReleaseStringChars(text, textArray);
        return count;
    }

    static jfloat doTextRunAdvances(JNIEnv *env, SkPaint *paint, const jchar *text,
                                    jint start, jint count, jint contextCount, jint flags,
                                    jfloatArray advances, jint advancesIndex) {
        jfloat advancesArray[count];
        jfloat totalAdvance;

        TextLayout::getTextRunAdvances(paint, text, start, count, contextCount, flags,
                                       advancesArray, totalAdvance);

        if (advances != NULL) {
            env->SetFloatArrayRegion(advances, advancesIndex, count, advancesArray);
        }
        return totalAdvance;
    }

    static jfloat doTextRunAdvancesICU(JNIEnv *env, SkPaint *paint, const jchar *text,
                                    jint start, jint count, jint contextCount, jint flags,
                                    jfloatArray advances, jint advancesIndex) {
        jfloat advancesArray[count];
        jfloat totalAdvance;

        TextLayout::getTextRunAdvancesICU(paint, text, start, count, contextCount, flags,
                                       advancesArray, totalAdvance);

        if (advances != NULL) {
            env->SetFloatArrayRegion(advances, advancesIndex, count, advancesArray);
        }
        return totalAdvance;
    }

    static float getTextRunAdvances___CIIIII_FII(JNIEnv* env, jobject clazz, SkPaint* paint,
            jcharArray text, jint index, jint count, jint contextIndex, jint contextCount,
            jint flags, jfloatArray advances, jint advancesIndex, jint reserved) {
        jchar* textArray = env->GetCharArrayElements(text, NULL);
        jfloat result = (reserved == 0) ?
                doTextRunAdvances(env, paint, textArray + contextIndex, index - contextIndex,
                        count, contextCount, flags, advances, advancesIndex) :
                doTextRunAdvancesICU(env, paint, textArray + contextIndex, index - contextIndex,
                        count, contextCount, flags, advances, advancesIndex);
        env->ReleaseCharArrayElements(text, textArray, JNI_ABORT);
        return result;
    }

    static float getTextRunAdvances__StringIIIII_FII(JNIEnv* env, jobject clazz, SkPaint* paint,
            jstring text, jint start, jint end, jint contextStart, jint contextEnd, jint flags,
            jfloatArray advances, jint advancesIndex, jint reserved) {
        const jchar* textArray = env->GetStringChars(text, NULL);
        jfloat result = (reserved == 0) ?
                doTextRunAdvances(env, paint, textArray + contextStart, start - contextStart,
                        end - start, contextEnd - contextStart, flags, advances, advancesIndex) :
                doTextRunAdvancesICU(env, paint, textArray + contextStart, start - contextStart,
                        end - start, contextEnd - contextStart, flags, advances, advancesIndex);
        env->ReleaseStringChars(text, textArray);
        return result;
    }

    static jint doTextRunCursor(JNIEnv *env, SkPaint* paint, const jchar *text, jint start,
            jint count, jint flags, jint offset, jint opt) {
#if RTL_USE_HARFBUZZ
        jfloat scalarArray[count];
        jfloat totalAdvance;

        TextLayout::getTextRunAdvances(paint, text, start, count, count, flags,
                scalarArray, totalAdvance);
#else
        SkScalar scalarArray[count];
        jchar buffer[count];

        // this is where we'd call harfbuzz
        // for now we just use ushape.c and widths returned from skia

        int widths;
        if (flags & 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(text + start, count, buffer, count,
                    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 = 0; i < count; ++i) {
              if (buffer[i] == 0xffff) {
                buffer[i] = 0x200b; // zero-width-space for skia
              }
            }
            widths = paint->getTextWidths(buffer, count << 1, scalarArray);
        } else {
            widths = paint->getTextWidths(text + start, count << 1, scalarArray);
        }

        if (widths < count) {
            // 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.
            const jchar *chars = text + start;
            for (int i = count, p = widths - 1; --i > p;) {
                if (chars[i] >= 0xdc00 && chars[i] < 0xe000 &&
                        chars[i-1] >= 0xd800 && chars[i-1] < 0xdc00) {
                    scalarArray[i] = 0;
                } else {
                  scalarArray[i] = scalarArray[--p];
                }
            }
        }
#endif
        jint pos = offset - start;
        switch (opt) {
        case AFTER:
          if (pos < count) {
            pos += 1;
          }
          // fall through
        case AT_OR_AFTER:
          while (pos < count && scalarArray[pos] == 0) {
            ++pos;
          }
          break;
        case BEFORE:
          if (pos > 0) {
            --pos;
          }
          // fall through
        case AT_OR_BEFORE:
          while (pos > 0 && scalarArray[pos] == 0) {
            --pos;
          }
          break;
        case AT:
        default:
          if (scalarArray[pos] == 0) {
            pos = -1;
          }
          break;
        }

        if (pos != -1) {
          pos += start;
        }

        return pos;
    }

    static jint getTextRunCursor___C(JNIEnv* env, jobject clazz, SkPaint* paint, jcharArray text,
            jint contextStart, jint contextCount, jint flags, jint offset, jint cursorOpt) {
        jchar* textArray = env->GetCharArrayElements(text, NULL);
        jint result = doTextRunCursor(env, paint, textArray, contextStart, contextCount, flags,
                offset, cursorOpt);
        env->ReleaseCharArrayElements(text, textArray, JNI_ABORT);
        return result;
    }

    static jint getTextRunCursor__String(JNIEnv* env, jobject clazz, SkPaint* paint, jstring text,
            jint contextStart, jint contextEnd, jint flags, jint offset, jint cursorOpt) {
        const jchar* textArray = env->GetStringChars(text, NULL);
        jint result = doTextRunCursor(env, paint, textArray, contextStart,
                contextEnd - contextStart, flags, offset, cursorOpt);
        env->ReleaseStringChars(text, textArray);
        return result;
    }

    static void getTextPath(JNIEnv* env, SkPaint* paint, const jchar* text, jint count,
                            jint bidiFlags, jfloat x, jfloat y, SkPath *path) {
        TextLayout::getTextPath(paint, text, count, bidiFlags, x, y, path);
    }

    static void getTextPath___C(JNIEnv* env, jobject clazz, SkPaint* paint, jint bidiFlags,
            jcharArray text, int index, int count, jfloat x, jfloat y, SkPath* path) {
        const jchar* textArray = env->GetCharArrayElements(text, NULL);
        getTextPath(env, paint, textArray + index, count, bidiFlags, x, y, path);
        env->ReleaseCharArrayElements(text, const_cast<jchar*>(textArray), JNI_ABORT);
    }

    static void getTextPath__String(JNIEnv* env, jobject clazz, SkPaint* paint, jint bidiFlags,
            jstring text, int start, int end, jfloat x, jfloat y, SkPath* path) {
        const jchar* textArray = env->GetStringChars(text, NULL);
        getTextPath(env, paint, textArray + start, end - start, bidiFlags, x, y, path);
        env->ReleaseStringChars(text, textArray);
    }

    static void setShadowLayer(JNIEnv* env, jobject jpaint, jfloat radius,
                               jfloat dx, jfloat dy, int color) {
        NPE_CHECK_RETURN_VOID(env, jpaint);

        SkPaint* paint = GraphicsJNI::getNativePaint(env, jpaint);
        if (radius <= 0) {
            paint->setLooper(NULL);
        }
        else {
            paint->setLooper(new SkBlurDrawLooper(SkFloatToScalar(radius),
                                                  SkFloatToScalar(dx),
                                                  SkFloatToScalar(dy),
                                                  (SkColor)color))->unref();
        }
    }

    static int breakText(JNIEnv* env, const SkPaint& paint, const jchar text[],
                         int count, float maxWidth, jfloatArray jmeasured,
                         SkPaint::TextBufferDirection tbd) {
        SkASSERT(paint.getTextEncoding() == SkPaint::kUTF16_TextEncoding);

        SkScalar     measured;
        size_t       bytes = paint.breakText(text, count << 1,
                                   SkFloatToScalar(maxWidth), &measured, tbd);
        SkASSERT((bytes & 1) == 0);

        if (jmeasured && env->GetArrayLength(jmeasured) > 0) {
            AutoJavaFloatArray autoMeasured(env, jmeasured, 1);
            jfloat* array = autoMeasured.ptr();
            array[0] = SkScalarToFloat(measured);
        }
        return bytes >> 1;
    }

    static int breakTextC(JNIEnv* env, jobject jpaint, jcharArray jtext,
            int index, int count, float maxWidth, jfloatArray jmeasuredWidth) {
        NPE_CHECK_RETURN_ZERO(env, jpaint);
        NPE_CHECK_RETURN_ZERO(env, jtext);

        SkPaint::TextBufferDirection tbd;
        if (count < 0) {
            tbd = SkPaint::kBackward_TextBufferDirection;
            count = -count;
        }
        else {
            tbd = SkPaint::kForward_TextBufferDirection;
        }

        if ((index < 0) || (index + count > env->GetArrayLength(jtext))) {
            doThrowAIOOBE(env);
            return 0;
        }

        SkPaint*     paint = GraphicsJNI::getNativePaint(env, jpaint);
        const jchar* text = env->GetCharArrayElements(jtext, NULL);
        count = breakText(env, *paint, text + index, count, maxWidth,
                          jmeasuredWidth, tbd);
        env->ReleaseCharArrayElements(jtext, const_cast<jchar*>(text),
                                      JNI_ABORT);
        return count;
    }

    static int breakTextS(JNIEnv* env, jobject jpaint, jstring jtext,
                bool forwards, float maxWidth, jfloatArray jmeasuredWidth) {
        NPE_CHECK_RETURN_ZERO(env, jpaint);
        NPE_CHECK_RETURN_ZERO(env, jtext);

        SkPaint::TextBufferDirection tbd = forwards ?
                                        SkPaint::kForward_TextBufferDirection :
                                        SkPaint::kBackward_TextBufferDirection;

        SkPaint* paint = GraphicsJNI::getNativePaint(env, jpaint);
        int count = env->GetStringLength(jtext);
        const jchar* text = env->GetStringChars(jtext, NULL);
        count = breakText(env, *paint, text, count, maxWidth,
                          jmeasuredWidth, tbd);
        env->ReleaseStringChars(jtext, text);
        return count;
    }

    static void doTextBounds(JNIEnv* env, const jchar* text, int count,
                             jobject bounds, const SkPaint& paint)
    {
        SkRect  r;
        SkIRect ir;

        paint.measureText(text, count << 1, &r);
        r.roundOut(&ir);
        GraphicsJNI::irect_to_jrect(ir, env, bounds);
    }

    static void getStringBounds(JNIEnv* env, jobject, const SkPaint* paint,
                                jstring text, int start, int end, jobject bounds)
    {
        const jchar* textArray = env->GetStringChars(text, NULL);
        doTextBounds(env, textArray + start, end - start, bounds, *paint);
        env->ReleaseStringChars(text, textArray);
    }

    static void getCharArrayBounds(JNIEnv* env, jobject, const SkPaint* paint,
                        jcharArray text, int index, int count, jobject bounds)
    {
        const jchar* textArray = env->GetCharArrayElements(text, NULL);
        doTextBounds(env, textArray + index, count, bounds, *paint);
        env->ReleaseCharArrayElements(text, const_cast<jchar*>(textArray),
                                      JNI_ABORT);
    }

};

static JNINativeMethod methods[] = {
    {"finalizer", "(I)V", (void*) SkPaintGlue::finalizer},
    {"native_init","()I", (void*) SkPaintGlue::init},
    {"native_initWithPaint","(I)I", (void*) SkPaintGlue::intiWithPaint},
    {"native_reset","(I)V", (void*) SkPaintGlue::reset},
    {"native_set","(II)V", (void*) SkPaintGlue::assign},
    {"getFlags","()I", (void*) SkPaintGlue::getFlags},
    {"setFlags","(I)V", (void*) SkPaintGlue::setFlags},
    {"setAntiAlias","(Z)V", (void*) SkPaintGlue::setAntiAlias},
    {"setSubpixelText","(Z)V", (void*) SkPaintGlue::setSubpixelText},
    {"setLinearText","(Z)V", (void*) SkPaintGlue::setLinearText},
    {"setUnderlineText","(Z)V", (void*) SkPaintGlue::setUnderlineText},
    {"setStrikeThruText","(Z)V", (void*) SkPaintGlue::setStrikeThruText},
    {"setFakeBoldText","(Z)V", (void*) SkPaintGlue::setFakeBoldText},
    {"setFilterBitmap","(Z)V", (void*) SkPaintGlue::setFilterBitmap},
    {"setDither","(Z)V", (void*) SkPaintGlue::setDither},
    {"native_getStyle","(I)I", (void*) SkPaintGlue::getStyle},
    {"native_setStyle","(II)V", (void*) SkPaintGlue::setStyle},
    {"getColor","()I", (void*) SkPaintGlue::getColor},
    {"setColor","(I)V", (void*) SkPaintGlue::setColor},
    {"getAlpha","()I", (void*) SkPaintGlue::getAlpha},
    {"setAlpha","(I)V", (void*) SkPaintGlue::setAlpha},
    {"getStrokeWidth","()F", (void*) SkPaintGlue::getStrokeWidth},
    {"setStrokeWidth","(F)V", (void*) SkPaintGlue::setStrokeWidth},
    {"getStrokeMiter","()F", (void*) SkPaintGlue::getStrokeMiter},
    {"setStrokeMiter","(F)V", (void*) SkPaintGlue::setStrokeMiter},
    {"native_getStrokeCap","(I)I", (void*) SkPaintGlue::getStrokeCap},
    {"native_setStrokeCap","(II)V", (void*) SkPaintGlue::setStrokeCap},
    {"native_getStrokeJoin","(I)I", (void*) SkPaintGlue::getStrokeJoin},
    {"native_setStrokeJoin","(II)V", (void*) SkPaintGlue::setStrokeJoin},
    {"native_getFillPath","(III)Z", (void*) SkPaintGlue::getFillPath},
    {"native_setShader","(II)I", (void*) SkPaintGlue::setShader},
    {"native_setColorFilter","(II)I", (void*) SkPaintGlue::setColorFilter},
    {"native_setXfermode","(II)I", (void*) SkPaintGlue::setXfermode},
    {"native_setPathEffect","(II)I", (void*) SkPaintGlue::setPathEffect},
    {"native_setMaskFilter","(II)I", (void*) SkPaintGlue::setMaskFilter},
    {"native_setTypeface","(II)I", (void*) SkPaintGlue::setTypeface},
    {"native_setRasterizer","(II)I", (void*) SkPaintGlue::setRasterizer},
    {"native_getTextAlign","(I)I", (void*) SkPaintGlue::getTextAlign},
    {"native_setTextAlign","(II)V", (void*) SkPaintGlue::setTextAlign},
    {"getTextSize","()F", (void*) SkPaintGlue::getTextSize},
    {"setTextSize","(F)V", (void*) SkPaintGlue::setTextSize},
    {"getTextScaleX","()F", (void*) SkPaintGlue::getTextScaleX},
    {"setTextScaleX","(F)V", (void*) SkPaintGlue::setTextScaleX},
    {"getTextSkewX","()F", (void*) SkPaintGlue::getTextSkewX},
    {"setTextSkewX","(F)V", (void*) SkPaintGlue::setTextSkewX},
    {"ascent","()F", (void*) SkPaintGlue::ascent},
    {"descent","()F", (void*) SkPaintGlue::descent},
    {"getFontMetrics", "(Landroid/graphics/Paint$FontMetrics;)F", (void*)SkPaintGlue::getFontMetrics},
    {"getFontMetricsInt", "(Landroid/graphics/Paint$FontMetricsInt;)I", (void*)SkPaintGlue::getFontMetricsInt},
    {"native_measureText","([CII)F", (void*) SkPaintGlue::measureText_CII},
    {"native_measureText","(Ljava/lang/String;)F", (void*) SkPaintGlue::measureText_String},
    {"native_measureText","(Ljava/lang/String;II)F", (void*) SkPaintGlue::measureText_StringII},
    {"native_breakText","([CIIF[F)I", (void*) SkPaintGlue::breakTextC},
    {"native_breakText","(Ljava/lang/String;ZF[F)I", (void*) SkPaintGlue::breakTextS},
    {"native_getTextWidths","(I[CII[F)I", (void*) SkPaintGlue::getTextWidths___CII_F},
    {"native_getTextWidths","(ILjava/lang/String;II[F)I", (void*) SkPaintGlue::getTextWidths__StringII_F},
    {"native_getTextRunAdvances","(I[CIIIII[FII)F",
        (void*) SkPaintGlue::getTextRunAdvances___CIIIII_FII},
    {"native_getTextRunAdvances","(ILjava/lang/String;IIIII[FII)F",
        (void*) SkPaintGlue::getTextRunAdvances__StringIIIII_FII},


    {"native_getTextGlyphs","(ILjava/lang/String;IIIII[C)I",
        (void*) SkPaintGlue::getTextGlyphs__StringIIIII_C},
    {"native_getTextRunCursor", "(I[CIIIII)I", (void*) SkPaintGlue::getTextRunCursor___C},
    {"native_getTextRunCursor", "(ILjava/lang/String;IIIII)I",
        (void*) SkPaintGlue::getTextRunCursor__String},
    {"native_getTextPath","(II[CIIFFI)V", (void*) SkPaintGlue::getTextPath___C},
    {"native_getTextPath","(IILjava/lang/String;IIFFI)V", (void*) SkPaintGlue::getTextPath__String},
    {"nativeGetStringBounds", "(ILjava/lang/String;IILandroid/graphics/Rect;)V",
                                        (void*) SkPaintGlue::getStringBounds },
    {"nativeGetCharArrayBounds", "(I[CIILandroid/graphics/Rect;)V",
                                    (void*) SkPaintGlue::getCharArrayBounds },
    {"nSetShadowLayer", "(FFFI)V", (void*)SkPaintGlue::setShadowLayer}
};

static jfieldID req_fieldID(jfieldID id) {
    SkASSERT(id);
    return id;
}

int register_android_graphics_Paint(JNIEnv* env) {
    gFontMetrics_class = env->FindClass("android/graphics/Paint$FontMetrics");
    SkASSERT(gFontMetrics_class);
    gFontMetrics_class = (jclass)env->NewGlobalRef(gFontMetrics_class);

    gFontMetrics_fieldID.top = req_fieldID(env->GetFieldID(gFontMetrics_class, "top", "F"));
    gFontMetrics_fieldID.ascent = req_fieldID(env->GetFieldID(gFontMetrics_class, "ascent", "F"));
    gFontMetrics_fieldID.descent = req_fieldID(env->GetFieldID(gFontMetrics_class, "descent", "F"));
    gFontMetrics_fieldID.bottom = req_fieldID(env->GetFieldID(gFontMetrics_class, "bottom", "F"));
    gFontMetrics_fieldID.leading = req_fieldID(env->GetFieldID(gFontMetrics_class, "leading", "F"));

    gFontMetricsInt_class = env->FindClass("android/graphics/Paint$FontMetricsInt");
    SkASSERT(gFontMetricsInt_class);
    gFontMetricsInt_class = (jclass)env->NewGlobalRef(gFontMetricsInt_class);

    gFontMetricsInt_fieldID.top = req_fieldID(env->GetFieldID(gFontMetricsInt_class, "top", "I"));
    gFontMetricsInt_fieldID.ascent = req_fieldID(env->GetFieldID(gFontMetricsInt_class, "ascent", "I"));
    gFontMetricsInt_fieldID.descent = req_fieldID(env->GetFieldID(gFontMetricsInt_class, "descent", "I"));
    gFontMetricsInt_fieldID.bottom = req_fieldID(env->GetFieldID(gFontMetricsInt_class, "bottom", "I"));
    gFontMetricsInt_fieldID.leading = req_fieldID(env->GetFieldID(gFontMetricsInt_class, "leading", "I"));

    int result = AndroidRuntime::registerNativeMethods(env, "android/graphics/Paint", methods,
        sizeof(methods) / sizeof(methods[0]));
    return result;
}

}