编译 skia

0、准备工作

在 https://android.googlesource.com/ 用 git 代码，当然也可以从skia的官方https://code.google.com/p/skia/ 中获取，但是个人觉得前一种方法与Android适配更好，更方便。

1、依赖关系

动态库libcutils，libz  libjpeg ，libexpat ，liblog 去掉 libemoji libutils

静态库  libft2  libpng  libgif  libwebp-decode  libwebp-encode

libcutils 来自systerm/core, 其余在external目录

2、头文件

由于NDK自带的头文件不完整，因此需要关联

libcutils  utils （来自framework/native/libs)

另外编libcutils时还需要依赖bionc中的头文件（不需要编译bionic），直接在源代码的更目录下

顺便将framework/base目录也抓下来，因为用到GraphicJNI.h头文件还需要引用其中的一些头文件

3、一些环境相关的宏

见 /build/core/combo/include/arch/linux-arm/AndroidConfig.h
关闭 HAVE_LIBC_SYSTEM_PROPERTIES=1

4、编译过程问题

1）/home/workspace/webos_dalvik/external/skia/src/opts/SkBlitRow_opts_arm.cpp: In function ‘void S32A_Blend_BlitRow32_arm(SkPMColor*, const SkPMColor*, int, U8CPU)’:
/home/workspace/webos_dalvik/external/skia/src/opts/SkBlitRow_opts_arm.cpp:789: error: fp cannot be used in asm here

主要是汇编指令不支持

#ifeq ($(TARGET_ARCH),arm)
#
#ifeq ($(ARCH_ARM_HAVE_NEON),true)
#LOCAL_SRC_FILES += \
#    src/opts/memset16_neon.S \
#    src/opts/memset32_neon.S
#endif
#
#LOCAL_SRC_FILES += \
#    src/opts/opts_check_arm.cpp \
#    src/opts/memset.arm.S \
#    src/opts/SkBitmapProcState_opts_arm.cpp \
#    src/opts/SkBlitRow_opts_arm.cpp
#else
LOCAL_SRC_FILES += \
    src/opts/SkBlitRow_opts_none.cpp \
    src/opts/SkBitmapProcState_opts_none.cpp \
    src/opts/SkUtils_opts_none.cpp
#endif

2）/home/likai/lib/android-ndk-r8d/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi/objs-debug/corkscrew/src/backtrace.o: in function unwind_backtrace_thread:jni/libcorkscrew/src/backtrace.c:182: error: undefined reference to '__android_log_print'
需要链接 -llog 或者直接编译liblog模块（来自system/core)

5、Android.mk

BASE_PATH := $(call my-dir)
LOCAL_PATH:= $(call my-dir)

###############################################################################
#
# PROBLEMS WITH SKIA DEBUGGING?? READ THIS...
#
# The debug build results in changes to the Skia headers. This means that those
# using libskia must also be built with the debug version of the Skia headers.
# There are a few scenarios where this comes into play:
#
# (1) You're building debug code that depends on libskia.
#   (a) If libskia is built in release, then define SK_RELEASE when building
#       your sources.
#   (b) If libskia is built with debugging (see step 2), then no changes are
#       needed since your sources and libskia have been built with SK_DEBUG.
# (2) You're building libskia in debug mode.
#   (a) RECOMMENDED: You can build the entire system in debug mode. Do this by
#       updating your buildspec.mk to include TARGET_BUILD_TYPE=debug
#   (b) You can update all the users of libskia to define SK_DEBUG when they are
#       building their sources.
#
# NOTE: If neither SK_DEBUG or SK_RELEASE are defined then Skia checks NDEBUG to
#       determine which build type to use.
###############################################################################

#############################################################
#   build the skia+fretype+png+jpeg+zlib+gif+webp library
#

include $(CLEAR_VARS)

LOCAL_ARM_MODE := arm

# need a flag to tell the C side when we're on devices with large memory
# budgets (i.e. larger than the low-end devices that initially shipped)
ifeq ($(ARCH_ARM_HAVE_VFP),true)
    LOCAL_CFLAGS += -DANDROID_LARGE_MEMORY_DEVICE
endif

ifeq ($(TARGET_ARCH),x86)
    LOCAL_CFLAGS += -DANDROID_LARGE_MEMORY_DEVICE
endif

ifneq ($(ARCH_ARM_HAVE_VFP),true)
    LOCAL_CFLAGS += -DSK_SOFTWARE_FLOAT
endif

ifeq ($(ARCH_ARM_HAVE_NEON),true)
    LOCAL_CFLAGS += -D__ARM_HAVE_NEON
endif

# special checks for alpha == 0 and alpha == 255 in S32A_Opaque_BlitRow32
# procedures (C and assembly) seriously improve skia performance
LOCAL_CFLAGS += -DTEST_SRC_ALPHA

# using freetype's embolden allows us to adjust fake bold settings at
# draw-time, at which point we know which SkTypeface is being drawn
LOCAL_CFLAGS += -DSK_USE_FREETYPE_EMBOLDEN

LOCAL_SRC_FILES:= \
    src/core/Sk64.cpp \
    src/core/SkAAClip.cpp \
    src/core/SkAdvancedTypefaceMetrics.cpp \
    src/core/SkAlphaRuns.cpp \
    src/core/SkBitmap.cpp \
    src/core/SkBitmapProcShader.cpp \
    src/core/SkBitmapProcState.cpp \
    src/core/SkBitmapProcState_matrixProcs.cpp \
    src/core/SkBitmapSampler.cpp \
    src/core/SkBitmap_scroll.cpp \
    src/core/SkBlitMask_D32.cpp \
    src/core/SkBlitRow_D16.cpp \
    src/core/SkBlitRow_D32.cpp \
    src/core/SkBlitRow_D4444.cpp \
    src/core/SkBlitter.cpp \
    src/core/SkBlitter_4444.cpp \
    src/core/SkBlitter_A1.cpp \
    src/core/SkBlitter_A8.cpp \
    src/core/SkBlitter_ARGB32.cpp \
    src/core/SkBlitter_RGB16.cpp \
    src/core/SkBlitter_Sprite.cpp \
    src/core/SkBuffer.cpp \
    src/core/SkCanvas.cpp \
    src/core/SkChunkAlloc.cpp \
    src/core/SkClampRange.cpp \
    src/core/SkClipStack.cpp \
    src/core/SkColor.cpp \
    src/core/SkColorFilter.cpp \
    src/core/SkColorTable.cpp \
    src/core/SkComposeShader.cpp \
    src/core/SkConcaveToTriangles.cpp \
    src/core/SkConfig8888.cpp \
    src/core/SkCordic.cpp \
    src/core/SkCubicClipper.cpp \
    src/core/SkData.cpp \
    src/core/SkDebug.cpp \
    src/core/SkDeque.cpp \
    src/core/SkDevice.cpp \
    src/core/SkDeviceProfile.cpp \
    src/core/SkDither.cpp \
    src/core/SkDraw.cpp \
  src/core/SkEdgeBuilder.cpp \
    src/core/SkEdgeClipper.cpp \
  src/core/SkEdge.cpp \
    src/core/SkFilterProc.cpp \
    src/core/SkFlattenable.cpp \
    src/core/SkFloat.cpp \
    src/core/SkFloatBits.cpp \
    src/core/SkFontHost.cpp \
    src/core/SkGeometry.cpp \
    src/core/SkGlyphCache.cpp \
    src/core/SkGraphics.cpp \
    src/core/SkLanguage.cpp \
    src/core/SkLineClipper.cpp \
    src/core/SkMallocPixelRef.cpp \
    src/core/SkMask.cpp \
    src/core/SkMaskFilter.cpp \
    src/core/SkMath.cpp \
    src/core/SkMatrix.cpp \
    src/core/SkMetaData.cpp \
    src/core/SkMMapStream.cpp \
    src/core/SkPackBits.cpp \
    src/core/SkPaint.cpp \
    src/core/SkPath.cpp \
    src/core/SkPathEffect.cpp \
    src/core/SkPathHeap.cpp \
    src/core/SkPathMeasure.cpp \
    src/core/SkPicture.cpp \
    src/core/SkPictureFlat.cpp \
    src/core/SkPicturePlayback.cpp \
    src/core/SkPictureRecord.cpp \
    src/core/SkPixelRef.cpp \
    src/core/SkPoint.cpp \
    src/core/SkProcSpriteBlitter.cpp \
    src/core/SkPtrRecorder.cpp \
    src/core/SkQuadClipper.cpp \
    src/core/SkRasterClip.cpp \
    src/core/SkRasterizer.cpp \
    src/core/SkRect.cpp \
    src/core/SkRefDict.cpp \
    src/core/SkRegion.cpp \
    src/core/SkRegion_path.cpp \
  src/core/SkScalar.cpp \
  src/core/SkScalerContext.cpp \
    src/core/SkScan.cpp \
    src/core/SkScan_AntiPath.cpp \
    src/core/SkScan_Antihair.cpp \
    src/core/SkScan_Hairline.cpp \
    src/core/SkScan_Path.cpp \
    src/core/SkShader.cpp \
    src/core/SkShape.cpp \
    src/core/SkSpriteBlitter_ARGB32.cpp \
    src/core/SkSpriteBlitter_RGB16.cpp \
    src/core/SkStream.cpp \
    src/core/SkString.cpp \
    src/core/SkStroke.cpp \
    src/core/SkStrokerPriv.cpp \
    src/core/SkTSearch.cpp \
    src/core/SkTypeface.cpp \
    src/core/SkTypefaceCache.cpp \
    src/core/SkUnPreMultiply.cpp \
    src/core/SkUtils.cpp \
    src/core/SkFlate.cpp \
    src/core/SkWriter32.cpp \
    src/core/SkXfermode.cpp \
    src/effects/Sk1DPathEffect.cpp \
    src/effects/Sk2DPathEffect.cpp \
    src/effects/SkAvoidXfermode.cpp \
    src/effects/SkArithmeticMode.cpp \
    src/effects/SkBitmapCache.cpp \
    src/effects/SkBlurDrawLooper.cpp \
    src/effects/SkBlurImageFilter.cpp \
    src/effects/SkBlurMask.cpp \
    src/effects/SkBlurMaskFilter.cpp \
    src/effects/SkColorFilters.cpp \
    src/effects/SkColorMatrixFilter.cpp \
    src/effects/SkCornerPathEffect.cpp \
    src/effects/SkDashPathEffect.cpp \
    src/effects/SkDiscretePathEffect.cpp \
    src/effects/SkEffects.cpp \
    src/effects/SkEmbossMask.cpp \
    src/effects/SkEmbossMaskFilter.cpp \
    src/effects/SkGradientShader.cpp \
    src/effects/SkGroupShape.cpp \
    src/effects/SkKernel33MaskFilter.cpp \
    src/effects/SkLayerDrawLooper.cpp \
    src/effects/SkLayerRasterizer.cpp \
    src/effects/SkMorphologyImageFilter.cpp \
    src/effects/SkPaintFlagsDrawFilter.cpp \
    src/effects/SkPixelXorXfermode.cpp \
    src/effects/SkPorterDuff.cpp \
    src/effects/SkRectShape.cpp \
    src/effects/SkTableColorFilter.cpp \
  src/effects/SkTableMaskFilter.cpp \
  src/effects/SkTestImageFilters.cpp \
    src/effects/SkTransparentShader.cpp \
    src/images/bmpdecoderhelper.cpp \
    src/images/SkBitmapRegionDecoder.cpp \
    src/images/SkCreateRLEPixelRef.cpp \
    src/images/SkFDStream.cpp \
    src/images/SkFlipPixelRef.cpp \
    src/images/SkImageDecoder.cpp \
    src/images/SkImageDecoder_Factory.cpp \
    src/images/SkImageDecoder_libbmp.cpp \
    src/images/SkImageDecoder_libgif.cpp \
    src/images/SkImageDecoder_libico.cpp \
    src/images/SkImageDecoder_libjpeg.cpp \
    src/images/SkImageDecoder_libpng.cpp \
    src/images/SkImageDecoder_libwebp.cpp \
    src/images/SkImageDecoder_wbmp.cpp \
    src/images/SkImageEncoder.cpp \
    src/images/SkImageEncoder_Factory.cpp \
    src/images/SkImageRef.cpp \
    src/images/SkImageRefPool.cpp \
    src/images/SkImageRef_GlobalPool.cpp \
    src/images/SkJpegUtility.cpp \
    src/images/SkMovie.cpp \
    src/images/SkMovie_gif.cpp \
    src/images/SkPageFlipper.cpp \
    src/images/SkScaledBitmapSampler.cpp \
    src/ports/FontHostConfiguration_android.cpp \
    src/ports/SkDebug_android.cpp \
    src/ports/SkGlobalInitialization_default.cpp \
    src/ports/SkFontHost_FreeType.cpp \
    src/ports/SkFontHost_sandbox_none.cpp    \
    src/ports/SkFontHost_android.cpp \
    src/ports/SkFontHost_gamma.cpp \
    src/ports/SkFontHost_tables.cpp \
    src/ports/SkImageRef_ashmem.cpp \
    src/ports/SkMemory_malloc.cpp \
    src/ports/SkOSFile_stdio.cpp \
    src/ports/SkThread_pthread.cpp \
    src/ports/SkTime_Unix.cpp \
    src/utils/SkBase64.cpp \
    src/utils/SkBoundaryPatch.cpp \
    src/utils/SkCamera.cpp \
    src/utils/SkColorMatrix.cpp \
  src/utils/SkCubicInterval.cpp \
    src/utils/SkCullPoints.cpp \
    src/utils/SkDeferredCanvas.cpp \
    src/utils/SkDumpCanvas.cpp \
    src/utils/SkInterpolator.cpp \
    src/utils/SkLayer.cpp \
    src/utils/SkMatrix44.cpp \
    src/utils/SkMeshUtils.cpp \
    src/utils/SkNinePatch.cpp \
    src/utils/SkNWayCanvas.cpp \
    src/utils/SkOSFile.cpp \
    src/utils/SkParse.cpp \
    src/utils/SkParseColor.cpp \
    src/utils/SkParsePath.cpp \
    src/utils/SkProxyCanvas.cpp \
    src/utils/SkSfntUtils.cpp \
    src/utils/SkUnitMappers.cpp

#ifeq ($(TARGET_ARCH),arm)
#
#ifeq ($(ARCH_ARM_HAVE_NEON),true)
#LOCAL_SRC_FILES += \
#    src/opts/memset16_neon.S \
#    src/opts/memset32_neon.S
#endif
#
#LOCAL_SRC_FILES += \
#    src/opts/opts_check_arm.cpp \
#    src/opts/memset.arm.S \
#    src/opts/SkBitmapProcState_opts_arm.cpp \
#    src/opts/SkBlitRow_opts_arm.cpp
#else
LOCAL_SRC_FILES += \
    src/opts/SkBlitRow_opts_none.cpp \
    src/opts/SkBitmapProcState_opts_none.cpp \
    src/opts/SkUtils_opts_none.cpp
#endif
LOCAL_SRC_FILES := $(subst $(BASE_PATH),.,$(LOCAL_SRC_FILES))
# these are for emoji support, needed by webkit
#LOCAL_SRC_FILES += \
#    emoji/EmojiFont.cpp

LOCAL_SHARED_LIBRARIES := \
    libcutils \
    libz \
    libjpeg \
    libexpat \
    liblog
#libemoji
#libutils

LOCAL_STATIC_LIBRARIES := \
    libft2 \
    libpng \
    libgif \
    libwebp-decode \
    libwebp-encode

LOCAL_C_INCLUDES += \
    $(LOCAL_PATH)/src/core \
    $(LOCAL_PATH)/include/core \
    $(LOCAL_PATH)/include/config \
    $(LOCAL_PATH)/include/effects \
    $(LOCAL_PATH)/include/images \
    $(LOCAL_PATH)/include/ports \
    $(LOCAL_PATH)/include/utils \
    $(LOCAL_PATH)/include/xml \
    $(LOCAL_PATH)/../../libcutils \
    $(LOCAL_PATH)/../../utils \
    $(LOCAL_PATH)/../freetype/include \
    $(LOCAL_PATH)/../zlib \
    $(LOCAL_PATH)/../libpng \
    $(LOCAL_PATH)/../giflib \
    $(LOCAL_PATH)/../jpeg \
    $(LOCAL_PATH)/../webp/include\
    $(LOCAL_PATH)/../expat/lib
    #frameworks/opt/emoji \

# Android's -D_FORTIFY_SOURCE=2 extensions are incompatibile with SkString.
# Revert to -D_FORTIFY_SOURCE=1
LOCAL_CFLAGS += -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1
LOCAL_CXXFLAGS += \
-DHAVE_POSIX_CLOCKS \
-DHAVE_PTHREADS \
-DHAVE_ANDROID_PTHREAD_SETNAME_NP \
-DHAVE_FUTEX \
-DHAVE_FUTEX_WRAPPERS=1 \
-DHAVE_FORKEXEC \
-DHAVE_OOM_ADJ \
-DHAVE_ANDROID_IPC \
-DHAVE_POSIX_FILEMAP \
-DHAVE_TERMIO_H=1 \
-DHAVE_SYS_SENDFILE_H=1 \
-DHAVE_SYS_UIO_H=1 \
-DHAVE_SYMLINKS \
-DHAVE_IOCTL \
-DHAVE_TIMEDWAIT_MONOTONIC \
-DHAVE_EPOLL \
-DHAVE_ENDIAN_H \
-DHAVE_LITTLE_ENDIAN \
-DHAVE_OFF64_T \
-DHAVE_BACKTRACE=0 \
-DHAVE_DLADDR=1 \
-DHAVE_CXXABI=0 \
-DHAVE_GETTID \
-DHAVE_SCHED_SETSCHEDULER \
-DHAVE_MALLOC_H \
-DHAVE_ANDROID_OS=1 \
-DHAVE_LINUX_LOCAL_SOCKET_NAMESPACE=1 \
-DHAVE_INOTIFY=1 \
-DHAVE_MADVISE=1 \
-DHAVE_TM_GMTOFF=1 \
-DHAVE_DIRENT_D_TYPE=1 \
-DARCH_ARM \
-DHAVE__MEMCMP16=1 \
-DHAVE_SA_NOCLDWAIT \
-DOS_PATH_SEPARATOR=\'/\' \
-DOS_CASE_SENSITIVE \
-DHAVE_SYS_SOCKET_H=1 \
-DHAVE_STRLCPY=1 \
-DHAVE_FUNOPEN=1 \
-DHAVE_PRCTL=1 \
-DHAVE_WRITEV=1 \
-DHAVE_STDINT_H=1 \
-DHAVE_STDBOOL_H=1 \
-DHAVE_SCHED_H=1 \
-DHAVE_PREAD=1 \
-DHAVE_STAT_ST_MTIM=1 \
-DHAVE_PRINTF_ZD=1 \
-DHAVE_BSD_QSORT_R=0 \
-DHAVE_GNU_QSORT_R=0
ifeq ($(NO_FALLBACK_FONT),true)
    LOCAL_CFLAGS += -DNO_FALLBACK_FONT
endif

#LOCAL_LDLIBS += -lpthread #默认已经有了

LOCAL_MODULE:= libskia

include $(BUILD_SHARED_LIBRARY)