一、           介绍

TIFF全名 tag image file format,是一种基于标志域的图形。

TIFF图像是靠指针连接来组织数据的，文件头和数据可以任意数据的存储。TIFF由四种类型：TIFF-B，二色；TIFF-G，黑白灰度；TIFF-P，带调色板的彩色图形；TIFF-R，适合RGB色彩的图形。

二、           组成

TIFF一般来说由四部分组成：文件头、文件目录、目录内容、图像数据；如下图，下面具体说明。

三、           具体格式

1.        文件头部分

文件头部分有8个字节，格式为：

0                                      2                                      4

5                                                                                                                                                                                                                                                                              8

注意这里的值不一定就是紧接头后的0A地址，可以是任意的。

2.        文件目录部分

0                                    2                                      14

每个项的12个字节，其是连续的，有前两个字节说明其项的总数。对于不同的TIFF格式文件，这里的不同。

3.        目录项

每个目录项由12个字节组成，格式如下：

TAG的值由TIFF标准定义；不同的TAG表示不同的意思，例如0X0100表示图像的宽度。

TAG的数据类型表示数据值的类型；例如使用long类型来表示宽度。

数据长度是以数据类型为单位的，真正的数据长度是：数据长度*sizeof(数据类型)

数据值或值的偏移：如果数据长度小于4个字节，一般直接以该字段来表示其值，如果其值大于4个字节，就指定一个文件范围的偏移地址，从那里开始的“数据长度*sizeof(数据类型)”个字节表示该标志的值。

4.        图像数据：

紧接上面数据之后就是图像数据了；图像数据的存储形式有不同的形式，有以像素位来存储的，也有以颜色面来存储的；具体的存储方式在目录项中定义。

四、           一些TAG值

更多的参考TIFF标准

五、           一个TIFF文件格式分析

　在arm-linux环境下运行可执行程序mocp，在加载动态库libdecoder.so时，却总是报错：File not found。在代码中添加很多printf，找到是在dlopen时报错。最初以为，是函数dlopen找不到lib_decoder.so文件。那么就认为有以下几种可能：

１，动态库给的搜索路径不对；

２，编译生成动态库的编译工具和程序的运行环境不同；

３，交叉编译环境不能识别dlopen（当然这个可能性是瞎猜的）。

　　于是写了个测试程序并交叉编译，自己创建一个动态库libabc.so，并用dlopen加载它。

１，更改动态库的存放路径，结果是在任何路径下都可以找到；

２，用这个正确的测试程序加载libdecoder.so，结果是不管什么路径，就是找不到；

３，在mocp运行时加载libabd.so，能找到；

结论：只要给了dlopen函数一个路径，它就能到这个路径下去寻找指定的库；都是用arm-linux-uclibc-编译的，编译环境相同。那么就是libdecoder.so这个库本身的问题。

　　于是将命令从Makefile中抽出来，在shell中单独运行命令生成这个库，结果还是找不到。然后把命令简化，去掉各种选项，比如链接选项，仅仅用

arm-linux-uclibc-gcc -fpic -shared snow.c rain.c -o libdecoder.so

生成库后，测试发现能找到了。添加一个链接选项-ldl，又找不到了。

　　这才想到，libdecoder.so还要加载一个动态库libdl.so，file not found是不是指的是这个库找不到啊？查找运行环境下的/lib发现，果然没有libdl.so文件。把这个库拷进来，mocp在dlopen的时候就通过了。Done！

　　其实，如果我在运行程序之前就检查好这个程序究竟需要那些动态库，也就不至于花了这么大力气查找这个问题。

　　用objdump命令就可以查看目标文件包含的信息，其中就有程序需要链接的动态库。

Android 开机会出现3个画面：
a. Linux 系统启动，出现Linux小企鹅画面(reboot)；
b. Android平台启动初始化，出现"A N D R I O D"文字字样画面；
c. Android平台图形系统启动，出现含闪动的ANDROID字样的动画图片(start)。

1/ 开机图片(Linux小企鹅)

Linux Kernel引导启动后，加载该图片。
/kernel/trunk/drivers/video/fbmem.c
/kernel/trunk/drivers/video/fbmem.h
/kernel/trunk/drivers/video/logo/logo.c
/kernel/trunk/drivers/video/logo/logo.h
/kernel/trunk/drivers/video/logo/Kconfig
/kernel/trunk/include/linux/linux_logo.h

2/ 开机文字("A N D R I O D")

Android 系统启动后，读取 /initlogo.rle（一张565 rle压缩的位图），如果读取成功，测在/dev/graphics/fb0显示Logo图片；如果读取失败，则将/dev/tty0设为TEXT模式， 并打开/dev/tty0，输出文本“A N D R I O D”字样。

相关代码：

/system/core/init/init.c
/system/core/init/init.h
/system/core/init/init.rc
/system/core/init/logo.c

*.rle文件的制作步骤:
a. 使用GIMP或者Advanced Batch Converter软件，将图象转换为RAW格式；
b. 使用android自带的rgb2565工具，将RAW格式文件转换为RLE格式(如：rgb2565 -rle < initlogo.raw > initlogo.rle)。

3/ 开机动画(闪动的ANDROID字样的动画图片)

Android 的系统登录动画类似于Windows系统的滚动条，是由前景和背景两张PNG图片组成，这两张图片存在于/system/framework /framework-res.apk文件当中。前景图片（android-logo-mask.png）上的Android文字部分镂空，背景图片 （android-logo-shine.png）则是简单的纹理。系统登录时，前景图片在最上层显示，程序代码控制背景图片连续滚动，透过前景图片文字 镂空部分滚动显示背景纹理，从而实现动画效果。

相关代码：
/frameworks/base/libs/surfaceflinger/BootAnimation.h
/frameworks/base/libs/surfaceflinger/BootAnimation.cpp

/frameworks/base/core/res/assets/images/android-logo-mask.png
Android默认的前景图片，文字部分镂空，大小256×64
/frameworks/base/core/res/assets/images/android-logo-shine.png
Android默认的背景图片，有动感效果，大小512×64

参考文档：

图说Android开机画面和开机动画
http://www.shudoo.com/09/1030/15/13418431.html

initlogo.rle: display an image on boot
http://forum.xda-developers.com/showthread.php?t=443431

分析Android 根文件系统启动过程（init守护进程分析）
http://crazier9527.javaeye.com/blog/454635

G1带有实体键盘，可以侧推。虽然如今的G2 G3去掉了实体键盘，但同志们开发的应用还是得兼容一下G1吧。先从几个问题入手：
1、不管键盘是否滑出，都要设置屏幕为竖屏或者横屏。这个该怎么处理？
2、当用户在竖屏状态下编辑了一个文本框，又突然想推出实体键盘进行编辑，而此时Activity重绘，文本框内未保存的信息又该怎么办？
3、监听键盘滑动事件。让纵横屏状态下载入不同的layout。

当然你也许可以再java代码中去设置很多事件捕获，但有一个更好的方法，那就是修改Androidmanifest.xml.

默认的情况下推出或缩进键盘会重新启动activity
要不关闭activity 则可以在manifest.xml中增加 android:configChanges=”keyboardHidden|orientation”
然后重载public void onConfigurationChanged(Configuration newConfig) 函数
键盘被抽出后会首先调用onConfigurationChanged

如果你希望滑动键盘不改变屏幕分辨率 则可以增加属性：android:screenOrientation=”portrait“>
portrait :竖   
landscape: 横
sensor:根据手机的角度自动调整

详细说明：

<activity …
          android:configChanges=[one or more of: "mcc" "mnc" "locale"
                                 "touchscreen" "keyboard" "keyboardHidden"
                                 "navigation" "orientation" "fontScale"]
…
</activity>
android:configChanges
    Lists configuration changes that the activity will handle itself. When changes that are not listed occur, the activity is shut down and restarted. When a listed change occurs, the activity remains running and its onConfigurationChanged() method is called.

    Any or all of the following strings can be used to set this attribute. Values are separated by ‘|’ — for example, “locale|navigation|orientation”.
    Value         Description
    “mcc”         The IMSI mobile country code (MCC) has changed — that is, a SIM has been detected and updated the MCC.
    “mnc”         The IMSI mobile network code (MNC) has changed — that is, a SIM has been detected and updated the MNC.
    “locale”         The locale has changed — for example, the user has selected a new language that text should be displayed in.
    “touchscreen”         The touchscreen has changed. (This should never normally happen.)
    “keyboard”         The keyboard type has changed — for example, the user has plugged in an external keyboard.
    “keyboardHidden”         The keyboard accessibility has changed — for example, the user has slid the keyboard out to expose it.
    “navigation”         The navigation type has changed. (This should never normally happen.)
    “orientation”         The screen orientation has changed — that is, the user has rotated the device.
    “fontScale”         The font scaling factor has changed — that is, the user has selected a new global font size.

    All of these configuration changes can impact the resource values seen by the application. Therefore, when onConfigurationChanged() is called, it will generally be necessary to again retrieve all resources (including view layouts, drawables, and so on) to correctly handle the change.

Status: Draft   (as of May 18, 2006)

Contents

Objective

The primary goals of reworking the build system are (1) to make dependencies work more reliably, so that when files need to rebuilt, they are, and (2) to improve performance of the build system so that unnecessary modules are not rebuilt, and so doing a top-level build when little or nothing needs to be done for a build takes as little time as possible.

Principles and Use Cases and Policy

Given the above objective, these are the overall principles and use cases that we will support. This is not an exhaustive list.

Multiple Targets

It needs to be possible to build the Android platform for multiple targets. This means:

• The build system will support building tools for the host platform, both ones that are used in the build process itself, and developer tools like the simulator.
• The build system will need to be able to build tools on Linux (definitely Goobuntu and maybe Grhat), MacOS, and to some degree on Windows.
• The build system will need to be able to build the OS on Linux, and in the short-term, MacOS. Note that this is a conscious decision to stop building the OS on Windows. We are going to rely on the emulator there and not attempt to use the simulator. This is a requirement change now that the emulator story is looking brighter.

Non-Recursive Make

To achieve the objectives, the build system will be rewritten to use make non-recursively. For more background on this, read Recursive Make Considered Harmful. For those that don't want PDF, here is the Google translated version.

Rapid Compile-Test Cycles

When developing a component, for example a C++ shared library, it must be possible to easily rebuild just that component, and not have to wait more than a couple seconds for dependency checks, and not have to wait for unneeded components to be built.

Both Environment and Config File Based Settings

To set the target, and other options, some people on the team like to have a configuration file in a directory so they do not have an environment setup script to run, and others want an environment setup script to run so they can run builds in different terminals on the same tree, or switch back and forth in one terminal. We will support both.

Object File Directory / make clean

Object files and other intermediate files will be generated into a directory that is separate from the source tree. The goal is to have make clean be "rm -rf " in the tree root directory. The primary goals of this are to simplify searching the source tree, and to make "make clean" more reliable.

SDK

The SDK will be a tarball that will allow non-OS-developers to write apps. The apps will actually be built by first building the SDK, and then building the apps against that SDK. This will hopefully (1) make writing apps easier for us, because we won't have to rebuild the OS as much, and we can use the standard java-app development tools, and (2) allow us to dog-food the SDK, to help ensure its quality. Cedric has suggested (and I agree) that apps built from the SDK should be built with ant. Stay tuned for more details as we figure out exactly how this will work.

Dependecies

Dependencies should all be automatic. Unless there is a custom tool involved (e.g. the webkit has several), the dependencies for shared and static libraries, .c, .cpp, .h, .java, java libraries, etc., should all work without intervention in the Android.mk file.

Hiding command lines

The default of the build system will be to hide the command lines being executed for make steps. It will be possible to override this by specifying the showcommands pseudo-target, and possibly by setting an environment variable.

Wildcard source files

Wildcarding source file will be discouraged. It may be useful in some scenarios. The default $(wildcard *) will not work due to the current directory being set to the root of the build tree.

Multiple targets in one directory

It will be possible to generate more than one target from a given subdirectory. For example, libutils generates a shared library for the target and a static library for the host.

Makefile fragments for modules

Android.mk is the standard name for the makefile fragments that control the building of a given module. Only the top directory should have a file named "Makefile".

Use shared libraries

Currently, the simulator is not built to use shared libraries. This should be fixed, and now is a good time to do it. This implies getting shared libraries to work on Mac OS.

Nice to Have

These things would be nice to have, and this is a good place to record them, however these are not promises.

Simultaneous Builds

The hope is to be able to do two builds for different combos in the same tree at the same time, but this is a stretch goal, not a requirement. Doing two builds in the same tree, not at the same time must work. (update: it's looking like we'll get the two builds at the same time working)

Deleting headers (or other dependecies)

Problems can arise if you delete a header file that is referenced in ".d" files. The easy way to deal with this is "make clean". There should be a better way to handle it. (from fadden)

One way of solving this is introducing a dependency on the directory. The problem is that this can create extra dependecies and slow down the build. It's a tradeoff.

Multiple builds

General way to perform builds across the set of known platforms. This would make it easy to perform multiple platform builds when testing a change, and allow a wide-scale "make clean". Right now the buildspec.mk or environment variables need to be updated before each build. (from fadden)

Aftermarket Locales and Carrier

We will eventually need to add support for creating locales and carrier customizations to the SDK, but that will not be addressed right now.

Usage

You've read (or scrolled past) all of the motivations for this build system, and you want to know how to use it. This is the place.

Your first build

The Building document describes how do do builds.

build/envsetup.sh functions

• printconfig - Prints the current configuration as set by the lunch and choosecombo commands.
• m - Runs make from the top of the tree. This is useful because you can run make from within subdirectories. If you have the TOP environment variable set, it uses that. If you don't, it looks up the tree from the current directory, trying to find the top of the tree.
• croot - cd to the top of the tree.
• sgrep - grep for the regex you provide in all .c, .cpp, .h, .java, and .xml files below the current directory.

Build flavors/types

When building for a particular product, it's often useful to have minor variations on what is ultimately the final release build. These are the currently-defined "flavors" or "types" (we need to settle on a real name for these).

If you build one flavor and then want to build another, you should run "make installclean" between the two makes to guarantee that you don't pick up files installed by the previous flavor. "make clean" will also suffice, but it takes a lot longer.

More pseudotargets

Sometimes you want to just build one thing. The following pseudotargets are there for your convenience:

• droid - make droid is the normal build. This target is here because the default target has to have a name.
• all - make all builds everything make droid does, plus everything whose LOCAL_MODULE_TAGS do not include the "droid" tag. The build server runs this to make sure that everything that is in the tree and has an Android.mk builds.
• clean-$(LOCAL_MODULE) and clean-$(LOCAL_PACKAGE_NAME) - Let you selectively clean one target. For example, you can type make clean-libutils and it will delete libutils.so and all of the intermediate files, or you can type make clean-Home and it will clean just the Home app.
• clean - make clean deletes all of the output and intermediate files for this configuration. This is the same as rm -rf out/<configuration>/
• clobber - make clobber deletes all of the output and intermediate files for all configurations. This is the same as rm -rf out/.
• dataclean - make dataclean deletes contents of the data directory inside the current combo directory. This is especially useful on the simulator and emulator, where the persistent data remains present between builds.
• showcommands - showcommands is a modifier target which causes the build system to show the actual command lines for the build steps, instead of the brief descriptions. Most people don't like seeing the actual commands, because they're quite long and hard to read, but if you need to for debugging purposes, you can add showcommands to the list of targets you build. For example make showcommands will build the default android configuration, and make runtime showcommands will build just the runtime, and targets that it depends on, while displaying the full command lines. Please note that there are a couple places where the commands aren't shown here. These are considered bugs, and should be fixed, but they're often hard to track down. Please let android-build-team know if you find any.
• LOCAL_MODULE - Anything you specify as a LOCAL_MODULE in an Android.mk is made into a pseudotarget. For example, make runtime might be shorthand for make out/linux-x86-debug/system/bin/runtime (which would work), and make libkjs might be shorthand for make out/linux-x86-debug/system/lib/libkjs.so (which would also work).
• targets - make targets will print a list of all of the LOCAL_MODULE names you can make.

How to add another component to the build - Android.mk templates

You have a new library, a new app, or a new executable. For each of the common types of modules, there is a corresponding file in the templates directory. It will usually be enough to copy one of these, and fill in your own values. Some of the more esoteric values are not included in the templates, but are instead just documented here, as is the documentation on using custom tools to generate files.

Mostly, you can just look for the TODO comments in the templates and do what it says. Please remember to delete the TODO comments when you're done to keep the files clean. The templates have minimal documentation in them, because they're going to be copied, and when that gets stale, the copies just won't get updated. So read on...

Apps

Use the templates/apps file.

This template is pretty self-explanitory. See the variables below for more details.

Java Libraries

Use the templates/java_library file.

The interesting thing here is the value of LOCAL_MODULE, which becomes the name of the jar file. (Actually right now, we're not making jar files yet, just directories of .class files, but the directory is named according to what you put in LOCAL_MODULE). This name will be what goes in the LOCAL_JAVA_LIBRARIES variable in modules that depend on your java library.

C/C++ Executables

Use the templates/executable file, or the templates/executable_host file.

This template has a couple extra options that you usually don't need. Please delete the ones you don't need, and remove the TODO comments. It makes the rest of them easier to read, and you can always refer back to the templates if you need them again later.

By default, on the target these are built into /system/bin, and on the host, they're built into /host/bin. These can be overridden by setting LOCAL_MODULE_PATH. See Putting targets elsewhere for more.

Shared Libraries

Use the templates/shared_library file, or the templates/shared_library_host file.

Remember that on the target, we use shared libraries, and on the host, we use static libraries, since executable size isn't as big an issue, and it simplifies distribution in the SDK.

Static Libraries

Use the templates/static_library file, or the templates/static_library_host file.

Remember that on the target, we use shared libraries, and on the host, we use static libraries, since executable size isn't as big an issue, and it simplifies distribution in the SDK.

Using Custom Tools

If you have a tool that generates source files for you, it's possible to have the build system get the dependencies correct for it. Here are a couple of examples. $@ is the make built-in variable for "the current target." The red parts are the parts you'll need to change.

You need to put this after you have declared LOCAL_PATH and LOCAL_MODULE, because the $(local-intermediates-dir) and $(local-host-intermediates-dir) macros use these variables to determine where to put the files.

Example 1

Here, there is one generated file, called chartables.c, which doesn't depend on anything. And is built by the tool built to $(HOST_OUT_EXECUTABLES)/dftables. Note on the second to last line that a dependency is created on the tool.

intermediates:= $(local-intermediates-dir)

GEN := $(intermediates)/chartables.c

$(GEN): PRIVATE_CUSTOM_TOOL = $(HOST_OUT_EXECUTABLES)/dftables $@

$(GEN): $(HOST_OUT_EXECUTABLES)/dftables

$(transform-generated-source)

LOCAL_GENERATED_SOURCES += $(GEN)

Example 2

Here as a hypothetical example, we use use cat as if it were to transform a file. Pretend that it does something useful. Note how we use a target-specific variable called PRIVATE_INPUT_FILE to store the name of the input file.

intermediates:= $(local-intermediates-dir)

GEN := $(intermediates)/file.c

$(GEN): PRIVATE_INPUT_FILE := $(LOCAL_PATH)/input.file

$(GEN): PRIVATE_CUSTOM_TOOL = cat $(PRIVATE_INPUT_FILE) > $@

$(GEN): $(LOCAL_PATH)/file.c

$(transform-generated-source)

LOCAL_GENERATED_SOURCES += $(GEN)

Example 3

If you have several files that are all similar in name, and use the same tool, you can combine them. (here the *.lut.h files are the generated ones, and the *.cpp files are the input files)

intermediates:= $(local-intermediates-dir)

GEN := $(addprefix $(intermediates)/kjs/, \

array_object.lut.h \

bool_object.lut.h \

)

$(GEN): PRIVATE_CUSTOM_TOOL = perl libs/WebKitLib/WebKit/JavaScriptCore/kjs/create_hash_table $< -i > $@

$(GEN): $(intermediates)/%.lut.h : $(LOCAL_PATH)/%.cpp

$(transform-generated-source)

LOCAL_GENERATED_SOURCES += $(GEN)

Platform specific conditionals

Sometimes you need to set flags specifically for different platforms. Here is a list of which values the different build-system defined variables will be set to and some examples.

For a device build, TARGET_OS is linux (we're using linux!), and TARGET_ARCH is arm.

For a simulator build, TARGET_OS and TARGET_ARCH are set to the same as HOST_OS and HOST_ARCH are on your platform. TARGET_PRODUCT is the name of the target hardware/product you are building for. The value sim is used for the simulator. We haven't thought through the full extent of customization that will happen here, but likely there will be additional UI configurations specified here as well.

TARGET_SIMULATOR

If we're building the simulator, as opposed to the arm or emulator builds, TARGET_SIMULATOR will be set to true.

Some Examples

ifeq ($(TARGET_SIMULATOR),true)

LOCAL_CFLAGS += -DSIMULATOR

endif



ifeq ($(TARGET_BUILD_TYPE),release)

LOCAL_CFLAGS += -DNDEBUG=1

endif



# from libutils

ifeq ($(TARGET_OS),linux)

# Use the futex based mutex and condition variable

# implementation from android-arm because it's shared mem safe

LOCAL_SRC_FILES += futex_synchro.c

LOCAL_LDLIBS += -lrt -ldl

endif

Putting modules elsewhere

If you have modules that normally go somewhere, and you need to have them build somewhere else, read this. One use of this is putting files on the root filesystem instead of where they normally go in /system. Add these lines to your Android.mk:

LOCAL_MODULE_PATH := $(TARGET_ROOT_OUT_SBIN)



LOCAL_UNSTRIPPED_PATH := $(TARGET_ROOT_OUT_SBIN_UNSTRIPPED)

For executables and libraries, you need to also specify a LOCAL_UNSTRIPPED_PATH location, because on target builds, we keep the unstripped executables so GDB can find the symbols.

Look in config/envsetup.make for all of the variables defining places to build things.

FYI: If you're installing an executable to /sbin, you probably also want to set LOCAL_FORCE_STATIC_EXCUTABLE := true in your Android.mk, which will force the linker to only accept static libraries.

Android.mk variables

These are the variables that you'll commonly see in Android.mk files, listed alphabetically.

But first, a note on variable naming:

• LOCAL_ - These variables are set per-module. They are cleared by the include $(CLEAR_VARS) line, so you can rely on them being empty after including that file. Most of the variables you'll use in most modules are LOCAL_ variables.
• PRIVATE_ - These variables are make-target-specific variables. That means they're only usable within the commands for that module. It also means that they're unlikely to change behind your back from modules that are included after yours. This link to the make documentation describes more about target-specific variables. Please note that there are a couple of these laying around the tree that aren't prefixed with PRIVATE_. It is safe, and they will be fixed as they are discovered. Sorry for the confusion.
• INTERNAL_ - These variables are critical to functioning of the build system, so you shouldn't create variables named like this, and you probably shouldn't be messing with these variables in your makefiles.
• HOST_ and TARGET_ - These contain the directories and definitions that are specific to either the host or the target builds. Do not set variables that start with HOST_ or TARGET_ in your makefiles.
• BUILD_ and CLEAR_VARS - These contain the names of well-defined template makefiles to include. Some examples are CLEAR_VARS and BUILD_HOST_PACKAGE.
• Any other name is fair-game for you to use in your Android.mk. However, remember that this is a non-recursive build system, so it is possible that your variable will be changed by another Android.mk included later, and be different when the commands for your rule / module are executed.

LOCAL_ASSET_FILES

In Android.mk files that include $(BUILD_PACKAGE) set this to the set of files you want built into your app. Usually:

LOCAL_ASSET_FILES += $(call find-subdir-assets)

This will probably change when we switch to ant for the apps' build system.

LOCAL_CC

If you want to use a different C compiler for this module, set LOCAL_CC to the path to the compiler. If LOCAL_CC is blank, the appropriate default compiler is used.

LOCAL_CXX

If you want to use a different C++ compiler for this module, set LOCAL_CXX to the path to the compiler. If LOCAL_CXX is blank, the appropriate default compiler is used.

LOCAL_CFLAGS

If you have additional flags to pass into the C or C++ compiler, add them here. For example:

LOCAL_CFLAGS += -DLIBUTILS_NATIVE=1

LOCAL_CPPFLAGS

If you have additional flags to pass into only the C++ compiler, add them here. For example:

LOCAL_CPPFLAGS += -ffriend-injection

LOCAL_CPP_EXTENSION

If your C++ files end in something other than ".cpp", you can specify the custom extension here. For example:

LOCAL_CPP_EXTENSION := .cc

LOCAL_NO_DEFAULT_COMPILER_FLAGS

Normally, the compile line for C and C++ files includes global include paths and global cflags. If LOCAL_NO_DEFAULT_COMPILER_FLAGS is non-empty, none of the default includes or flags will be used when compiling C and C++ files in this module. LOCAL_C_INCLUDES, LOCAL_CFLAGS, and LOCAL_CPPFLAGS will still be used in this case, as will any DEBUG_CFLAGS that are defined for the module.

LOCAL_COPY_HEADERS

This will be going away.

The set of files to copy to the install include tree. You must also supply LOCAL_COPY_HEADERS_TO.

This is going away because copying headers messes up the error messages, and may lead to people editing those headers instead of the correct ones. It also makes it easier to do bad layering in the system, which we want to avoid. We also aren't doing a C/C++ SDK, so there is no ultimate requirement to copy any headers.

LOCAL_COPY_HEADERS_TO

This will be going away.

The directory within "include" to copy the headers listed in LOCAL_COPY_HEADERS to.

This is going away because copying headers messes up the error messages, and may lead to people editing those headers instead of the correct ones. It also makes it easier to do bad layering in the system, which we want to avoid. We also aren't doing a C/C++ SDK, so there is no ultimate requirement to copy any headers.

LOCAL_C_INCLUDES

Additional directories to instruct the C/C++ compilers to look for header files in. These paths are rooted at the top of the tree. Use LOCAL_PATH if you have subdirectories of your own that you want in the include paths. For example:

LOCAL_C_INCLUDES += extlibs/zlib-1.2.3
LOCAL_C_INCLUDES += $(LOCAL_PATH)/src

You should not add subdirectories of include to LOCAL_C_INCLUDES, instead you should reference those files in the #include statement with their subdirectories. For example:

#include <utils/KeyedVector.h>
not #include <KeyedVector.h>

There are some components that are doing this wrong, and should be cleaned up.

LOCAL_MODULE_TAGS

Set LOCAL_MODULE_TAGS to any number of whitespace-separated tags. If the tag list is empty or contains droid, the module will get installed as part of a make droid. Otherwise, it will only get installed by running make <your-module> or with the make all pseudotarget.

LOCAL_REQUIRED_MODULES

Set LOCAL_REQUIRED_MODULES to any number of whitespace-separated module names, like "libblah" or "Email". If this module is installed, all of the modules that it requires will be installed as well. This can be used to, e.g., ensure that necessary shared libraries or providers are installed when a given app is installed.

LOCAL_FORCE_STATIC_EXECUTABLE

If your executable should be linked statically, set LOCAL_FORCE_STATIC_EXECUTABLE:=true. There is a very short list of libraries that we have in static form (currently only libc). This is really only used for executables in /sbin on the root filesystem.

LOCAL_GENERATED_SOURCES

Files that you add to LOCAL_GENERATED_SOURCES will be automatically generated and then linked in when your module is built. See the Custom Tools template makefile for an example.

LOCAL_JAVA_LIBRARIES

When linking Java apps and libraries, LOCAL_JAVA_LIBRARIES specifies which sets of java classes to include. Currently there are two of these: core and framework. In most cases, it will look like this:

LOCAL_JAVA_LIBRARIES := core framework

Note that setting LOCAL_JAVA_LIBRARIES is not necessary (and is not allowed) when building an APK with "include $(BUILD_PACKAGE)". The appropriate libraries will be included automatically.

LOCAL_LDFLAGS

You can pass additional flags to the linker by setting LOCAL_LDFLAGS. Keep in mind that the order of parameters is very important to ld, so test whatever you do on all platforms.

LOCAL_LDLIBS

LOCAL_LDLIBS allows you to specify additional libraries that are not part of the build for your executable or library. Specify the libraries you want in -lxxx format; they're passed directly to the link line. However, keep in mind that there will be no dependency generated for these libraries. It's most useful in simulator builds where you want to use a library preinstalled on the host. The linker (ld) is a particularly fussy beast, so it's sometimes necessary to pass other flags here if you're doing something sneaky. Some examples:

LOCAL_LDLIBS += -lcurses -lpthread
LOCAL_LDLIBS += -Wl,-z,origin

LOCAL_NO_MANIFEST

If your package doesn't have a manifest (AndroidManifest.xml), then set LOCAL_NO_MANIFEST:=true. The common resources package does this.

LOCAL_PACKAGE_NAME

LOCAL_PACKAGE_NAME is the name of an app. For example, Dialer, Contacts, etc. This will probably change or go away when we switch to an ant-based build system for the apps.

LOCAL_PATH

The directory your Android.mk file is in. You can set it by putting the following as the first line in your Android.mk:

LOCAL_PATH := $(my-dir)

The my-dir macro uses the MAKEFILE_LIST variable, so you must call it before you include any other makefiles. Also, consider that any subdirectories you inlcude might reset LOCAL_PATH, so do your own stuff before you include them. This also means that if you try to write several include lines that reference LOCAL_PATH, it won't work, because those included makefiles might reset LOCAL_PATH.

LOCAL_POST_PROCESS_COMMAND

For host executables, you can specify a command to run on the module after it's been linked. You might have to go through some contortions to get variables right because of early or late variable evaluation:

module := $(HOST_OUT_EXECUTABLES)/$(LOCAL_MODULE)
LOCAL_POST_PROCESS_COMMAND := /Developer/Tools/Rez -d __DARWIN__ -t APPL\
       -d __WXMAC__ -o $(module) Carbon.r

LOCAL_PREBUILT_EXECUTABLES

When including $(BUILD_PREBUILT) or $(BUILD_HOST_PREBUILT), set these to executables that you want copied. They're located automatically into the right bin directory.

LOCAL_PREBUILT_LIBS

When including $(BUILD_PREBUILT) or $(BUILD_HOST_PREBUILT), set these to libraries that you want copied. They're located automatically into the right lib directory.

LOCAL_SHARED_LIBRARIES

These are the libraries you directly link against. You don't need to pass transitively included libraries. Specify the name without the suffix:

LOCAL_SHARED_LIBRARIES := \
    libutils \
    libui \
    libaudio \
    libexpat \
    libsgl

LOCAL_SRC_FILES

The build system looks at LOCAL_SRC_FILES to know what source files to compile -- .cpp .c .y .l .java. For lex and yacc files, it knows how to correctly do the intermediate .h and .c/.cpp files automatically. If the files are in a subdirectory of the one containing the Android.mk, prefix them with the directory name:

LOCAL_SRC_FILES := \
    file1.cpp \
    dir/file2.cpp

LOCAL_STATIC_LIBRARIES

These are the static libraries that you want to include in your module. Mostly, we use shared libraries, but there are a couple of places, like executables in sbin and host executables where we use static libraries instead.

LOCAL_STATIC_LIBRARIES := \
    libutils \
    libtinyxml

LOCAL_MODULE

LOCAL_MODULE is the name of what's supposed to be generated from your Android.mk. For exmample, for libkjs, the LOCAL_MODULE is "libkjs" (the build system adds the appropriate suffix -- .so .dylib .dll). For app modules, use LOCAL_PACKAGE_NAME instead of LOCAL_MODULE. We're planning on switching to ant for the apps, so this might become moot.

LOCAL_MODULE_PATH

Instructs the build system to put the module somewhere other than what's normal for its type. If you override this, make sure you also set LOCAL_UNSTRIPPED_PATH if it's an executable or a shared library so the unstripped binary has somewhere to go. An error will occur if you forget to.

See Putting modules elsewhere for more.

LOCAL_UNSTRIPPED_PATH

Instructs the build system to put the unstripped version of the module somewhere other than what's normal for its type. Usually, you override this because you overrode LOCAL_MODULE_PATH for an executable or a shared library. If you overrode LOCAL_MODULE_PATH, but not LOCAL_UNSTRIPPED_PATH, an error will occur.

See Putting modules elsewhere for more.

LOCAL_WHOLE_STATIC_LIBRARIES

These are the static libraries that you want to include in your module without allowing the linker to remove dead code from them. This is mostly useful if you want to add a static library to a shared library and have the static library's content exposed from the shared library.

LOCAL_WHOLE_STATIC_LIBRARIES := \
    libsqlite3_android


LOCAL_YACCFLAGS

Any flags to pass to invocations of yacc for your module. A known limitation here is that the flags will be the same for all invocations of YACC for your module. This can be fixed. If you ever need it to be, just ask.

LOCAL_YACCFLAGS := -p kjsyy

Implementation Details

You should never have to touch anything in the config directory unless you're adding a new platform, new tools, or adding new features to the build system. In general, please consult with the build system owner(s) (android-build-team) before you go mucking around in here. That said, here are some notes on what's going on under the hood.

Environment Setup / buildspec.mk Versioning

In order to make easier for people when the build system changes, when it is necessary to make changes to buildspec.mk or to rerun the environment setup scripts, they contain a version number in the variable BUILD_ENV_SEQUENCE_NUMBER. If this variable does not match what the build system expects, it fails printing an error message explaining what happened. If you make a change that requires an update, you need to update two places so this message will be printed.

• In config/envsetup.make, increment the CORRECT_BUILD_ENV_SEQUENCE_NUMBER definition.
• In buildspec.mk.default, update the BUILD_ENV_SEQUENCE_DUMBER definition to match the one in config/envsetup.make

Additional makefile variables

You probably shouldn't use these variables. Please consult android-build-team before using them. These are mostly there for workarounds for other issues, or things that aren't completely done right.

LOCAL_ADDITIONAL_DEPENDENCIES

If your module needs to depend on anything else that isn't actually built in to it, you can add those make targets to LOCAL_ADDITIONAL_DEPENDENCIES. Usually this is a workaround for some other dependency that isn't created automatically.

LOCAL_BUILT_MODULE

When a module is built, the module is created in an intermediate directory then copied to its final location. LOCAL_BUILT_MODULE is the full path to the intermediate file. See LOCAL_INSTALLED_MODULE for the path to the final installed location of the module.

LOCAL_HOST

Set by the host_xxx.make includes to tell base_rules.make and the other includes that we're building for the host. Kenneth did this as part of openbinder, and I would like to clean it up so the rules, includes and definitions aren't duplicated for host and target.

LOCAL_INSTALLED_MODULE

The fully qualified path name of the final location of the module. See LOCAL_BUILT_MODULE for the location of the intermediate file that the make rules should actually be constructing.

LOCAL_REPLACE_VARS

Used in some stuff remaining from the openbinder for building scripts with particular values set,

LOCAL_SCRIPTS

Used in some stuff remaining from the openbinder build system that we might find handy some day.

LOCAL_MODULE_CLASS

Which kind of module this is. This variable is used to construct other variable names used to locate the modules. See base_rules.make and envsetup.make.

LOCAL_MODULE_NAME

Set to the leaf name of the LOCAL_BUILT_MODULE. I'm not sure, but it looks like it's just used in the WHO_AM_I variable to identify in the pretty printing what's being built.

LOCAL_MODULE_SUFFIX

The suffix that will be appended to LOCAL_MODULE to form LOCAL_MODULE_NAME. For example, .so, .a, .dylib.

LOCAL_STRIP_MODULE

Calculated in base_rules.make to determine if this module should actually be stripped or not, based on whether LOCAL_STRIPPABLE_MODULE is set, and whether the combo is configured to ever strip modules. With Iliyan's stripping tool, this might change.

LOCAL_STRIPPABLE_MODULE

Set by the include makefiles if that type of module is strippable. Executables and shared libraries are.

LOCAL_SYSTEM_SHARED_LIBRARIES

Used while building the base libraries: libc, libm, libdl. Usually it should be set to "none," as it is in $(CLEAR_VARS). When building these libraries, it's set to the ones they link against. For example, libc, libstdc++ and libdl don't link against anything, and libm links against libc. Normally, when the value is none, these libraries are automatically linked in to executables and libraries, so you don't need to specify them manually.

当你创建工程时，系统帮助生成一个原始的 manifest文件。对于只包含一个 activity的简单的应用程序，原始的 manifest文件够了，或者只需要很小的改动。另外， manifest也可以很复杂，比如 Android自带的 API样例，该文件就超过 1000多行。你的应用程序的 manifest行数大概也就介于此间吧。

manifest文件的大部分有趣的功能会在以后相应的章节更加详细的介绍。比如 service元素会在创建 service章节详细讲述。现在，主要关注 manifest文件的作用和它的一般结构。

在文件开始，有根，文件基本上就正确

manifest文件的根是这样一个 manifest元素：

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.commonsware.android.search">
      ...
</manifest>

注意命名空间声明。奇怪的是，自动生成的 manifest文件，命名空间是应用在属性上，而不是元素上（例如，是 manifest，不是 android:manifest），然而，这种形式工作正确，只要 android不发生改变，就坚持用这种形式。

根元素 manifest里面最有用的信息是 package属性（奇怪的是 package前没有命名空间）。这里，你可填成你的 java package的名子，以后在 manifest文件里，如果需要类的名子，就可以用点来代替 package的名子，例如：如果在 manifest文件需要引用 com.commonsware.android.search.Snicklefritz，你就可以写成 .Snicklefitz，因为 com.commonsware.android.search已经被定义成应用程序的包。

权限，特殊工具，和应用程序

在 manifest元素里有如下子元素：

l  uses-permission元素，表示应用程序必须据有这些权限才能工作正常－ permissions章节

l  permission元素，定义一些权限，当其它的程序如果想使用你的程序的数据或者逻辑时，必须据有这些权限，参考 permissions章节

l  instrumentation元素，表示某些代码，当一些重要的系统事件发生时，这些代码被调用，例如：启动一个 activities，打印 log或者监视某些信息。

l  uses-library元素，挂钩（ hook）进可选的 android组件里，例如 mapping services。

l  application元素，定义 manifest描述的应用程序的细节。

在上面的例子中， uses-permission元素表明了应用程序将要使用的一些设备的功能，在这个例子中，就是程序据有了定位自己的功能。 applicaton元素描述了一些 activities， serives和其它组成应用的一些组件。

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.commonsware.android">
    <uses-permission
         android:name="android.permission.ACCESS_LOCATION" />
    <uses-permission
         android:name="android.permission.ACCESS_GPS" />
    <uses-permission
         android:name="android.permission.ACCESS_ASSISTED_GPS" />
    <uses-permission
          android:name="android.permission.ACCESS_CELL_ID" />
    <application>
         ...
    </application>
</manifest>

应用程序需要实现一些功能，对吗？

manifest文件最重要的部分就是 application元素的子元素。

创建新工程时，默认生成只含一个 activity元素的 manifest文件，如下：

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.commonsware.android.skeleton">
     <application>
             <activity android:name=".Now" android:label="Now">
                  <intent-filter>
                     <action android:name="android.intent.action.MAIN" />
                      <category android:name="android.intent.category.LAUNCHER" />
                  </intent-filter>
            </activity>
       </application>
</manifest>

这个 activity元素提供了如下信息， android:name－实现 activity的类；和 android:label－当运行 activity时显示的名字； intent-filter子元素－描述在什么条件下 activity才显示。这个 activity元素设置在运行时显示这个 activity，现在你可以运行它了。在后面的章节，会看到有多个 activities的工程。

可能还会有一个或者多个 receiver元素，表示在一定条件下，一些非 activites组件需要被触发，例如收到一条短信。这被称作是 intent receivers，在后续章节会讲到。

可能还会有一个或者多个 provider元素，表示 content providers组件，它们负责提供数据给 activities使用，并且，如果有权限，其它应用程序也可以使用它们提供的数据。它们把数据库或者其它数据存储包装成一个接口 供其它应用程序使用。后续章节会讲怎么创建 content provides和如何使用 content provides。

最后，可能会有一个或者多个 service元素，描述 services－独立于 activity，并且长期运行的一些代码片段。最好的例子就是 mp3播放器，你想边听音乐，边打开其它 activities，这时候 mp3播放器的使用界面被覆盖。后面有两章会讲如何创建和使用 services。