Added Using CMAKE Applications Module in Developer Guides

Revised and added Using CMAKE Applications Module as a part of Developer Guides.

Bug-AGL: [SPEC-3633]

Signed-off-by: Shankho Boron Ghosh <shankhoghosh123@gmail.com>
Change-Id: I2cf8e06d3f4c43e748476eaddcb950417f5f0eba

1 files changed, 152 insertions, 0 deletions

diff --git a/docs/3_Developer_Guides/5_Using_CMAKE_Applications_Module/5_Autobuild.md b/docs/3_Developer_Guides/5_Using_CMAKE_Applications_Module/5_Autobuild.md
new file mode 100644
index 0000000..c32a6da
--- /dev/null
+++ b/docs/3_Developer_Guides/5_Using_CMAKE_Applications_Module/5_Autobuild.md
@@ -0,0 +1,152 @@
+---
+title: Autobuild
+---
+
+Applications based on the AGL framework should have a
+full build and packaging solution that is independent of the
+[Yocto Project](https://www.yoctoproject.org) workflow.
+
+You can create a script named **autobuild** to control applications
+build operations.
+AGL provides a BitBake class file (`aglwgt.bbclass`) that calls the
+**autobuild** script for all operations.
+The class file is located at the top level of the application repository.
+
+You can write the **autobuild** script using any of the following languages:
+
+* Makefile
+* Bash
+* Python
+
+The script executes directly after applying a `chmod()` command.
+The caller, which can be the `aglwgt.bbclass`, a Jenkins job, or an actual person,
+must make the **autobuild** executable before calling it.
+To facilitate direct execution, you need to start the script with a
+[shebang](https://en.wikipedia.org/wiki/Shebang_(Unix)) sequence:
+
+* '#!/usr/bin/make -f' for Makefile format
+* '#!/usr/bin/bash' for Bash format
+
+The calling convention is similar to the convention used in `make`.
+To pass arguments, use environment variables.
+
+**NOTE:** For Bash, an evaluation of the arguments
+sets the environment variables correctly.
+
+The following format shows the generic call:
+
+```bash
+autobuild/agl/autobuild <command> [ARG1="value1" [ARG2="value2" ... ]]
+```
+
+The **autobuild** script can be invoked from any directory
+with all paths considered to be relative to the
+script's location.
+For makefile scripts, this is the usual behavior.
+For Bash scripts, a `cd $(dirname $0)` command must be run at
+the beginning of the script.
+
+At build time, the following calls must be made in the following order:
+
+1. Initialize the build environment (e.g if the application uses
+   `cmake` the configure step runs CMake).
+
+    ```bash
+    autobuild/agl/autobuild configure CONFIGURE_ARGS="..."
+    ```
+
+2. Build the application (i.e. compile, link binaries, assembles javascript,
+   and so forth).
+
+    ```bash
+    autobuild/agl/autobuild build BUILD_ARGS="...."
+    ```
+
+3. Create the widget package(s) in the specified destination path
+   prepared by the caller.
+
+    ```bash
+    autobuild/agl/autobuild package PACKAGE_ARGS="..." DEST=<path-for-resulting-wgt-files>
+    ```
+
+4. Create the test widget package(s) in the specified destination path
+   prepared by the caller.
+
+    ```bash
+    autobuild/agl/autobuild package-test PACKAGE_ARGS="..." DEST=<path-for-resulting-wgt-files>
+    ```
+
+5. Clean the built files by removing the result of the **autobuild** build.
+
+    ```bash
+    autobuild/agl/autobuild clean CLEAN_ARGS="..."
+    ```
+
+6. Clean everything by removing the result of the **autobuild** build
+   and the **autobuild** configure.
+
+    ```bash
+    autobuild/agl/autobuild distclean DISTCLEAN_ARGS="..."
+    ```
+
+## Integrating **autobuild** into the Yocto Project Workflow
+
+If you want to integrate the **autobuild** script into the Yocto Project
+workflow, you need to generate the script.
+To generate the script, use the `autobuild` target.
+
+The following commands create the **autobuild** script in the
+`autobuild/agl` directory:
+
+```bash
+mkdir -p build
+cd build
+cmake .. && make autobuild
+```
+
+## Available Targets
+
+Following are the targets available from the **autobuild** script:
+
+- **clean**: Removes all the object files and target results generated by Makefile.
+- **clean-{release,debug,coverage,test}**: Removes all the object files and target results generated by Makefile for the specified build type.
+- **clean-all**: Deletes the build directories for all build types.
+- **distclean**: Deletes the build directories for all build types.
+- **configure**: Generates the project Makefile from the `CMakeLists.txt` files for the release build type.
+- **configure-{release,debug,coverage,test}**: Generates the project Makefile from the `CMakeLists.txt` files for the specified build type.
+- **build**: Compiles all project targets for the release build type.
+- **build-{release,debug,coverage,test}**: Compiles all project targets for the specified build type.
+- **build-all**: Compiles all project targets for all specified build types.
+- **package**: Builds the widget (**wgt**) package for the release build type.
+- **package-{release,debug,coverage}**: Builds the widget (**wgt**) package for the specified build type.
+- **package-test**: Builds the test **wgt** package.
+- **package-all**: Builds the widget (**wgt**) packages for all build types.
+- **install**: Installs the project into your filesystem.
+
+Note that `aglwgt.bbclass` only will use the **package-{coverage,test}** targets (and thus the **build-{coverage,test}**, etc. targets) for service bindings by default, so **autobuild** scripts for  applications may omit support for those.
+
+Specifying the following variables lets you modify compilation behavior:
+
+- **CLEAN_ARGS**: Variable used at **clean** time.
+- **CONFIGURE_ARGS**: Variable used at **configure** time.
+- **BUILD_ARGS**: Variable used at **build** time.
+- **BUILD_DIR**: Build directory for release type build.
+  The default value is a "build" directory in the root of the project.
+- **BUILD_DIR_DEBUG**: Build directory for debug type build.
+  The default value is a "build-debug" directory in the root of the project.
+- **BUILD_DIR_TEST**: Build directory for test type build.
+  The default value is a "build-test" directory in the root of the project.
+- **BUILD_DIR_COVERAGE**: Build directory for coverage type build.
+  The default value is a "build-coverage" directory in the root of the project.
+- **DEST**: Directory in which to place the created ***wgt*** file(s).
+  The default directory is the build root directory.
+
+Note that the values of **BUILD_DIR_{DEBUG,TEST,COVERAGE}** are defined based on the value of **BUILD_DIR**, so this needs to be kept in mind if over-riding it and building those other widget types.
+
+When you provide a variable, use the CMake format (i.e.
+BUILD_ARGS="-DC_FLAGS='-g -O2'").
+Following is an example:
+
+```bash
+./autobuild/agl/autobuild package DEST=/tmp
+```