samples/BrowserPlugin/README

# Copyright (C) 2009 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.
#

##############################
######### CONTENTS ###########
A. INTRODUCTION
B. PLUGIN STRUCTURE
C. HOW TO DEPLOY
D. SUB-PLUGINS
    1. ANIMATION
    2. AUDIO
    3. BACKGROUND
    4. FORM
    5. PAINT


##############################
## (A) INTRODUCTION ##########

The sample plugin is intended to give plugin developers a point of reference to
see how an android browser plugin is created and how to use the available APIs.
A plugin is packaged like a standard apk and can be installed either via the 
market or adb.  The sample plugin attempts to exercise as many of the APIs as
possible but unfortunately not all are covered. 

Trying to have a single plugin demonstrate all possible API interactions on one
screen was not practical. On the other hand we also didn't want a separate
plugin for each interction, as that would result in many separate apk's that
would need to be maintained.  To solve this problem we developed the idea to use
"sub-plugins". With a sub-plugin only one specific feature of the plugin would
be active at a time, but they would all share as much common code as possible.
A detailed description of each sub-plugin and its function can be found in the
sub-plugins section.

##############################
## (B) PLUGIN STRUCTURE ######

The sample plugin is packaged as one plugin but contains many unique sub-plugins
(e.g. audio and paint).  The package consists of two pieces: (1) Java code
containing the config; (2) C++ shared library containing the brower/plugin
bindings and the sub-plugin classes.  

~~~~ (1) JAVA ~~~~~
Android.mk: specifies the name of the APK (SampleBrowserPlugin) as well as which
            shared libraries to include.

AndroidManifest.xml: similar to a standard android manifest file, except that it
                     must contain the "uses-permission" and "service"
                     elements that are plugin specific. The "service" element
                     contains sub-elements that describe the java component of
                     the service.

src/*: location of the java source files.  This contains the SamplePlugin.class
       which is the java component of our plugin.  The component must exist and
       implement the required interfaces, though simply returning null is valid.

res/*: location of the static resources (e.g. an icon for the plugin)

~~~~ (2) C++ ~~~~~
jni/Android.mk: specifies the build parameters for the shared library that is to
                be included with the apk. The library contains all the bindings
                between the plugin and the browser.

jni/main.*: this code is the binding point between the plugin and the browser.
            It supports all of the functions required for a standard netscape
            style plugin as well as all the android specific APIs. The initial
            starting point for the plugin is the NP_Initialize function. The
            NPP_New function is responsible for reading the input args and
            selecting the appropriate sub-plugin to instantiate. Most other
            functions either return fixed values or pass their inputs to the
            sub-plugin for processing.

jni/PluginObject.*: The pluginObject provides a convenient container in which to
                    store variables (the plugin's state).  This objects two main
                    responsibilities are (1) to construct and store the NPClass 
                    object (done using code provided by Apple) and (2) provide
                    the abstract class for the sub-plugin objects and a place to 
                    store the sub-plugin after it is instantiated.  

jni/*/*: Each of the sub-plugins has a folder that contains its class definition
         and logic. The sub-plugin receives events from the browser and it can
         also communicate with the browser using the netscape plugin functions
         as well as the specialized android interfaces.


##############################
## (C) HOW TO DEPLOY #########

To compile and install a plugin on a device/emulator simply...

1. run "make SampleBrowserPlugin" (compiles libsampleplugin.so and builds the apk)
2. the previous command produces an apk file so record its location
3. run "adb install [apk_file]" to install it on a device/emulator
4. the browser will auto recognize the plugin is available

Now that the plugin is installed you can manage it just like you would any other
application via Settings -> Applications -> Manage applications. To execute the
plugin you need to include an html snippet (similar to the one found below) in
a document that is accessible by the browser.  The mime-type cannot change but
you can change the width, height, and parameters.  The parameters are used to
notify the plugin which sub-plugin to execute and which drawing model to use.

<object type="application/x-testbrowserplugin" height=50 width=250>
    <param name="DrawingModel" value="Surface" />
    <param name="PluginType" value="Background" />
</object>


##############################
## (D) SUB-PLUGINS ###########

Each sub-plugin corresponds to exactly one plugin type and can support one or
more drawing models. In the subsections below there are descriptions of each of
the sub-plugins as well as the information required to create the html snippets. 

#######################
## (D1) ANIMATION #####

PLUGIN TYPE: Animation
DRAWING MODEL: Bitmap

This plugin draws a ball bouncing around the screen. If the plugin is not entirely
on the screen and it it touched, then it will attempt to center itself on screen.

#######################
## (D2) AUDIO #########

PLUGIN TYPE: Audio
DRAWING MODEL: Bitmap

This plugin plays a raw audio file located at /sdcard/sample.raw (need to supply
your own). It uses touch to trigger the play, pause, and stop buttons.

#######################
## (D3) BACKGROUND ####

PLUGIN TYPE: Background
DRAWING MODEL: Surface

This plugin has minimal visual components but mainly runs API tests in the 
background. The  plugin handles scaling its own bitmap on zoom which in this
case is a simple string of text. The output of this plugin is found in the logs
as it prints errors if it detects any API failures. Some of the API's tested are
timers, javascript access, and bitmap formatting.

#######################
## (D4) FORM ##########

PLUGIN TYPE: Form
DRAWING MODEL: Bitmap

This plugin mimics a simple username/password form. You can select a textbox by
either touching it or using the navigation keys.  Once selected the box will
highlight and the keyboard will appear. If the textbox selected is not fully
in view then the plugin will ensure it is centered on the screen.  

#######################
## (D5) PAINT #########

PLUGIN TYPE: Paint
DRAWING MODEL: Surface

This plugin provides a surface that the user can "paint" on.  The inputs method
can be toggled between mouse (dots) and touch (lines).  This plugin has a fixed
surface and allows the browser to scale the surface when zooming.