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112 changes: 112 additions & 0 deletions doc/Collaborating with Git.md
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# Collaborating with Git

## Basic
If you are new to Git, following are some of the resources you might find useful:
* [GitHub's blog post][https://github.com/blog/120-new-to-git]
* http://try.github.com/
* http://sixrevisions.com/resources/git-tutorials-beginners/
* http://rogerdudler.github.io/git-guide/

## Get latest code from the KOReader repository
First you need to add the official repo to your remote repo list:
```bash
git remote add upstream git@github.com:koreader/koreader.git
```

For koreader-base that is:
```bash
git remote add upstream git@github.com:koreader/koreader-base.git
```

You can verify the remote repo is successfully added by using:
```bash
git remote -v show
```

Now you can pull the latest development code:
```bash
git pull upstream master
```

If you've made some local changes, you'll often want to rebase your local commits on top of the most recent upstream:
```bash
git pull -r upstream master
```
You might want to test that in a new branch first.

## Get latest patches from other developer's branch
First you need to add his/her own repo to your remote repo list:
```bash
git remote add NAME REPO_ADDR
```
Where `NAME` is the alias name you want to give for the remote repo, for example:
```bash
git remote add dpavlin git://github.com/dpavlin/kindlepdfviewer.git
```

You can verify the remote repo is successfully added by using:
```bash
git remote -v show
```

Now you can merge their branch to your local branch. But before you do this, I recommend you create a new branch first and do experimental stuff on top of the new branch so you won't mess with the master branch:
```
git checkout -b NEW_TEST_BRANCH_NAME
git pull dpavlin REMOTE_BRANCH_NAME
```

## Submitting code change
How to submit my change on top of current development (which is master branch at origin).

This assumes that your repository clone have `origin` which points to upstream official repository as shown below. If you did checkout from your forked copy, and origin points to your local fork, you can always add another remote and replace `origin` in this instructions with another remote name.

```
dpavlin$ git remote -v | grep origin
origin git@github.com:koreader/koreader.git (fetch)
origin git@github.com:koreader/koreader.git (push)
dpavlin$ git fetch origin
dpavlin$ git checkout -b issue-235-toc-position origin/master
M djvulibre
M kpvcrlib/crengine
M mupdf
Branch issue-235-toc-position set up to track remote branch master from origin.
Switched to a new branch 'issue-235-toc-position'
```

integrate changes from this issue (or diff, patch, git cherry-pick sha-commit)

```
dpavlin$ git add -p unireader.lua
```
interactivly select just changes which are not whitespace

```
dpavlin$ git commit --author NuPogodi -m 'TOC position on current place in the tree #235'
[issue-235-toc-position 25edd31] TOC position on current place in the tree #235
Author: NuPogodi <surzh@mail.ru>
1 file changed, 9 insertions(+), 5 deletions(-)
dpavlin$ git show
```

verify that commit looks sane, if I wasn't happy I would do `git --commit --amend`

```
dpavlin$ git push dpavlin issue-235-toc-position
Counting objects: 5, done.
Delta compression using up to 2 threads.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 489 bytes, done.
Total 3 (delta 2), reused 0 (delta 0)
To git@github.com:dpavlin/koreader.git
* [new branch] issue-235-toc-position -> issue-235-toc-position
```

This assumes that your copy of github source is named `dpavlin` as here:

```
dpavlin$ git remote -v | grep dpavlin
dpavlin git@github.com:dpavlin/koreader.git (fetch)
dpavlin git@github.com:dpavlin/koreader.git (push)
```

Go to your github page and issue pull request
135 changes: 135 additions & 0 deletions doc/Development guide.md
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# Development Guide

The whole frontend part of KOReader is scripted in [Lua](http://www.lua.org/about.html) programming language which means you can start development with just a decent text editor. Instructions about how to get and compile the source of the backend part on a linux OS are [here](https://github.com/koreader/koreader#building-prerequisites)

The source tree of frontend looks like this:
```
frontend
├── apps
│ ├── filemanager
│ │ ├── filemanagerhistory.lua
│ │ ├── filemanager.lua
│ │ └── filemanagermenu.lua
│ └── reader *
│ ├── modules
│ │ ├── readeractivityindicator.lua
│ │ ├── readerbookmark.lua
│ │ ├── readerconfig.lua
│ │ ├── readercoptlistener.lua
│ │ ├── readercropping.lua
│ │ ├── readerdictionary.lua
│ │ ├── readerdogear.lua
│ │ ├── readerflipping.lua
│ │ ├── readerfont.lua
│ │ ├── readerfooter.lua
│ │ ├── readerfrontlight.lua
│ │ ├── readergoto.lua
│ │ ├── readerhighlight.lua
│ │ ├── readerhinting.lua
│ │ ├── readerhyphenation.lua
│ │ ├── readerkoptlistener.lua
│ │ ├── readerlink.lua
│ │ ├── readermenu.lua
│ │ ├── readerpaging.lua
│ │ ├── readerpanning.lua
│ │ ├── readerrolling.lua
│ │ ├── readerrotation.lua
│ │ ├── readerscreenshot.lua
│ │ ├── readertoc.lua
│ │ ├── readertypeset.lua
│ │ ├── readerview.lua
│ │ └── readerzooming.lua
│ ├── pluginloader.lua
│ └── readerui.lua
├── cacheitem.lua
├── cache.lua
├── configurable.lua
├── dbg.lua
├── docsettings.lua
├── document *
│ ├── credocument.lua
│ ├── djvudocument.lua
│ ├── document.lua
│ ├── documentregistry.lua
│ ├── koptinterface.lua
│ ├── pdfdocument.lua
│ ├── picdocument.lua
│ └── tilecacheitem.lua
├── gettext.lua
├── JSON.lua
├── optmath.lua
└── ui
├── data
│ ├── creoptions.lua
│ ├── koptoptions.lua
│ └── strings.lua
├── device
│ ├── basepowerd.lua
│ ├── kindlepowerd.lua
│ ├── kobopowerd.lua
│ └── screen.lua
├── device.lua
├── event.lua
├── font.lua
├── geometry.lua
├── gesturedetector.lua
├── gesturerange.lua
├── input.lua
├── language.lua
├── rendertext.lua
├── screen.lua
├── timeval.lua
├── uimanager.lua
└── widget *
├── bboxwidget.lua
├── buttondialog.lua
├── button.lua
├── buttontable.lua
├── closebutton.lua
├── configdialog.lua
├── confirmbox.lua
├── container
│ ├── bottomcontainer.lua
│ ├── centercontainer.lua
│ ├── framecontainer.lua
│ ├── inputcontainer.lua
│ ├── leftcontainer.lua
│ ├── rightcontainer.lua
│ ├── underlinecontainer.lua
│ └── widgetcontainer.lua
├── dictquicklookup.lua
├── eventlistener.lua
├── filechooser.lua
├── fixedtextwidget.lua
├── focusmanager.lua
├── horizontalgroup.lua
├── horizontalspan.lua
├── iconbutton.lua
├── imagewidget.lua
├── infomessage.lua
├── inputdialog.lua
├── inputtext.lua
├── linewidget.lua
├── menu.lua
├── notification.lua
├── overlapgroup.lua
├── progresswidget.lua
├── rectspan.lua
├── scrolltextwidget.lua
├── textboxwidget.lua
├── textwidget.lua
├── toggleswitch.lua
├── touchmenu.lua
├── verticalgroup.lua
├── verticalscrollbar.lua
├── verticalspan.lua
├── virtualkeyboard.lua
└── widget.lua
```
in which you will find the asterisked `frontend/document`, `frontend/apps/reader` and `frontend/ui/widget` the most interesting parts.

### document: API for document parsing and rendering

### reader: reader functionality implementation

### widget: a light-weight widget toolkit
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Expand Up @@ -11,6 +11,7 @@ to a widget, you can simply invoke the handleEvent method like the following:
widget_foo:handleEvent(Event:new("Timeout"))
```

Events are passed to child Widgets (or child containers) before their own handler sees them. See the implementation of WidgetContainer:handleEvent(). So a child widget, for instance a text input widget, gets the input events before the layout manager. The child widgets can "consume" an event by returning `true` from the event handler. Thus a text input widget just implements an input handler and consumes left/right presses, returning `true` in those cases. It can even make its return code dependent on whether the cursor is on the last position (do not consume press to right) or first position (do not consume press to left) to have proper focus movement in those cases.

## Builtin events ##

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return self["on"..event.name](self, unpack(event.args))
```

## Event system
Event system is used for widgets to communicate with each others.

Each event is an object that has two properties: `args` and `handler`. `handler` is the name of function that will be called on receive. `args` is a table that contains all the arguments needed to be passed to the event handler. When a widget receives a event, it will first check to see if `self[event.handler]` exists. If yes, the `self[event.handler]` function will be called and the return value of the handler will be returned to UIManager.

Notice that if you don't want the event propagate after consumed in your handler, your handler must return `true`. Otherwise, the event will be passed to other widgets' handlers until one of the handlers returns `true`.

`WidgetContainer` is a special kind of widget. When it receives an event, it will first propagate the event to all its children. If the event is still not consumed (handler returns `true`), then it will try to handle by itself.

When you call `UIManager:show` on an widget, this widget will be added to the top of `UIManager._window_stack`.
Events are sent to the first widget in `UIManager._window_stack`. If it is not consumed, then UIManager will try to send it to all active widgets (`widget.is_always_active` equals `true`) in the `_window_stack`.

## Draw Page Code Path
* **in readerview.lua:** ReaderView widget flag itself dirty in `ReaderView:recalculate`
* **in ui.lua:** UI main loop calls `ReaderView:paintTo`
* **in readerview.lua:** `ReaderView:paintTo` calls `document:drawPage`
* **in document.lua:** `document:drawPage` check for cache, if found, **return cache**
* **in document.lua:** if cache not found, `document:drawPage` calls `document:renderPage`
* **in document.lua:** `document:renderPage` calls `_document:openPage`, `page:draw` and put the result into cache
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Hacking
=======

## How to Debug

We have a helper function called `logger.dbg` to help with debugging. You can use that function to print string and tables:

```lua
local logger = require("logger")
a = {"1", "2", "3"}
logger.dbg("table a: ", a)
```

Anything printed by `logger.dbg` starts with `DEBUG`.

```
04/06/17-21:44:53 DEBUG foo
```

## Bug hunting in kpv

A real example for hunting bug in KPV's cache system: https://github.com/koreader/kindlepdfviewer/pull/475


## Developing UI widgets ##

`tools/wbuilder.lua` is your friend, if you need to create new UI widgets. It
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# Porting

This page aims to provide guidance on how to port KOReader to other platforms.

There are mainly two modules that you need to take care of: input and output.
After you finish these two, KOReader should have no problem running on your
platform. Feel free to open issues in our issue tracker if you need further help on this topic :)


## Output Module

KOReader uses framebuffer to control EInk devices, so the output module here is
[base/ffi/framebuffer_einkfb.lua](https://github.com/koreader/koreader-base/blob/master/ffi/framebuffer_einkfb.lua).

Following are the framebuffers that `framebuffer_einkfb.lua` currently supports:
* 4BPP inverted framebuffer
* 16 scale 8BPP inverted framebuffer
* 16 scale 8BPP framebuffer

For 4BPP framebuffer, it means every pixel is represented with 4 bits, so we
have 2 pixels in 1 byte. So the color depth is 16. The inverted part means all
the bits are flipped in the framebuffer. For example, two pixels `[0x00, 0xf0]`
will be stored as `0xff0f` in framebuffer.

For 16 scale 8BPP framebuffer, it means each pixel is instead stored in 1 byte,
but the color depth is still 16 (4bits). Since 1 byte has 8 bits, so to fill
up the remaining space, the most significant 4 bits is a copy of the least
significant one. For example, pixel with grey scale 15 will be represented as
`0xffff`. If it's a inverted 16 scale 8BPP framebuffer, then all the bits are
flipped in the same way as 4BPP inverted framebuffer does.

If your device's framebuffer does not fit into any of the categories above,
then you need to add a new transformation function in `framebuffer_einkfb.lua`.

The `framebuffer_einkfb.lua` module works in following ways for non 4BPP framebuffers;
* a shadow buffer is created and structured as 4BPP inverted framebuffer.
* all updates on screen bitmap are temporally written into the shadow buffer.
* each time we want to reflect the updated bitmap on screen, we translate
the shadow buffer into a format that the real framebuffer understands and
write into the mapped memory region. (varies on devices)
* call ioctl system call to refresh EInk screen. (varies on devices)

KOReader will handle the 4BPP shadow buffer for you, all you need to do is to
teach `framebuffer_einkfb.lua` how to control the EInk screen and translate the 4BPP inverted
bitmap into the format that your framebuffer understands.

## Input Module

We have a `input.c` module in [koreader-base][kb-framework] that reads input
events from Linux's input system and pass to Lua frontend. Basically, you don't
need to change on that module because it should support most of the events.

For this part, the file you have to hack on is [`koreader/frontend/ui/input.lua`](https://github.com/koreader/koreader/blob/master/frontend/ui/input.lua).

Firstly, you need to tell which input device to open on KOReader start. All the
input devices are opened in `Input:init()` function.

Next, you might need to define `Input:eventAdjustHook()` function in
`Input:init()` method. We use this hook function to translates events into a
format that KOReader understands. You can look at the KindleTouch initialization code for real example.

For Kobo devices (Mini, Touch, Glo and Aura HD) the function `Input:eventAdjustHook()` was skipped and the functions `Input:init()` and `Input:handleTypeBTouchEv` were changed to allow the single touch protocol. For Kobo Aura with multitouch support an extra function `Input:handlePhoenixTouchEv` was added.

Linux supports two kinds of Multi-touch protocols:
* http://www.kernel.org/doc/Documentation/input/multi-touch-protocol.txt

Currently, KOReader supports gesture detection of protocol B, so if your device sends out
protocol A, you need to make a variant of function `Input:handleTouchEv()` (like `Input:handleTypeBTouchEv` and `Input:handlePhoenixTouchEv`) and simulate protocol B.
Also you are welcome to send a PR that adds protocol A support to KOReader.

More information on Linux's input system:
* http://www.kernel.org/doc/Documentation/input/event-codes.txt
* http://www.kernel.org/doc/Documentation/input/input.txt



[einkfb-c]:https://github.com/koreader/koreader-base/blob/master/einkfb.c
[kb-framework]:https://github.com/koreader/koreader-base
[inputev]:https://github.com/koreader/koreader/blob/master/frontend/ui/inputevent.lua

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