Vim and Linux C++ Development

My workday generally revolves around .Net and the Microsoft stack, so for a change I thought it would be interesting to do some development under Linux. Finding a suitable text editor was the first task, but it didn’t take me long to settle on Vim, an incredibly flexible and popular text editor, available for most platforms. This post looks at working with Vim for C++ development under Linux.

Vim is very customisable, and a lot of tweaks can be made in the per user Vim.rc file, usually found in your home directory, so let’s start there.

Vim.rc Tweaks

We can makes some tweaks to Vim.rc to make working with C++ a little more pleasant by dealing with indentation and tabs in a more sensible way.

Firstly, let’s set up the auto-indentation:

set autoindent
set cindent

I prefer Visual Studio style tab settings of a 4 stop width and converting to spaces:

set softtabstop=4 shiftwidth=4 expandtab

Navigation

Coming from a Visual Studio background, I’m used to working with a full IDE and all it brings, including file navigation through a tree menu as part of the editor.

Vim is a world apart from Visual Studio, so despite the Project type plugins available for Vim, I’m trying to stay away from GUI like treeviews. CTags builds a list of all symbols in your project to enable quick navigation to function definitions, calls, methods etc. Ubuntu 10.10 doesn’t seem to include it as part of a standard install, so start with:

sudo apt-get install ctags

Then run it against your code directory; using -R will run it recursively:

ctags -R *

Now you can use the following commands to leap around your source with glee:

Ctrl + ]Jump to selected symbol
Ctrl + OMove back in history
Ctrl + IMove forward in history

Note: in order for vim to find the tags file, it needs to be launched from the directory in which the file was generated.

Neat Commands

Learning Vim is almost like learning an instrument, commands can be combined in a way that makes text editing almost fun. There are a number of good introductions to Vim’s commands, but here are a few that I find to be particularly useful:

gg=GReindent entire file
w / bNext Word / Prev Word
^ / $Start / End of line
cwChange word
viwcSelect inner word, change
😡Save changes and quit
bn / bpNext buffer / Prev buffer
bdClose buffer

Down The Rabbit Hole

This barely scratches the surface of what you can do with Vim, I haven’t even looked at what you can do with buffers, tabs or any of the multitude of plugins.

So go get stuck in and see what works for you.

Getting Started with MythTV Plugin Development

I’m a big fan of MythTV, having used it for years as a very comprehensive media centre.

MythTV also provides an excellent extension framework, which is a good excuse as any to have a bash at some development under Linux for a change.

This post starts at the beginning: getting a hello world plugin compiled and running. This is based heavily on the HelloMyth page on the MythTV Wiki, with tweaks needed for a vanilla MythTV 0.23 installation under Ubuntu 10.10.

Prerequisites

Assuming that you have a working MythTV installation, you will also need the following packages:

sudo apt-get install libmyth-dev qt4-qmake build-essential ccache libqt4-dev libfreetype6-dev libmp3lame-dev libasound2-dev libjack-dev libraw1394-dev libiec61883-dev libavc1394-dev libxv-dev libxvmc-dev

Once those are installed, grab a copy of the standard MythTV plugins from the myth git repository; note that you’ll want to work with the branch of MythTV you have installed (unless you’re working with the trunk version).

git clone -b fixes/0.23 git://github.com/MythTV/mythtv.git

Generate a config file by running the configure script in the mythplugins directory (You may or may not need the prefix argument, this is based on an Ubuntu 10.10 install):

./configure –prefix=/usr

Code

In the mythplugins folder, create a mythhello folder and add the following file:

mythhello/mythhello.pro

TEMPLATE = subdirs

# Directories
SUBDIRS = mythhello

Now inside the mythhello folder, create another mythhello folder, and add the following files:

mythhello/mythhello/mythhello.pro

include ( ../../mythconfig.mak )
include ( ../../settings.pro )
include ( ../../programs-libs.pro )

QT += network sql xml
TEMPLATE = lib
CONFIG += plugin thread
TARGET = mythhello
target.path = $${LIBDIR}/mythtv/plugins
INSTALLS += target

uifiles.path = $${PREFIX}/share/mythtv/themes/default
uifiles.files = hello-ui.xml
installfiles.path = $${PREFIX}/share/mythtv
installfiles.files = hello-ui.xml

INSTALLS += uifiles

# Input
HEADERS += mythhello.h
SOURCES += main.cpp mythhello.cpp

macx {
    QMAKE_LFLAGS += -flat_namespace -undefined suppress
}

mythhello/mythhello/main.cpp (Entry point for the plugin)

// C++ headers
#include <unistd.h>

// QT headers
#include <QApplication>

// MythTV headers
#include <mythcontext.h>
#include <mythplugin.h>
#include <mythpluginapi.h>
#include <mythversion.h>
#include <mythmainwindow.h>

// MythHello headers
#include "mythhello.h"


using namespace std;

void runHello(void);
int  RunHello(void);

void setupKeys(void)
{
    REG_JUMP("MythHello", QT_TRANSLATE_NOOP("MythHello",
        "Sample plugin"), "", runHello);
}


int mythplugin_init(const char *libversion)
{
    if (!gContext->TestPopupVersion("mythhello",
        libversion,
                                    MYTH_BINARY_VERSION))
        return -1;
    setupKeys();
    return 0;
}

void runHello(void)
{
    RunHello();
}

int RunHello(void)
{
    MythScreenStack *mainStack = GetMythMainWindow()->GetMainStack();
   
    MythHello *mythhello = new MythHello(mainStack, "hello");
   
    if (mythhello->Create())
    {
        mainStack->AddScreen(mythhello);
        return 0;
    }
    else
    {
        delete mythhello;
        return -1;
    }
}

int mythplugin_run(void)
{
    return RunHello();
}

int mythplugin_config(void)
{
   
}

mythhello/mythhello/mythhello.h (Plugin header)

#ifndef MYTHHELLO_H
#define MYTHHELLO_H

// MythTV headers

#include <mythscreentype.h>
#include <mythuibutton.h>


/** \class MythHello
*  \brief Example plugin.  Shows how to use Text areas and buttons
*/

class MythHello : public MythScreenType
{
    Q_OBJECT
   
    public:
        MythHello(MythScreenStack *parent, QString name);
        bool Create(void);
        bool keyPressEvent(QKeyEvent *);
   
       
    private:
        MythUIText *m_titleText;
        MythUIText *m_outText;
        MythUIButton   *m_cancelButton;
        MythUIButton   *m_okButton;

    private slots:
        void ok_clicked(void);
        void cancel_clicked(void);
};

#endif /* MYTHHELLO_H */

mythhello/mythhello/mythhello.cpp (Main plugin body)

// POSIX headers
#include <unistd.h>

// MythTV headers
#include <mythuibutton.h>
#include <mythuitext.h>
#include <mythmainwindow.h>
#include <mythcontext.h>
#include <mythdirs.h>

// MythHello headers
#include "mythhello.h"

#define LOC      QString("MythHello: ")
#define LOC_WARN QString("MythHello, Warning: ")
#define LOC_ERR  QString("MythHello, Error: ")

/** \brief Creates a new MythHello Screen
*  \param parent Pointer to the screen stack
*  \param name The name of the window
*/

MythHello::MythHello(MythScreenStack *parent, QString name) :
    MythScreenType(parent, name),
    m_cancelButton(NULL)

{
    //example of how to find the configuration dir currently used.
    QString confdir = GetConfDir();
    VERBOSE(VB_IMPORTANT, LOC + "Conf dir:"  + confdir);
}

bool MythHello::Create(void)
{
    bool foundtheme = false;

    // Load the theme for this screen
    foundtheme = LoadWindowFromXML("hello-ui.xml", "hello", this);
   
    if (!foundtheme)
        return false;
   
    bool err = false;
    UIUtilE::Assign(this, m_titleText, "title", &err);
    UIUtilE::Assign(this, m_outText, "outtext", &err);
    UIUtilE::Assign(this, m_cancelButton, "cancel", &err);
    UIUtilE::Assign(this, m_okButton, "ok", &err);

    if (err)
    {
        VERBOSE(VB_IMPORTANT, "Cannot load screen 'hello'");
        return false;
    }
   

    BuildFocusList();
    SetFocusWidget(m_cancelButton);

    connect(m_okButton, SIGNAL(Clicked()), this, SLOT(ok_clicked()));
    connect(m_cancelButton, SIGNAL(Clicked()), this, SLOT(cancel_clicked()));

   
    return true;
}
bool MythHello::keyPressEvent(QKeyEvent *event)
{
    if (GetFocusWidget() && GetFocusWidget()->keyPressEvent(event))
        return true;
   
    bool handled = false;
    QStringList actions;
    handled = GetMythMainWindow()->TranslateKeyPress("Hello", event, actions);

    for (int i = 0; i < actions.size() && !handled; i++)
    {
        QString action = actions[i];
        handled = true;

        if (action == "ESCAPE")
            Close();
        else
            handled = false;
    }
   
    if (!handled && MythScreenType::keyPressEvent(event))
        handled = true;

    return handled;
}

void MythHello::ok_clicked(void)
{
    m_outText->SetText(QString("OK clicked"));
}

void MythHello::cancel_clicked(void)
{
    m_outText->SetText(QString("Cancel clicked"));
}

mythhello/mythhello/hello-ui.xml (Plugin UI definition)

<?xml version="1.0" encoding="utf-8"?>
<mythuitheme>
    <window name="hello">
        <textarea name="title">
            <area>0,10,800,100</area>
            <font>large</font>
            <align>allcenter</align>
            <multiline>yes</multiline>
            <value>Hello World</value>
        </textarea>

        <textarea name="outtext">
            <area>0,300,800,100</area>
            <font>large</font>
            <align>allcenter</align>
            <multiline>yes</multiline>
        </textarea>

        <button name="cancel" from="basebutton">
            <position>500,400</position>
            <value>Cancel</value>
        </button>

        <button name="ok" from="basebutton">
            <position>200,400</position>
            <value>OK</value>
        </button>
    </window>
</mythuitheme>

Building

Change to mythplugins/mythhello and run the following:

qmake-qt4
make
sudo make install

Everything should be compiled and the plugin copied to /usr/lib/mythtv/plugins/.

To get the plugin to show up in the main menu edit /usr/share/mythtv/themes/defaultmenu/mainmenu.xml and add a new button entry:

<button>
   <type>HELLO_MYTH</type>
   <text>Hello Myth</text>
   <action>PLUGIN mythhello</action>
</button>

On starting mythfrontend at this point, the plugin should show up on the main menu.

Summary

At this point we have a working MythTV plugin which will serve as a good starting point for building further functionality.

Useful Links

MythTV Wiki HelloMyth Plugin
MythTV SVN