ROOT Tutorials - Session 5 1

ROOT Tutorials – Session 8

GUI, Signal/Slots, Image Processing, Carrot

Fons Rademakers

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GUI

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The ROOT GUI Classes

Originally based on the XClass’95 widget library from Hector Peraza A rich and complete set of widgets Uses only X11 and Xpm (no Motif, Xaw,

Xt, etc.) Object oriented class library, no wrapper

around a C library. Can be extended via inheritance

Small (12000 lines of C++) Win95 look and feel

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XClass’95 Integration in ROOT

All X11 calls abstracted via the TVirtualX abstract graphics interface

Use ROOT container classes, notably hash tables for fast lookup of frame and picture objects

Added TObject inheritance to the few base classes to get I/O and extended RTTI capabilities

Added many new widgets (now 35K lines)

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Available Widgets

Complete set of widgets: label, icon, button, check button, radio

button, picture button, button box, list box, combo box, list view, icon view, number entry, text entry, text view, text edit, tree view, tab view, scrollbar, slider, menubar, popup menu, cascading menu, statusbar, toolbar, message dialogs, file selection dialog, progress bars, tooltips, ...

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Creating a GUI The widgets are laid out in frames

TGFrame, TGCompositeFrame, TGMainFrame, TGTransientFrame, TGroupFrame

And arranged by layout managers TGHorizontalLayout, TGVerticalLayout,

TGRowLayout, TGListLayout, TGTileLayout, TGMatrixLayout, ...

Using a combination of layout hints TGLayoutHints (left, center x, right, top, center y,

bottom, expand x, expand y and fixed offsets) Event handling by messaging (as opposed to

callbacks). Like Win32. And by signals and slots. Like Qt.

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Basic Widgets

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Advanced Widgets

Color selector dialog: TGColorDialog

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GUI Examples –Histogram Browser

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More GUI Examples –Period System

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Signal and Slot Mechanism

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Signals and Slots

Integration of signal and slot mechanism into the ROOT core TQObject, TQConnection, TQClass, …

Signal and slots were pioneered by Trolltech in their Qt GUI toolkit

This mechanism facilitates component programming since it allows a total decoupling of the interacting classes

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Signals and Slots Example:Emitting a Signal

class A : public TQObject{

private:

Int_t fValue;

public:

A() { fValue = 0; }

Int_t GetValue() const { return fValue; }

void SetValue(Int_t); //*SIGNAL*

};

class A {

RQ_OBJECT(“A”)

private:

Int_t fValue;

public:

A() { fValue = 0; }

Int_t GetValue() const { return fValue; }

void SetValue(Int_t); //*SIGNAL*

};

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Signals and Slots Example:Emitting a Signal

void A::SetValue(Int_t v){ if (v != fValue) { fValue = v; Emit("SetValue(Int_t)", v); }}

void TGButton::Clicked(){ Emit(“Clicked()");}

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Signals and Slots Example:Connecting a Signal to a Slot

A *a = new A();

A *b = new A();

a->Connect("SetValue(Int_t)", "A", b, "SetValue(Int_t)");

a->SetValue(79);

b->GetValue(); // this is now 79

fButton->Connect("Clicked()", "MyFrame", this, "DoButton()");

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Signals and Slots

The ROOT signal and slot system uses the dictionary information and interpreter to connect signals to slots

Many different signals are emitted by: TVirtualPad (TCanvas and TPad) TSysEvtHandler (TTimer, TFileHandler) All GUI widgets

Let your classes emit signals whenever they change a significant state that others might be interested in

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Image Processing Classes

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Requirements

Developed by Reiner Rohlfs of ISDC User requirements coming from the

astrophysics community Main requirements:

Fast display Color editor Base class for astronomical display

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Example

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Zooming

Option:

always square pixels

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rotation by 90 °

vertical mirror

zoom smooth

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Basics

It is available since ROOT 3.03.08

The ROOT image class is build on top of a lower level C - library: libAfterImage (Sasha Vasko)

Read and write several image file formats (GIF ,TIFF, JPEG, ...) Zoom New: convert a 2 – D data array into color pixels

FOR MORE INFO...

http://afterstep.sourceforge.net/afterimage

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Class Hierarchy

TNamed

TImage

TASImage

TGMainFrame

TPaletteEditor

TASPaletteEditor

TImagePalette

TObject

TAttImage

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How to use TASImage

Build the libAfterImage library Download ftp://root.cern.ch/root/libAfterImage.tar.gz Create a shared library ( ${ROOTSYS}/lib )

There are two example macros: galaxy_image.C rose_image.C

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Foreseen Improvements

To simplify the build process of a libRootASImage.tar.gz

Interface TASimage to the 2 – D histogram classes

A text editor of the palette

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Carrot

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What is Carrot?

Carrot is a module for Apache web server which enables the use of C++ as an HTML-embedded scripting language as well as executing C++ macros. It is similar to PHP, in functionality:http://carrot.cern.ch/index_C.so?about