Development/Tutorials/Games/Palapeli Slicers

Creating a Palapeli pattern

Tutorial Series	Programming with the Palapeli API
Previous	Introduction to KDE4 programming
What's Next	n/a
Further Reading	Palapeli::Pattern, Palapeli::PatternConfiguration

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I'm currently creating this tutorial. You should not edit this page in the mean time. -- Majewsky 18:19, 20 July 2008 (CEST)
Warning to editors

Abstract

This tutorial shows you how to create a pattern for Palapeli, that is: a plugin for the Palapeli libraries that describes an algorithm to split an image into pieces.

The pattern we will be constructing is quite easy: It splits an image into two equally sized pieces.

Structure

A pattern plugin consists of two classes. The first one (derived from Palapeli::PatternConfiguration) tells Palapeli what features this pattern plugin has and which configuration values it needs. The second one (derived from Palapeli::Pattern) does the actual slicing.

The code: mypattern.h


ifndef MYPATTERN_H
define MYPATTERN_H

include <Palapeli/Pattern>
include <Palapeli/PatternConfiguration>

class MyPattern : public Palapeli::Pattern
{
	public:
		MyPattern();
		virtual ~MyPattern() {}
		virtual int estimatePieceCount() const;
	protected:
		virtual void doSlice(const QImage& image);
};
class MyPatternConfiguration : public Palapeli::PatternConfiguration
{
	public:
		MyPatternConfiguration(QObject* parent = 0, const QVariantList& args = QVariantList());
		virtual ~MyPatternConfiguration() {}
		virtual Palapeli::Pattern* createPattern() const;
};

endif // MYPATTERN_H

As described above, we have declared two classes deriving from the base classes Palapeli::Pattern and Palapeli::PatternConfiguration. For this simple example, we do only reimplement constructors, destructors and some pure virtual functions.

The code: mypattern.cpp


include "mypattern.h"

include <QImage>
include <KPluginFactory>
include <KPluginLoader>

K_PLUGIN_FACTORY(MyPatternFactory, registerPlugin<MyPatternConfiguration>();)
K_EXPORT_PLUGIN(MyPatternFactory("mypattern"))
MyPattern::MyPattern()
	: Palapeli::Pattern()
{
}
int MyPattern::estimatePieceCount() const
{

   return 2;

}
void MyPattern::doSlice(const QImage& image)
{

   //construct pixmaps for the pieces
   const int pieceWidth = image.width() / 2, pieceHeight = image.height();
   QImage leftPiece = image.copy(QRect(0, 0, pieceWidth, pieceHeight));
   QImage rightPiece = image.copy(QRect(pieceWidth, 0, pieceWidth, pieceHeight));
   //add pieces; define a neighborship relation between them
   addPiece(leftPiece, QRectF(0, 0, pieceWidth, pieceHeight));
   addPiece(rightPiece, QRectF(pieceWidth, 0, pieceWidth, pieceHeight));
   addRelation(0, 1, QPointF(pieceWidth, 0)); //0 and 1 are the consecutive indices of the pieces

}
MyPatternConfiguration::MyPatternConfiguration(QObject* parent, const QVariantList& args)

   : Palapeli::PatternConfiguration(parent, args)

{

   Q_UNUSED(parent)
   Q_UNUSED(args)
   setSizeDefinitionMode(Palapeli::PatternConfiguration::CustomSizeDefinition);

}
Palapeli::Pattern* MyPatternConfiguration::createPattern() const
{

   return new MyPattern;

}

We will start with the MyPatternConfiguration class, because this is the logical entry point. The pattern configuration class is created when Palapeli is started. It i

Integrate into Palapeli: mypattern.desktop

[Desktop Entry] X-KDE-Library=mypattern X-KDE-PluginInfo-Author=The best KDE hacker X-KDE-PluginInfo-Email=kdehacker@kde-hackers.example.org X-KDE-PluginInfo-Name=mypattern X-KDE-PluginInfo-Version=1.0 X-KDE-PluginInfo-Website=http://kde-hackers.example.org/palapelipatterns X-KDE-PluginInfo-Category= X-KDE-PluginInfo-Depends= X-KDE-PluginInfo-License=GPL X-KDE-PluginInfo-EnabledByDefault=true X-KDE-ParentApp=libpalapelipattern X-KDE-ServiceTypes=Palapeli/PatternPlugin Type=Service Icon=palapeli-pattern-mypattern PatternIdentifier=mypattern Name=My pattern Name[de]=Mein Schnittmuster Comment=The best pattern in the world Comment[de]=Das beste Schnittmuster auf der ganzen Welt

Build everything: CMakeLists.txt

project(mypattern)

find_package(KDE4 REQUIRED) find_package(Palapeli REQUIRED)

add_definitions(${QT_DEFINITIONS} ${KDE4_DEFINITIONS}) include_directories(${KDE4_INCLUDES} ${PALAPELI_INCLUDE_DIR})

set(mypattern_SRCS mypattern.cpp )

kde4_add_plugin(mypattern ${mypattern_SRCS}) target_link_libraries(mypattern ${KDE4_KDEUI_LIBS} palapelipattern)

install(TARGETS mypattern DESTINATION ${PLUGIN_INSTALL_DIR}) install(FILES mypattern.desktop DESTINATION ${SERVICES_INSTALL_DIR})