PyQGIS Programmer’s Guide: Extending Qgis 2.X with Python

Description

Welcome to the world of PyQGIS, the blending of Quantum GIS and Python to extend and enhance your open source GIS toolbox. With PyQGIS you can write scripts and plugins to implement new features and perform automated tasks. This book will guide you in getting started with PyQGIS. After a brief introduction to Python, you'll learn how to understand the QGIS Application Programmer Interface (API), write scripts, and build a plugin. This book is designed to allow you to work through the examples as you go along. At the end of each chapter you will find a set of exercises you can do to enhance your learning experience. The PyQGIS Programmer's Guide is compatible with the version 2.0 API released with QGIS 2.0. Both source code and data to accompany the book are available online. Contents......Page 3 Requirements......Page 11 Conventions Used in this Book......Page 12 Your First PyQGIS experiment......Page 13 Exercises......Page 16 Getting Help......Page 17 Data Structures......Page 18 Classes......Page 21 Strings, Ranges, and Other Handy Things......Page 25 Installing Packages......Page 29 Documenting Your Code......Page 30 Resources to Learn More......Page 32 Exercises......Page 33 Python......Page 35 IDE or Editor......Page 36 Qt/PyQt......Page 38 How Python and QGIS work together......Page 41 Core versus Contributed plugins......Page 42 Managing plugins......Page 43 Python Plugin Specifics......Page 46 Exercises......Page 47 A Simple Example......Page 49 Signals and Slots......Page 51 The Layout of QGIS and PyQt Documentation......Page 52 Choosing Between the Qt and PyQt Documentation......Page 57 Console Features and Options......Page 61 Using the Console Editor......Page 62 Loading a Vector Layer......Page 66 Exploring Vector Symbology......Page 68 Loading a Raster Layer......Page 70 Data Providers......Page 71 Exercises......Page 72 Standalone Scripts in the Console......Page 73 Running Scripts with Script Runner......Page 79 Exercises......Page 84 Loading Vector Layers......Page 85 Working with Databases......Page 89 Working with Symbology......Page 91 Selecting and Working with Features......Page 99 Editing Attributes......Page 101 Saving Images......Page 102 Getting QGIS Paths......Page 103 Messages and Feedback......Page 105 Creating a Map Tool......Page 109 Adding Existing Tools to a Custom Toolbar......Page 113 Accessing an Existing Plugin......Page 114 Setting Up a Repository......Page 115 Exercises......Page 117 The Imports......Page 119 The addOgrLayer and addGdalLayer Functions......Page 120 Using the addLayer Function......Page 122 Changing the Color and Transparency of a Vector Layer......Page 125 Exercises......Page 129 Python Plugin Architecture......Page 131 Creating a Simple Plugin......Page 134 Customizing the Icon......Page 139 Customizing the GUI......Page 141 Writing the Plugin Code......Page 144 One Last Tweak......Page 148 Exercises......Page 151 Creating a Development Workflow......Page 153 Choosing a Development Methodology......Page 154 Debugging......Page 157 Designing the Application......Page 161 Creating a Minimal PyQGIS Application......Page 163 Creating our Own Main Window class......Page 166 Adding Map Tools to the Application......Page 168 Summary......Page 172 Exercises: Python Basics......Page 173 Exercises: Using the Console......Page 174 Exercises: Running Scripts......Page 175 Exercises: Writing Plugins......Page 176 Exercises: Writing a Standalone Application......Page 177 Installing QGIS on Windows with OSGeo4W......Page 179 Installing QGIS on Linux......Page 180 Building QGIS......Page 181 wrapper.py......Page 183 WhereAmI Plugin......Page 185 Standalone Application......Page 188 Changes in __init__.py and metadata.txt......Page 191 SIP API Changes......Page 192 Index......Page 193