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A Beginner's Guide to Gambas Cover design by Fabien Bodard Foreword by Fabien B

A Beginner's Guide to Gambas Cover design by Fabien Bodard Foreword by Fabien Bodard and Benoît Minisini 1 A Beginner's Guide to Gambas Copyright Notice for the printed version of this work: A Beginner's Guide to Gambas (this work) is copyright © 2005 by John W. Rittinghouse, all rights are reserved. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the the author, John W. Rittinghouse. 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IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MIRROR AND/OR REDISTRIBUTE THE OC AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE OC, EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. 3 A Beginner's Guide to Gambas Table of Contents Acknowledgments........................................................................16 Foreword.......................................................................................17 Chapter 1 Introducing Gambas.................................................19 Gambas Architecture......................................................19 The Gambas Programming Environment......................22 Gambas IDE Components.................................................25 Chapter 2 – Gambas Language Concepts.................................30 Gambas Variables, Datatypes and Constants.............30 Variable Assignment..........................................................35 Assignment Using The WITH Statement...........................35 Operators and Expressions............................................36 Comparison operators ......................................................36 Arithmetic Operators..........................................................36 Let's Start Coding Gambas................................................37 END, RETURN and QUIT Statements.......................................37 String Operators................................................................44 Chapter 3 Keywords and Program Flow Control....................46 The PRINT Statement.......................................................46 The IF Statement...............................................................47 The SELECT / CASE Statement.......................................48 GOTO and LABELS..........................................................49 The FOR / NEXT Statement..............................................49 DO [WHILE] LOOP............................................................51 WHILE [Expression] WEND Loops ...................................52 The REPEAT UNTIL loop .................................................53 Defining and Using Arrays in Gambas..........................53 Collections.......................................................................55 The FOR EACH Statement...............................................55 Chapter 4 – Introducing the Gambas ToolBox..........................57 The Button Control..........................................................61 Common Control Properties..............................................62 Button Methods.................................................................70 4 A Beginner's Guide to Gambas Button Events....................................................................78 The Picture Class............................................................78 Chapter 5 – Controls for Gathering Input...................................80 TextLabel..........................................................................82 TextBox............................................................................83 ComboBox........................................................................85 ListBox.............................................................................89 Frame................................................................................92 ToggleButton...................................................................93 Checkbox.........................................................................93 Panel.................................................................................95 RadioButton.....................................................................95 Chapter 6 – Menus, Modules, Dialogs and Message Boxes.....97 The Gambas Menu Editor...............................................98 Building Menus..............................................................101 Dialogs............................................................................103 Modules..........................................................................105 MessageBoxes...............................................................112 Information Messages.....................................................112 Query/Confirm Messages................................................114 Error Messages...............................................................115 Warning or Alert Messages.............................................115 Delete Messages.............................................................116 Dialog Class Filerelated Functions.............................117 Dialog OpenFile Function................................................117 Dialog SaveFile Function.................................................118 Dialog SelectDirectory Function......................................119 Complete Example Listing............................................120 Module1.module listing.................................................123 Chapter 7 – Handling Strings and Converting Datatypes.....125 String Functions............................................................125 Len...................................................................................126 5 A Beginner's Guide to Gambas Upper$/Ucase$/Ucase and Lower$/Lcase$/Lcase ........126 Trim$, LTrim$, and RTrim$..............................................127 Left$, Mid$, and Right$ ..................................................128 Space$............................................................................130 Replace$ ........................................................................130 String$ ............................................................................131 Subst$ ............................................................................131 InStr.................................................................................132 RInStr..............................................................................134 Split..................................................................................134 Converting Datatypes..................................................135 Asc and Chr$ ..................................................................135 Bin$.................................................................................136 CBool ..............................................................................137 CByte...............................................................................138 CDate..............................................................................138 CFloat..............................................................................139 CInt / Cinteger and CShort .............................................140 CStr / CString .................................................................140 Hex$................................................................................141 Conv$ .............................................................................141 Val and Str$ ....................................................................142 Str$ .................................................................................142 Format$...........................................................................145 Datatype management .................................................147 TypeOf.............................................................................148 Chapter 8 – Using Advanced Controls.....................................149 IconView Control...........................................................149 ListView Control............................................................158 Using the Gambas Icon Edit Tool................................162 The TreeView Control....................................................163 The GridView Control....................................................171 The ColumnView Control..............................................174 Layout Controls – HBox, VBox, HPanel and Vpanel. .176 HBox and VBox...............................................................177 HPanel and Vpanel..........................................................177 6 A Beginner's Guide to Gambas The TabStrip Control.....................................................181 Chapter 9 – Working with Files.................................................188 Access............................................................................188 Dir....................................................................................189 Eof...................................................................................190 Exist................................................................................190 IsDir / Dir? .....................................................................191 Stat .................................................................................191 Temp / Temp$ ...............................................................192 OPEN and CLOSE..........................................................192 LINE INPUT.....................................................................193 READ, SEEK, WRITE and FLUSH.................................194 COPY, KILL and RENAME.............................................195 MKDIR, RMDIR...............................................................196 Chapter 10 – Math Operations..................................................215 Precedence of Operations............................................215 Abs..................................................................................216 Acs / ACos......................................................................216 Acsh / ACosh.................................................................217 Asn / ASin.......................................................................217 Asnh / ASinh..................................................................218 Atn / ATan.......................................................................218 Atnh / ATanh..................................................................219 Cos..................................................................................219 Cosh................................................................................220 Deg and Rad...................................................................221 Exp..................................................................................221 Fix and Frac...................................................................222 Int....................................................................................223 Log..................................................................................223 Log10..............................................................................224 7 A Beginner's Guide to Gambas Max and Min...................................................................224 Pi.....................................................................................225 Randomize and Rnd......................................................225 Round.............................................................................227 Sgn..................................................................................227 Sin...................................................................................228 Sinh.................................................................................229 Sqr...................................................................................229 Tan..................................................................................230 Tanh................................................................................231 Derived Math Functions................................................231 Chapter 11 – ObjectOriented Concepts..................................237 Fundamentals of Object Oriented Programming........238 Objects............................................................................239 Data Abstraction..............................................................239 Encapsulation..................................................................240 Polymorphism..................................................................240 Inheritance.......................................................................240 The Gambas Approach to OOP....................................241 Gambas Classes.............................................................241 Sample program: Contacts...........................................242 The Contact class............................................................242 Contact.GetData Method.................................................243 Contact.PutData Method.................................................246 Form1.class file...............................................................247 Form1 Constructor...........................................................249 Form_Open Subroutine...................................................250 Adding Controls to Form1.Form......................................250 The ToolButtons.......................................................................251 The Quit Button.........................................................................251 Adding the Labels and TextBoxes............................................252 UpdateForm() Subroutine................................................253 Coding Toolbuttons: First, Prev, Next, and Last.......................254 Coding ToolButtons: Adding a record.......................................256 Coding ToolButtons: Clearing data...........................................258 Validating User Input.......................................................258 8 A Beginner's Guide to Gambas Adding a Search Feature.................................................260 The DoFind Subroutine.............................................................262 ToolButtons again: Updating a Record............................263 Toolbuttons again: Deleting a Record.............................264 ToolButtons again: Saving Data......................................265 Creating a Standalone Executable..............................266 Chapter 12 – Learning to Draw.................................................267 Draw Properties.............................................................267 BackColor/Background and ForeColor/Foreground........267 Clip..................................................................................268 FillColor,FillStyle,FillX,FillY..............................................268 Font.................................................................................269 Invert................................................................................269 LineStyle/LineWidth.........................................................270 Transparent.....................................................................270 Draw Methods................................................................270 Text/TextHeight/TextWidth..............................................272 Draw Primitives: Point/Rect/Ellipse/Line..........................274 Draw Primitives: Polygon and Polyline............................280 Image/Picture/Tile............................................................284 Drawing with a Drawing object........................................292 Chapter 13 – Error Management...............................................298 General uploads/Litterature/ gambas-guide.pdf