Delphi - object pascal IDE

• Delphi Basics by Neil Moffatt
• Earl F. Glynn Computer Lab
• Merlyn Home Page. Site © J R Stockton 2005;
• Delphi For Fun byGary Darby
• VCL doc
• acces to pixels in Delphi

Tips for beginners in Pascal/Delphi programming:


• IMHO it is good practice to make the directory for each program and to keep all the units, drivers or libraries in that directory.
• use "program Manager" to check if all files of the project are in the same directory.
• to add new unit to program save it in program directory, add to project ( use main menu ) , open unit which must use new unit and then click main menu/File/use Unit.
• Delphi program ( project) consists of more then one files, so use "close all", "save all" "open project"
• " I can't create output file". Maybe you run program from cd (it is a read only (:-)) or maybe you have copied files fromcd. Check file properities, remove "read only"
• ~ = Alt+126
• pascal likes US keyboard ( type: "keyb us" in dos
• when You try to run programs from efg, sometimes errors occurs due to diffrent decimal character, so change temporaly your windows settings for decimal character ( efg likes dot for it) and then run the program.
• Delphi is not a language but IDE. So I'm programing in object Pascal for Windows using Borland Delphi IDE.
• Delphi Form = window
• Delphi project = program
• use program specification because there are meny programming languages, OS and so on.
• divide a problem into a single pieces. Solve one problem in one step ( simple program for solving only this problem). Check the solution. Appplay it to the bigger program
• turn off integrated dubugging / OS exception/ Debugger Options/ tools/Main Menu / Delphi 7.o PE
• "You should consider optimizing your program only after you have a working version and only if that version is too slow." from Laboratory in Software Engineering Spring 2003 MIT
• "Runtime error 216 " - maybe you use object not initialized . Use create as in example :
  zPlane:=TPlane.Create;

Pascal compilers and IDE:
• for Microsoft windows
  • Delphi 7.0 personal edition. (dcc (Borland Delphi Compiler)
  • Dev-Pascal
• for Microsoft DOS
  • Turbo Pascal from Borland (on one 1.44 disk with IDE)
  • Borland Pascal ( with IDE)
  • Free Pascal Compiler (without IDE)
• for Linux
  • Borland Kylix
  • Free Pascal Compiler (FPC)
  • Lazarus Pascal IDE for FPC
  • KDevelop

• pas2html by Primoz Gabrijelcic's
  pas2html pas_file html_file [Delphi version (numeric)]
  

• when :
  uses Graphics, windows;
  then you will get an error:
  [Error] Unit1.pas(155): Incompatible types: 'tagBITMAP' and 'TBitmap'
  ------------------
  solution ( I dont know why):
  uses windows, Graphics;
  
  ------------------
  Explanations :
  "Są 2 typy TBitamp :
  Windows.TBitmap
  Graphics.TBitmap.
  To który jest 'aktywnym" typem zależy od kolejności unitów Windows i Graphics w sekcji "uses".
  Typ Windows.TBitmap to THandle, który z kolei jest po prostu 32-bitowym intem." ( Arivald)
  
  Delphi Images by Robert Clemenzi

---

• How to display 2 bitmaps in one image ? - example program Directory with src code and exe-file



---



• How to display bitmap larger then image?
  
  • place a scrool Box on the form
  • place a image on the scroll box
  • procedure TForm1.FormCreate(Sender: TObject);
    begin
    Image1.Align:=alNone;
    Image1.AutoSize:=true;
    ScrollBox1.Align:=alClient;
    ScrollBox1.AutoSize:=False;
    end;

  ---

• How to open bitmap and display it in the image?
  
  • place a image on the form
  • place the OpenPictureDialog on the form
  • place the MainMenu on the form
  • create the MaineMenu item ( give the name in the Menu Designer)
  • procedure TForm1.openbmpfile1Click(Sender: TObject);
    var CurrentFile:string;
    begin
    if OpenPictureDialog1.Execute
    then begin
    CurrentFile := OpenPictureDialog1.FileName;
    Image1.Picture.LoadFromFile(CurrentFile);
    end;
    end;

---

• How to use radio group in dialog form?
  
  • create new form ( dialog form) here: OKBottomDlg
  • ( if exist delate bevel)
  • { probably add unit to program)
  • ad a new unit containing that dialog form to uses clauses of main unit( file/use unit)
  • place a radio group on the dialog form
  • create the MaineMenu item ( give the name in the Menu Designer)
  • procedure TForm1.transformations1Click(Sender: TObject);
    begin
    // display the dialog form
    OKBottomDlg.ShowModal;
    if OKBottomDlg.ModalResult=mrOk
    then // place the code here
    end;
    
  • add radio button to the radio group, using ObjectInspector ( click on Items to see the streing list editor)
  • //use radio button, procedure TOKBottomDlg.OKBtnClick(Sender: TObject);
    begin
    case OKBottomDlg.RadioGroup1.ItemIndex of
    // they are numbered from 0 0:;//place code here
    end;
    end;

---

• How to get the name (as a string) of enumerated type variable ?
  
  // add new unit to uses
  uses TypInfo;// getEnumName;
  // definition of enumerated type
  TFunctionType=(TrueColor=0,GrayScale,direct,BlackAndW);
  //declaration of variable
  var FunctionType:TFunctionType;
  str:string;
  // usage
  str:=getEnumName(typeInfo(TFunctionType),Ord(FunctionType) );
  

---

• How to make a link to www page in delphi
  thx to "Johans" johans2@o2.pl
  uses shellapi;
  Put label1 on a form
  In onClick of Label1 write:
  ShellExecute(Handle, 'open','http://ardes url' , nil, nil, SW_SHOWNORMAL);
  
  In onMouseEnter of label1
  label1.Cursor:=crHandPoint;
  label1.font.Color:=clBlue;
  
  In onMouseLeave of label1 write
  label1.Font.Color:=clBlack;
  

---

• // Define 256 shades of gray pf8it palette
  var NewPalette: TMaxLogPalette;
  //
  
  //in the body of procedure write:
  NewPalette.palVersion := $0300; // "Magic Number" for Windows LogPalette
  NewPalette.palNumEntries := 256;
  //
  FOR i := 0 TO 255 DO
  BEGIN
  NewPalette.palPalEntry[i].peRed := i;
  NewPalette.palPalEntry[i].peGreen := i;
  NewPalette.palPalEntry[i].peBlue := i;
  NewPalette.palPalEntry[i].peFlags := PC_NOCOLLAPSE;
  END;
  //
  Bitmapa.Palette := CreatePalette(pLogPalette(@NewPalette)^);
  

---

• How to count time of execution of procedure:
  
  uses windows; // GetTickCount
  var start, time:integer
  
  begin
  // start counting
  start:=GetTickCount;
  
  // here is place for time consuming code
  
  //stop counting and compute time of execution of procedure
  Time:=GetTickCount-Start;
  // display time
  Form1.Caption:=FloatToStrF(time,ffNumber,10,0);
  end;
  

---

• Dynamic arrays
  All dynamic arrays starts at index = 0. (from  delphibasics by Neil Moffatt )
  
  use:
  type TPrimeFactors= Array of integer;
  var PrimeFactors: TPrimeFactors;
  // if you want to set length of dynamic array inside the procedure:
  procedure FindPrimeFactors(var _PrimeFactors: TPrimeFactors);
  begin
  SetLength(_PrimeFactors,20);
  ...

---

• Strings and arrays
  Strings are indexed with 1 for the first character
  index of dynamic array starts form 0
  

Feel free to e-mail me!

Author: Adam Majewski   adammaj1-at-o2-dot-pl

http://republika.pl/fraktal/