delphi l05 files and dialogs

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Intro to Event-driven Programming and Forms with Delphi@ZGTRShaker

2010, 2011, 2012

Intro to Event-driven Programming and Forms with Delphi

L05 – Files and Dialogs

Small Tip

• StrToFloat();

FloatToStr();

StrToInt();

IntToStr();

What’s for today?

• FILES Processing () • MediaPlayer• Dialogs:

– OpenDialog– SaveDialog– MsgDlg

Files

• “Pascal Code” file processing, like the following:– Assign > AssignFile– ReSet (Reading from “file”)– ReWrite (Writing to “file”)– Close > CloseFile

• File Handlers: Windows• File Streams: Look like “Binary File”s

File Processing - Input & Output routinesProcedures &

FunctionsDescription

Append Opens an existing text file for appending.AssignFile Assigns the name of an external file to a file variable.BlockRead Reads one or more records from an untyped file.BlockWrite Writes one or more records into an untyped file.

ChDir Changes the current directory.CloseFile Closes an open file.

Eof Returns the end-of-file status of a file.Eoln Returns the end-of-line status of a text file.Erase Erases an external file.

FilePos Returns the current file position of a typed or untyped file.FileSize Returns the current size of a file; not used for text files.

IOResult Returns an integer value that is the status of the last I/O function performed.

File Processing - Input & Output routinesProcedures &

FunctionsDescription

Read Reads one or more values from a file into one or more variables.Readln Does what Read does and then skips to beginning of next line in the

text file.Rename Renames an external file.Reset Opens an existing file.

Rewrite Creates and opens a new file.Seek Moves the current position of a typed or untyped file to a specified

component. Not used with text files.SeekEof Returns the end-of-file status of a text file.SeekEoln Returns the end-of-line status of a text file.Truncate Truncates a typed or untyped file at the current file position.

Write Writes one or more values to a file.Writeln Does the same as Write, and then writes an end-of-line marker to the

text file.

File Processing

• File Coping:

procedure TForm1.Button1Click(Sender: TObject);

begin

CopyFile('D:\Sour.jpg','D:\TempFolder\Dest.jpg',False);

end;

Source Destination “Boolean” indicate

that the source

file will

overwrite the

targeted file

“IF FOUND”

File Processing

• File Moving:

procedure TForm1.Button1Click(Sender: TObject);

begin

MoveFile('D:\Player\Sour.jpg','D:\Crier\Dest.jpg‘);

end;

Source Destination No “Boolean”

Indicator for

overwriting

File Processing

• File Moving:

procedure TForm1.Button1Click(Sender: TObject);

begin

MoveFile('D:\Player\Sour.jpg','D:\Crier\Dest.jpg‘);

end;

Note that: the “Source” file will be renamed to be the “Destination” file name in

Destination path. Watch out

The function “MoveFile” will fail if:

The “Source” file is not exist. The “Destination” file existed.

File Processing

• File Deleting:– Delete a “specific” file.

procedure TForm1.Button1Click(Sender: TObject);

begin

Delete('D:\Flier\Sour.jpg’);

end;

File Processing

• “2 Be Or Not 2 Be” Files Prop. (Boolean):– FileExists > Boolean

procedure TForm1.Button1Click(Sender: TObject);

begin

if (FileExists('D:\Dest.jpg')=true)then

Edit1.Text:='The file exists.'

else

Edit1.Text:='The file does not exist.';

end;

Watch out for “VAR” in the procedure’s header when calling a “file” as a “variables”.

File Processingtest is live!

File Features

• Types:– Text, Typed, UnTyped

• Text files:– opened with ReSet are read-only.– opened with ReWrite and Append are write-only.

• Typed & UnTyped files:– always allow both reading and writing, regardless whether they are

opened with ReSet or ReWrite.

File Features

• Caution:– The type “Text” is distinct from the typed file “ file of Char ”.

• Text files:– there are special forms of Read and Write that let you read and write

values that are not of type Char. Such values are automatically translated to and from their character representation. For example, Read(F, I), where I is a type Integer variable, reads a sequence of digits, interprets that sequence as a decimal integer, and stores it in I.

– “file of Char” don’t

– UnTyped files:• are low-level I/O channels used primarily for direct access to disk files

regardless of type and structuring. An UnTyped file is declared with the word file and nothing more.

// we declare the file like any other variables

Var FUnTyped:file; // UnTyped File

File features

• Types:– Text, Typed, UnTyped

// Text file declaration

Var FText: text;

Var FTyped: file of Real;

// Un Typed file declaration

Var FUnTyped: file;

Var FReal: file of Real;

// Typed file declaration

Var FRecd: file of Recd;

Var FInt: file of integer;

Var FTyped: file of Recd;

Var FTyped: file of integer;

Delphi code areaunit Unit1;

interface

uses

Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

Dialogs;

type

TForm1 = class(TForm)

private

{ Private declarations }

public

{ Public declarations }

end;

var

Form1: TForm1;

implementation

{$R *.dfm}

end.

Name of the “unit” we are working in

Here begins the “unit”

implementation

Public Variables

Types & classes

Libraries we can take functions &

procedures from it

File

• Files containing types:– Every file is a “linear sequence” of components, each of which has the

component type (or record type) of the file. – The components are numbered starting with zero.– Files are normally accessed sequentially. That is, when a component

is:• READ : using the standard procedure Read• WRITTEN : using the standard procedure Write• the current file position moves to the next numerically ordered file

component.

File

• Typed files and UnTyped files can also be accessed randomly through the standard procedure Seek, which moves the current file position to a “specified” component.

• We can use the following functions:– FilePos : determines the current file position– FileSize : determines the current file size

File

• Like Pascal:– Before a file variable can be used:

• it must be associated with an “External File” through a call to the AssignFile procedure.

– “External File”:• Stores the information written to it (Input).• Supplies the information read it (Output).

– Once the association with an “External File” is established, the file variable must be "opened" to prepare it for input or output.

• ReWrite (Input).• ReSet(Output).

File

• Existence & Creation:– An “Existing file” can be opened via the Reset procedure– A “New file” can be created and opened via the Rewrite procedure.

• Caution:– When a program completes processing a file, the file must be closed

using the standard procedure CloseFile (As Usual).– After a file is closed, its associated “External File” is updated.– The file variable can then be associated with another “External File”.

File Processing Example• Let’s have a “FInteger= file of integer” Type that is “Type of integer

file” and have the following “form” style• Now, what we need is that we must enter “integer” values in “Input to file” in associationwith the “Write” button.• Then, we want to see each “Entered” value when pressing “Read” button each time.• Note that:

– The 2nd edit “Edit2” is “ReadOnly”’– When pressing the “Read” button, the “Write” button becomes un-

Enabled.– We consider the “ReSet” & “ReWrite” Procedures’ “restrictions”. – The initial case for edits controls are “-1” that is all the entered values

afterward should be “positive” [0,+∞[.

File Processing Exampletik-tok

File Processing Example’s solution

• First of all we make the “Edit 2” is “ReadOnly:– ”Edit2 > Properties > ReadOnly > True

Type

FInteger= file of integer;

Var

Form1: TForm1;

F:FInteger;

File Processing Example’s solution

// (Write) button

procedure TForm1.Button1Click(Sender: TObject);

var x:integer;

begin

x:=strtoint(Edit1.Text);

write(F,x);

end;

// initializing the file for the 1st time

procedure TForm1.FormCreate(Sender: TObject);

begin

AssignFile(F,'D:\IntegerFile.txt');

Rewrite(F);

end;

File Processing Example’s solution

// (Read) button

procedure TForm1.Button2Click(Sender: TObject);

var x:integer;

Begin

if (Edit2.Text=‘-1’) then

begin

Button1.Enabled:=false; // disabling Button1 for 1st time

CloseFile(F);

ReSet(F);

end;

if (not(eof(f))=true) then

begin

read(F,x);

Edit2.Text:=inttostr(x);

end;

end;

File Run

File Run

• First of all, we should include the “ExtActns” unit to our project.

• We declare the “File” like any other “Variable”

Uses ExtActns;

Var FRun: TFileRun;

Delphi code areaunit Unit1;

interface

uses

Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

Dialogs;

type

TForm1 = class(TForm)

private

{ Private declarations }

public

{ Public declarations }

end;

var

Form1: TForm1;

implementation

{$R *.dfm}

end.

Name of the “unit” we are working in

Here begins the “unit”

implementation

Public Variables

Types & classes

Libraries we can take functions &

procedures from it

File Run

• 1st Code Sample (No browse dialog needed):

• 2nd Code Sample (Browse dialog showed & needed):

Frun:= TFileRun.Create(nil);

FRun.FileName:= ‘D:\kekoke.exe’;

FRun.Execute; // here the specified

// file will be opened

// and executed

FRun:= TFileRun.Create(nil);

FRun.browse:= true;

FRun.Execute; // here a browse dialog

// will be opened to let

// the user choose the

// file she\she wants:D

File Run

• Note that when you execute the following code the player you have will be opened and that’s inconvenient

• So.. What to do?

Frun:= TFileRun.Create(nil);

FRun.FileName:= 'D:\SthInMind.mp3';

FRun.Execute();

Mediaplayer, Component

Mediaplayer

• Here nothing will be displayed.. And also u can control how to play your music throw MediaPlayer

procedure TForm2.Button1Click(Sender: TObject);

begin

// FileName can be changed at Run\Design Time

mediaplayer1.filename:= 'D:\SthInMind.mp3’;

mediaplayer1.open;

mediaplayer1.play;

end;

File Run Test Live

OpenDialog

OpenDialog

• It won’t “open” anything • It’s just an “OpenDialog”

OpenDialog Prop.• Properties:

– InitialDir*– File name:

• The “Default” directory of the targeted “file”• This would maybe change at Runtime as it’s up for user to choose.

– Filter:• Filter Name | Filter• “Text” files | *.txt

– Filterindex:• determines which of the file types in Filter is selected by default when the

dialog opens. Set FilterIndex to 1 to choose the first file type in the list as the default, or set FilterIndex to 2 to choose the second file type as the default, and so forth. If the value of FilterIndex is out or range, the first file type listed in Filter is the default.

• ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ– *InitialDir: After some slides.. So don’t worry:D

OpenDialog

• “OpenDialog1.Execute()” Procedure:– Execute opens the file-selection dialog, returning:

• true when the user selects a file and clicks Open. • If the user clicks Cancel, Execute returns false.

• Code example:procedure TForm2.Button1Click(Sender: TObject);

begin

OpenDialog1.Execute();

End;

OpenDialog

• “OpenDialog1.Execute()” Procedure:– Execute opens the file-selection dialog, returning:

• true when the user selects a file and clicks Open. • If the user clicks Cancel, Execute returns false.

• Code example:

procedure TForm2.Button1Click(Sender: TObject);

begin

If (OpenDialog1.Execute()) then

Begin

Label1.caption := OpenDialog1.filename;

Edit1.text := OpenDialog1.filename;

Memo1.lines.Add(OpenDialog1.filename);

End;

End;

OpenDialog

• Code example:

// OpenDialog with instant running file sample

procedure TForm1.Button1Click(Sender: TObject);

begin

If (OpenDialog1.Execute()) then

Begin

FRun:= TFileRun.Create(nil);

FRun.FileName:= OpenDialog1.FileName;

FRun.Execute();

End;

end;

OpenDialog

• Code example

procedure TForm1.Button1Click(Sender: TObject);

begin

If (OpenDialog1.Execute()) then

Begin

FRun:=TFileRun.Create(nil);

FRun.Browse:= true;

FRun.Execute();

End;

end;

OpenDialog

• Code example:– So we’ll have 2 “OpenDialog”s to browse from them.– The Question now is:

• Which of the selected “files” will run?

procedure TForm1.Button1Click(Sender: TObject);

begin

If (OpenDialog1.Execute()) then

Begin

FRun:= TFileRun.Create(nil);

FRun.browse:= true;

FRun.Execute();

End;

end;

OpenDialog

procedure TForm1.Button1Click(Sender: TObject);

begin

if(OpenDialog1.Execute()) then

Begin

Image1.Picture.LoadFromFile(OpenDialog1.FileName);

End;

end;

OpenDialog

Design Time Runtime

TOpenDialog.InitialDir PropertyDelphi Help • InitialDir:

– determines the default directory displayed in the file-selection dialog when it opens.

– For example, to point the dialog at the (WINDOWS\SYSTEM) directory, set the value of InitialDir to (C:\WINDOWS\SYSTEM).

– If no value is assigned to InitialDir, or if the specified directory does not exist.

• the initial directory is controlled by the global ForceCurrentDirectoryvariable. If ForceCurrentDirectory is true, the dialog opens with the current working directory displayed. Otherwise, the dialog opens with either the current working directory or the “My Documents” directory, depending on the version of your Windows.

SaveDialog

SaveDialog

• Exactly like OpenDialog• It won’t “save” anything • It’s just an “SaveDialog”

SaveDialog Prop.

• Properties:– InitialDir*– File name: The directory of the targeted “file”– Filter:

• Filter Name | Filter• “Text” files | *.txt

– Filterindex

SaveDialog

• “SaveDialog1.Execute” Procedure:– Execute opens the file-selection dialog, returning:

• true when the user selects a file and clicks Save. • If the user clicks Cancel, Execute returns false.

• Code example:

procedure TForm2.Button2Click(Sender: TObject);

begin

If (SaveDialog1.Execute()) then

Begin

Label1.caption := SaveDialog1.filename;

Edit1.text := SaveDialog1.filename;

Memo1.lines[0] := SaveDialog1.filename;

End;

End;

SaveDialog

procedure TForm2.Button2Click(Sender: TObject);

begin

If (SaveDialog1.Execute()) then

Begin

// Save file by the dialog’s name

End;

End;

MessageDlg

MessageDlg

MessageDlg

• function MessageDlg• (const Msg: string; • DlgType: TMsgDlgType;• Buttons: TMsgDlgButtons; • HelpCtx: Longint

MessageDlg

procedure TForm1.Button1Click(Sender: TObject);

begin

MessageDlg(‘Hello lk where are u going, jd bdak troo7?’

, mtConfirmation, [mbYes, mbNo, mbCancel],0);

end;

MessageDlg

procedure TForm1.Button1Click(Sender: TObject);

begin

MessageDlg(‘Hello lk where are u going, jd bdak troo7?’

, mtWarning, [mbYes, mbNo, mbCancel],0);

end;

MessageDlg

• TMsgDlgBtn

MessageDlg

• Dealing With MsgDlg

// Show a custom dialog

buttonSelected:= MessageDlg('Custom dialog',mtCustom,

[mbYes,mbAll,mbCancel], 0);

// Show the button type selected

if buttonSelected = mrYes then ShowMessage('Yes pressed');

if buttonSelected = mrAll then ShowMessage('All pressed');

if buttonSelected = mrCancel then ShowMessage('Cancel pressed');

MessageDlg

• Dealing With MsgDlgprocedure TForm1.Button1Click(Sender: TObject);

begin

if (MessageDlg('Hello lk where are u going, jd bdak troo7?'

,mtWarning, [mbYes, mbNo, mbCancel],0) = mrYes) then

begin

// Form1.Close(); // Not True, all the time

Application.Terminate();

end;

end;

MessageDlg

• Consider we have the followingprocedure TForm1.Button1Click(Sender: TObject);

begin

if (MessageDlg('Hello lk where are u going, jd bdak troo7?'

,mtWarning, [mbYes, mbNo, mbCancel],0) = mrYes) then

begin

Form1.hide();

Form2.Close(); // Not True, all the time

//Application.Terminate();

end;

end;

MessageDlg

MessageDlg

Note that The Application is

still Running

MessageDlg

• Dealing With MsgDlg

procedure TForm1.Button1Click(Sender: TObject);

begin

if (MessageDlg('Hello lk where are u going, jd bdak troo7?'

,mtWarning, [mbYes, mbNo, mbCancel],0) = mrYes) then

begin

// Form1.hide();

// Form2.Close(); // Not True, all the time

Application.Terminate();

end;

end;

This is the proper thing

See you!