Delphi L02 Controls P1

Intro to Event-driven Programming
and Forms with Delphi
L02 – Controls P1

Mohammad Shaker
mohammadshakergtr.wordpress.com
Intro to Event-driven Programming and Forms with Delphi
@ZGTRShaker
2010, 2011, 2012

What’s for today?
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Label
Edit
ComboBox
CheckBox
GroupBox
RadioButton
RadioGroup
ListBox

General ‘Info’s & Tips
• Don’t forget the CTRL+Space auto-completion
– CTRL+Space: code in-sightauto-completion.

• You can’t write in Arabic in a component’s “NAME”.
• Delphi is a not a “Case Sensitive ” language.
• dpr *: when saving, the project you have will be saved as a
‘dpr’ termination.

*dpr: Delphi Project

Runtime
• Form the upper bar > Run > Run.
• Form the button in the upper bar.
• Or F9

Sth to Remember
• Differentiate between Visible & Enabled in Component’s
properties.
• Differentiate between Name & Caption in Component’s
properties.
• F9: RUN.
• F9+CTRL: Compile.

Changing your “.exe” icon
• “.ico” files extension
• Project > Options > Application > Load Icon
• It appears in the upper left corner of the application form

Chase the button
Exercise Do it & enjoy catching it :D

Label
• Is an Info
• It can be used as an output as a “String”
• “caption” manipulating.

Label1.caption:= ‘Hello World’;

String & only String

Pre-Made String Functions
• StrAlloc
– Allocates a character buffer of a given size on the heap.

• StrBufSize
– Returns the size of a character buffer allocated using StrAlloc or
StrNew.

• StrCat
– Concatenates two strings.

• StrComp
– Compares two strings.

• StrCopy
– Copies a string.

• StrDispose
– Disposes a character buffer allocated using StrAlloc or StrNew.

• StrECopy
– Copies a string and returns a pointer to the end of the string.

• StrEnd
– Returns a pointer to the end of a string.

• StrFmt
– Formats one or more values into a string.

• StrIComp
– Compares two strings without case sensitivity.

• StrLCat
– Concatenates two strings with a given maximum length of the resulting
string.

• StrLComp
– Compares two strings for a given maximum length.

• StrLCopy
– Copies a string up to a given maximum length.

• StrLen
– Returns the length of a string.

• StrLFmt
– Formats one or more values into a string with a given maximum length.

• StrLIComp
– Compares two strings for a given maximum length without case sensitivity.

• StrLower
– Converts a string to lowercase.

• StrMove
– Moves a block of characters from one string to another.

• StrNew
– Allocates a string on the heap.

• StrPCopy
– Copies a Pascal string to a null-terminated string.

• StrPLCopy
– Copies a Pascal string to a null-terminated string with a given maximum length.

• StrPos
– Returns a pointer to the first occurrence of a given substring within a string.

• StrRScan
– Returns a pointer to the last occurrence of a given character within a string.

• StrScan
– Returns a pointer to the first occurrence of a given character within a string.

• StrUpper
– Converts a string to uppercase.

• What we need the most:
– String to integer
– Integer to string

: StrToInt()
: IntToStr()

Edit Prop.
•
•
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•
•

No “Caption” Prop., “Text”.
PassWord
Visible, Enabled
Hint, ShowHint
Top, Left

Edit
• Text:“String” inner valued.
• Can be used as an input & output.
Var temp:integer;
Edit1.Text:= temp;
temp:= Edit1.Text;

// output
// input

• Have a supposition value (text Prop.).
– Can be changed.

• ReadOnly Prop.

Edit
• Can be used to contain other variables types.
• Input:
Var temp:integer;
temp:= StrToInt(Edit1.Text);

• Output:
Var temp:String;
Edit1.Text:= IntToStr(temp); //no need for -IntToStr-

CheckBox Properties
•
•
•
•
•

Caption
“true OR false”
Can be used as a “boolean” input
“Checked” Prop.
Can be referenced to other “boolean” variable.

Crack the code
If (CheckBox1.Checked=true) then
Begin
// code
End
Else
if (CheckBox2.checked=true) then
Begin
// code
End
else
Begin
// code
End

x:=5;
CheckBox1: Not Checked
Begin
CheckBox2: Checked
x:=10;
End
Else
if ((CheckBox1.Checked=false) and (CheckBox2.checked=false))
then
Begin
x:=11;
End;
x:=5;
CheckBox1: Checked
Begin
CheckBox2: Checked
x:=10;
End
Else
if ((CheckBox1.Checked=true) and (CheckBox2.checked=true))
then
Begin
x:=11;
End;

x:=5;
CheckBox1: Checked
Begin
x:=10;
End
if ((CheckBox1.Checked=false) Or (CheckBox2.checked=false)) then
Begin
x:=11;
End;

x:=5;
If (CheckBox1.Checked=false) then
CheckBox2: Checked
Begin
x:=10;
End
Else
if ((CheckBox1.Checked=true) Or (CheckBox2.checked=true)) then
Begin
x:=11;
End;

x:=5;
Begin
CheckBox2: Checked
x:=10;
End
Else
if ((CheckBox1.Checked=false) or (CheckBox2.checked=false))
then
Begin
x:=11;
End;

x:=5;
Begin
x:=10;
End
Else
if


((CheckBox1.Checked=true)or(CheckBox2.checked=not(CheckBox1.Checked)))
then
Begin
x:=11;
End;

Crack the code
x:=5;
Begin
x:=10;
End;
Else
if (CheckBox2.Checked=true) then
Begin
x:=11;
End;


Var Bool1,Bool2: boolean;
Begin
Bool1: = CheckBox1.Checked; Bool2:-=false;
If (Bool1=true) then
Begin
// your code
End
Else
if (Bool2=not(true)) then
Begin
//your code
End
else
Begin
//your code
End
End;

Var Bool1,Bool2: boolean; x:integer;
Begin
x:=5;
Bool1: = CheckBox1.Checked; Bool2:-=false;
If (Bool1=true) then
Begin
x:=3;
End
Else
if (Bool2=not(true)) then
Begin
x:=x+1;
End
End;

Var Bool1,Bool2: boolean; x:integer;
Begin
x:=5;
Bool1: = CheckBox1.Checked; Bool2:-=true;
If (Bool1=Bool2) then
Begin
x:=3;
End
if (Bool2=not(not(Bool1)) then
Begin
x:=x+1;
End
End;

CheckBox1: Checked

ListBox Prop.
• Properties:
– Sorted:
• If “true”, sorted in ascending order, default false

– Items:
• Items.add > (String)
• Items.string > [index] > (String)

– ItemIndex:
• ItemIndex > Return selected index [] > (Integer)
• No “ItemIndex” change at Design time

– Columns:
• Multiple “column”s in ListBox if greater than Zero “0”.

– MultiSelect:
• Enables “multiselect” to be “selected” if “true”, default “false”.

– “Auto” ScrollBar

ListBox example
procedure TForm2.Button1Click(Sender: TObject);
var x:integer; s:string;
begin
//Items
ListBox1.Items.Add('hehe');
//String
s:=ListBox1.Items.Strings[0];
Label1.caption:=s;

//ItemIndex
x:=ListBox1.ItemIndex;
Label2.caption:=inttostr(x);
end;

ComboBox
• Look like “ListBox”, but it’s a one “Choice at a time” one.
– No “MultiSelect” Prop.

ComboBox Prop.
• Properties:
– Text
• Text > (string) like a “caption” for “ComboBox”

– Items
• The available “option”s for user.
• Items.add > (String)
• Items.string > [index] > (String)

// func. Runtime
// func. Runtime

– ItemIndex
• ItemIndex > Return selected index [] > (Integer)
• “ItemIndex” changable at Design time , in contrary to “ListBox”

– Sorted:
• If “true”, sorted in ascending order, default false

ComboBox Event
• Most important: Onchange
• Code: let’s “just” change the option “3” times.

ComboBox – Code example
procedure TForm2.ComboBox1Change(Sender: TObject);
begin
memo1.lines.add('krkrkrkr');
end;

//Now let us add this new block of code on Button1Click
procedure TForm2.Button1Click(Sender: TObject);
var x:integer; s:string;
begin
if ComboBox1.ItemIndex=0 then
memo1.Lines.Add('You chose English')
else
begin
memo1.Lines.Add('You chose Arabic')
else
begin
memo1.Lines.Add('You chose German')
else
memo1.Lines.Add('You chose French');
end;
end;
end;

ComboBox – Code example
• Now, what is the output on “Memo1” (Just Think it as if it’s a
Multi-Lines “Edit”) that can show just 5 lines, without a
scrollbar, when we choose 3 options (Arabic, German, French)
in row, and clicking the button after each choice?
• Think Think Think.

RadioButton
• What it looks like?
• It’s like when we choose the ages, languages,
– example
– It’s represent “constant values” for one “variables”

• So it’s like CheckBox that we learned but with a key
difference.

RadioButton - Differences
• Let’s have 3 CheckBox & 3 Radio buttons.
CheckBox

RadioButton

We can select all 3
(one or more)

We can’t select all 3
(just one of them)

Not connected with each other

Connected with each other

RadioButton - Example
•

Remember that only one option can be chosen at a time

Block of code
Block of code
Block of code
Block of code

Many ways to “CRACK” the restriction
• GroupBox
• RadioGroup
• Panel

RadioGroup
simplifies the task of grouping radio buttons

RadioGroup Prop.
• Item:
– Numbers of option in the “RadioGroup” depends on “item” Prop.
– each string in “item” makes a radio button appears in the group box
with string as its “caption”.

• ItemIndex:
– determines which “RadioButton” is currently selected.
• It’s which we’ll deal with in code in “Runtime”.

• Column:
– Display the radio buttons in a single column or in multiple columns.

RadioGroup Prop.
No “Checked” Prop., It’s “ItemIndex”
Live example.

RadioGroup Prop.
procedure TForm1.NextClick(Sender: TObject);
begin
ShowMessage(RadioGroup1.Items.Strings[RadioGroup1.ItemIndex]
+ ' with Index '
+ IntToStr(RadioGroup1.ItemIndex));
end;

GroupBox
• What it looks like?
• Its main function is to arrange all the related “control”s in
the “form”.
• The most known related “control” is “RadioGroup” as we have
seen.
• “Caption” Prop. Labels the GroupBox
• Remember “cut & paste” method.

Adding component to GroupBox
• Tool Pallete > Choose what you want to add
– Place it in the “GroupBox”

• Now you can deal with your GroupBox as a complete block
that contains related “control”s

Delphi L02 Controls P1

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