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TMemo

 

 

 

TMemo is a wrapper for a Windows multiline edit control. Use TMemo to put a standard Windows multiline edit control on a form. Multiline edit boxes allow the user to enter more than one line of text. They are appropriate for representing lengthy information.

 

In some examples we assume an memo control has been created and is named "Memo1".

 

TMemo Memo1 = TMemo.Create(form);

 


Properties



 

property TAlign Align;

Determines how the control aligns within its container (parent control).


enum TAlign {

  alNone,

  alTop,

  alBottom,

  alLeft,

  alRight,

  alClient,

  alCustom

};

 

Ex. Memo1.Align = alNone;


 

property TLeftRight Alignment;

Controls the horizontal placement of the text within the memo. Set Alignment to specify how the text is justified within the ClientRect of the memo control.

The effect of the Alignment property is more obvious if the WordWrap property is true and the label includes more than one line of text.  

 

taLeftJustify    - This is the default value. Text is displayed from the left edge of the memo.

taRightJustify   - The text is placed to the right in the memo area.

taCenter         - Text is placed in the memo center.


 

property Bool AlignWithMargins;

Indicates whether a control should be constrained by margins. If AlignWithMargins is true, use the Margins property of the control to govern the spacing relative to other controls that are aligned with this one.


 

property TAnchors Anchors;

Specifies how the control is anchored to its parent.

 

enum TAnchorKind {

  akLeft,

  akTop,

  akRight,

  akBottom

};

 

Ex. Memo1.Anchors = akLeft + akTop + akRight + akBottom;


 

property TColor Color;

Specifies the background color of the control. The color value can be an hexadecimal or a color constant.


 

Defined color constants are:

clAqua, clBlack, clBlue, clCream, clDkGray, clFuchsia, clGray, clGreen, clLime, clLtGray, clMaroon, clMedGray, clMoneyGreen, clNavy, clOlive, clPurple, clRed, clSilver, clSkyBlue, clTeal, clWhite, clYellow.


 

Defined system color constants:

clNone                     White on Windows 9x, Black on NT.

clScrollBar                Current color for the of scroll bar track.

clBackground               Current background color of the Windows desktop

clActiveCaption            Current color of the title bar of the active window

clInactiveCaption          Current color of the title bar of inactive windows

clMenu                     Current background color of menus

clWindow                   Current background color of windows

clWindowFrame              Current color of window frames

clMenuText                 Current color of text on menus

clWindowText               Current color of text in windows

clCaptionText              Current color of the text on the title bar of the active window

clActiveBorder             Current border color of the active window

clInactiveBorder           Current border color of inactive windows

clAppWorkSpace             Current color of the application workspace

clHighlight                Current background color of selected text

clHightlightText           Current color of selected text

clBtnFace                  Current color of a button face

clBtnShadow                Current color of a shadow cast by a button

clGrayText                 Current color of text that is dimmed

clBtnText                  Current color of text on a button

clInactiveCaptionText      Current color of the text on the title bar of an inactive window

clBtnHighlight             Current color of the highlighting on a button

cl3DDkShadow               Windows 95 or NT 4.0 only: Dark shadow for three-dimensional display elements

cl3DLight                  Windows 95 or NT 4.0 only: Light color for three-dimensional display elements (for edges facing the light source)

clInfoText                 Windows 95 or NT 4.0 only: Text color for tool tip controls

clInfoBk                   Windows 95 or NT 4.0 only: Background color for tool tip controls

clGradientActiveCaption    Windows 98 or Windows 2000: Right side color in the color gradient of an active window's title bar.

clActiveCaption            specifies the left side color.

clGradientInactiveCaption  Windows 98 or Windows 2000: Right side color in the color gradient of an inactive window's title bar. clInactiveCaption          specifies the left side color.

clDefault                  The default color for the control to which the color is assigned.


 

Ex. Memo1.Color = 0x0000FF00;

Ex. Memo1.Color = clGreen;


 

property Bool Enabled;

Controls whether the control responds to mouse, keyboard, and timer events.


 

property TFont Font;

Controls the attributes of text written on or in the control. To change to a new font, specify a new TFont object. To modify a font, change the value of the Charset, Color, Height, Name, Pitch, Size, or Style of the TFont object.

 

Ex. Memo1.Font.Size = 12;


 

property int Height;

Specifies the vertical size of the control in pixels.

 

Ex. Memo1.Height = 400;


 

property Bool HideSelection;

Determines whether the visual indication of the selected text remains when focus shifts to another control. Set HideSelection to false to provide visual feedback of the selected portion of the text even when the edit control does not have focus. Set HideSelection to true to show the selection only when the edit control has focus. HideSelection does not affect the actual value of the selection, only the visual indication.


 

property String Hint;

Contains the text string that can appear when the user moves the mouse over the control.


 

property int Left;

Specifies the horizontal coordinate of the left edge of a component relative to its parent.


 

property TStrings Lines;

Contains the individual lines of text in the memo control. Use Lines to manipulate text in an memo control on a line-by-line basis.

 

Ex. String s = Memo1.Lines[0];

Ex. Memo1.Lines[0] = "Hello World!";

 

Common TStrings methods:

 

       function    int Add(const String S);                   // Adds a string at the end of the list.

       procedure       Clear();                               // Clear the entire list

       procedure       Delete(int Index);                     // Delete a string in the list

       function    int IndexOf(const String S);               // Returns the position of a string in the list.

       procedure       Insert(int Index, const String S);     // Insert string in a specific position

       procedure       LoadFromFile(const String FileName);   // Load strings from a file

       procedure       SaveToFile(const String FileName);     // Save strings to a file


 

property TMargins Margins;

Specifies the margins for the control. TMargins help define the relative position between components on a form, and between the edges of the form and the component. For example, when you set a left margin for a component to 10 pixels, the component will not come closer than 10 pixels to the edge of the container, or to another component on the left edge. The number of pixels by which two components are separated is the sum of the pixels of both components.

TMargins have the class members top, bottom, left and right.

 

Ex. Memo1.Margins.Left = 10;


 

property Int MaxLength;

Specifies the maximum number of characters the user can type into the edit control.


 

property String Name;

Specifies the name of the component as referenced in code.


 

property TPadding Padding;

Specifies the padding of a control. Padding works similar to margins.

 

Ex. Memo1.Padding.Left = 4;


 

property TWinControl Parent;

Use the Parent property to get or set the parent of this control. The parent of a control is the control that contains the control. For example, if an application includes three radio buttons in a group box, the group box is the parent of the three radio buttons, and the radio buttons are the child controls of the group box.


Ex.

TMemo Memo1 = TMemo.Create(form);

Memo1.Parent = form;

Memo1.Left = 8;


 

property Bool ParentColor;

To have a control use the same color as its parent control, set ParentColor to true. If ParentColor is false, the control uses its own Color property.


 

property Bool ParentFont;

Determines where a control looks for its font information.

To have a control use the same font as its parent control, set ParentFont to true. If ParentFont is false, the control uses its own Font property.


 

property TPopupMenu PopupMenu;

Identifies the pop-up menu associated with the control.


 

property Bool ReadOnly;

Determines whether the user can change the text of the edit control. To restrict the edit control to display only, set the ReadOnly property to true. Set ReadOnly to false to allow the contents of the edit control to be edited.


 

property ScrollBars;

Determines whether the memo control has scroll bars.


Use ScrollBars to give a multiline edit control horizontal or vertical scroll bars. ScrollBars can take one of the following values:

 

ssNone

The control has no scroll bars.

ssHorizontal

The control has a single scroll bar on the bottom edge.

ssVertical

The control has a single scroll bar on the right edge.

ssBoth

The control has a scroll bar on both the bottom and right edges.


 

property Bool ShowHint;

Determines whether the control displays a Help Hint when the mouse pointer rests momentarily on the control.


 

property TTabOrder TabOrder;

TabOrder is the order in which child windows are visited when the user presses the Tab key. The control with the TabOrder value of 0 is the control that has the focus when the form first appears.

 

Initially, the tab order is always the order in which the controls were added to the form. The first control added to the form has a TabOrder value of 0, the second is 1, the third is 2, and so on. Change this by changing the TabOrder property.  


 

property Bool TabStop;

Determines if the user can tab to a control.


 

property int Tag;

Stores an integer value as part of a component.


 

property String Text;

Use the Text property to read the entire Text of the control or specify a new text.

 

Ex.

     // Add text to the edit control

     Memo1.Text = "Hello World!";


 

     // Get text from the edit control

     String s = Memo1.Text;


 

property int Top;

Specifies the Y coordinate of the top left corner of a control, relative to its parent or containing control in pixels.


 

property Boolean Visible;

Indicates whether the control is visible.


 

property Bool WantReturns;

Determines whether the user can insert return characters into the text. Set WantReturns to true to allow users to enter return characters into the text.


 

property Bool WantTabs;

Determines whether the user can insert tab characters into the text. Set WantTabs to true to allow users to enter tab characters into the text. Set WantTabs to false if you want the tab character to select the next control on the form instead.


 

property int Width;

Specifies the horizontal size of the control or form in pixels.


 

property Bool WordWrap;

Determines whether the edit control inserts soft carriage returns so text wraps at the right margin. Set WordWrap to true to make the edit control wrap text at the right margin so it fits in the client area. The wrapping is cosmetic only.


 


Methods



 

constructor Create(TComponent AOwner) 

Creates and initializes a new TMemo object.


Ex. TMemo Memo1 = TMemo.Create(form);


 

procedure Free;

Destroys an object and frees its associated memory, if necessary. Visual controls added to a form is automatically destroyed when the form closes.


Ex.

TForm form = new TForm(nil);

TMemo Memo1 = TMemo.Create(form);

...

Memo1.Free;


 

procedure Hide;

Hides the control.


 

procedure Show;

Shows the control. Use Show to set the control's Visible property to true.


 


Events



 

OnChange 

Occurs when the text for the edit control may have changed.

 

Ex.

 

TForm form;

TMemo Memo1;

void Memo1Change(TObject Sender)

{

  // Do some work here

}

 

{

  form = new TForm(nil);  

 

  Memo1 = TMemo.Create(form);

  Memo1.Parent = form;

  Memo1.OnChange = &Memo1Change;

}


 

OnClick 

Occurs when the user clicks the control.


Ex.

 

TForm form;

TMemo Memo1;

void Memo1Click(TObject Sender)

{

  // Do some work here

}

 

{

  form = new TForm(nil);  

 

  Memo1 = TMemo.Create(form);

  Memo1.Parent = form;

  Memo1.OnClick = &Memo1Click;

}


 

OnDblClick 

Occurs when the user clicks the control.


Ex.

 

TForm form;

TMemo Memo1;

void Memo1DblClick(TObject Sender)

{

  // Do some work here

}

 

{

  form = new TForm(nil);  

 

  Memo1 = TMemo.Create(form);

  Memo1.Parent = form;

  Memo1.OnDblClick = &Memo1DblClick;

}


 

OnEnter 

Occurs when a control receives the input focus. Use the OnEnter event handler to cause any special processing to occur when a control becomes active.


Ex.

 

TForm form;

TMemo Memo1;

void Memo1Enter(TObject Sender)

{

  // Do some work here

}

 

{

  form = new TForm(nil);

 

  Memo1 = TMemo.Create(form);

  Memo1.Parent = form;

  Memo1.OnEnter = &Memo1Enter;

}


 

OnExit 

Occurs when the input focus shifts away from one control to another. Use the OnExit event handler to provide special processing when the control ceases to be active.


Ex.

 

TForm form;

TMemo Memo1;

void Memo1Exit(TObject Sender)

{

  // Do some work here

}

 

{

  form = new TForm(nil);

 

  Memo1 = TMemo.Create(form);

  Memo1.Parent = form;

  Memo1.OnExit = &Memo1Exit;

}


 

OnKeyDown 

Occurs when a user presses any key while the control has focus.


(ssShift, ssAlt, ssCtrl, ssLeft, ssRight, ssMiddle, ssDouble) TShiftState;


Ex.

 

TForm form;

TMemo Memo1;

void Memo1KeyDown(TObject Sender, WORD &Key, TShiftState Shift)

{

  // Do some work here

  if (Key == VK_F1) {

    // F1 was pressed, lets do something...

 

  }

}

 

{

  form = new TForm(nil);

 

  Memo1 = TMemo.Create(form);

  Memo1.Parent = form;

  Memo1.OnKeyDown = &Memo1KeyDown;

}


 

OnKeyPress 

Occurs when a key is pressed.

 

Ex.

 

TForm form;

TMemo Memo1;

void Memo1KeyPress(TObject Sender, char &Key)

{

  // Do something

}

 

{

  form = new TForm(nil);

  Memo1 = TMemo.Create(form);

  Memo1.Parent = form;

  Memo1.OnKeyPress = &Memo1KeyPress;

}


 

OnKeyUp 

Occurs when the user releases a key that has been pressed.


(ssShift, ssAlt, ssCtrl, ssLeft, ssRight, ssMiddle, ssDouble) TShiftState;

 

Ex.

 

TForm form;

TMemo Memo1;

void Memo1KeyUp(TObject Sender, WORD &Key, TShiftState Shift)

{

  // Do some work here

}

 

{

  form = new TForm(nil);

 

  Memo1 = TMemo.Create(form);

  Memo1.Parent = form;

  Memo1.OnKeyUp = &Memo1KeyUp;

}


 

OnMouseDown 

Occurs when the user presses a mouse button with the mouse pointer over a control.

 

(ssShift, ssAlt, ssCtrl, ssLeft, ssRight, ssMiddle, ssDouble) TShiftState;

 

enum TMouseButton {

  mbLeft,

  mbRight,

  mbMiddle

};

 

Ex.

 

TForm form;

TMemo Memo1;

void Memo1MouseDown(TObject Sender, TMouseButton Button, TShiftState Shift, int X, int Y)

{

  // Do some work here if left mouse button was pressed

  if (Button == mbLeft) {

    // Left mouse button was pressed. Lets do something...

 

  }

}

 

{

  form = new TForm(nil);

 

  Memo1 = TMemo.Create(form);

  Memo1.Parent = form;

  Memo1.OnMouseDown = &Memo1MouseDown;

}


 

OnMouseEnter 

Occurs when the user moves the mouse into a control.


Ex.

 

TForm form;

TMemo Memo1;

void Memo1MouseEnter(TObject Sender)

{

  // Do some work here

}

 

{

  form = new TForm(nil);

 

  Memo1 = TMemo.Create(form);

  Memo1.Parent = form;

  Memo1.OnMouseEnter = &Memo1MouseEnter;

}


 

OnMouseLeave 

Occurs when the user moves the mouse outside of a control.

 

Ex.

 

TForm form;

TMemo Memo1;

void Memo1MouseLeave(TObject Sender)

{

  // Do some work here

}

 

{

  form = new TForm(nil);

 

  Memo1 = TMemo.Create(form);

  Memo1.Parent = form;

  Memo1.OnMouseLeave = &Memo1MouseLeave;

}


 

OnMouseMove 

Occurs when the user moves the mouse pointer while the mouse pointer is over a control.

 

Ex.

 

int FMouseX,FMouseY;

TForm form;

TMemo Memo1;

void Memo1MouseMove(TObject Sender, TMouseButton Button, TShiftState Shift, int X, int Y)

{

  // Do some work here

  FMouseX = X;

  FMouseY = Y;

}

 

{

  form = new TForm(nil);

 

  Memo1 = TMemo.Create(form);

  Memo1.Parent = form;

  Memo1.OnMouseMove = &Memo1MouseMove;

}


 

OnMouseUp 

Occurs when the user releases a mouse button that was pressed with the mouse pointer over a component.

 

Ex.

 

TForm form;

TMemo Memo1;

void Memo1MouseUp(TObject Sender, TMouseButton Button, TShiftState Shift, int X, int Y)

{

  // Do some work here

}

 

{

  form = new TForm(nil);

 

  Memo1 = TMemo.Create(form);

  Memo1.Parent = form;

  Memo1.OnMouseUp = &Memo1MouseUp;

}


 


 


 


 


 


 

 

 

 

Copyright © 2022 Rickard Johansson