{
* UMessageBox.pas
*
* Implements a static class that can display message and confirmation dialog
* boxes at an appropriate position on screen.
*
* $Rev$
* $Date$
*
* ***** BEGIN LICENSE BLOCK *****
*
* Version: MPL 1.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
* the specific language governing rights and limitations under the License.
*
* The Original Code is UMessageBox.pas
*
* The Initial Developer of the Original Code is Peter Johnson
* (http://www.delphidabbler.com/).
*
* Portions created by the Initial Developer are Copyright (C) 2005-2011 Peter
* Johnson. All Rights Reserved.
*
* Contributor(s)
* NONE
*
* ***** END LICENSE BLOCK *****
}
unit UMessageBox;
interface
uses
// Delphi
Classes, Controls, Dialogs,
// Project
UBaseObjects, UIStringList;
resourcestring
// Button captions
sBtnYes = '&Yes'; // Yes button caption
sBtnNo = '&No'; // No button caption
sBtnOK = 'OK'; // OK button caption
sBtnCancel = 'Cancel'; // Cancel button caption
type
{
TMessageBoxButton:
Record that contains attributes of a button that appears in a TMessageBox
dialog box.
}
TMessageBoxButton = record
Caption: TCaption; // button's caption
ModalResult: Integer; // button's modal result (0 to prevent form closure)
Default: Boolean; // true if button is default
Cancel: Boolean; // true if button is cancel button
constructor Create(const ACaption: TCaption; const AModalResult: Integer;
const ADefault: Boolean = False; const ACancel: Boolean = False);
{Initialises fields of record.
@param ACaption [in] Button's caption.
@param AModalResult [in] Modal result returned when button is clicked.
@param Default [in] Optional: value of button's Default property.
@param Cancel [in] Optional: value of button's Cancel property.
}
end;
{
TMessageBox:
Static class that can display message and confirmation dialog boxes at an
appropriate position on screen.
}
TMessageBox = class sealed(TNoConstructObject)
public
// Constants to pass to methods that require Title or IconRes parameters to
// indicate default value is to be used.
const DefaultTitle = ''; // Indicates default title required
const DefaultIcon = nil; // Indicates default icon required
strict private
class function Display(const Parent: TComponent;
MsgLines: IStringList; const DlgType: TMsgDlgType;
const Buttons: array of TMessageBoxButton; const Title: string;
const IconRes: PChar): Word; overload;
{Displays a message in a customised dialog box located over the calling
form.
@param Parent [in] Component that dialog box is aligned over and that
becomes parent of dialog box. If Parent is nil then current active
form is used.
@param MsgLines [in] Message displayed in dialog. Can store mulitple
lines. Use empty lines to insert space between paragraphs.
@param DlgType [in] Type of dialog box.
@param Buttons [in] Array of records decribing buttons to be displayed.
@param Title [in] Title of dialog box. If '' title used depends on
DlgType.
@param IconRes [in] Icon resource identifier. If nil icon used depends
on DlgType.
@return Value indicating which button was pressed to close dialog box.
This will be value of ModalResult field of one of the buttons
specified in Buttons.
}
class function Display(const Parent: TComponent; const Msg: string;
const DlgType: TMsgDlgType; const Buttons: array of TMessageBoxButton;
const Title: string; const IconRes: PChar): Word; overload;
{Displays a message in a customised dialog box located over the calling
form.
@param Parent [in] Component that dialog box is aligned over and that
becomes parent of dialog box. If Parent is nil then current active
form is used.
@param Msg [in] Message displayed in dialog. Separate lines with LF or
CRLF. Separate paragraphs with two line breaks.
@param DlgType [in] Type of dialog box.
@param Buttons [in] Array of records decribing buttons to be displayed.
@param Title [in] Title of dialog box. If '' title used depends on
DlgType.
@param IconRes [in] Icon resource identifier. If nil icon used depends
on DlgType.
@return Value indicating which button was pressed to close dialog box.
This will be value of ModalResult field of one of the buttons
specified in Buttons.
}
public
class procedure Information(const Parent: TComponent; const Msg: string);
{Displays a message in an information dialog box located relative to owner
form.
@param Parent [in] Component that dialog box is aligned over and that
becomes parent of dialog box. If Parent is nil then current active
form is used.
@param Msg [in] Message displayed in dialog. Multi-line messages should
be separated by LF or CRLF.
}
class procedure Error(const Parent: TComponent; const Msg: string);
{Displays a message in an error dialog box located relative to owner form.
@param Parent [in] Component that dialog box is aligned over and that
becomes parent of dialog box. If Parent is nil then current active
form is used.
@param Msg [in] Message displayed in dialog. Multi-line messages should
be separated by LF or CRLF.
}
class function Confirm(const Parent: TComponent;
const Msg: string): Boolean;
{Displays a message in a confirmation dialog box located relative to owner
form.
@param Parent [in] Component that dialog box is aligned over and that
becomes parent of dialog box. If Parent is nil then current active
form is used.
@param Msg [in] Message displayed in dialog. Multi-line messages should
be separated by LF or CRLF.
@return True if user clicks Yes and false otherwise.
}
class function Custom(const Parent: TComponent; const Msg: string;
const Buttons: array of TMessageBoxButton;
const Title: string = DefaultTitle; const IconRes: PChar = DefaultIcon):
Word;
{Displays a message in a dialog box with custom buttons and no icon that
is located relative to owner form.
@param Parent [in] Component that dialog box is aligned over and that
becomes parent of dialog box. If Parent is nil then current active
form is used.
@param Msg [in] Message displayed in dialog. Multi-line messages should
be separated by LF or CRLF.
@param Buttons [in] Array of records decribing buttons to be displayed.
@param Title [in] Optional title of dialog box. If Title='' then
application title is used.
@param IconRes [in] Optional icon resource. No icon is displayed if not
provided.
@return Value indicating which button was pressed to close dialog box.
This will be value of ModalResult field of one of the buttons
specified in the Buttons array.
}
end;
implementation
uses
// Delphi
SysUtils, Windows, Forms, StdCtrls, ExtCtrls, Consts, Math,
// Project
UConsts, UDlgHelper, UFontHelper, UGraphicUtils, UStructs, UStrUtils;
type
{
TMessageBoxForm:
Implements a message dialog box that has configurable lines and paragraphs
of text, buttons and icon.
}
TMessageBoxForm = class sealed(TForm)
strict private
var
fImage: TImage; // Image control: displays any icon
fButtons: array of TButton; // Buttons displayed in dialog box
fLabels: array of TLabel; // Labels that display text in dialog box.
const
cXPadding = 16; // Left and right dialog box margins
cYPadding = 16; // Top and bottom dialog box margins
cParaSpacing = 8; // Spacing between paragraphs
cBtnSpacing = 8; // Spacing between buttons
cBtnStripTopMargin = 24; // Margin above button strip
cMaxTextWidth = 512; // Maximum width of text in dialog box
function MaxTextWidth: Integer;
{Calculates maximum horizontal space that can be occupied by the dialog's
text.
@return Required width in pixels.
}
function LabelsHeight: Integer;
{Finds height required to display all labels.
@return Required height in pixels.
}
function LabelHeight(const Lbl: TLabel): Integer;
{Calculates height of a label.
@param Lbl [in] Label for which height is required.
@return Label height in pixels.
}
function LabelsWidth: Integer;
{Finds width of text in widest label.
@return Required width in pixels.
}
function ButtonsHeight: Integer;
{Calculates vertical space required to display button strip.
@return Required height in pixels.
}
function ButtonsWidth: Integer;
{Calculates horizontal space required to display strip of all buttons.
@return Required width in pixels.
}
function TextLeftMargin: Integer;
{Calculates offset of text from dialog box's left hand margin. Depends on
whether dialog box displays an icon.
@return Required margin in pixels.
}
function TextAndIconHeight: Integer;
{Calculates vertical space required to accommodate text and any icon.
@return Required height in pixels.
}
function TextAndIconWidth: Integer;
{Calculates horizontal spaces required to accommodate text and any icon.
@return Required width in pixels.
}
procedure InitCaption(const Title: string; const DlgType: TMsgDlgType);
{Sets text of dialog's caption.
@param Title [in] Title to display in dialog's caption. If '' a default
caption dependent on dialog type is used.
@param DlgType [in] Type of dialog box. Used to determine default
caption if Title is ''.
}
procedure InitImage(const IconRes: PChar; const DlgType: TMsgDlgType);
{Creates and initialises and locates image control required to display any
icon. No image control is created if no icon is required.
@param IconRes [in] Icon resource. If nil then icon is determined by
DlgType.
@param DlgType [in] Type of dialog to be displayed. Determines which, if
any icon is required when IconRes is nil.
}
procedure InitButtons(const Buttons: array of TMessageBoxButton);
{Creates and sizes dialog's buttons.
@param Buttons [in] Array of records describing buttons to display.
}
procedure InitLabels(const Lines: IStringList);
{Creates and sizes labels used to display text in dialog box.
@param Lines [in] String list containing lines of text to display. Blank
lines indicate a paragraph break.
}
procedure SizeDialogBox;
{Sets size of dialog box to accomodate text, optional icon and buttons.
}
procedure ArrangeControls;
{Arranges all controls within dialog box.
}
public
constructor Create(const Owner: TComponent;
const Text: IStringList;
const Buttons: array of TMessageBoxButton;
const DlgType: TMsgDlgType;
const Title: string;
const IconRes: PChar); reintroduce;
{Object constructor. Reintroduced constructor that creates dialog box form
with components required to display text, buttons and optional icon.
@param Owner [in] Control that owns this dialog box.
@param Text [in] List of lines of text to display. Blank lines indicate
a paragraph spacer.
@param Buttons [in] Array of records that define buttons to be
displayed.
@param DlgType [in] Type of dialog box to be displayed.
@param Title [in] Optional dialog box caption text. If Title='' caption
depends on DlgType.
@param IconRes [in] Resource to be used for icon displayed. If nil then
any icon displayed depends on DlgType.
}
end;
{ TMessageBox }
class function TMessageBox.Confirm(const Parent: TComponent;
const Msg: string): Boolean;
{Displays a message in a confirmation dialog box located relative to owner
form.
@param Parent [in] Component that dialog box is aligned over and that
becomes parent of dialog box. If Parent is nil then current active form
is used.
@param Msg [in] Message displayed in dialog. Multi-line messages should be
separated by LF or CRLF.
@return True if user clicks Yes and false otherwise.
}
begin
Result := Display(
Parent,
Msg,
mtConfirmation,
[
TMessageBoxButton.Create(sBtnYes, mrYes, True),
TMessageBoxButton.Create(sBtnNo, mrNo, False, True)
],
DefaultTitle,
DefaultIcon
) = mrYes;
end;
class function TMessageBox.Custom(const Parent: TComponent; const Msg: string;
const Buttons: array of TMessageBoxButton; const Title: string;
const IconRes: PChar): Word;
{Displays a message in a dialog box with custom buttons and no icon that is
located relative to owner form.
@param Parent [in] Component that dialog box is aligned over and that
becomes parent of dialog box. If Parent is nil then current active form
is used.
@param Msg [in] Message displayed in dialog. Multi-line messages should be
separated by LF or CRLF.
@param Buttons [in] Array of records decribing buttons to be displayed.
@param Title [in] Optional title of dialog box. If Title='' then application
title is used.
@param IconRes [in] Optional icon resource. No icon is displayed if not
provided.
@return Value indicating which button was pressed to close dialog box. This
will be value of ModalResult field of one of the buttons specified in the
Buttons array.
}
begin
Result := Display(Parent, Msg, mtCustom, Buttons, Title, IconRes);
end;
class function TMessageBox.Display(const Parent: TComponent;
MsgLines: IStringList; const DlgType: TMsgDlgType;
const Buttons: array of TMessageBoxButton; const Title: string;
const IconRes: PChar): Word;
{Displays a message in a customised dialog box located over the calling form.
@param Parent [in] Component that dialog box is aligned over and that
becomes parent of dialog box. If Parent is nil then current active form is
used.
@param MsgLines [in] Message displayed in dialog. Can store mulitple lines.
Use empty lines to insert space between paragraphs.
@param DlgType [in] Type of dialog box.
@param Buttons [in] Array of records decribing buttons to be displayed.
@param Title [in] Title of dialog box. If '' title used depends on DlgType.
@param IconRes [in] Icon resource identifier. If nil icon used depends on
DlgType.
@return Value indicating which button was pressed to close dialog box. This
will be value of ModalResult field of one of the buttons specified in
Buttons.
}
var
Dlg: TForm; // dialog box instance
begin
// Create a dialog box of required type
Dlg := TMessageBoxForm.Create(
Parent, MsgLines, Buttons, DlgType, Title, IconRes
);
try
// Make sure "Parent" control is parent of dialog and align over it
TDlgHelper.SetDlgParent(Dlg, Parent);
TDlgAligner.Align(Dlg, Parent);
// Display the dialog and return result
Result := Dlg.ShowModal;
finally
FreeAndNil(Dlg);
end;
end;
class function TMessageBox.Display(const Parent: TComponent; const Msg: string;
const DlgType: TMsgDlgType; const Buttons: array of TMessageBoxButton;
const Title: string; const IconRes: PChar): Word;
{Displays a message in a customised dialog box located over the calling form.
@param Parent [in] Component that dialog box is aligned over and that
becomes parent of dialog box. If Parent is nil then current active form is
used.
@param Msg [in] Message displayed in dialog. Separate lines with LF or CRLF.
Separate paragraphs with two line breaks.
@param DlgType [in] Type of dialog box.
@param Buttons [in] Array of records decribing buttons to be displayed.
@param Title [in] Title of dialog box. If '' title used depends on DlgType.
@param IconRes [in] Icon resource identifier. If nil icon used depends on
DlgType.
@return Value indicating which button was pressed to close dialog box. This
will be value of ModalResult field of one of the buttons specified in
Buttons.
}
begin
Result := Display(
Parent,
// convert line breaks in Msg to LF only, remove leading and trailing LFs,
// ensure proper sentence and then convert text string list.
TIStringList.Create(
StrMakeSentence(StrTrimChars(StrUnixLineBreaks(Msg), LF)),
LF,
True
),
DlgType,
Buttons,
Title,
IconRes
);
end;
class procedure TMessageBox.Error(const Parent: TComponent; const Msg: string);
{Displays a message in an error dialog box located relative to owner form.
@param Parent [in] Component that dialog box is aligned over and that
becomes parent of dialog box. If Parent is nil then current active form
is used.
@param Msg [in] Message displayed in dialog. Multi-line messages should be
separated by LF or CRLF.
}
begin
MessageBeep(MB_ICONERROR);
Display(
Parent,
Msg,
mtError,
[TMessageBoxButton.Create(sBtnOK, mrOK, True, True)],
DefaultTitle,
DefaultIcon
);
end;
class procedure TMessageBox.Information(const Parent: TComponent;
const Msg: string);
{Displays a message in an information dialog box located relative to owner
form.
@param Parent [in] Component that dialog box is aligned over and that
becomes parent of dialog box. If Parent is nil then current active form
is used.
@param Msg [in] Message displayed in dialog. Multi-line messages should be
separated by LF or CRLF.
}
begin
Display(
Parent,
Msg,
mtInformation,
[TMessageBoxButton.Create(sBtnOK, mrOK, True, True)],
DefaultTitle,
DefaultIcon
);
end;
{ TMessageBoxButton }
constructor TMessageBoxButton.Create(const ACaption: TCaption;
const AModalResult: Integer; const ADefault, ACancel: Boolean);
{Initialises fields of record.
@param ACaption [in] Button's caption.
@param AModalResult [in] Modal result returned when button is clicked.
@param Default [in] Optional: value of button's Default property.
@param Cancel [in] Optional: value of button's Cancel property.
}
begin
Caption := ACaption;
ModalResult := AModalResult;
Default := ADefault;
Cancel := ACancel;
end;
{ TMessageBoxForm }
procedure TMessageBoxForm.ArrangeControls;
{Arranges all controls within dialog box.
}
// ---------------------------------------------------------------------------
procedure ArrangeLabels(const Left, Top: Integer);
{Arranges labels within dialog box.
@param Left [in] Left margin for all labels.
@param Top [in] Vertical position of first label.
}
var
Idx: Integer; // loops through all labels
NextTop: Integer; // vertical position of next label
begin
NextTop := Top;
for Idx := Low(fLabels) to High(fLabels) do
begin
fLabels[Idx].Left := Left;
fLabels[Idx].Top := NextTop;
Inc(NextTop, LabelHeight(fLabels[Idx]));
end;
end;
procedure ArrangeButtons(const Width, Top: Integer);
{Arranges buttons in a centred strip in dialog box.
@param Width [in] Width of button strip.
@param Top [in] Top of button strip.
}
var
Idx: Integer; // loops through all buttons
NextLeft: Integer; // horizontal position of each button
begin
NextLeft := (Width - ButtonsWidth) div 2;
for Idx := Low(fButtons) to High(fButtons) do
begin
fButtons[Idx].Top := Top;
fButtons[Idx].Left := NextLeft;
Inc(NextLeft, fButtons[Idx].Width + cBtnSpacing);
end;
end;
// ---------------------------------------------------------------------------
begin
ArrangeLabels(TextLeftMargin, cYPadding);
ArrangeButtons(
ClientWidth, TextAndIconHeight + cYPadding + cBtnStripTopMargin
);
end;
function TMessageBoxForm.ButtonsHeight: Integer;
{Calculates vertical space required to display button strip.
@return Required height in pixels.
}
begin
Result := fButtons[0].Height;
end;
function TMessageBoxForm.ButtonsWidth: Integer;
{Calculates horizontal space required to display strip of all buttons.
@return Required width in pixels.
}
begin
Result := Length(fButtons) * fButtons[0].Width
+ (Length(fButtons) - 1) * cBtnSpacing;
end;
constructor TMessageBoxForm.Create(const Owner: TComponent;
const Text: IStringList; const Buttons: array of TMessageBoxButton;
const DlgType: TMsgDlgType; const Title: string; const IconRes: PChar);
{Object constructor. Reintroduced constructor that creates dialog box form
with components required to display text, buttons and optional icon.
@param Owner [in] Control that owns this dialog box.
@param Text [in] List of lines of text to display. Blank lines indicate a
paragraph spacer.
@param Buttons [in] Array of records that define buttons to be displayed.
@param DlgType [in] Type of dialog box to be displayed.
@param Title [in] Optional dialog box caption text. If Title='' caption
depends on DlgType.
@param IconRes [in] Resource to be used for icon displayed. If nil then any
icon displayed depends on DlgType.
}
begin
Assert(Length(Buttons) > 0, ClassName + '.Create: Buttons array is empty');
Assert(Assigned(Text) and (Text.Count > 0),
ClassName + '.Ctreate: No message text provided');
inherited CreateNew(Owner);
Position := poDesigned; // must be poDesgined to enable alignment
BorderStyle := bsDialog; // it's a dialog box
// Set font to OS default
TFontHelper.SetDefaultFont(Font, False);
// Initialise controls
InitCaption(Title, DlgType);
InitImage(IconRes, DlgType);
InitButtons(Buttons);
InitLabels(Text);
// Size the dialog box
SizeDialogBox;
// Arrange controls within dialog box
ArrangeControls;
end;
procedure TMessageBoxForm.InitButtons(
const Buttons: array of TMessageBoxButton);
{Creates and sizes dialog's buttons.
@param Buttons [in] Array of records describing buttons to display.
}
// ---------------------------------------------------------------------------
procedure CreateButtons;
{Creates each required button control and stores reference in fButtons.
}
var
Idx: Integer; // loops through all button definition records
Btn: TButton; // reference to a created button control
begin
SetLength(fButtons, Length(Buttons));
for Idx := Low(Buttons) to High(Buttons) do
begin
Btn := TButton.Create(Self);
Btn.Parent := Self;
Btn.Name := Format('Button%d', [Idx]);
// set values from button definition record
Btn.Caption := Buttons[Idx].Caption;
Btn.ModalResult := Buttons[Idx].ModalResult;
Btn.Default := Buttons[Idx].Default;
Btn.Cancel := Buttons[Idx].Cancel;
fButtons[Idx] := Btn;
end;
end;
function ButtonTextExtent: TSize;
{Calculates text size of largest button caption. MUST be called after
CreateButtons.
@return Size structure that can hold largest caption.
}
var
Idx: Integer; // loops thru all buttons
Btn: TButton; // references each button
BtnTextExtent: TSize; // text extent of each button caption
begin
Result.cx := -1;
Result.cy := -1;
for Idx := Low(fButtons) to High(fButtons) do
begin
Btn := fButtons[Idx];
BtnTextExtent := StringExtent(Btn.Caption, Btn.Font);
Result.cx := Max(Result.cx, BtnTextExtent.cx);
Result.cy := Max(Result.cy, BtnTextExtent.cy);
end;
end;
procedure SizeButtons(const Size: TSize);
{Sets size of every button to a specified size. MUST be called after
CreateButtons.
@param Size [in] Required button size.
}
var
Idx: Integer; // loops thru all buttons
begin
for Idx := Low(fButtons) to High(fButtons) do
begin
fButtons[Idx].Width := Size.cx;
fButtons[Idx].Height := Size.cy;
end;
end;
// ---------------------------------------------------------------------------
var
TextExtent: TSize; // size of largest button caption
BtnSize: TSize; // size of every button
begin
// Create all required button controls
CreateButtons;
// Find size of largest button caption
TextExtent := ButtonTextExtent;
// Size of each button to be large enough to hold largest caption, but ensure
// buttons are no smaller than default size. All buttons have same size.
BtnSize.cx := Max(
fButtons[0].Width,
TextExtent.cx + fButtons[0].Margins.Left + fButtons[0].Margins.Right
);
BtnSize.cy := Max(
fButtons[0].Height,
TextExtent.cy + fButtons[0].Margins.Top + fButtons[0].Margins.Bottom
);
SizeButtons(BtnSize);
end;
procedure TMessageBoxForm.InitCaption(const Title: string;
const DlgType: TMsgDlgType);
{Sets text of dialog's caption.
@param Title [in] Title to display in dialog's caption. If '' a default
caption dependent on dialog type is used.
@param DlgType [in] Type of dialog box. Used to determine default caption
if Title is ''.
}
const
// Map of dialog types onto resource id of default caption
cCaptions: array[TMsgDlgType] of Pointer = (
@SMsgDlgWarning, @SMsgDlgError, @SMsgDlgInformation, @SMsgDlgConfirm, nil
);
begin
if Title <> TMessageBox.DefaultTitle then
// Caller specified a title: use it
Caption := Title
else
begin
// Caller did not specify a caption: use default
if Assigned(cCaptions[DlgType]) then
// get default from a resource string
Caption := LoadResString(cCaptions[DlgType])
else
// no default resource string: use application's title
Caption := Application.Title;
end;
end;
procedure TMessageBoxForm.InitImage(const IconRes: PChar;
const DlgType: TMsgDlgType);
{Creates and initialises and locates image control required to display any
icon. No image control is created if no icon is required.
@param IconRes [in] Icon resource. If nil then icon is determined by
DlgType.
@param DlgType [in] Type of dialog to be displayed. Determines which, if any
icon is required when IconRes is nil.
}
// ---------------------------------------------------------------------------
function ResourceInstance(const IconId: PChar): THandle;
{Returns instance handle for specified icon resource. If resource is a
recognised system icon then instance is 0, otherwise resource is assumed to
be in application's resources.
@param IconId [in] Icon resource identifier.
@return Required instance handle.
}
var
ID: PChar;
const
cSystemIcons: array[1..7] of PChar = (
IDI_APPLICATION, IDI_HAND, IDI_QUESTION, IDI_EXCLAMATION, IDI_ASTERISK,
IDI_WINLOGO, IDI_SHIELD
// IDI_WARNING, IDI_ERROR & IDI_INFORMATION excluded because they are
// alternates for above values
);
begin
for ID in cSystemIcons do
if Assigned(ID) and (IconID = ID) then
Exit(0);
Result := HInstance;
end;
// ---------------------------------------------------------------------------
const
// Map of dialog types onto icon resources
cIconIDs: array[TMsgDlgType] of PChar = (
IDI_EXCLAMATION, IDI_HAND, IDI_ASTERISK, IDI_QUESTION, nil
);
var
IconId: PChar; // resource id of icon (nil if no icon required)
begin
if IconRes <> TMessageBox.DefaultIcon then
IconId := IconRes
else
IconId := cIconIDs[DlgType];
if Assigned(IconId) then
begin
fImage := TImage.Create(Self);
fImage.Parent := Self;
fImage.Name := 'Image';
fImage.Picture.Icon.Handle := LoadIcon(ResourceInstance(IconID), IconID);
// icon is positioned at top left of dialog box, inside dialog's margins
fImage.BoundsRect := TRectEx.CreateBounds(
cXPadding, cYPadding,
fImage.Picture.Icon.Width, fImage.Picture.Icon.Height
);
end;
end;
procedure TMessageBoxForm.InitLabels(const Lines: IStringList);
{Creates and sizes labels used to display text in dialog box.
@param Lines [in] String list containing lines of text to display. Blank
lines indicate a paragraph break.
}
// ---------------------------------------------------------------------------
procedure CreateLabels;
{Creates all required labels and stores reference in fLabels[].
}
var
Idx: Integer; // loops through all lines of text
Lbl: TLabel; // reference to a label
begin
SetLength(fLabels, Lines.Count);
for Idx := 0 to Pred(Lines.Count) do
begin
Lbl := TLabel.Create(Self);
Lbl.Parent := Self;
Lbl.Name := Format('Label%d', [Idx]);
Lbl.Caption := Lines[Idx];
Lbl.AutoSize := False;
Lbl.WordWrap := True;
Lbl.ShowAccelChar := False;
Lbl.Width := 0; // width and height MUST be initialised to 0 here
Lbl.Height := 0;
fLabels[Idx] := Lbl;
end;
end;
procedure SizeLabels;
{Sets the width and height of the labels. MUST be called after CreateLabels.
}
var
Idx: Integer; // loops through all labels
TextRect: TRectEx; // bounding rectangle of text in label
const
// Text formatting flags
cTextFlags = DT_EXPANDTABS or DT_WORDBREAK or DT_NOPREFIX;
begin
for Idx := Low(fLabels) to High(fLabels) do
begin
// Treat empty labels differently: leave width and height at 0
if fLabels[Idx].Caption = '' then
Continue;
// Get size of rectangle required to display a label
TextRect := GetTextRect(
fLabels[Idx].Caption,
Canvas,
Rect(0, 0, MaxTextWidth, 0),
cTextFlags or fLabels[Idx].DrawTextBiDiModeFlagsReadingOnly
);
// Size the label
fLabels[Idx].Width := TextRect.Width;
fLabels[Idx].Height := TextRect.Height;
end;
end;
// ---------------------------------------------------------------------------
begin
CreateLabels;
SizeLabels;
end;
function TMessageBoxForm.LabelHeight(const Lbl: TLabel): Integer;
{Calculates height of a label.
@param Lbl [in] Label for which height is required.
@return Label height in pixels.
}
begin
// We treat blank labels differently: they represent paragraph breaks
if Lbl.Caption <> '' then
Result := Lbl.Height
else
Result := cParaSpacing;
end;
function TMessageBoxForm.LabelsHeight: Integer;
{Finds height required to display all labels.
@return Required height in pixels.
}
var
Idx: Integer; // loops thru all labels
begin
Result := 0;
for Idx := Low(fLabels) to High(fLabels) do
Inc(Result, LabelHeight(fLabels[Idx]));
end;
function TMessageBoxForm.LabelsWidth: Integer;
{Finds width of text in widest label.
@return Required width in pixels.
}
var
Idx: Integer; // loops thru all labels
begin
Result := 0;
for Idx := Low(fLabels) to High(fLabels) do
begin
if fLabels[Idx].Width > Result then
Result := fLabels[Idx].Width;
end;
end;
function TMessageBoxForm.MaxTextWidth: Integer;
{Calculates maximum horizontal space that can be occupied by the dialog's
text.
@return Required width in pixels.
}
begin
// For smaller screens, max space is half of screen width. For larger screens
// max space is cMaxDlgWidth pixels.
Result := Min(cMaxTextWidth, Screen.Width div 2);
end;
procedure TMessageBoxForm.SizeDialogBox;
{Sets size of dialog box to accomodate text, optional icon and buttons.
}
begin
ClientWidth := Max(ButtonsWidth, TextAndIconWidth) + 2 * cXPadding;
ClientHeight := TextAndIconHeight + ButtonsHeight
+ 2 * cyPadding + cBtnStripTopMargin;
end;
function TMessageBoxForm.TextAndIconHeight: Integer;
{Calculates vertical space required to accommodate text and any icon.
@return Required height in pixels.
}
begin
if Assigned(fImage) then
Result := Max(LabelsHeight, fImage.Height)
else
Result := LabelsHeight;
end;
function TMessageBoxForm.TextAndIconWidth: Integer;
{Calculates horizontal spaces required to accommodate text and any icon.
@return Required width in pixels.
}
begin
Result := LabelsWidth;
if Assigned(fImage) then
Inc(Result, fImage.Width + cXPadding);
end;
function TMessageBoxForm.TextLeftMargin: Integer;
{Calculates offset of text from dialog box's left hand margin. Depends on
whether dialog box displays an icon.
@return Required margin in pixels.
}
begin
if Assigned(fImage) then
Result := fImage.Width + 2 * cXPadding
else
Result := cXPadding;
end;
end.
