| Description |
The MessageDlg function is used to display messages to the user. These messages may be informational, or warnings or whatever. There is complete freedom over the choice of buttons that the user may press to acknowledge the dialog.
For example, the user may be shown an error message, and be allowed to abort, retry or cancel the erroneous process.
The DialogType may have one of the following enumerated values:
| mtWarning | Displays a exclamation symbol |
| mtError | Displays a red 'X' |
| mtInformation | Displays an 'i' in a bubble |
| mtConfirmation | Displays an question mark |
| mtCustom | Displays just the message |
The Buttons value may be one or more of the following enumerated values :
| mbYes | Displays a 'Yes' button |
| mbNo | Displays a 'No' button |
| mbOK | Displays an 'OK' button |
| mbCancel | Displays a 'Cancel' button |
| mbAbort | Displays an 'Abort' button |
| mbRetry | Displays a 'Retry' button |
| mbIgnore | Displays an 'Ignore' button |
| mbAll | Displays an 'All' button |
| mbNoToAll | Displays a 'No to all' button |
| mbYesToAll | Displys a 'Yes to all' button |
| mbHelp | Displays a 'Help' button |
You specify these values comma separated in square brackets, as in the second code example.
Delphi provides a number of predefined button combinations:
| mbYesNoCancel | = [mbYes,mbNO,mbCancel] |
| mbYesAllNoAllCancel | =[mbYes,mbYesToAll, mbNo,mbNoToAll,mbCancel] |
| mbOKCancel | =[mbOK,mbCancel] |
| mbAbortRetryCancel | =[mbAbort,mbRetry,mbCancel] |
| mbAbortIgnore | =[mbAbort,mbIgnore] |
Now Delphi seem to have made a design error when setting the return value from the dialog box. Instead of specifying the enumeration value of the button pressed, it uses a completely different set of enumeration names:
| mrYes | = 6 |
| mrNo | = 7 |
| mrOK | = 1 |
| mrCancel | = 2 |
| mrAbort | = 3 |
| mrRetry | = 4 |
| mrIgnore | = 5 |
| mrAll | = 8 |
| mrNoToAll | = 9 |
| mrYesToAll | = 10 |
The values given are the numerical values of these enumerations, given in the numerical order that the mb equivalents are defined. This is very odd.
Additionally, these values are defined in the Controls unit, not the Dialogs unit.
Note that the Help button has no equivalent return value. This is because it does not terminate the dialog.
The HelpContext value is used in conjunction with the Help button. It's use is beyond the scope of Smart Pascal.
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| Related commands |
| InputBox |
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Display a dialog that asks for user text input, with default |
| InputQuery |
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Display a dialog that asks for user text input |
| MessageDlgPos |
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Displays a message plus buttons at a given screen position |
| ShowMessage |
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Display a string in a simple dialog with an OK button |
| ShowMessageFmt |
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Display formatted data in a simple dialog with an OK button |
| ShowMessagePos |
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Display a string in a simple dialog at a given screen position |
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| Example code : Display a confirmation dialog |
var
buttonSelected : Integer;
begin
// Show a confirmation dialog
buttonSelected := MessageDlg('Confirmation',mtError, mbOKCancel, 0);
// Show the button type selected
if buttonSelected = mrOK then WriteLn('OK pressed');
if buttonSelected = mrCancel then WriteLn('Cancel pressed');
end;
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| Show full unit code |
A confirmation dialog is displayed with OK and Cancel buttons.
The user presses OK :
OK pressed
is displayed in another dialog box.
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| Example code : Displays a custom dialog with custom button selection |
var
buttonSelected : Integer;
begin
// Show a custom dialog
buttonSelected := MessageDlg('Custom dialog',mtCustom,
[mbYes,mbAll,mbCancel], 0);
// Show the button type selected
if buttonSelected = mrYes then WriteLn('Yes pressed');
if buttonSelected = mrAll then WriteLn('All pressed');
if buttonSelected = mrCancel then WriteLn('Cancel pressed');
end;
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| Show full unit code |
A dialog with no icon is displayed with Yes, Cancel and All buttons.
The user presses the All button :
All pressed
is shown in another dialog
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