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TQMessageBox Class Reference

The TQMessageBox class provides a modal dialog with a short message, an icon, and some buttons. More...

#include <tqmessagebox.h>

Inherits TQDialog.

List of all member functions.

Public Members

Static Public Members

Properties


Detailed Description

The TQMessageBox class provides a modal dialog with a short message, an icon, and some buttons.

Message boxes are used to provide informative messages and to ask simple questions.

TQMessageBox provides a range of different messages, arranged roughly along two axes: severity and complexity.

Severity is

Question For message boxes that ask a question as part of normal operation. Some style guides recommend using Information for this purpose.
Information For message boxes that are part of normal operation.
Warning For message boxes that tell the user about unusual errors.
Critical For message boxes that tell the user about critical errors.

The message box has a different icon for each of the severity levels.

Complexity is one button (OK) for simple messages, or two or even three buttons for questions.

There are static functions for the most common cases.

Examples:

If a program is unable to find a supporting file, but can do perfectly well without it:

    TQMessageBox::information( this, "Application name",
    "Unable to find the user preferences file.\n"
    "The factory default will be used instead." );
    

question() is useful for simple yes/no questions:

    if ( TQFile::exists( filename ) &&
        TQMessageBox::question(
            this,
            tr("Overwrite File? -- Application Name"),
            tr("A file called %1 already exists."
                "Do you want to overwrite it?")
                .arg( filename ),
            tr("&Yes"), tr("&No"),
            TQString::null, 0, 1 ) )
        return false;
    

warning() can be used to tell the user about unusual errors, or errors which can't be easily fixed:

    switch( TQMessageBox::warning( this, "Application name",
        "Could not connect to the <mumble> server.\n"
        "This program can't function correctly "
        "without the server.\n\n",
        "Retry",
        "Quit", 0, 0, 1 ) ) {
    case 0: // The user clicked the Retry again button or pressed Enter
        // try again
        break;
    case 1: // The user clicked the Quit or pressed Escape
        // exit
        break;
    }
    

The text part of all message box messages can be either rich text or plain text. If you specify a rich text formatted string, it will be rendered using the default stylesheet. See TQStyleSheet::defaultSheet() for details. With certain strings that contain XML meta characters, the auto-rich text detection may fail, interpreting plain text incorrectly as rich text. In these rare cases, use TQStyleSheet::convertFromPlainText() to convert your plain text string to a visually equivalent rich text string or set the text format explicitly with setTextFormat().

Note that the Microsoft Windows User Interface Guidelines recommend using the application name as the window's caption.

Below are more examples of how to use the static member functions. After these examples you will find an overview of the non-static member functions.

Exiting a program is part of its normal operation. If there is unsaved data the user probably should be asked if they want to save the data. For example:

    switch( TQMessageBox::information( this, "Application name here",
        "The document contains unsaved changes\n"
        "Do you want to save the changes before exiting?",
        "&Save", "&Discard", "Cancel",
        0,      // Enter == button 0
        2 ) ) { // Escape == button 2
    case 0: // Save clicked or Alt+S pressed or Enter pressed.
        // save
        break;
    case 1: // Discard clicked or Alt+D pressed
        // don't save but exit
        break;
    case 2: // Cancel clicked or Escape pressed
        // don't exit
        break;
    }
    

The Escape button cancels the entire exit operation, and pressing Enter causes the changes to be saved before the exit occurs.

Disk full errors are unusual and they certainly can be hard to correct. This example uses predefined buttons instead of hard-coded button texts:

    switch( TQMessageBox::warning( this, "Application name here",
        "Could not save the user preferences,\n"
        "because the disk is full. You can delete\n"
        "some files and press Retry, or you can\n"
        "abort the Save Preferences operation.",
        TQMessageBox::Retry | TQMessageBox::Default,
        TQMessageBox::Abort | TQMessageBox::Escape )) {
    case TQMessageBox::Retry: // Retry clicked or Enter pressed
        // try again
        break;
    case TQMessageBox::Abort: // Abort clicked or Escape pressed
        // abort
        break;
    }
    

The critical() function should be reserved for critical errors. In this example errorDetails is a TQString or const char*, and TQString is used to concatenate several strings:

    TQMessageBox::critical( 0, "Application name here",
        TQString("An internal error occurred. Please ") +
        "call technical support at 1234-56789 and report\n"+
        "these numbers:\n\n" + errorDetails +
        "\n\nApplication will now exit." );
    

In this example an OK button is displayed.

TQMessageBox provides a very simple About box which displays an appropriate icon and the string you provide:

    TQMessageBox::about( this, "About <Application>",
        "<Application> is a <one-paragraph blurb>\n\n"
        "Copyright 1991-2003 Such-and-such. "
        "<License words here.>\n\n"
        "For technical support, call 1234-56789 or see\n"
        "http://www.such-and-such.com/Application/\n" );
    

See about() for more information.

If you want your users to know that the application is built using TQt (so they know that you use high quality tools) you might like to add an "About TQt" menu option under the Help menu to invoke aboutTQt().

If none of the standard message boxes is suitable, you can create a TQMessageBox from scratch and use custom button texts:

    TQMessageBox mb( "Application name here",
        "Saving the file will overwrite the original file on the disk.\n"
        "Do you really want to save?",
        TQMessageBox::Information,
        TQMessageBox::Yes | TQMessageBox::Default,
        TQMessageBox::No,
        TQMessageBox::Cancel | TQMessageBox::Escape );
    mb.setButtonText( TQMessageBox::Yes, "Save" );
    mb.setButtonText( TQMessageBox::No, "Discard" );
    switch( mb.exec() ) {
    case TQMessageBox::Yes:
        // save and exit
        break;
    case TQMessageBox::No:
        // exit without saving
        break;
    case TQMessageBox::Cancel:
        // don't save and don't exit
        break;
    }
    

TQMessageBox defines two enum types: Icon and an unnamed button type. Icon defines the Question, Information, Warning, and Critical icons for each GUI style. It is used by the constructor and by the static member functions question(), information(), warning() and critical(). A function called standardIcon() gives you access to the various icons.

The button types are:

Button types can be combined with two modifiers by using OR, '|':

The text(), icon() and iconPixmap() functions provide access to the current text and pixmap of the message box. The setText(), setIcon() and setIconPixmap() let you change it. The difference between setIcon() and setIconPixmap() is that the former accepts a TQMessageBox::Icon and can be used to set standard icons, whereas the latter accepts a TQPixmap and can be used to set custom icons.

setButtonText() and buttonText() provide access to the buttons.

TQMessageBox has no signals or slots.

See also TQDialog, Isys on error messages, GUI Design Handbook: Message Box, and Dialog Classes.


Member Type Documentation

TQMessageBox::Icon

This enum has the following values:


Member Function Documentation

TQMessageBox::TQMessageBox ( TQWidget * parent = 0, const char * name = 0 )

Constructs a message box with no text and a button with the label "OK".

If parent is 0, the message box becomes an application-global modal dialog box. If parent is a widget, the message box becomes modal relative to parent.

The parent and name arguments are passed to the TQDialog constructor.

TQMessageBox::TQMessageBox ( const TQString & caption, const TQString & text, Icon icon, int button0, int button1, int button2, TQWidget * parent = 0, const char * name = 0, bool modal = TRUE, WFlags f = WStyle_DialogBorder )

Constructs a message box with a caption, a text, an icon, and up to three buttons.

The icon must be one of the following:

Each button, button0, button1 and button2, can have one of the following values:

Use TQMessageBox::NoButton for the later parameters to have fewer than three buttons in your message box. If you don't specify any buttons at all, TQMessageBox will provide an Ok button.

One of the buttons can be OR-ed with the TQMessageBox::Default flag to make it the default button (clicked when Enter is pressed).

One of the buttons can be OR-ed with the TQMessageBox::Escape flag to make it the cancel or close button (clicked when Escape is pressed).

Example:

    TQMessageBox mb( "Application Name",
        "Hardware failure.\n\nDisk error detected\nDo you want to stop?",
        TQMessageBox::Question,
        TQMessageBox::Yes | TQMessageBox::Default,
        TQMessageBox::No  | TQMessageBox::Escape,
        TQMessageBox::NoButton );
    if ( mb.exec() == TQMessageBox::No )
        // try again
    

If parent is 0, the message box becomes an application-global modal dialog box. If parent is a widget, the message box becomes modal relative to parent.

If modal is TRUE the message box is modal; otherwise it is modeless.

The parent, name, modal, and f arguments are passed to the TQDialog constructor.

See also caption, text, and icon.

TQMessageBox::~TQMessageBox ()

Destroys the message box.

void TQMessageBox::about ( TQWidget * parent, const TQString & caption, const TQString & text ) [static]

Displays a simple about box with caption caption and text text. The about box's parent is parent.

about() looks for a suitable icon in four locations:

  1. It prefers parent->icon() if that exists.
  2. If not, it tries the top-level widget containing parent.
  3. If that fails, it tries the main widget.
  4. As a last resort it uses the Information icon.

The about box has a single button labelled "OK".

See also TQWidget::icon and TQApplication::mainWidget().

Examples: action/application.cpp, application/application.cpp, chart/chartform.cpp, helpviewer/helpwindow.cpp, mdi/application.cpp, menu/menu.cpp, and themes/themes.cpp.

void TQMessageBox::aboutTQt ( TQWidget * parent, const TQString & caption = TQString::null ) [static]

Displays a simple message box about TQt, with caption caption and centered over parent (if parent is not 0). The message includes the version number of TQt being used by the application.

This is useful for inclusion in the Help menu of an application. See the examples/menu/menu.cpp example.

TQApplication provides this functionality as a slot.

See also TQApplication::aboutTQt().

Examples: action/application.cpp, application/application.cpp, chart/chartform.cpp, helpviewer/helpwindow.cpp, menu/menu.cpp and themes/themes.cpp.

void TQMessageBox::adjustSize () [virtual]

Adjusts the size of the message box to fit the contents just before TQDialog::exec() or TQDialog::show() is called.

This function will not be called if the message box has been explicitly resized before showing it.

Reimplemented from TQWidget.

TQString TQMessageBox::buttonText ( int button ) const

Returns the text of the message box button button, or TQString::null if the message box does not contain the button.

See also setButtonText().

int TQMessageBox::critical ( TQWidget * parent, const TQString & caption, const TQString & text, int button0, int button1, int button2 = 0 ) [static]

Opens a critical message box with the caption caption and the text text. The dialog may have up to three buttons. Each of the button parameters, button0, button1 and button2 may be set to one of the following values:

If you don't want all three buttons, set the last button, or last two buttons to TQMessageBox::NoButton.

One button can be OR-ed with TQMessageBox::Default, and one button can be OR-ed with TQMessageBox::Escape.

Returns the identity (TQMessageBox::Ok, or TQMessageBox::No, etc.) of the button that was clicked.

If parent is 0, the message box becomes an application-global modal dialog box. If parent is a widget, the message box becomes modal relative to parent.

See also information(), question(), and warning().

Examples: network/archivesearch/archivedialog.ui.h, network/ftpclient/ftpmainwindow.ui.h, process/process.cpp, and xml/outliner/outlinetree.cpp.

int TQMessageBox::critical ( TQWidget * parent, const TQString & caption, const TQString & text, const TQString & button0Text = TQString::null, const TQString & button1Text = TQString::null, const TQString & button2Text = TQString::null, int defaultButtonNumber = 0, int escapeButtonNumber = -1 ) [static]

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Displays a critical error message box with a caption, a text, and 1, 2 or 3 buttons. Returns the number of the button that was clicked (0, 1 or 2).

button0Text is the text of the first button, and is optional. If button0Text is not supplied, "OK" (translated) will be used. button1Text is the text of the second button, and is optional, and button2Text is the text of the third button, and is optional. defaultButtonNumber (0, 1 or 2) is the index of the default button; pressing Return or Enter is the same as clicking the default button. It defaults to 0 (the first button). escapeButtonNumber is the index of the Escape button; pressing Escape is the same as clicking this button. It defaults to -1; supply 0, 1, or 2 to make pressing Escape equivalent to clicking the relevant button.

If parent is 0, the message box becomes an application-global modal dialog box. If parent is a widget, the message box becomes modal relative to parent.

See also information(), question(), and warning().

Icon TQMessageBox::icon () const

Returns the message box's icon. See the "icon" property for details.

const TQPixmap * TQMessageBox::iconPixmap () const

Returns the current icon. See the "iconPixmap" property for details.

int TQMessageBox::information ( TQWidget * parent, const TQString & caption, const TQString & text, int button0, int button1 = 0, int button2 = 0 ) [static]

Opens an information message box with the caption caption and the text text. The dialog may have up to three buttons. Each of the buttons, button0, button1 and button2 may be set to one of the following values:

If you don't want all three buttons, set the last button, or last two buttons to TQMessageBox::NoButton.

One button can be OR-ed with TQMessageBox::Default, and one button can be OR-ed with TQMessageBox::Escape.

Returns the identity (TQMessageBox::Ok, or TQMessageBox::No, etc.) of the button that was clicked.

If parent is 0, the message box becomes an application-global modal dialog box. If parent is a widget, the message box becomes modal relative to parent.

See also question(), warning(), and critical().

Examples: action/application.cpp, application/application.cpp, dirview/dirview.cpp, fileiconview/tqfileiconview.cpp, picture/picture.cpp and qwerty/qwerty.cpp.

int TQMessageBox::information ( TQWidget * parent, const TQString & caption, const TQString & text, const TQString & button0Text = TQString::null, const TQString & button1Text = TQString::null, const TQString & button2Text = TQString::null, int defaultButtonNumber = 0, int escapeButtonNumber = -1 ) [static]

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Displays an information message box with caption caption, text text and one, two or three buttons. Returns the index of the button that was clicked (0, 1 or 2).

button0Text is the text of the first button, and is optional. If button0Text is not supplied, "OK" (translated) will be used. button1Text is the text of the second button, and is optional. button2Text is the text of the third button, and is optional. defaultButtonNumber (0, 1 or 2) is the index of the default button; pressing Return or Enter is the same as clicking the default button. It defaults to 0 (the first button). escapeButtonNumber is the index of the Escape button; pressing Escape is the same as clicking this button. It defaults to -1; supply 0, 1 or 2 to make pressing Escape equivalent to clicking the relevant button.

If parent is 0, the message box becomes an application-global modal dialog box. If parent is a widget, the message box becomes modal relative to parent.

Note: If you do not specify an Escape button then if the Escape button is pressed then -1 will be returned. It is suggested that you specify an Escape button to prevent this from happening.

See also question(), warning(), and critical().

int TQMessageBox::message ( const TQString & caption, const TQString & text, const TQString & buttonText = TQString::null, TQWidget * parent = 0, const char * = 0 ) [static]

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Opens a modal message box directly using the specified parameters.

Please use information(), warning(), question(), or critical() instead.

bool TQMessageBox::query ( const TQString & caption, const TQString & text, const TQString & yesButtonText = TQString::null, const TQString & noButtonText = TQString::null, TQWidget * parent = 0, const char * = 0 ) [static]

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Queries the user using a modal message box with two buttons. Note that caption is not always shown, it depends on the window manager.

Please use information(), question(), warning(), or critical() instead.

int TQMessageBox::question ( TQWidget * parent, const TQString & caption, const TQString & text, int button0, int button1 = 0, int button2 = 0 ) [static]

Opens a question message box with the caption caption and the text text. The dialog may have up to three buttons. Each of the buttons, button0, button1 and button2 may be set to one of the following values:

If you don't want all three buttons, set the last button, or last two buttons to TQMessageBox::NoButton.

One button can be OR-ed with TQMessageBox::Default, and one button can be OR-ed with TQMessageBox::Escape.

Returns the identity (TQMessageBox::Yes, or TQMessageBox::No, etc.) of the button that was clicked.

If parent is 0, the message box becomes an application-global modal dialog box. If parent is a widget, the message box becomes modal relative to parent.

See also information(), warning(), and critical().

int TQMessageBox::question ( TQWidget * parent, const TQString & caption, const TQString & text, const TQString & button0Text = TQString::null, const TQString & button1Text = TQString::null, const TQString & button2Text = TQString::null, int defaultButtonNumber = 0, int escapeButtonNumber = -1 ) [static]

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Displays a question message box with caption caption, text text and one, two or three buttons. Returns the index of the button that was clicked (0, 1 or 2).

button0Text is the text of the first button, and is optional. If button0Text is not supplied, "OK" (translated) will be used. button1Text is the text of the second button, and is optional. button2Text is the text of the third button, and is optional. defaultButtonNumber (0, 1 or 2) is the index of the default button; pressing Return or Enter is the same as clicking the default button. It defaults to 0 (the first button). escapeButtonNumber is the index of the Escape button; pressing Escape is the same as clicking this button. It defaults to -1; supply 0, 1 or 2 to make pressing Escape equivalent to clicking the relevant button.

If parent is 0, the message box becomes an application-global modal dialog box. If parent is a widget, the message box becomes modal relative to parent.

Note: If you do not specify an Escape button then if the Escape button is pressed then -1 will be returned. It is suggested that you specify an Escape button to prevent this from happening.

See also information(), warning(), and critical().

void TQMessageBox::setButtonText ( int button, const TQString & text )

Sets the text of the message box button button to text. Setting the text of a button that is not in the message box is silently ignored.

See also buttonText().

void TQMessageBox::setIcon ( Icon )

Sets the message box's icon. See the "icon" property for details.

void TQMessageBox::setIconPixmap ( const TQPixmap & )

Sets the current icon. See the "iconPixmap" property for details.

void TQMessageBox::setText ( const TQString & )

Sets the message box text to be displayed. See the "text" property for details.

void TQMessageBox::setTextFormat ( TextFormat )

Sets the format of the text displayed by the message box. See the "textFormat" property for details.

TQPixmap TQMessageBox::standardIcon ( Icon icon ) [static]

Returns the pixmap used for a standard icon. This allows the pixmaps to be used in more complex message boxes. icon specifies the required icon, e.g. TQMessageBox::Question, TQMessageBox::Information, TQMessageBox::Warning or TQMessageBox::Critical.

TQPixmap TQMessageBox::standardIcon ( Icon icon, GUIStyle style ) [static]

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Returns the pixmap used for a standard icon. This allows the pixmaps to be used in more complex message boxes. icon specifies the required icon, e.g. TQMessageBox::Information, TQMessageBox::Warning or TQMessageBox::Critical.

style is unused.

TQString TQMessageBox::text () const

Returns the message box text to be displayed. See the "text" property for details.

TextFormat TQMessageBox::textFormat () const

Returns the format of the text displayed by the message box. See the "textFormat" property for details.

int TQMessageBox::warning ( TQWidget * parent, const TQString & caption, const TQString & text, int button0, int button1, int button2 = 0 ) [static]

Opens a warning message box with the caption caption and the text text. The dialog may have up to three buttons. Each of the button parameters, button0, button1 and button2 may be set to one of the following values:

If you don't want all three buttons, set the last button, or last two buttons to TQMessageBox::NoButton.

One button can be OR-ed with TQMessageBox::Default, and one button can be OR-ed with TQMessageBox::Escape.

Returns the identity (TQMessageBox::Ok, or TQMessageBox::No, etc.) of the button that was clicked.

If parent is 0, the message box becomes an application-global modal dialog box. If parent is a widget, the message box becomes modal relative to parent.

See also information(), question(), and critical().

Examples: chart/chartform.cpp, i18n/main.cpp, network/mail/smtp.cpp, qwerty/qwerty.cpp, showimg/showimg.cpp, and sound/sound.cpp.

int TQMessageBox::warning ( TQWidget * parent, const TQString & caption, const TQString & text, const TQString & button0Text = TQString::null, const TQString & button1Text = TQString::null, const TQString & button2Text = TQString::null, int defaultButtonNumber = 0, int escapeButtonNumber = -1 ) [static]

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Displays a warning message box with a caption, a text, and 1, 2 or 3 buttons. Returns the number of the button that was clicked (0, 1, or 2).

button0Text is the text of the first button, and is optional. If button0Text is not supplied, "OK" (translated) will be used. button1Text is the text of the second button, and is optional, and button2Text is the text of the third button, and is optional. defaultButtonNumber (0, 1 or 2) is the index of the default button; pressing Return or Enter is the same as clicking the default button. It defaults to 0 (the first button). escapeButtonNumber is the index of the Escape button; pressing Escape is the same as clicking this button. It defaults to -1; supply 0, 1, or 2 to make pressing Escape equivalent to clicking the relevant button.

If parent is 0, the message box becomes an application-global modal dialog box. If parent is a widget, the message box becomes modal relative to parent.

Note: If you do not specify an Escape button then if the Escape button is pressed then -1 will be returned. It is suggested that you specify an Escape button to prevent this from happening.

See also information(), question(), and critical().


Property Documentation

Icon icon

This property holds the message box's icon.

The icon of the message box can be one of the following predefined icons:

The actual pixmap used for displaying the icon depends on the current GUI style. You can also set a custom pixmap icon using the TQMessageBox::iconPixmap property. The default icon is TQMessageBox::NoIcon.

See also iconPixmap.

Set this property's value with setIcon() and get this property's value with icon().

TQPixmap iconPixmap

This property holds the current icon.

The icon currently used by the message box. Note that it's often hard to draw one pixmap that looks appropriate in both Motif and Windows GUI styles; you may want to draw two pixmaps.

See also icon.

Set this property's value with setIconPixmap() and get this property's value with iconPixmap().

TQString text

This property holds the message box text to be displayed.

The text will be interpreted either as a plain text or as rich text, depending on the text format setting (TQMessageBox::textFormat). The default setting is AutoText, i.e. the message box will try to auto-detect the format of the text.

The default value of this property is TQString::null.

See also textFormat.

Set this property's value with setText() and get this property's value with text().

TextFormat textFormat

This property holds the format of the text displayed by the message box.

The current text format used by the message box. See the TQt::TextFormat enum for an explanation of the possible options.

The default format is AutoText.

See also text.

Set this property's value with setTextFormat() and get this property's value with textFormat().


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TQt 3.3.8