JUCE: FileBasedDocument Class Reference

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FileBasedDocument Class Referenceabstract
juce_gui_extra » documents

A class to take care of the logic involved with the loading/saving of some kind of document. More...

`#include <juce_FileBasedDocument.h>`

Inheritance diagram for FileBasedDocument:

## Public Types
enum | SaveResult { savedOk = 0 , userCancelledSave , failedToWriteToFile }
| A set of possible outcomes of one of the save() methods. More...

## Public Member Functions
| FileBasedDocument (const String &fileExtension, const String &fileWildCard, const String &openFileDialogTitle, const String &saveFileDialogTitle)
| Creates a FileBasedDocument.
| ~FileBasedDocument () override
| Destructor.
bool | hasChangedSinceSaved () const
| Returns true if the changed() method has been called since the file was last saved or loaded.
virtual void | changed ()
| Called to indicate that the document has changed and needs saving.
void | setChangedFlag (bool hasChanged)
| Sets the state of the 'changed' flag.
Result | loadFrom (const File &fileToLoadFrom, bool showMessageOnFailure, bool showWaitCursor=true)
| Tries to open a file.
void | loadFromAsync (const File &fileToLoadFrom, bool showMessageOnFailure, std::function< void(Result)> callback)
| Tries to open a file.
Result | loadFromUserSpecifiedFile (bool showMessageOnFailure)
| Asks the user for a file and tries to load it.
void | loadFromUserSpecifiedFileAsync (bool showMessageOnFailure, std::function< void(Result)> callback)
| Asks the user for a file and tries to load it.
SaveResult | save (bool askUserForFileIfNotSpecified, bool showMessageOnFailure)
| Tries to save the document to the last file it was saved or loaded from.
void | saveAsync (bool askUserForFileIfNotSpecified, bool showMessageOnFailure, std::function< void(SaveResult)> callback)
| Tries to save the document to the last file it was saved or loaded from.
SaveResult | saveIfNeededAndUserAgrees ()
| If the file needs saving, it'll ask the user if that's what they want to do, and save it if they say yes.
void | saveIfNeededAndUserAgreesAsync (std::function< void(SaveResult)> callback)
| If the file needs saving, it'll ask the user if that's what they want to do, and save it if they say yes.
SaveResult | saveAs (const File &newFile, bool warnAboutOverwritingExistingFiles, bool askUserForFileIfNotSpecified, bool showMessageOnFailure, bool showWaitCursor=true)
| Tries to save the document to a specified file.
void | saveAsAsync (const File &newFile, bool warnAboutOverwritingExistingFiles, bool askUserForFileIfNotSpecified, bool showMessageOnFailure, std::function< void(SaveResult)> callback)
| Tries to save the document to a specified file.
SaveResult | saveAsInteractive (bool warnAboutOverwritingExistingFiles)
| Prompts the user for a filename and tries to save to it.
void | saveAsInteractiveAsync (bool warnAboutOverwritingExistingFiles, std::function< void(SaveResult)> callback)
| Prompts the user for a filename and tries to save to it.
const File & | getFile () const
| Returns the file that this document was last successfully saved or loaded from.
void | setFile (const File &newFile)
| Sets the file that this document thinks it was loaded from.
Public Member Functions inherited from ChangeBroadcaster
| ChangeBroadcaster () noexcept
| Creates an ChangeBroadcaster.
virtual | ~ChangeBroadcaster ()
| Destructor.
void | addChangeListener (ChangeListener *listener)
| Registers a listener to receive change callbacks from this broadcaster.
void | removeChangeListener (ChangeListener *listener)
| Unregisters a listener from the list.
void | removeAllChangeListeners ()
| Removes all listeners from the list.
void | sendChangeMessage ()
| Causes an asynchronous change message to be sent to all the registered listeners.
void | sendSynchronousChangeMessage ()
| Sends a synchronous change message to all the registered listeners.
void | dispatchPendingMessages ()
| If a change message has been sent but not yet dispatched, this will call sendSynchronousChangeMessage() to make the callback immediately.

## Protected Member Functions
virtual String | getDocumentTitle ()=0
| Overload this to return the title of the document.
virtual Result | loadDocument (const File &file)=0
| This method should try to load your document from the given file.
virtual void | loadDocumentAsync (const File &file, std::function< void(Result)> callback)
| This method should try to load your document from the given file, then call the provided callback on the message thread, passing the result of the load.
virtual Result | saveDocument (const File &file)=0
| This method should try to write your document to the given file.
virtual void | saveDocumentAsync (const File &file, std::function< void(Result)> callback)
| This method should try to write your document to the given file, then call the provided callback on the message thread, passing the result of the write.
virtual File | getLastDocumentOpened ()=0
| This is used for dialog boxes to make them open at the last folder you were using.
virtual void | setLastDocumentOpened (const File &file)=0
| This is used for dialog boxes to make them open at the last folder you were using.
virtual File | getSuggestedSaveAsFile (const File &defaultFile)
| This is called by saveAsInteractiveAsync() to allow you to optionally customise the filename that the user is presented with in the save dialog.

## Detailed Description

A class to take care of the logic involved with the loading/saving of some kind of document.

There's quite a lot of tedious logic involved in writing all the load/save/save-as functions you need for documents that get saved to a file, so this class attempts to abstract most of the boring stuff.

Your subclass should just implement all the pure virtual methods, and you can then use the higher-level public methods to do the load/save dialogs, to warn the user about overwriting files, etc.

The document object keeps track of whether it has changed since it was last saved or loaded, so when you change something, call its changed() method. This will set a flag so it knows it needs saving, and will also broadcast a change message using the ChangeBroadcaster base class.

See also
  ChangeBroadcaster

## Member Enumeration Documentation

## ◆ SaveResult

enum FileBasedDocument::SaveResult

A set of possible outcomes of one of the save() methods.

Enumerator
savedOk | indicates that a file was saved successfully.
userCancelledSave | indicates that the user aborted the save operation.
failedToWriteToFile | indicates that it tried to write to a file but this failed.

## Constructor & Destructor Documentation

## ◆ FileBasedDocument()

FileBasedDocument::FileBasedDocument | ( | const String & | fileExtension,
|  | const String & | fileWildCard,
|  | const String & | openFileDialogTitle,
|  | const String & | saveFileDialogTitle
| ) |  |

Creates a FileBasedDocument.

Parameters

  fileExtension | the extension to use when loading/saving files, e.g. ".doc"
  fileWildCard | the wildcard to use in file dialogs, e.g. "*.doc"
  openFileDialogTitle | the title to show on an open-file dialog, e.g. "Choose a file to open.."
  saveFileDialogTitle | the title to show on an save-file dialog, e.g. "Choose a file to save as.."

## ◆ ~FileBasedDocument()

FileBasedDocument::~FileBasedDocument | ( |  | ) |
| override

Destructor.

## Member Function Documentation

## ◆ hasChangedSinceSaved()

bool FileBasedDocument::hasChangedSinceSaved | ( |  | ) | const

Returns true if the changed() method has been called since the file was last saved or loaded.

See also
  setChangedFlag, changed

## ◆ changed()

virtual void FileBasedDocument::changed | ( |  | ) |
| virtual

Called to indicate that the document has changed and needs saving.

This method will also trigger a change message to be sent out using the ChangeBroadcaster base class.

After calling the method, the hasChangedSinceSaved() method will return true, until it is reset either by saving to a file or using the setChangedFlag() method.

See also
  hasChangedSinceSaved, setChangedFlag

## ◆ setChangedFlag()

void FileBasedDocument::setChangedFlag | ( | bool | hasChanged | ) |

Sets the state of the 'changed' flag.

The 'changed' flag is set to true when the changed() method is called - use this method to reset it or to set it without also broadcasting a change message.

See also
  changed, hasChangedSinceSaved

## ◆ loadFrom()

Result FileBasedDocument::loadFrom | ( | const File & | fileToLoadFrom,
|  | bool | showMessageOnFailure,
|  | bool | showWaitCursor = `true`
| ) |  |

Tries to open a file.

If the file opens correctly the document's file (see the getFile() method) is set to this new one; if it fails, the document's file is left unchanged, and optionally a message box is shown telling the user there was an error.

Returns
  A result indicating whether the new file loaded successfully, or the error message if it failed.

See also
  loadDocument, loadFromUserSpecifiedFile

## ◆ loadFromAsync()

void FileBasedDocument::loadFromAsync | ( | const File & | fileToLoadFrom,
|  | bool | showMessageOnFailure,
|  | std::function< void(Result)> | callback
| ) |  |

Tries to open a file.

The callback is called with the result indicating whether the new file loaded successfully, or the error message if it failed.

If the file opens correctly the document's file (see the getFile() method) is set to this new one; if it fails, the document's file is left unchanged, and optionally a message box is shown telling the user there was an error.

See also
  loadDocumentAsync, loadFromUserSpecifiedFileAsync

## ◆ loadFromUserSpecifiedFile()

Result FileBasedDocument::loadFromUserSpecifiedFile | ( | bool | showMessageOnFailure | ) |

Asks the user for a file and tries to load it.

This will pop up a dialog box using the title, file extension and wildcard specified in the document's constructor, and asks the user for a file. If they pick one, the loadFrom() method is used to try to load it, optionally showing a message if it fails.

Returns
  a result indicating success; This will be a failure message if the user cancelled or if they picked a file which failed to load correctly

See also
  loadFrom

## ◆ loadFromUserSpecifiedFileAsync()

void FileBasedDocument::loadFromUserSpecifiedFileAsync | ( | bool | showMessageOnFailure,
|  | std::function< void(Result)> | callback
| ) |  |

Asks the user for a file and tries to load it.

This will pop up a dialog box using the title, file extension and wildcard specified in the document's constructor, and asks the user for a file. If they pick one, the loadFrom() method is used to try to load it, optionally showing a message if it fails. The result of the operation is provided in the callback function.

See also
  loadFrom

## ◆ save()

SaveResult FileBasedDocument::save | ( | bool | askUserForFileIfNotSpecified,
|  | bool | showMessageOnFailure
| ) |  |

Tries to save the document to the last file it was saved or loaded from.

This will always try to write to the file, even if the document isn't flagged as having changed.

Parameters

  askUserForFileIfNotSpecified | if there's no file currently specified and this is true, it will prompt the user to pick a file, as if saveAsInteractive() was called.
  showMessageOnFailure | if true it will show a warning message when if the save operation fails

See also
  saveIfNeededAndUserAgrees, saveAs, saveAsInteractive

## ◆ saveAsync()

void FileBasedDocument::saveAsync | ( | bool | askUserForFileIfNotSpecified,
|  | bool | showMessageOnFailure,
|  | std::function< void(SaveResult)> | callback
| ) |  |

Tries to save the document to the last file it was saved or loaded from.

This will always try to write to the file, even if the document isn't flagged as having changed.

Parameters

  askUserForFileIfNotSpecified | if there's no file currently specified and this is true, it will prompt the user to pick a file, as if saveAsInteractive() was called.
  showMessageOnFailure | if true it will show a warning message when if the save operation fails
  callback | called after the save operation with the result

See also
  saveIfNeededAndUserAgrees, saveAs, saveAsInteractive

## ◆ saveIfNeededAndUserAgrees()

SaveResult FileBasedDocument::saveIfNeededAndUserAgrees | ( |  | ) |

If the file needs saving, it'll ask the user if that's what they want to do, and save it if they say yes.

If you've got a document open and want to close it (e.g. to quit the app), this is the method to call.

If the document doesn't need saving it'll return the value savedOk so you can go ahead and delete the document.

If it does need saving it'll prompt the user, and if they say "discard changes" it'll return savedOk, so again, you can safely delete the document.

If the user clicks "cancel", it'll return userCancelledSave, so if you can abort the close-document operation.

And if they click "save changes", it'll try to save and either return savedOk, or failedToWriteToFile if there was a problem.

See also
  save, saveAs, saveAsInteractive

## ◆ saveIfNeededAndUserAgreesAsync()

void FileBasedDocument::saveIfNeededAndUserAgreesAsync | ( | std::function< void(SaveResult)> | callback | ) |

If the file needs saving, it'll ask the user if that's what they want to do, and save it if they say yes.

If you've got a document open and want to close it (e.g. to quit the app), this is the method to call.

If the document doesn't need saving the callback will be called with the value savedOk so you can go ahead and delete the document.

If it does need saving it'll prompt the user, and if they say "discard changes" the callback will be called with savedOk, so again, you can safely delete the document.

If the user clicks "cancel", the callback will be called with userCancelledSave, so you can abort the close-document operation.

And if they click "save changes", it'll try to save and the callback will be called with either savedOk, or failedToWriteToFile if there was a problem.

See also
  saveAsync, saveAsAsync, saveAsInteractiveAsync

## ◆ saveAs()

SaveResult FileBasedDocument::saveAs | ( | const File & | newFile,
|  | bool | warnAboutOverwritingExistingFiles,
|  | bool | askUserForFileIfNotSpecified,
|  | bool | showMessageOnFailure,
|  | bool | showWaitCursor = `true`
| ) |  |

Tries to save the document to a specified file.

If this succeeds, it'll also change the document's internal file (as returned by the getFile() method). If it fails, the file will be left unchanged.

Parameters

  newFile | the file to try to write to
  warnAboutOverwritingExistingFiles | if true and the file exists, it'll ask the user first if they want to overwrite it
  askUserForFileIfNotSpecified | if the file is non-existent and this is true, it'll use the saveAsInteractive() method to ask the user for a filename
  showMessageOnFailure | if true and the write operation fails, it'll show a message box to warn the user
  showWaitCursor | if true, the 'wait' mouse cursor will be showin during saving

See also
  saveIfNeededAndUserAgrees, save, saveAsInteractive

## ◆ saveAsAsync()

void FileBasedDocument::saveAsAsync | ( | const File & | newFile,
|  | bool | warnAboutOverwritingExistingFiles,
|  | bool | askUserForFileIfNotSpecified,
|  | bool | showMessageOnFailure,
|  | std::function< void(SaveResult)> | callback
| ) |  |

Tries to save the document to a specified file.

If this succeeds, it'll also change the document's internal file (as returned by the getFile() method). If it fails, the file will be left unchanged.

Parameters

  newFile | the file to try to write to
  warnAboutOverwritingExistingFiles | if true and the file exists, it'll ask the user first if they want to overwrite it
  askUserForFileIfNotSpecified | if the file is non-existent and this is true, it'll use the saveAsInteractive() method to ask the user for a filename
  showMessageOnFailure | if true and the write operation fails, it'll show a message box to warn the user
  callback | called with the result of the save operation

See also
  saveIfNeededAndUserAgreesAsync, saveAsync, saveAsInteractiveAsync

## ◆ saveAsInteractive()

SaveResult FileBasedDocument::saveAsInteractive | ( | bool | warnAboutOverwritingExistingFiles | ) |

Prompts the user for a filename and tries to save to it.

This will pop up a dialog box using the title, file extension and wildcard specified in the document's constructor, and asks the user for a file. If they pick one, the saveAs() method is used to try to save to this file.

Parameters

  warnAboutOverwritingExistingFiles | if true and the file exists, it'll ask the user first if they want to overwrite it

See also
  saveIfNeededAndUserAgrees, save, saveAs

## ◆ saveAsInteractiveAsync()

void FileBasedDocument::saveAsInteractiveAsync | ( | bool | warnAboutOverwritingExistingFiles,
|  | std::function< void(SaveResult)> | callback
| ) |  |

Prompts the user for a filename and tries to save to it.

This will pop up a dialog box using the title, file extension and wildcard specified in the document's constructor, and asks the user for a file. If they pick one, the saveAs() method is used to try to save to this file.

Parameters

  warnAboutOverwritingExistingFiles | if true and the file exists, it'll ask the user first if they want to overwrite it
  callback | called with the result of the save operation

See also
  saveIfNeededAndUserAgreesAsync, saveAsync, saveAsAsync

## ◆ getFile()

const File & FileBasedDocument::getFile | ( |  | ) | const

Returns the file that this document was last successfully saved or loaded from.

When the document object is created, this will be set to File().

It is changed when one of the load or save methods is used, or when setFile() is used to explicitly set it.

## ◆ setFile()

void FileBasedDocument::setFile | ( | const File & | newFile | ) |

Sets the file that this document thinks it was loaded from.

This won't actually load anything - it just changes the file stored internally.

See also
  getFile

## ◆ getDocumentTitle()

virtual String FileBasedDocument::getDocumentTitle | ( |  | ) |
| protectedpure virtual

Overload this to return the title of the document.

This is used in message boxes, filenames and file choosers, so it should be something sensible.

## ◆ loadDocument()

virtual Result FileBasedDocument::loadDocument | ( | const File & | file | ) |
| protectedpure virtual

This method should try to load your document from the given file.

Returns
  a Result object to indicate the whether there was an error.

## ◆ loadDocumentAsync()

virtual void FileBasedDocument::loadDocumentAsync | ( | const File & | file,
|  | std::function< void(Result)> | callback
| ) |  |
| protectedvirtual

This method should try to load your document from the given file, then call the provided callback on the message thread, passing the result of the load.

By default, this will synchronously call through to loadDocument.

For longer-running load operations, you may wish to override this function to run the load on a background thread, and then to call the callback later on the message thread to signal that the load has completed.

## ◆ saveDocument()

virtual Result FileBasedDocument::saveDocument | ( | const File & | file | ) |
| protectedpure virtual

This method should try to write your document to the given file.

Returns
  a Result object to indicate the whether there was an error.

## ◆ saveDocumentAsync()

virtual void FileBasedDocument::saveDocumentAsync | ( | const File & | file,
|  | std::function< void(Result)> | callback
| ) |  |
| protectedvirtual

This method should try to write your document to the given file, then call the provided callback on the message thread, passing the result of the write.

By default, this will synchronously call through to saveDocument.

For longer-running save operations, you may wish to override this function to run the save on a background thread, and then to call the callback later on the message thread to signal that the save has completed.

## ◆ getLastDocumentOpened()

virtual File FileBasedDocument::getLastDocumentOpened | ( |  | ) |
| protectedpure virtual

This is used for dialog boxes to make them open at the last folder you were using.

getLastDocumentOpened() and setLastDocumentOpened() are used to store the last document that was used - you might want to store this value in a static variable, or even in your application's properties. It should be a global setting rather than a property of this object.

This method works very well in conjunction with a RecentlyOpenedFilesList object to manage your recent-files list.

As a default value, it's ok to return File(), and the document object will use a sensible one instead.

See also
  RecentlyOpenedFilesList

## ◆ setLastDocumentOpened()

virtual void FileBasedDocument::setLastDocumentOpened | ( | const File & | file | ) |
| protectedpure virtual

This is used for dialog boxes to make them open at the last folder you were using.

getLastDocumentOpened() and setLastDocumentOpened() are used to store the last document that was used - you might want to store this value in a static variable, or even in your application's properties. It should be a global setting rather than a property of this object.

This method works very well in conjunction with a RecentlyOpenedFilesList object to manage your recent-files list.

See also
  RecentlyOpenedFilesList

## ◆ getSuggestedSaveAsFile()

virtual File FileBasedDocument::getSuggestedSaveAsFile | ( | const File & | defaultFile | ) |
| protectedvirtual

This is called by saveAsInteractiveAsync() to allow you to optionally customise the filename that the user is presented with in the save dialog.

The defaultFile parameter is an initial suggestion based on what the class knows about the current document - you can return a variation on this file with a different extension, etc, or just return something completely different.

The documentation for this class was generated from the following file:

- juce_FileBasedDocument.h