A class to take care of the logic involved with the loading/saving of some kind of document. More...
Inherits ChangeBroadcaster.
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. | |
| virtual | ~FileBasedDocument () |
| 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. | |
| bool | loadFrom (const File &fileToLoadFrom, bool showMessageOnFailure) |
| Tries to open a file. | |
| bool | loadFromUserSpecifiedFile (bool showMessageOnFailure) |
| 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. | |
| 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. | |
| SaveResult | saveAs (const File &newFile, bool warnAboutOverwritingExistingFiles, bool askUserForFileIfNotSpecified, bool showMessageOnFailure) |
| 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. | |
| 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. | |
Protected Member Functions | |
| virtual const String | getDocumentTitle ()=0 |
| Overload this to return the title of the document. | |
| virtual const String | loadDocument (const File &file)=0 |
| This method should try to load your document from the given file. | |
| virtual const String | saveDocument (const File &file)=0 |
| This method should try to write your document to the given file. | |
| virtual const 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. | |
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.
A set of possible outcomes of one of the save() methods.
| FileBasedDocument::FileBasedDocument | ( | const String & | fileExtension, |
| const String & | fileWildCard, | ||
| const String & | openFileDialogTitle, | ||
| const String & | saveFileDialogTitle | ||
| ) |
Creates a FileBasedDocument.
| 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.." |
| virtual FileBasedDocument::~FileBasedDocument | ( | ) | [virtual] |
Destructor.
| bool FileBasedDocument::hasChangedSinceSaved | ( | ) | const |
| 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 resetChangedFlag() method.
| 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.
| bool FileBasedDocument::loadFrom | ( | const File & | fileToLoadFrom, |
| bool | showMessageOnFailure | ||
| ) |
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.
| bool 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.
| 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.
| 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 |
| 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.
| SaveResult FileBasedDocument::saveAs | ( | const File & | newFile, |
| bool | warnAboutOverwritingExistingFiles, | ||
| bool | askUserForFileIfNotSpecified, | ||
| bool | showMessageOnFailure | ||
| ) |
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.
| 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 |
| 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.
| warnAboutOverwritingExistingFiles | if true and the file exists, it'll ask the user first if they want to overwrite it |
| 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::nonexistent.
It is changed when one of the load or save methods is used, or when setFile() is used to explicitly set it.
| 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.
| virtual const String FileBasedDocument::getDocumentTitle | ( | ) | [protected, pure 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.
| virtual const String FileBasedDocument::loadDocument | ( | const File & | file ) | [protected, pure virtual] |
This method should try to load your document from the given file.
If it fails, it should return an error message. If it succeeds, it should return an empty string.
| virtual const String FileBasedDocument::saveDocument | ( | const File & | file ) | [protected, pure virtual] |
This method should try to write your document to the given file.
If it fails, it should return an error message. If it succeeds, it should return an empty string.
| virtual const File FileBasedDocument::getLastDocumentOpened | ( | ) | [protected, pure 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::nonexistent, and the document object will use a sensible one instead.
| virtual void FileBasedDocument::setLastDocumentOpened | ( | const File & | file ) | [protected, pure 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.
