8a80ce2ca4
It's basically a port of #10951 to the new start page implementation. Note: Icon files are not removed but re-used instead. The commit adds some new functions: * getThumbnailsImage() Returns the name of the PNG inside a project file * getThumbnailsName() Returns the directory name containing the image files * getThumnailsParentDir() Returns the parent directory of the directory containing the image files * getThumbnailsDir() Returns the path to the thumbnail directory. There is no need to always create a unique directory after each restart because it doesn't harm if the thumbnail directoy contains deprecated files. * createThumbnailsDir() Creates the thumbnail directoy if it doesn't exist yet. * getSha1Hash Helper function to compute a SHA-1 hash of a given path. If the same path is passed then the hash value will be the same. This way it can be avoided to create a different image file from a project file after each restart. * getUniquePNG Computes the path of a PNG image file for a given project file. It's also possible to pass an arbitrary string as argument. * useCachedPNG If the PNG image exists and if it's newer than the project file True is returned and False otherwise. For a given project file it is checked if the thumbnail directory already contains a cached image. If it's newer than the project file it will used, otherwise it will be re-created. Fix freecadCanOpen() abd DisplayedFilesModel::addFile() to also check for lower-case file extensions.
Start Workbench
This Workbench is intended to eventually replace (and be renamed to) Start. Its main reason for existing is to eliminate FreeCAD's dependency on QtWebEngine by redesigning Start to eliminate the HTML component.
The long-term plan for this workbench is to migrate from Qt Widgets to QtQuick/QML with a C++ backend providing access to things like FreeCAD's Recent Files list. This switch will happen sometime after we no longer have to support building on Ubuntu 20.04 LTS, which still uses Qt 5.12. The cMake integration of QML and C++ together in a single project is greatly improved in Qt 5.15 and later.
In the meantime the workbench is written in C++ so that the models can be reused later, and only the UI itself will have to change.
Structure
The main UI file for the Start screen is in Gui/StartView.cpp -- that class is a QScrollArea that gets embedded
into a new FreeCAD MDIView. Inside the scroll area are three regions:
- New File. A set of
QPushButtonswith embeddedQLayoutsdisplaying an image and two lines of text. Currently laid out manually in aQGridLayout, but eventually it would be nice to dynamically calculate that layout to allow the buttons to exist on a single line when there is enough space for them. - Recent Files. One of two "File Card" regions, this shows a list of recent files. It uses the
Model-View-Controller architecture for flexibility and re-usability. In that architecture, the data being displayed is
called the "model", and the actual mechanism for doing the display is called the "view". Qt further differentiates
between the overall view and the display of the individual items in the view. The items are rendered by a "delegate"
when they are too complex to be displayed by the simple view (e.g. if you want images and text in a particular layout).
- The "model" in this case is
RecentFilesModel, a simple read-only interface to FreeCAD's preferences system, where it gets the list of recent files. That class is inApp/RecentFilesModel.*. It is implemented using a set of User Roles, one for each piece of data about a file. Not all data is available for all files. For example, when givenconst QModelIndex &index, you can callindex.data(DisplayedFilesModelRoles::author)to get the "author" metadata item of anFCStdfile. See theDisplayedFilesModelRolesenumeration for possible values. These roles are also exposed to QML via their names. - The View is a class derived from
QListView,Gui/FileCardView.*, whose only function beyond the standardQListViewis to implement the "height for width" functionality, so the widget can properly resize based on the number of file cards and the screen width, laying them out in a grid. - The file cards are rendered using the
FileCardDelegateclass inGui/FileCardDelegate.*. That class uses a simpleQVBoxLayoutto paint the icon, filename, and file size.
- The "model" in this case is
- Examples. Another "File Card" widget, using the same classes as Recent Files, but with a different model. In this
case the model is
ExamplesModelinApp/ExamplesModel.*. It fetches a read-only list of files from the FreeCADresources/examplesdirectory and displays them.
UI Design
This Workbench does the minimum amount of design customization, preferring to allow Stylesheet authors control over the
display via the normal QSS mechanisms in Qt. There are three FreeCAD Parameters that control the spacing between the
widgets and the size of the icons, all in the BaseApp/Preferences/Mod/Start/ preferences group:
FileCardSpacing(default: 20). The space between and around the individual File Cards.FileThumbnailIconsSize(default: 128). The size of the file thumbnail on the File Cards.NewFileIconSize(default: 48). The size of the icons on each of the "new file" buttons.
At present none of these are directly exposed to the user, and the new Start workbench does not have a preferences panel. The parameters are intended to be used by Preference Pack authors to assist in customization of FreeCAD themes. It is likely that this will be expanded once feedback from theme designers is received.