import os import time from PySide2.QtCore import QFileSystemWatcher, QUrl, Slot, QTimer, Property, QObject from PySide2.QtQml import QQmlApplicationEngine try: from PySide2 import shiboken2 except: import shiboken2 class QmlInstantEngine(QQmlApplicationEngine): """ QmlInstantEngine is an utility class helping developing QML applications. It reloads itself whenever one of the watched source files is modified. As it consumes resources, make sure to disable file watching in production mode. """ def __init__(self, sourceFile="", watching=True, verbose=False, parent=None): """ watching -- Defines whether the watcher is active (default: True) verbose -- if True, output log infos (default: False) """ super(QmlInstantEngine, self).__init__(parent) self._fileWatcher = QFileSystemWatcher() # Internal Qt File Watcher self._sourceFile = "" self._watchedFiles = [] # Internal watched files list self._verbose = verbose # Verbose bool self._watching = False # self._extensions = ["qml", "js"] # File extensions that defines files to watch when adding a folder self._rootItem = None def onObjectCreated(root, url): if not root: return # Restore root item geometry if self._rootItem: root.setGeometry(self._rootItem.geometry()) self._rootItem.deleteLater() self._rootItem = root self.objectCreated.connect(onObjectCreated) # Update the watching status self.setWatching(watching) if sourceFile: self.load(sourceFile) def load(self, sourceFile): self._sourceFile = sourceFile super(QmlInstantEngine, self).load(sourceFile) def setWatching(self, watchValue): """ Enable (True) or disable (False) the file watching. Tip: file watching should be enable only when developing. """ if self._watching is watchValue: return self._watching = watchValue # Enable the watcher if self._watching: # 1. Add internal list of files to the internal Qt File Watcher self.addFiles(self._watchedFiles) # 2. Connect 'filechanged' signal self._fileWatcher.fileChanged.connect(self.onFileChanged) # Disabling the watcher else: # 1. Remove all files in the internal Qt File Watcher self._fileWatcher.removePaths(self._watchedFiles) # 2. Disconnect 'filechanged' signal self._fileWatcher.fileChanged.disconnect(self.onFileChanged) @property def watchedExtensions(self): """ Returns the list of extensions used when using addFilesFromDirectory. """ return self._extensions @watchedExtensions.setter def watchedExtensions(self, extensions): """ Set the list of extensions to search for when using addFilesFromDirectory. """ self._extensions = extensions def setVerbose(self, verboseValue): """ Activate (True) or desactivate (False) the verbose. """ self._verbose = verboseValue def addFile(self, filename): """ Add the given 'filename' to the watched files list. 'filename' can be an absolute or relative path (str and QUrl accepted) """ # Deal with QUrl type # NOTE: happens when using the source() method on a QQuickView if isinstance(filename, QUrl): filename = filename.path() # Make sure the file exists if not os.path.isfile(filename): raise ValueError("addFile: file %s doesn't exist." % filename) # Return if the file is already in our internal list if filename in self._watchedFiles: return # Add this file to the internal files list self._watchedFiles.append(filename) # And, if watching is active, add it to the internal watcher as well if self._watching: if self._verbose: print("instantcoding: addPath", filename) self._fileWatcher.addPath(filename) def addFiles(self, filenames): """ Add the given 'filenames' to the watched files list. filenames -- a list of absolute or relative paths (str and QUrl accepted) """ # Convert to list if not isinstance(filenames, list): filenames = [filenames] for filename in filenames: self.addFile(filename) def addFilesFromDirectory(self, dirname, recursive=False): """ Add files from the given directory name 'dirname'. dirname -- an absolute or a relative path recursive -- if True, will search inside each subdirectories recursively. """ if not os.path.isdir(dirname): raise RuntimeError("addFilesFromDirectory : %s is not a valid directory." % dirname) if recursive: for dirpath, dirnames, filenames in os.walk(dirname): for filename in filenames: # Removing the starting dot from extension if os.path.splitext(filename)[1][1:] in self._extensions: self.addFile(os.path.join(dirpath, filename)) else: filenames = os.listdir(dirname) filenames = [os.path.join(dirname, filename) for filename in filenames if os.path.splitext(filename)[1][1:] in self._extensions] self.addFiles(filenames) def removeFile(self, filename): """ Remove the given 'filename' from the watched file list. Tip: make sure to use relative or absolute path according to how you add this file. """ if filename in self._watchedFiles: self._watchedFiles.remove(filename) if self._watching: self._fileWatcher.removePath(filename) def getRegisteredFiles(self): """ Returns the list of watched files """ return self._watchedFiles @Slot(str) def onFileChanged(self, filepath): """ Handle changes in a watched file. """ if filepath not in self._watchedFiles: # could happen if a file has just been reloaded # and has not been re-added yet to the watched files return if self._verbose: print("Source file changed : ", filepath) # Clear the QQuickEngine cache self.clearComponentCache() # Remove the modified file from the watched list self.removeFile(filepath) cptTry = 0 # Make sure file is available before doing anything # NOTE: useful to handle editors (Qt Creator) that deletes the source file and # creates a new one when saving while not os.path.exists(filepath) and cptTry < 10: time.sleep(0.1) cptTry += 1 self.reload() # Finally, re-add the modified file to the watch system # after a short cooldown to avoid multiple consecutive reloads QTimer.singleShot(200, lambda: self.addFile(filepath)) def reload(self): print("Reloading {}".format(self._sourceFile)) self.load(self._sourceFile) def makeProperty(T, attributeName, notify=None, resetOnDestroy=False): """ Shortcut function to create a Qt Property with generic getter and setter. Getter returns the underlying attribute value. Setter sets and emit notify signal only if the given value is different from the current one. Args: T (type): the type of the property attributeName (str): the name of underlying instance attribute to get/set notify (Signal): the notify signal; if None, property will be constant resetOnDestroy (bool): Only applicable for QObject-type properties. Whether to reset property to None when current value gets destroyed. Examples: class Foo(QObject): _bar = 10 barChanged = Signal() # read/write bar = makeProperty(int, "_bar", notify=barChanged) # read only (constant) bar = makeProperty(int, "_bar") Returns: Property: the created Property """ def setter(instance, value): """ Generic setter. """ currentValue = getattr(instance, attributeName) if currentValue == value: return resetCallbackName = '__reset__' + attributeName if resetOnDestroy and not hasattr(instance, resetCallbackName): # store reset callback on instance, only way to keep a reference to this function # that can be used for destroyed signal (dis)connection setattr(instance, resetCallbackName, lambda self=instance, *args: setter(self, None)) resetCallback = getattr(instance, resetCallbackName, None) if resetCallback and currentValue and shiboken2.isValid(currentValue): currentValue.destroyed.disconnect(resetCallback) setattr(instance, attributeName, value) if resetCallback and value: value.destroyed.connect(resetCallback) getattr(instance, signalName(notify)).emit() def getter(instance): """ Generic getter. """ return getattr(instance, attributeName) def signalName(signalInstance): """ Get signal name from instance. """ # string representation contains trailing '()', remove it return str(signalInstance)[:-2] if resetOnDestroy and not issubclass(T, QObject): raise RuntimeError("destroyCallback can only be used with QObject-type properties.") if notify: return Property(T, getter, setter, notify=notify) else: return Property(T, getter, constant=True)