[ui] add and use QmlInstantEngine for QML hot reload

meshroom/ui/utils.py

@@ -0,0 +1,182 @@
+import os
+import time
+
+from PySide2.QtCore import QFileSystemWatcher, QUrl, Slot
+from PySide2.QtQml import QQmlApplicationEngine
+
+
+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):
+            # 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 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
+
+        print("Reloading ", self._sourceFile)
+        self.load(self._sourceFile)
+
+        # Finally, read the modified file to the watch system
+        self.addFile(filepath)