1 files changed, 90 insertions, 0 deletions
diff --git a/src/gui/preview_thread.py b/src/gui/preview_thread.py
new file mode 100644
index 0000000..d3e0581
--- /dev/null
+++ b/src/gui/preview_thread.py
@@ -0,0 +1,90 @@
+'''
+    Thread that runs to create QImages for MainWindow's preview label.
+    Processes a queue of component lists.
+'''
+from PyQt5 import QtCore, QtGui, uic
+from PyQt5.QtCore import pyqtSignal, pyqtSlot
+from PIL import Image
+from PIL.ImageQt import ImageQt
+from queue import Queue, Empty
+import os
+import logging
+
+from toolkit.frame import Checkerboard
+from toolkit import disableWhenOpeningProject
+
+
+log = logging.getLogger("AVP.Gui.PreviewThread")
+
+
+class Worker(QtCore.QObject):
+
+    imageCreated = pyqtSignal(QtGui.QImage)
+    error = pyqtSignal(str)
+
+    def __init__(self, parent=None, queue=None):
+        QtCore.QObject.__init__(self)
+        parent.newTask.connect(self.createPreviewImage)
+        parent.processTask.connect(self.process)
+        self.parent = parent
+        self.core = parent.core
+        self.settings = parent.settings
+        self.queue = queue
+
+        width = int(self.settings.value('outputWidth'))
+        height = int(self.settings.value('outputHeight'))
+        self.background = Checkerboard(width, height)
+
+    @disableWhenOpeningProject
+    @pyqtSlot(list)
+    def createPreviewImage(self, components):
+        dic = {
+          "components": components,
+        }
+        self.queue.put(dic)
+
+    @pyqtSlot()
+    def process(self):
+        try:
+            nextPreviewInformation = self.queue.get(block=False)
+            while self.queue.qsize() >= 2:
+                try:
+                    self.queue.get(block=False)
+                except Empty:
+                    continue
+            width = int(self.settings.value('outputWidth'))
+            height = int(self.settings.value('outputHeight'))
+            if self.background.width != width \
+                    or self.background.height != height:
+                self.background = Checkerboard(width, height)
+
+            frame = self.background.copy()
+            log.info('Creating new preview frame')
+            components = nextPreviewInformation["components"]
+            for component in reversed(components):
+                try:
+                    component.lockSize(width, height)
+                    newFrame = component.previewRender()
+                    component.unlockSize()
+                    frame = Image.alpha_composite(
+                        frame, newFrame
+                    )
+
+                except ValueError as e:
+                    errMsg = "Bad frame returned by %s's preview renderer. " \
+                        "%s. New frame size was %s*%s; should be %s*%s." % (
+                            str(component), str(e).capitalize(),
+                            newFrame.width, newFrame.height,
+                            width, height
+                        )
+                    log.critical(errMsg)
+                    self.error.emit(errMsg)
+                    break
+                except RuntimeError as e:
+                    log.error(str(e))
+            else:
+                self.frame = ImageQt(frame)
+                self.imageCreated.emit(QtGui.QImage(self.frame))
+
+        except Empty:
+            True