move previewWindow class into new file

and cache frequently-created blank frames

src/mainwindow.py

@@ -17,6 +17,7 @@ import logging
 
 from core import Core
 import preview_thread
+from preview_win import PreviewWindow
 from presetmanager import PresetManager
 from toolkit import disableWhenEncoding, disableWhenOpeningProject, checkOutput
 
@@ -24,66 +25,6 @@ from toolkit import disableWhenEncoding, disableWhenOpeningProject, checkOutput
 log = logging.getLogger('AVP.MainWindow')
 
 
-class PreviewWindow(QtWidgets.QLabel):
-    '''
-        Paints the preview QLabel and maintains the aspect ratio when the
-        window is resized.
-    '''
-    log = logging.getLogger('AVP.MainWindow.Preview')
-
-    def __init__(self, parent, img):
-        super(PreviewWindow, self).__init__()
-        self.parent = parent
-        self.setFrameStyle(QtWidgets.QFrame.StyledPanel)
-        self.pixmap = QtGui.QPixmap(img)
-
-    def paintEvent(self, event):
-        size = self.size()
-        painter = QtGui.QPainter(self)
-        point = QtCore.QPoint(0, 0)
-        scaledPix = self.pixmap.scaled(
-            size,
-            QtCore.Qt.KeepAspectRatio,
-            transformMode=QtCore.Qt.SmoothTransformation)
-
-        # start painting the label from left upper corner
-        point.setX((size.width() - scaledPix.width())/2)
-        point.setY((size.height() - scaledPix.height())/2)
-        painter.drawPixmap(point, scaledPix)
-
-    def changePixmap(self, img):
-        self.pixmap = QtGui.QPixmap(img)
-        self.repaint()
-
-    def mousePressEvent(self, event):
-        if self.parent.encoding:
-            return
-
-        i = self.parent.window.listWidget_componentList.currentRow()
-        if i >= 0:
-            component = self.parent.core.selectedComponents[i]
-            if not hasattr(component, 'previewClickEvent'):
-                self.log.info('Ignored click event')
-                return
-            pos = (event.x(), event.y())
-            size = (self.width(), self.height())
-            butt = event.button()
-            self.log.info('Click event for #%s: %s button %s' % (
-                i, pos, butt))
-            component.previewClickEvent(
-                pos, size, butt
-            )
-            self.parent.core.updateComponent(i)
-
-    @QtCore.pyqtSlot(str)
-    def threadError(self, msg):
-        self.parent.showMessage(
-            msg=msg,
-            icon='Critical',
-            parent=self
-        )
-
-
 class MainWindow(QtWidgets.QMainWindow):
     '''
         The MainWindow wraps many Core methods in order to update the GUI

src/preview_win.py

@@ -0,0 +1,62 @@
+from PyQt5 import QtCore, QtGui, QtWidgets
+import logging
+
+
+class PreviewWindow(QtWidgets.QLabel):
+    '''
+        Paints the preview QLabel in MainWindow and maintains the aspect ratio
+        when the window is resized.
+    '''
+    log = logging.getLogger('AVP.PreviewWindow')
+
+    def __init__(self, parent, img):
+        super(PreviewWindow, self).__init__()
+        self.parent = parent
+        self.setFrameStyle(QtWidgets.QFrame.StyledPanel)
+        self.pixmap = QtGui.QPixmap(img)
+
+    def paintEvent(self, event):
+        size = self.size()
+        painter = QtGui.QPainter(self)
+        point = QtCore.QPoint(0, 0)
+        scaledPix = self.pixmap.scaled(
+            size,
+            QtCore.Qt.KeepAspectRatio,
+            transformMode=QtCore.Qt.SmoothTransformation)
+
+        # start painting the label from left upper corner
+        point.setX((size.width() - scaledPix.width())/2)
+        point.setY((size.height() - scaledPix.height())/2)
+        painter.drawPixmap(point, scaledPix)
+
+    def changePixmap(self, img):
+        self.pixmap = QtGui.QPixmap(img)
+        self.repaint()
+
+    def mousePressEvent(self, event):
+        if self.parent.encoding:
+            return
+
+        i = self.parent.window.listWidget_componentList.currentRow()
+        if i >= 0:
+            component = self.parent.core.selectedComponents[i]
+            if not hasattr(component, 'previewClickEvent'):
+                self.log.info('Ignored click event')
+                return
+            pos = (event.x(), event.y())
+            size = (self.width(), self.height())
+            butt = event.button()
+            self.log.info('Click event for #%s: %s button %s' % (
+                i, pos, butt))
+            component.previewClickEvent(
+                pos, size, butt
+            )
+            self.parent.core.updateComponent(i)
+
+    @QtCore.pyqtSlot(str)
+    def threadError(self, msg):
+        self.parent.showMessage(
+            msg=msg,
+            icon='Critical',
+            parent=self
+        )

src/toolkit/frame.py

@@ -77,27 +77,40 @@ def defaultSize(framefunc):
 
 
 def FloodFrame(width, height, RgbaTuple):
+    log.debug('Creating new %s*%s %s flood frame' % (
+        width, height,
+        'blank' if RgbaTuple[3] == 0 else RgbaTuple
+        )
+    )
     return Image.new("RGBA", (width, height), RgbaTuple)
 
 
 @defaultSize
-def BlankFrame(width, height):
+def BlankFrame(width, height, blankFrames={}):
     '''The base frame used by each component to start drawing.'''
-    log.debug('Creating new %s*%s blank frame' % (width, height))
-    return FloodFrame(width, height, (0, 0, 0, 0))
+    try:
+        return blankFrames[(width, height)]
+    except KeyError:
+        newFrame = FloodFrame(width, height, (0, 0, 0, 0))
+        blankFrames[(width, height)] = newFrame
+        return newFrame
 
 
 @defaultSize
-def Checkerboard(width, height):
+def Checkerboard(width, height, checkerboards={}):
     '''
         A checkerboard to represent transparency to the user.
         TODO: Would be cool to generate this image with numpy instead.
     '''
-    log.debug('Creating new %s*%s checkerboard' % (width, height))
-    image = FloodFrame(1920, 1080, (0, 0, 0, 0))
-    image.paste(Image.open(
-        os.path.join(core.Core.wd, "background.png")),
-        (0, 0)
-    )
-    image = image.resize((width, height))
-    return image
+    try:
+        return checkerboards[(width, height)]
+    except KeyError:
+        log.debug('Creating new %s*%s checkerboard' % (width, height))
+        image = FloodFrame(1920, 1080, (0, 0, 0, 0))
+        image.paste(Image.open(
+            os.path.join(core.Core.wd, "background.png")),
+            (0, 0)
+        )
+        image = image.resize((width, height))
+        checkerboards[(width, height)] = image
+        return image