Use a progress spinner in the PDF covers dialog

src/calibre/gui2/metadata/pdf_covers.py

@@ -13,14 +13,15 @@ from glob import glob
 
 import sip
 from PyQt5.Qt import (
-    QDialog, QApplication, QLabel, QStackedLayout, QVBoxLayout, QDialogButtonBox, Qt,
-    pyqtSignal, QListWidget, QListWidgetItem, QSize, QPixmap, QStyledItemDelegate, QWidget
+    QDialog, QApplication, QLabel, QVBoxLayout, QDialogButtonBox, Qt,
+    pyqtSignal, QListWidget, QListWidgetItem, QSize, QPixmap, QStyledItemDelegate
 )
 
 from calibre import as_unicode
 from calibre.ebooks.metadata.pdf import page_images
 from calibre.gui2 import error_dialog, file_icon_provider
 from calibre.ptempfile import PersistentTemporaryDirectory
+from calibre.gui2.progress_indicator import WaitLayout
 
 
 class CoverDelegate(QStyledItemDelegate):
@@ -44,14 +45,10 @@ class PDFCovers(QDialog):
     def __init__(self, pdfpath, parent=None):
         QDialog.__init__(self, parent)
         self.pdfpath = pdfpath
-        self.stack = QStackedLayout(self)
-        self.loading = QLabel('<b>'+_('Rendering PDF pages, please wait...'))
-        self.stack.addWidget(self.loading)
+        self.stack = WaitLayout(_('Rendering PDF pages, please wait...'), parent=self)
+        self.container = self.stack.after
 
-        self.container = QWidget(self)
-        self.stack.addWidget(self.container)
         self.container.l = l = QVBoxLayout(self.container)
-
         self.la = la = QLabel(_('Choose a cover from the list of PDF pages below'))
         l.addWidget(la)
         self.covers = c = QListWidget(self)
@@ -113,7 +110,7 @@ class PDFCovers(QDialog):
             self.rendering_done.emit()
 
     def hide_pages(self):
-        self.stack.setCurrentIndex(0)
+        self.stack.start()
         self.more_pages.setVisible(False)
 
     def show_pages(self):
@@ -122,7 +119,7 @@ class PDFCovers(QDialog):
                 _('Could not render this PDF file'), show=True, det_msg=self.error)
             self.reject()
             return
-        self.stack.setCurrentIndex(1)
+        self.stack.stop()
         files = glob(os.path.join(self.current_tdir, '*.jpg')) + glob(os.path.join(self.current_tdir, '*.jpeg'))
         if not files and not self.covers.count():
             error_dialog(self, _('Failed to render'),

src/calibre/gui2/progress_indicator/__init__.py

@@ -7,7 +7,7 @@ from __future__ import (unicode_literals, division, absolute_import,
 
 from PyQt5.Qt import (
     Qt, QWidget, QSizePolicy, QSize, QRect, QConicalGradient, QPen, QBrush,
-    QPainter, QTimer, QVBoxLayout, QLabel, QStackedWidget, QDialog
+    QPainter, QTimer, QVBoxLayout, QLabel, QStackedWidget, QDialog, QStackedLayout
 )
 
 
@@ -113,6 +113,7 @@ class ProgressSpinner(QWidget):
                 traceback.print_exc()
                 self.errored_out = True
 
+
 ProgressIndicator = ProgressSpinner
 
 
@@ -167,6 +168,35 @@ class WaitStack(QStackedWidget):
     def msg(self, val):
         self.wp.msg = val
 
+
+class WaitLayout(QStackedLayout):
+
+    def __init__(self, msg, after=None, parent=None, size=256, interval=10):
+        QStackedLayout.__init__(self, parent)
+        self.wp = WaitPanel(msg, parent, size, interval)
+        if after is None:
+            after = QWidget(parent)
+        self.after = after
+        self.addWidget(self.wp)
+        self.addWidget(after)
+
+    def start(self):
+        self.setCurrentWidget(self.wp)
+        self.wp.start()
+
+    def stop(self):
+        self.wp.stop()
+        self.setCurrentWidget(self.after)
+
+    @property
+    def msg(self):
+        return self.wp.msg
+
+    @msg.setter
+    def msg(self, val):
+        self.wp.msg = val
+
+
 if __name__ == '__main__':
     from calibre.gui2 import Application
     app = Application([])