PDF Output: Fix regression that caused some svg images to be rendered as black rectangles. Fixes #1105294 (conversion error svg -> kdp _> pdf)

src/calibre/ebooks/pdf/render/engine.py

@@ -108,6 +108,7 @@ class PdfEngine(QPaintEngine):
 
     def init_page(self):
         self.pdf.transform(self.pdf_system)
+        self.pdf.apply_fill(color=(1, 1, 1)) # QPainter has a default background brush of white
         self.graphics.reset()
         self.pdf.save_stack()
         self.current_page_inited = True

src/calibre/ebooks/pdf/render/graphics.py

@@ -252,7 +252,7 @@ class GraphicsState(object):
                   'clip_updated', 'do_fill', 'do_stroke')
 
     def __init__(self):
-        self.fill = QBrush()
+        self.fill = QBrush(Qt.white)
         self.stroke = QPen()
         self.opacity = 1.0
         self.transform = QTransform()

src/calibre/ebooks/pdf/render/test.py

@@ -113,7 +113,7 @@ def main():
     app
     tdir = os.path.abspath('.')
     pdf = os.path.join(tdir, 'painter.pdf')
-    func = brush
+    func = full
     dpi = 100
     with open(pdf, 'wb') as f:
         dev = PdfDevice(f, xdpi=dpi, ydpi=dpi, compress=False)