README.md: add more examples of how to use the library

README.md

@@ -135,7 +135,33 @@ You can then test the converter using:
 The package can also be used as a library:
 
 	import img2pdf
-	pdf_bytes = img2pdf.convert('test.jpg')
 
-	file = open("name.pdf","wb")
-	file.write(pdf_bytes)
+	# opening from filename
+	with open("name.pdf","wb") as f:
+		f.write(img2pdf.convert('test.jpg'))
+
+	# opening from file handle
+	with open("name.pdf","wb") as f1, open("test.jpg") as f2:
+		f1.write(img2pdf.convert(f2))
+
+	# using in-memory image data
+	with open("name.pdf","wb") as f:
+		f.write(img2pdf.convert("\x89PNG...")
+
+	# multiple inputs (variant 1)
+	with open("name.pdf","wb") as f:
+		f.write(img2pdf.convert("test1.jpg", "test2.png"))
+
+	# multiple inputs (variant 2)
+	with open("name.pdf","wb") as f:
+		f.write(img2pdf.convert(["test1.jpg", "test2.png"]))
+
+	# writing to file descriptor
+	with open("name.pdf","wb") as f1, open("test.jpg") as f2:
+		img2pdf.convert(f2, outputstream=f1)
+
+	# specify paper size (A4)
+	a4inpt = (img2pdf.mm_to_pt(210),img2pdf.mm_to_pt(297))
+	layout_fun = img2pdf.get_layout_fun(a4inpt)
+	with open("name.pdf","wb") as f:
+		f.write(img2pdf.convert('test.jpg', layout_fun=layout_fun))