add autoscale option

Instead of fixed 1.5 scale ratio, the autoscale feature uses current page's
image width, and dynamically determine the needed scale ratio. The rendering
effects looks okay and speed is fine in my KPW1.

The generated panel view will have two view ports: (top and bottom).

kcc/comic2ebook.py

@@ -80,6 +80,9 @@ def main(argv=None):
         makeBook(source)
     return 0
 
+def calculateZoomImageSize(imageSize, deviceRes):
+    scale = float(deviceRes[0])/float(imageSize[0])
+    return (float(deviceRes[0]), scale * imageSize[1])
 
 def buildHTML(path, imgfile, imgfilepath):
     imgfilepath = md5Checksum(imgfilepath)
@@ -132,6 +135,8 @@ def buildHTML(path, imgfile, imgfilepath):
             imgfilepv = imgfile
             sizeTmp = Image.open(os.path.join(head, "Images", postfix, imgfilepv)).size
             size = (int(sizeTmp[0] * 1.5), int(sizeTmp[1] * 1.5))
+        if options.autoscale:
+          size = calculateZoomImageSize(sizeTmp, deviceres)
         if size[0] <= deviceres[0]:
             noHorizontalPV = True
         else:
@@ -961,6 +966,9 @@ def makeParser():
     mainOptions.add_option("-p", "--profile", action="store", dest="profile", default="KV",
                            help="Device profile (Available options: K1, K2, K3, K45, KDX, KPW, KV, KoMT, KoG, KoGHD,"
                                 " KoA, KoAHD, KoAH2O, KoAO) [Default=KV]")
+    mainOptions.add_option("-a", "--auto-scale", action="store_true", dest="autoscale", default=False,
+                           help="Auto scale image in panel view by width. The zoom-in mode will have two view ports"
+                                "(top and bottom)")
     mainOptions.add_option("-m", "--manga-style", action="store_true", dest="righttoleft", default=False,
                            help="Manga style (right-to-left reading and splitting)")
     mainOptions.add_option("-w", "--webtoon", action="store_true", dest="webtoon", default=False,