memory optimization: store metadata in filenames, not a global dict (#853)

* remove options.imgMetadata and store metadata in filename

* make kcc much more memory efficient by removing imgMetadata and imgOld dicts

kindlecomicconverter/comic2ebook.py

@@ -77,15 +77,14 @@ def main(argv=None):
     return 0
 
 
-def buildHTML(path, imgfile, imgfilepath):
-    key = pathlib.Path(imgfilepath).name
+def buildHTML(path, imgfile):
     filename = getImageFileName(imgfile)
     deviceres = options.profileData[1]
-    if not options.noprocessing and "Rotated" in options.imgMetadata[key]:
+    if not options.noprocessing and "Rotated" in imgfile:
         rotatedPage = True
     else:
         rotatedPage = False
-    if not options.noprocessing and "BlackBackground" in options.imgMetadata[key]:
+    if not options.noprocessing and "BlackBackground" in imgfile:
         additionalStyle = 'background-color:#000000;'
     else:
         additionalStyle = ''
@@ -518,7 +517,7 @@ def buildEPUB(path, chapternames, tomenumber, ischunked):
             if not chapter:
                 chapterlist.append((dirpath.replace('Images', 'Text'), afile))
                 chapter = True
-            filelist.append(buildHTML(dirpath, afile, os.path.join(dirpath, afile)))
+            filelist.append(buildHTML(dirpath, afile))
     build_html_end = perf_counter()
     print(f"buildHTML: {build_html_end - build_html_start} seconds")
     # Overwrite chapternames if tree is flat and ComicInfo.xml has bookmarks
@@ -557,8 +556,6 @@ def imgDirectoryProcessing(path):
     global workerPool, workerOutput
     workerPool = Pool(maxtasksperchild=100)
     workerOutput = []
-    options.imgMetadata = {}
-    options.imgOld = []
     work = []
     pagenumber = 0
     for dirpath, _, filenames in os.walk(path):
@@ -581,9 +578,6 @@ def imgDirectoryProcessing(path):
         if len(workerOutput) > 0:
             rmtree(os.path.join(path, '..', '..'), True)
             raise RuntimeError("One of workers crashed. Cause: " + workerOutput[0][0], workerOutput[0][1])
-        for file in options.imgOld:
-            if os.path.isfile(file):
-                os.remove(file)
     else:
         rmtree(os.path.join(path, '..', '..'), True)
         raise UserWarning("Source directory is empty.")
@@ -593,11 +587,7 @@ def imgFileProcessingTick(output):
     if isinstance(output, tuple):
         workerOutput.append(output)
         workerPool.terminate()
-    else:
-        for page in output:
-            if page is not None:
-                options.imgMetadata[page[0]] = page[1]
-                options.imgOld.append(page[2])
+
     if GUI:
         GUI.progressBarTick.emit('tick')
         if not GUI.conversionAlive: