Edit book: Compress images: Support compression of images in the WEBP format as well. Fixes #2017195 [[feature] support webp in epub](https://bugs.launchpad.net/calibre/+bug/2017195)

src/calibre/ebooks/oeb/polish/images.py

@@ -4,22 +4,23 @@
 
 import os
 from functools import partial
-from threading import Thread, Event
+from threading import Event, Thread
 
-from calibre import detect_ncpus, human_readable, force_unicode, filesystem_encoding
+from calibre import detect_ncpus, filesystem_encoding, force_unicode, human_readable
 from polyglot.builtins import iteritems
-from polyglot.queue import Queue, Empty
+from polyglot.queue import Empty, Queue
 
 
 class Worker(Thread):
 
     daemon = True
 
-    def __init__(self, abort, name, queue, results, jpeg_quality, progress_callback):
+    def __init__(self, abort, name, queue, results, jpeg_quality, webp_quality, progress_callback):
         Thread.__init__(self, name=name)
         self.queue, self.results = queue, results
         self.progress_callback = progress_callback
         self.jpeg_quality = jpeg_quality
+        self.webp_quality = webp_quality
         self.abort = abort
         self.start()
 
@@ -43,9 +44,16 @@ class Worker(Thread):
                 self.queue.task_done()
 
     def compress(self, name, path, mime_type):
-        from calibre.utils.img import optimize_png, optimize_jpeg, encode_jpeg
+        from calibre.utils.img import (
+            encode_jpeg, encode_webp, optimize_jpeg, optimize_png, optimize_webp,
+        )
         if 'png' in mime_type:
             func = optimize_png
+        elif 'webp' in mime_type:
+            if self.webp_quality is None:
+                func = optimize_webp
+            else:
+                func = partial(encode_webp, quality=self.jpeg_quality)
         elif self.jpeg_quality is None:
             func = optimize_jpeg
         else:
@@ -65,12 +73,12 @@ class Worker(Thread):
 def get_compressible_images(container):
     mt_map = container.manifest_type_map
     images = set()
-    for mt in 'png jpg jpeg'.split():
+    for mt in 'png jpg jpeg webp'.split():
         images |= set(mt_map.get('image/' + mt, ()))
     return images
 
 
-def compress_images(container, report=None, names=None, jpeg_quality=None, progress_callback=lambda n, t, name:True):
+def compress_images(container, report=None, names=None, jpeg_quality=None, webp_quality=None, progress_callback=lambda n, t, name:True):
     images = get_compressible_images(container)
     if names is not None:
         images &= set(names)
@@ -92,7 +100,7 @@ def compress_images(container, report=None, names=None, jpeg_quality=None, progr
         if not keep_going:
             abort.set()
     progress_callback(0, num_to_process, '')
-    [Worker(abort, 'CompressImage%d' % i, queue, results, jpeg_quality, pc) for i in range(min(detect_ncpus(), num_to_process))]
+    [Worker(abort, 'CompressImage%d' % i, queue, results, jpeg_quality, webp_quality, pc) for i in range(min(detect_ncpus(), num_to_process))]
     queue.join()
     before_total = after_total = 0
     processed_num = 0

src/calibre/gui2/tweak_book/boss.py

@@ -1620,7 +1620,7 @@ class Boss(QObject):
         if d.exec() == QDialog.DialogCode.Accepted:
             with BusyCursor():
                 self.add_savepoint(_('Before: compress images'))
-                d = CompressImagesProgress(names=d.names, jpeg_quality=d.jpeg_quality, parent=self.gui)
+                d = CompressImagesProgress(names=d.names, jpeg_quality=d.jpeg_quality, webp_quality=d.webp_quality, parent=self.gui)
                 if d.exec() != QDialog.DialogCode.Accepted:
                     self.rewind_savepoint()
                     return

src/calibre/gui2/tweak_book/polish.py

@@ -9,7 +9,7 @@ from qt.core import (
     QAbstractItemView, QApplication, QCheckBox, QDialog, QDialogButtonBox, QHBoxLayout,
     QIcon, QLabel, QListWidget, QListWidgetItem, QPalette, QPen, QPixmap, QProgressBar,
     QSize, QSpinBox, QStyle, QStyledItemDelegate, Qt, QTextBrowser, QVBoxLayout,
-    pyqtSignal,
+    QWidget, pyqtSignal,
 )
 from threading import Thread
 
@@ -176,6 +176,35 @@ class ImageItemDelegate(QStyledItemDelegate):
         painter.restore()
 
 
+class LossyCompression(QWidget):
+
+    def __init__(self, image_type, default_compression=80, parent=None):
+        super().__init__(parent)
+        l = QVBoxLayout(self)
+        image_type = image_type.upper()
+        self.enable_lossy = el = QCheckBox(_('Enable &lossy compression of {} images').format(image_type))
+        el.setToolTip(_('This allows you to change the quality factor used for {} images.\nBy lowering'
+                        ' the quality you can greatly reduce file size, at the expense of the image looking blurred.'.format(image_type)))
+        l.addWidget(el)
+        self.h2 = h = QHBoxLayout()
+        l.addLayout(h)
+        self.jq = jq = QSpinBox(self)
+        image_type = image_type.lower()
+        self.image_type = image_type
+        self.quality_pref_name = f'{image_type}_compression_quality_for_lossless_compression'
+        jq.setMinimum(1), jq.setMaximum(100), jq.setValue(tprefs.get(self.quality_pref_name, default_compression))
+        jq.setEnabled(False)
+        jq.setToolTip(_('The image quality, 1 is high compression with low image quality, 100 is low compression with high image quality'))
+        jq.valueChanged.connect(self.save_compression_quality)
+        el.toggled.connect(jq.setEnabled)
+        self.jql = la = QLabel(_('Image &quality:'))
+        la.setBuddy(jq)
+        h.addWidget(la), h.addWidget(jq)
+
+    def save_compression_quality(self):
+        tprefs.set(self.quality_pref_name, self.jq.value())
+
+
 class CompressImages(Dialog):
 
     def __init__(self, parent=None):
@@ -203,38 +232,30 @@ class CompressImages(Dialog):
             ' without affecting image quality. Typically image size is reduced by 5 - 15%.'))
         la.setWordWrap(True)
         la.setMinimumWidth(250)
-        l.addWidget(la), l.addSpacing(30)
+        l.addWidget(la)
-
+        self.jpeg = LossyCompression('jpeg', parent=self)
-        self.enable_lossy = el = QCheckBox(_('Enable &lossy compression of JPEG images'))
+        l.addSpacing(30), l.addWidget(self.jpeg)
-        el.setToolTip(_('This allows you to change the quality factor used for JPEG images.\nBy lowering'
+        self.webp = LossyCompression('webp', default_compression=75, parent=self)
-                        ' the quality you can greatly reduce file size, at the expense of the image looking blurred.'))
+        l.addSpacing(30), l.addWidget(self.webp)
-        l.addWidget(el)
-        self.h2 = h = QHBoxLayout()
-        l.addLayout(h)
-        self.jq = jq = QSpinBox(self)
-        jq.setMinimum(0), jq.setMaximum(100), jq.setValue(tprefs.get('jpeg_compression_quality_for_lossless_compression', 80)), jq.setEnabled(False)
-        jq.setToolTip(_('The compression quality, 1 is high compression, 100 is low compression.\nImage'
-                        ' quality is inversely correlated with compression quality.'))
-        jq.valueChanged.connect(self.save_compression_quality)
-        el.toggled.connect(jq.setEnabled)
-        self.jql = la = QLabel(_('Compression &quality:'))
-        la.setBuddy(jq)
-        h.addWidget(la), h.addWidget(jq)
         l.addStretch(10)
         l.addWidget(self.bb)
 
-    def save_compression_quality(self):
-        tprefs.set('jpeg_compression_quality_for_lossless_compression', self.jq.value())
-
     @property
     def names(self):
         return {item.text() for item in self.images.selectedItems()}
 
     @property
     def jpeg_quality(self):
-        if not self.enable_lossy.isChecked():
+        if not self.jpeg.enable_lossy.isChecked():
             return None
-        return self.jq.value()
+        return self.jpeg.jq.value()
+
+    @property
+    def webp_quality(self):
+        if not self.webp.enable_lossy.isChecked():
+            return None
+        return self.webp.jq.value()
+
 
 
 class CompressImagesProgress(Dialog):
@@ -242,8 +263,9 @@ class CompressImagesProgress(Dialog):
     gui_loop = pyqtSignal(object, object, object)
     cidone = pyqtSignal()
 
-    def __init__(self, names=None, jpeg_quality=None, parent=None):
+    def __init__(self, names=None, jpeg_quality=None, webp_quality=None, parent=None):
         self.names, self.jpeg_quality = names, jpeg_quality
+        self.webp_quality = webp_quality
         self.keep_going = True
         self.result = (None, '')
         Dialog.__init__(self, _('Compressing images...'), 'compress-images-progress', parent=parent)
@@ -259,7 +281,7 @@ class CompressImagesProgress(Dialog):
         report = []
         try:
             self.result = (compress_images(
-                current_container(), report=report.append, names=self.names, jpeg_quality=self.jpeg_quality,
+                current_container(), report=report.append, names=self.names, jpeg_quality=self.jpeg_quality, webp_quality=self.webp_quality,
                 progress_callback=self.progress_callback
             )[0], report)
         except Exception: