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Write optimized JPEG data by default

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This commit is contained in:
Kovid Goyal 2016-05-06 21:32:45 +05:30
parent 8dd533bd5f
commit 6115eb9330
1 changed files with 10 additions and 4 deletions
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14
src/calibre/utils/img.py
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@ -84,7 +84,7 @@ def blend_image(img, bgcolor='#ffffff'):
overlay(img, nimg)
return nimg
def image_to_data(img, compression_quality=95, fmt='JPEG', png_compression_level=9):
def image_to_data(img, compression_quality=95, fmt='JPEG', png_compression_level=9, jpeg_optimized=True, jpeg_progressive=True):
''' Serialize image to bytestring in the specified format.
compression_quality is for JPEG and goes from 0 to 100.
png_compression_level is for PNG and goes from 0-9 '''
@ -92,10 +92,16 @@ def image_to_data(img, compression_quality=95, fmt='JPEG', png_compression_level
buf = QBuffer(ba)
buf.open(QBuffer.WriteOnly)
fmt = fmt.upper()
is_jpeg = fmt in ('JPG', 'JPEG')
w = QImageWriter(buf, fmt.encode('ascii'))
if img.hasAlphaChannel() and fmt in 'JPEG JPG'.split():
img = blend_image(img)
if fmt == 'PNG':
if is_jpeg:
if img.hasAlphaChannel():
img = blend_image(img)
if jpeg_optimized and hasattr(QImageWriter, 'setOptimizedWrite'):
w.setOptimizedWrite(True)
if jpeg_progressive and hasattr(QImageWriter, 'setProgressiveScanWrite'):
w.setProgressiveScanWrite(True)
elif fmt == 'PNG':
cl = min(9, max(0, png_compression_level))
w.setQuality(10 * (9-cl))
else: