soliloque has proposed merging lp:~soliloque/simple-scan/fastpdf into
lp:simple-scan.
Commit message:
Hasten the save_pdf method
Requested reviews:
Robert Ancell (robert-ancell)
For more details, see:
https://code.launchpad.net/~soliloque/simple-scan/fastpdf/+merge/322610
Sorry, the diff is pretty hard to read.
Saving pdf currently take a long time, in part because it currently encode each
page two times: one time with zlib, then with jpeg, and finally discard the
biggest version. However this is mostly useless because in all test I did, the
ZLIB compression was choosen when using the "Text" setting and JPEG compression
when using the "Photo" setting.
I modified save_pdf so when using "Text" setting, it directly encode with zlib
and when using "Photo" setting, it directly encode with jpeg. As the zlib
algorithm take longer when not compressing effectively, the speedup can be very
high: with only one page and an empty flatbed using "Photo" setting, the
book.save method take right now 26 seconds on my computer, vs 0,1 seconds with
this change.
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=== modified file 'src/book.vala'
--- src/book.vala 2017-03-29 09:40:01 +0000
+++ src/book.vala 2017-04-16 15:04:24 +0000
@@ -341,152 +341,119 @@
unowned uint8[] pixels = image.get_pixels ();
var page_width = width * 72.0 / page.dpi;
var page_height = height * 72.0 / page.dpi;
-
- int depth = 8;
- string color_space = "DeviceRGB";
- string? filter = null;
+ int depth;
+ string color_space;
+ string filter;
char[] width_buffer = new char[double.DTOSTR_BUF_SIZE];
char[] height_buffer = new char[double.DTOSTR_BUF_SIZE];
uint8[] data;
+
if (page.is_color)
{
depth = 8;
color_space = "DeviceRGB";
- var data_length = height * width * 3;
- data = new uint8[data_length];
- for (var row = 0; row < height; row++)
- {
- var in_offset = row * image.rowstride;
- var out_offset = row * width * 3;
- for (var x = 0; x < width; x++)
- {
- var in_o = in_offset + x*3;
- var out_o = out_offset + x*3;
-
- data[out_o] = pixels[in_o];
- data[out_o+1] = pixels[in_o+1];
- data[out_o+2] = pixels[in_o+2];
- }
- }
+ data = compress_jpeg (image, quality, page.dpi);
+ filter = "DCTDecode"; /* JPEG compression applied to color image data */
}
- else if (page.depth == 2)
+ else
{
- int shift_count = 6;
- depth = 2;
color_space = "DeviceGray";
- var data_length = height * ((width * 2 + 7) / 8);
- data = new uint8[data_length];
- var offset = 0;
- for (var row = 0; row < height; row++)
+ if (page.depth == 2)
{
- /* Pad to the next line */
- if (shift_count != 6)
- {
- offset++;
- shift_count = 6;
- }
-
- var in_offset = row * image.rowstride;
- for (var x = 0; x < width; x++)
- {
- /* Clear byte */
- if (shift_count == 6)
- data[offset] = 0;
-
- /* Set bits */
- var p = pixels[in_offset + x*3];
- if (p >= 192)
- data[offset] |= 3 << shift_count;
- else if (p >= 128)
- data[offset] |= 2 << shift_count;
- else if (p >= 64)
- data[offset] |= 1 << shift_count;
-
- /* Move to the next position */
- if (shift_count == 0)
+ int shift_count = 6;
+ depth = 2;
+ var data_length = height * ((width * 2 + 7) / 8);
+ data = new uint8[data_length];
+ var offset = 0;
+ for (var row = 0; row < height; row++)
+ {
+ /* Pad to the next line */
+ if (shift_count != 6)
{
offset++;
shift_count = 6;
}
- else
- shift_count -= 2;
+
+ var in_offset = row * image.rowstride;
+ for (var x = 0; x < width; x++)
+ {
+ /* Clear byte */
+ if (shift_count == 6)
+ data[offset] = 0;
+
+ /* Set bits */
+ var p = pixels[in_offset + x*3];
+ if (p >= 192)
+ data[offset] |= 3 << shift_count;
+ else if (p >= 128)
+ data[offset] |= 2 << shift_count;
+ else if (p >= 64)
+ data[offset] |= 1 << shift_count;
+
+ /* Move to the next position */
+ if (shift_count == 0)
+ {
+ offset++;
+ shift_count = 6;
+ }
+ else
+ shift_count -= 2;
+ }
}
}
- }
- else if (page.depth == 1)
- {
- int mask = 0x80;
-
- depth = 1;
- color_space = "DeviceGray";
- var data_length = height * ((width + 7) / 8);
- data = new uint8[data_length];
- var offset = 0;
- for (var row = 0; row < height; row++)
+ else if (page.depth == 1)
{
- /* Pad to the next line */
- if (mask != 0x80)
- {
- offset++;
- mask = 0x80;
- }
-
- var in_offset = row * image.rowstride;
- for (var x = 0; x < width; x++)
- {
- /* Clear byte */
- if (mask == 0x80)
- data[offset] = 0;
-
- /* Set bit */
- if (pixels[in_offset+x*3] != 0)
- data[offset] |= (uint8) mask;
-
- /* Move to the next bit */
- mask >>= 1;
- if (mask == 0)
+ int mask = 0x80;
+
+ depth = 1;
+ var data_length = height * ((width + 7) / 8);
+ data = new uint8[data_length];
+ var offset = 0;
+ for (var row = 0; row < height; row++)
+ {
+ /* Pad to the next line */
+ if (mask != 0x80)
{
offset++;
mask = 0x80;
}
+
+ var in_offset = row * image.rowstride;
+ for (var x = 0; x < width; x++)
+ {
+ /* Clear byte */
+ if (mask == 0x80)
+ data[offset] = 0;
+
+ /* Set bit */
+ if (pixels[in_offset+x*3] != 0)
+ data[offset] |= (uint8) mask;
+
+ /* Move to the next bit */
+ mask >>= 1;
+ if (mask == 0)
+ {
+ offset++;
+ mask = 0x80;
+ }
+ }
}
}
- }
- else
- {
- depth = 8;
- color_space = "DeviceGray";
- var data_length = height * width;
- data = new uint8 [data_length];
- for (var row = 0; row < height; row++)
- {
- var in_offset = row * image.rowstride;
- var out_offset = row * width;
- for (var x = 0; x < width; x++)
- data[out_offset+x] = pixels[in_offset+x*3];
- }
- }
-
- /* Compress data */
- var compressed_data = compress_zlib (data);
- if (compressed_data != null)
- {
- /* Try if JPEG compression is better */
- if (depth > 1)
- {
- var jpeg_data = compress_jpeg (image, quality, page.dpi);
- if (jpeg_data.length < compressed_data.length)
+ else
+ {
+ depth = 8;
+ var data_length = height * width;
+ data = new uint8 [data_length];
+ for (var row = 0; row < height; row++)
{
- filter = "DCTDecode";
- data = jpeg_data;
+ var in_offset = row * image.rowstride;
+ var out_offset = row * width;
+ for (var x = 0; x < width; x++)
+ data[out_offset+x] = pixels[in_offset+x*3];
}
}
-
- if (filter == null)
- {
- filter = "FlateDecode";
- data = compressed_data;
- }
+ data = compress_zlib (data);
+ filter = "FlateDecode"; /* ZLIB compression applied to gray image data */
}
/* Page */
@@ -528,7 +495,7 @@
writer.start_object (struct_tree_root_number);
writer.write_string ("%u 0 obj\n".printf (struct_tree_root_number));
writer.write_string ("<<\n");
- writer.write_string ("/Type /StructTreeRoot\n");
+ writer.write_string ("/Type /StructTreeRoot\n");
writer.write_string (">>\n");
writer.write_string ("endobj\n");
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