From 4e5d32aa655a7290782fa19aa2aeae6a5408e465 Mon Sep 17 00:00:00 2001
From: Jakub Wilk <jwilk@jwilk.net>
Date: Mon, 1 Apr 2019 14:44:36 +0200
Subject: [PATCH] Remove unused decode_png

The function hasn't been used since 18b6216150fa39d5e3cdbf353339e1c010bcee8d.
---
 youtube_dl/utils.py | 107 --------------------------------------------
 1 file changed, 107 deletions(-)

diff --git a/youtube_dl/utils.py b/youtube_dl/utils.py
index 71713f63a..942d13416 100644
--- a/youtube_dl/utils.py
+++ b/youtube_dl/utils.py
@@ -3811,113 +3811,6 @@ def urshift(val, n):
     return val >> n if val >= 0 else (val + 0x100000000) >> n
 
 
-# Based on png2str() written by @gdkchan and improved by @yokrysty
-# Originally posted at https://github.com/ytdl-org/youtube-dl/issues/9706
-def decode_png(png_data):
-    # Reference: https://www.w3.org/TR/PNG/
-    header = png_data[8:]
-
-    if png_data[:8] != b'\x89PNG\x0d\x0a\x1a\x0a' or header[4:8] != b'IHDR':
-        raise IOError('Not a valid PNG file.')
-
-    int_map = {1: '>B', 2: '>H', 4: '>I'}
-    unpack_integer = lambda x: compat_struct_unpack(int_map[len(x)], x)[0]
-
-    chunks = []
-
-    while header:
-        length = unpack_integer(header[:4])
-        header = header[4:]
-
-        chunk_type = header[:4]
-        header = header[4:]
-
-        chunk_data = header[:length]
-        header = header[length:]
-
-        header = header[4:]  # Skip CRC
-
-        chunks.append({
-            'type': chunk_type,
-            'length': length,
-            'data': chunk_data
-        })
-
-    ihdr = chunks[0]['data']
-
-    width = unpack_integer(ihdr[:4])
-    height = unpack_integer(ihdr[4:8])
-
-    idat = b''
-
-    for chunk in chunks:
-        if chunk['type'] == b'IDAT':
-            idat += chunk['data']
-
-    if not idat:
-        raise IOError('Unable to read PNG data.')
-
-    decompressed_data = bytearray(zlib.decompress(idat))
-
-    stride = width * 3
-    pixels = []
-
-    def _get_pixel(idx):
-        x = idx % stride
-        y = idx // stride
-        return pixels[y][x]
-
-    for y in range(height):
-        basePos = y * (1 + stride)
-        filter_type = decompressed_data[basePos]
-
-        current_row = []
-
-        pixels.append(current_row)
-
-        for x in range(stride):
-            color = decompressed_data[1 + basePos + x]
-            basex = y * stride + x
-            left = 0
-            up = 0
-
-            if x > 2:
-                left = _get_pixel(basex - 3)
-            if y > 0:
-                up = _get_pixel(basex - stride)
-
-            if filter_type == 1:  # Sub
-                color = (color + left) & 0xff
-            elif filter_type == 2:  # Up
-                color = (color + up) & 0xff
-            elif filter_type == 3:  # Average
-                color = (color + ((left + up) >> 1)) & 0xff
-            elif filter_type == 4:  # Paeth
-                a = left
-                b = up
-                c = 0
-
-                if x > 2 and y > 0:
-                    c = _get_pixel(basex - stride - 3)
-
-                p = a + b - c
-
-                pa = abs(p - a)
-                pb = abs(p - b)
-                pc = abs(p - c)
-
-                if pa <= pb and pa <= pc:
-                    color = (color + a) & 0xff
-                elif pb <= pc:
-                    color = (color + b) & 0xff
-                else:
-                    color = (color + c) & 0xff
-
-            current_row.append(color)
-
-    return width, height, pixels
-
-
 def write_xattr(path, key, value):
     # This mess below finds the best xattr tool for the job
     try: