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examples/cgi/WwwCounter/gifcat.pl  view on Meta::CPAN

	$leftpos = 0;
	$logicalScreenWidth = 0;
	$logicalScreenHeight = 0;
	$useLocalColorTable = 0;
	
	foreach $file (@files) {
		$size = -s $file;
		open(IN, "$file") || return("ERROR");
		binmode(IN);
		read(IN, $buf, $size) || return("ERROR");
		close(IN);

		$cnt = 0;
		&GifHeader();
		while (1) {
			$x1 = ord(substr($buf, $cnt, 1));
			if ($x1 == 0x2c) {
				&ImageBlock();
			} elsif ($x1 == 0x21) {
				$x2 = ord(substr($buf, $cnt + 1, 1));
				if ($x2 == 0xf9) {
					&GraphicControlExtension();
				} elsif ($x2 == 0xfe) {
					&CommentExtension();
				} elsif ($x2 == 0x01) {
					&PlainTextExtension();
				} elsif ($x2 == 0xff) {
					&ApplicationExtension();
				} else {
					return("ERROR");
				}
			} elsif ($x1 == 0x3b) {
				&Trailer();
				last;
			} elsif ($cnt == $size) {
				last;
			} else {
				return("ERROR");
			}
		}

		undef($buf);
		$Gif++;
	}
	if ($pflag == 1) {
		return;
	}

	$GifImage = "GIF89a";
	$GifImage .= pack("C", $logicalScreenWidth & 0x00ff);
	$GifImage .= pack("C", ($logicalScreenWidth & 0xff00) >> 8);
	$GifImage .= pack("C", $logicalScreenHeight & 0x00ff);
	$GifImage .= pack("C", ($logicalScreenHeight & 0xff00) >> 8);
	if ($useLocalColorTable) {
		$PackedFields18[0] &= ~0x80;
	}
	$GifImage .= pack("C", $PackedFields18[0]);
	$GifImage .= pack("C", $BackgroundColorIndex);
	$GifImage .= pack("C", $PixelAspectRatio);
	if ($useLocalColorTable == 0) {
		$GifImage .= $globalColorTable[0];
	}
	for ($i = -1; $i < $Gif; $i++) {
		$j = ($i == -1) ? 0 : $i;
		$GifImage .= pack("CCC", 0x21, 0xf9, 0x04);
		$GifImage .= pack("C", $PackedFields23 | $TransparentColorFlag[$j]);
		$GifImage .= pack("CC", 0x00, 0x00);
		$GifImage .= pack("C", $TransparentColorIndex[$j]);
		$GifImage .= pack("C", 0x00);
		$GifImage .= pack("C", 0x2c);
		$n = $leftpos;
		$leftpos += ($i == -1) ? 0 : $ImageWidth[$j];
		$GifImage .= pack("C", $n & 0x00ff);
		$GifImage .= pack("C", ($n & 0xff00) >> 8);
		$GifImage .= pack("CC", 0x00, 0x00);
		$GifImage .= pack("C", $ImageWidth[$j] & 0x00ff);
		$GifImage .= pack("C", ($ImageWidth[$j] & 0xff00) >> 8);
		$GifImage .= pack("C", $ImageHeight & 0x00ff);
		$GifImage .= pack("C", ($ImageHeight & 0xff00) >> 8);
		if ($useLocalColorTable) {
			$PackedFields20[$j] |= 0x80;
			$PackedFields20[$j] &= ~0x07;
			$PackedFields20[$j] |= ($PackedFields18[$j] & 0x07);
			$GifImage .= pack("C", $PackedFields20[$j]);
			$GifImage .= $globalColorTable[$j];
		} else {
			$GifImage .= pack("C", $PackedFields20[$j]);
		}
		$GifImage .= pack("C", $LzwMinimumCodeSize[$j]);
		$GifImage .= $ImageData[$j];
	}
	$GifImage .= pack("C", 0x3b);

}

;# =====================================
;# GifHeader
;# =====================================
sub GifHeader {
	$Signature = substr($buf, $cnt, 3); $cnt += 3;
	$Version   = substr($buf, $cnt, 3); $cnt += 3;
	$LogicalScreenWidth
			= ord(substr($buf, $cnt + 0, 1))
			+ ord(substr($buf, $cnt + 1, 1)) * 256; $cnt += 2;
	$LogicalScreenHeight
			= ord(substr($buf, $cnt + 0, 1))
			+ ord(substr($buf, $cnt + 1, 1)) * 256; $cnt += 2;
	$PackedFields18[$Gif]   = ord(substr($buf, $cnt, 1)); $cnt++;
	$GlobalColorTableFlag   = ($PackedFields18[$Gif] & 0x80) >> 7;
	$ColorResolution        = (($PackedFields18[$Gif] & 0x70) >> 4) + 1;
	$SortFlag               = ($PackedFields18[$Gif] & 0x08) >> 3;
	$SizeOfGlobalColorTable = 2 ** (($PackedFields18[$Gif] & 0x07) + 1);
	$BackgroundColorIndex   = ord(substr($buf, $cnt, 1)); $cnt++;
	$PixelAspectRatio       = ord(substr($buf, $cnt, 1)); $cnt++;
	if ($GlobalColorTableFlag) {
		$GlobalColorTable 
			= substr($buf, $cnt, $SizeOfGlobalColorTable * 3);
		$cnt += $SizeOfGlobalColorTable * 3;
	} else {
		$GlobalColorTable = "";
	}

	$logicalScreenWidth += $LogicalScreenWidth;
	if ($logicalScreenHeight < $LogicalScreenHeight) {
		$logicalScreenHeight = $LogicalScreenHeight;
	}
	if ($GlobalColorTableFlag) {
		$globalColorTable[$Gif] = $GlobalColorTable;
		if ($Gif > 0) {
			if ($GlobalColorTable ne $globalColorTable[$Gif - 1]) {
				$useLocalColorTable = 1;
			}
		}
	}

	if ($pflag) {
		printf("=====================================\n");
		printf("GifHeader\n");
		printf("=====================================\n");
		printf("Signature:                     %s\n", $Signature);
		printf("Version:                       %s\n", $Version);
		printf("Logical Screen Width:          %d\n", $LogicalScreenWidth);
		printf("Logical Screen Height:         %d\n", $LogicalScreenHeight);
		printf("Global Color Table Flag:       %d\n", $GlobalColorTableFlag);
		printf("Color Resolution:              %d\n", $ColorResolution);
		printf("Sort Flag:                     %d\n", $SortFlag);
		printf("Size of Global Color Table:    %d * 3\n", $SizeOfGlobalColorTable);
		printf("Background Color Index:        %d\n", $BackgroundColorIndex);
		printf("Pixel Aspect Ratio:            %d\n", $PixelAspectRatio);
		printf("Global Color Table:            \n");
		Dump($GlobalColorTable);
	}
}

;# =====================================
;# Image Block
;# =====================================
sub ImageBlock {
	$ImageSeparator    = ord(substr($buf, $cnt, 1)); $cnt++;
	$ImageLeftPosition = ord(substr($buf, $cnt, 1))
			   + ord(substr($buf, $cnt + 1, 1)) * 256; $cnt += 2;
	$ImageTopPosition  = ord(substr($buf, $cnt, 1))
			   + ord(substr($buf, $cnt + 1, 1)) * 256; $cnt += 2;
	$ImageWidth[$Gif]  = ord(substr($buf, $cnt, 1))
			   + ord(substr($buf, $cnt + 1, 1)) * 256; $cnt += 2;
	$ImageHeight       = ord(substr($buf, $cnt, 1))
			   + ord(substr($buf, $cnt + 1, 1)) * 256; $cnt += 2;
	$PackedFields20[$Gif]  = ord(substr($buf, $cnt, 1)); $cnt++;
	$LocalColorTableFlag   = ($PackedFields20[$Gif] & 0x80) >> 7;
	$InterlaceFlag         = ($PackedFields20[$Gif] & 0x40) >> 6;
	$SortFlag              = ($PackedFields20[$Gif] & 0x20) >> 5;
	$Reserved              = ($PackedFields20[$Gif] & 0x18) >> 3;
	if ($LocalColorTableFlag) {
		$SizeOfLocalColorTable = 2 ** (($PackedFields20[$Gif] & 0x07) + 1);
		$LocalColorTable = substr($buf, $cnt, $SizeOfLocalColorTable);
		$cnt += $SizeOfLocalColorTable * 3;
	} else {
		$SizeOfLocalColorTable = 0;
		$LocalColorTable = "";
	}
	$LzwMinimumCodeSize[$Gif] = ord(substr($buf, $cnt, 1)); $cnt++;
	$ImageData[$Gif] = &DataSubBlock();

	if ($pflag) {
		printf("=====================================\n");
		printf("Image Block\n");
		printf("=====================================\n");
		printf("Image Separator:               0x%02x\n", $ImageSeparator);
		printf("Image Left Position:           %d\n", $ImageLeftPosition);
		printf("Image Top Position:            %d\n", $ImageTopPosition);