randy
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ReceiptBuilder#image implements GS v 0 raster printing (no image library needed for the demo -- a procedural 8px checkerboard proves it end to end). Skipped attempting the printer's real-time clock: unsure the TM-T20II actually has a battery-backed RTC (that's usually an option on higher-end models), not worth guessing at an undocumented command.
124 lines
3.1 KiB
Ruby
124 lines
3.1 KiB
Ruby
# Minimal chainable ESC/POS builder for the Epson TM-T20II.
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#
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# Written instead of pulling in the `escpos` gem: the gem's diacritics
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# handling needed the same manual UTF-8->CP852 `.encode` call anyway, and a
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# couple of its helpers didn't behave as documented against this printer --
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# fewer moving parts doing it directly.
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class ReceiptBuilder
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INIT = "\x1B\x40".freeze
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CP852 = "\x1B\x74\x12".freeze # code page for Slovak diacritics
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ALIGN_LEFT = "\x1B\x61\x00".freeze
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ALIGN_CENT = "\x1B\x61\x01".freeze
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ALIGN_RIGH = "\x1B\x61\x02".freeze
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BOLD_ON = "\x1B\x45\x01".freeze
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BOLD_OFF = "\x1B\x45\x00".freeze
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UNDER_ON = "\x1B\x2D\x01".freeze
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UNDER_OFF = "\x1B\x2D\x00".freeze
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TXT_NORM = "\x1D\x21\x00".freeze
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TXT_BIG = "\x1D\x21\x11".freeze # double height and width
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TXT_HIGH = "\x1D\x21\x01".freeze # double height
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TXT_WIDE = "\x1D\x21\x10".freeze # double width
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CUT = "\x1D\x56\x00".freeze
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def initialize
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@buffer = "".b
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init
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end
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def init
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@buffer << INIT << CP852
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self
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end
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def text(str)
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@buffer << str.encode('CP852', invalid: :replace, undef: :replace, replace: '?')
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self
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end
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# Appends already-encoded/raw bytes as-is (e.g. pre-parsed ESC/POS command
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# sequences), bypassing the CP852 text encoding `text` applies.
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def raw(bytes)
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@buffer << bytes
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self
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end
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def align(mode)
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@buffer << case mode
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when :center then ALIGN_CENT
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when :right then ALIGN_RIGH
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else ALIGN_LEFT
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end
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self
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end
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def bold(enable = true)
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@buffer << (enable ? BOLD_ON : BOLD_OFF)
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self
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end
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def underline(enable = true)
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@buffer << (enable ? UNDER_ON : UNDER_OFF)
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self
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end
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def size(mode)
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@buffer << case mode
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when :big then TXT_BIG
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when :high then TXT_HIGH
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when :wide then TXT_WIDE
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else TXT_NORM
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end
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self
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end
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# Native ESC/POS QR code
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def qr(data, size: 6)
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qr_data = data.b
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store_len = qr_data.bytesize + 3
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@buffer << "\x1D\x28\x6B\x03\x00\x31\x43" << size.chr
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@buffer << "\x1D\x28\x6B\x03\x00\x31\x45\x30" # error correction L
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@buffer << "\x1D\x28\x6B" << [store_len % 256, store_len / 256].pack('CC') << "\x31\x50\x30" << qr_data
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@buffer << "\x1D\x28\x6B\x03\x00\x31\x51\x30" # print
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self
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end
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# Native ESC/POS EAN-13
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def ean13(code)
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@buffer << "\x1D\x6B\x02" << code.b << "\x00"
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self
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end
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# Raster bit image (GS v 0) -- bytes must already be packed 1bpp,
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# row-major, (width_px/8 rounded up) bytes per row, MSB-first, 1=black.
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def image(width_px, height_px, bytes)
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width_bytes = (width_px + 7) / 8
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@buffer << "\x1D\x76\x30\x00"
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@buffer << [width_bytes % 256, width_bytes / 256, height_px % 256, height_px / 256].pack('C4')
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@buffer << bytes
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self
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end
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def feed(lines = 3)
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@buffer << ("\n" * lines)
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self
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end
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def cut
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@buffer << CUT
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self
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end
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def render
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@buffer
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end
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def print!(device)
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File.open(device, 'wb') { |f| f.write(@buffer) }
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end
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end
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