This adds support for printing images using the older GS v 0 command.
I'm 100% not sure about the API so hints or suggestions are welcome!
+42
src/escpos/document.gleam
+42
src/escpos/document.gleam
···
40
40
LineFeed(Int)
41
41
Cut(protocol.Cut)
42
42
Image(image: image.PrintableImage)
43
+
RasterImage(image: image.PrintableImage)
43
44
Styled(modifiers: Set(Modifier), commands: List(Command))
44
45
Raw(BitArray)
45
46
}
···
65
66
DoLineFeed(Int)
66
67
DoCut(protocol.Cut)
67
68
DoImage(image.PrintableImage)
69
+
DoRasterImage(image.PrintableImage)
68
70
DoRaw(BitArray)
69
71
SetBold(Bool)
70
72
SetUnderline(Bool)
···
183
185
Image(image)
184
186
}
185
187
188
+
/// Prints a monochrome image prepared by the `image` module. This is using an older
189
+
/// method to print images, useful for some printers that do not understand graphic buffer
190
+
/// commands.
191
+
///
192
+
/// ## Example
193
+
///
194
+
/// ```gleam
195
+
/// let assert Ok(pgm) = simplifile.read_bits(from: "./lucy.pgm")
196
+
/// let assert Ok(img) = image.from_pgm(raw_pgm)
197
+
/// let img = image.dither_bayer4x4(img, 0)
198
+
///
199
+
/// document.render([
200
+
/// raster_image(img),
201
+
/// cut(),
202
+
/// ])
203
+
/// ```
204
+
pub fn image_raster(image: image.PrintableImage) -> Command {
205
+
RasterImage(image)
206
+
}
207
+
186
208
/// Performs a full paper cut.
187
209
pub fn cut() -> Command {
188
210
Cut(protocol.Full)
···
353
375
do_build_ast(
354
376
rest,
355
377
[DoImage(i), ..acc],
378
+
State(..state, new_line: True),
379
+
)
380
+
}
381
+
RasterImage(i) -> {
382
+
let #(acc, state) = ensure_new_line(state, acc)
383
+
do_build_ast(
384
+
rest,
385
+
[DoRasterImage(i), ..acc],
356
386
State(..state, new_line: True),
357
387
)
358
388
}
···
560
590
do_compile_ast(rest, bit_array.append(acc, protocol.justify(j)))
561
591
SetFont(f) ->
562
592
do_compile_ast(rest, bit_array.append(acc, protocol.font(f)))
593
+
DoRasterImage(i) ->
594
+
do_compile_ast(
595
+
rest,
596
+
bit_array.append(
597
+
acc,
598
+
protocol.image_to_raster(
599
+
image.width(i),
600
+
image.height(i),
601
+
image.pixels(i),
602
+
),
603
+
),
604
+
)
563
605
}
564
606
}
565
607
}
+37
src/escpos/protocol.gleam
+37
src/escpos/protocol.gleam
···
239
239
pub fn print_graphics_buffer() -> BitArray {
240
240
<<gs, "(", "L", 2, 0, 48, 50>>
241
241
}
242
+
243
+
/// Encodes a raster bit image print command (`GS v 0`).
244
+
///
245
+
/// `width` is in dots (pixels) and must be a multiple of 8, since the
246
+
/// `packed_pixels` payload is 1 bit per pixel packed into bytes (MSB first),
247
+
/// with each byte representing 8 horizontal pixels.
248
+
///
249
+
/// `height` is in dots (rows).
250
+
///
251
+
/// The payload size must be exactly `(width / 8) * height` bytes.
252
+
pub fn image_to_raster(
253
+
width: Int,
254
+
height: Int,
255
+
packed_pixels: BitArray,
256
+
) -> BitArray {
257
+
let width_bytes = width / 8
258
+
let x_low = width_bytes % 256
259
+
let x_high = width_bytes / 256
260
+
let y_low = height % 256
261
+
let y_high = height / 256
262
+
263
+
<<
264
+
gs,
265
+
"v",
266
+
"0",
267
+
0,
268
+
// m = 0 (normal mode)
269
+
x_low,
270
+
x_high,
271
+
// xL/xH = width in bytes (width / 8), little-endian
272
+
y_low,
273
+
y_high,
274
+
// yL/yH = height in dots, little-endian
275
+
packed_pixels:bits,
276
+
// raster data (1 bpp, MSB first)
277
+
>>
278
+
}
+27
src/escpos.gleam
+27
src/escpos.gleam
···
165
165
|> printer.append_to_buffer(protocol.print_graphics_buffer())
166
166
}
167
167
168
+
/// Prints a monochrome image prepared by the `image` module. This is using an older
169
+
/// method to print images, useful for some printers that do not understand graphic buffer
170
+
/// commands.
171
+
///
172
+
/// ## Example
173
+
///
174
+
/// ```gleam
175
+
/// let assert Ok(pgm) = simplifile.read_bits(from: "./lucy.pgm")
176
+
/// let assert Ok(img) = image.from_pgm(raw_pgm)
177
+
/// let img = image.dither_bayer4x4(img, 0)
178
+
///
179
+
/// escpos.new()
180
+
/// |> escpos.image_raster(img)
181
+
/// |> printer.print(printer)
182
+
/// ```
183
+
pub fn image_raster(
184
+
cb: CommandBuffer,
185
+
image: image.PrintableImage,
186
+
) -> CommandBuffer {
187
+
ensure_new_line(cb)
188
+
|> append(protocol.image_to_raster(
189
+
image.width(image),
190
+
image.height(image),
191
+
image.pixels(image),
192
+
))
193
+
}
194
+
168
195
/// Appends raw bytes to the buffer.
169
196
pub fn raw(cb: CommandBuffer, data: BitArray) -> CommandBuffer {
170
197
printer.append_to_buffer(cb, data)
History
2 rounds
2 comments
kwando.tngl.sh
submitted
#1
expand 1 comment
pull request successfully merged
kwando.tngl.sh
submitted
#0
1 commit
expand
collapse
rasterized image support
expand 1 comment
Typo in escpos.gleam on line 169: "do" instead of "does"
Also could you add the same disclaimer to the "document" api.
In the protocol.gleam on line 265: There's a constant for gs so you can use that instead of 29. Also you can type "v" instead of 118 and "0" instead of 48. That should make the comments redundant.
I've already pushed the CommandBuffer change, so you'll need to rebase and use printer.append_to_buffer in escpos.gleam
Thank you so much for the contribution 💕
Thank you :)