64 lines
2.5 KiB
Markdown
64 lines
2.5 KiB
Markdown
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# Receipt Printer driver functions
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PostalPoint abstracts the receipt printer hardware commands, so the same functions are available on
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all brands and languages of receipt printer, and printer media size and settings are also handled for you.
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The drivers operate in line mode, where each successive command appends content to the bottom of the page.
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These functions are available on the object supplied by the promise returned from
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`global.apis.print.getReceiptPrinter()`.
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## Functions
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```javascript
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//
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// Add one or more lines of text, with automatic wrapping.
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// If both firsttext and secondtext are provided, two columns of text are generated,
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// with the first left-justified and the second right-justified.
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// `firstjustify` can be "L" (left), "C" (center), or "R" (right).
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// Not all printers support all the formatting options, and may render them in different ways,
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// but the formatting intent is made clear regardless.
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addFieldBlock(firsttext, firstjustify, secondtext = "", secondjustify = "R", bold = false, doubleheight = false, underline = false);
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// Add a blank line to the label.
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newLine();
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// Draw a horizontal line across the page.
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drawLine();
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// Render a Code 128 barcode, centered horizontally, with a human-readable label beneath.
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// Important: this function is sometimes asynchronous depending on the printer driver.
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barcode128(content);
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// Print an image. Width is in pixels.
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// pixelByteArray is a Uint8Array where each bit is a pixel (1=black, 0=white),
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// starting at the top-left of the image and going across and then down. Use `imageToBitmap` to
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// obtain this data from a Jimp image.
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// Use "L" as the position to print on the next line, centered horizontally.
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// Some printers also support position = "C", which will
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// ignore other commands and print the image centered on the label,
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// but if you're doing that, just use `global.apis.print.printLabelImage()` instead.
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drawImage(width, position, pixelByteArray);
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// If supported by the printer, opens an attached cash drawer. Command is ignored if unavailable.
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openCashDrawer();
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// The last command to run, when ready to print. Returns the raw data to send to the printer.
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// Important: this function is sometimes asynchronous depending on the printer driver.
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getData();
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```
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## Example
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```javascript
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var printer = await global.apis.print.getReceiptPrinter();
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printer.addFieldBlock("Hello Bold World!", "C", "", "", true);
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printer.drawLine();
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await printer.barcode128("1234567890");
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printer.newLine();
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await global.apis.printer.printReceiptData(await printer.getData());
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```
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