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使用PHP或Javascript将RGB图像转换为Floyd-Steinberg图像以适用于Zebra打印机

javascriptphpimage-processingzebra-printersdithering
7
我正在开发一个基于桌面的 PHP 应用程序，需要使用 Zebra GC420t 打印机来捕获人物图像并将其打印在标签上。期望的图像应该像下面的图像一样。

enter image description here

当我尝试打印时，输出的结果会像下面的图像一样。

enter image description here我正在使用以下代码将 rgb 图像转换为 dithering 图像，使用 php 代码：

 $photo_url="";
if(isset($_GET['photo'])){
  $photo_url=$_GET['photo'];
}

function image2grf($filename='$photo_url', $targetname = 'R:IMAGE.GRF')
{
  $info = getimagesize($filename);
  $im = imagecreatefrompng($filename);
  $width = $info[0]; // imagesx($im);
  $height = $info[1]; // imagesy($im);
  $depth = $info['bits'] ?: 1;
  $threshold = $depth > 1 ? 160 : 0;
  $hexString = '';
  $byteShift = 7;
  $currentByte = 0;
  // iterate over all image pixels
  for ($y = 0; $y < $height; $y++) {
    for ($x = 0; $x < $width; $x++) {
      $color = imagecolorat($im, $x, $y);
      // compute gray value from RGB color
      if ($depth > 1) {
        $value = max($color >> 16, $color >> 8 & 255, $color & 255);
      } else {
        $value = $color;
      }
      // set (inverse) bit for the current pixel
      $currentByte |= (($value > $threshold ? 0 : 1) << $byteShift);
      $byteShift--;
      // 8 pixels filled one byte => append to output as hex
      if ($byteShift < 0) {
        $hexString .= sprintf('%02X', $currentByte);
        $currentByte = 0;
        $byteShift = 7;
      }
    }
    // append last byte at end of row
    if ($byteShift < 7) {
      $hexString .= sprintf('%02X', $currentByte);
      $currentByte = 0;
      $byteShift = 7;
    }
    $hexString .= PHP_EOL;
  }
  // compose ZPL ~DG command
  $totalBytes = ceil(($width * $height) / 8);
  $bytesPerRow = ceil($width / 8);
return sprintf('~DG%s,%05d,%03d,' . PHP_EOL, $targetname, $totalBytes, $bytesPerRow) . $hexString;
}
// Usage:
print "^XA N ^XZ" . PHP_EOL;
print image2grf($photo_url, 'R:SAMPLE.GRF');
//print "^XA^FO20,20^XGR:SAMPLE.GRF,1,1^FS^XZ" . PHP_EOL;

我正在使用以下javascript代码连接我的应用程序并将参数传递给打印机

    var available_printers = null;
var selected_category = null;
var default_printer = null;
var selected_printer = null;
var format_start = "^XA^LL200^FO80,50^A0N36,36^FD";
var format_end = "^FS^XZ";
var default_mode = true;

function setup_web_print()
{
    $('#printer_select').on('change', onPrinterSelected);
    showLoading("Loading Printer Information...");
    default_mode = true;
    selected_printer = null;
    available_printers = null;
    selected_category = null;
    default_printer = null;

    BrowserPrint.getDefaultDevice('printer', function(printer)
    {
        default_printer = printer
        if((printer != null) && (printer.connection != undefined))
        {
            selected_printer = printer;
            var printer_details = $('#printer_details');
            var selected_printer_div = $('#selected_printer');

            selected_printer_div.text("Using Default Printer: " + printer.name);
            hideLoading();
            printer_details.show();
            $('#print_form').show();

        }
        BrowserPrint.getLocalDevices(function(printers)
            {
                available_printers = printers;
                var sel = document.getElementById("printers");
                var printers_available = false;
                sel.innerHTML = "";
                if (printers != undefined)
                {
                    for(var i = 0; i < printers.length; i++)
                    {
                        if (printers[i].connection == 'usb')
                        {
                            var opt = document.createElement("option");
                            opt.innerHTML = printers[i].connection + ": " + printers[i].uid;
                            opt.value = printers[i].uid;
                            sel.appendChild(opt);
                            printers_available = true;
                        }
                    }
                }

                if(!printers_available)
                {
                    showErrorMessage("No Zebra Printers could be found!");
                    hideLoading();
                    $('#print_form').hide();
                    return;
                }
                else if(selected_printer == null)
                {
                    default_mode = false;
                    changePrinter();
                    $('#print_form').show();
                    hideLoading();
                }
            }, undefined, 'printer');
    }, 
    function(error_response)
    {
        showBrowserPrintNotFound();
    });
};
function showBrowserPrintNotFound()
{
    showErrorMessage("An error occured while attempting to connect to your Zebra Printer. You may not have Zebra Browser Print installed, or it may not be running. Install Zebra Browser Print, or start the Zebra Browser Print Service, and try again.");

};
  // new Date().toLocaleTimeString('en-US', { hour12: false, 
  //                                            hour: "numeric", 
  //                                            minute: "numeric"});

function sendData(photoURL)
{

    var test;
        $.ajax({
            url: 'db/zpl.php?photo='+photoURL,
            cache: false,
            contentType: false,
            processData: false,
            type: 'GET',
            success: function(data) {
            test=data;
            console.log("From ZPL:"+data);

            }

        });



    var mob="",lap="",other="";
    if($("#emobile").val()==="on"){
        mob="Mobile";
    }

    if($("#elaptop").val()==="on"){
        lap="Laptop";
    }

    if($("#eother").val()==="on"){
        other="Other";
    }

    showLoading("Printing...");
    checkPrinterStatus( function (text){
        if (text == "Ready to Print")
        {
        selected_printer.send("^XA N ^XZ");
        selected_printer.send("~DYE:SAMPLE.GRF,A,GRF,5000,030"+test+",A");          selected_printer.send("^XA^FX^CFA,30^FO10,70^FDVisitorName:"+$("#user").val()+"^FS^FO10,120^FDCompany:"+$("#compName").val()+"^FS ^FO10,170^FDTo Meet:"+$("#toMeet").val()+"^FS ^FO10,220^FDPurpose:"+$("#reason").val()+"^FS ^FO10,270^FDAuthorise^FS ^FO10,320^FDto Carry:"+mob+" "+lap+"^FS^FO250,70^XG R:SAMPLE.GRF,1,1^FS^XZ");
        }
        else
        {
            printerError(text);
        }
    });
};

function checkPrinterStatus(finishedFunction)
{
    selected_printer.sendThenRead("~HQES", 
                function(text){
                        var that = this;
                        var statuses = new Array();
                        var ok = false;
                        var is_error = text.charAt(70);
                        var media = text.charAt(88);
                        var head = text.charAt(87);
                        var pause = text.charAt(84);
                        // check each flag that prevents printing
                        if (is_error == '0')
                        {
                            ok = true;
                            statuses.push("Ready to Print");
                        }
                        if (media == '1')
                            statuses.push("Paper out");
                        if (media == '2')
                            statuses.push("Ribbon Out");
                        if (media == '4')
                            statuses.push("Media Door Open");
                        if (media == '8')
                            statuses.push("Cutter Fault");
                        if (head == '1')
                            statuses.push("Printhead Overheating");
                        if (head == '2')
                            statuses.push("Motor Overheating");
                        if (head == '4')
                            statuses.push("Printhead Fault");
                        if (head == '8')
                            statuses.push("Incorrect Printhead");
                        if (pause == '1')
                            statuses.push("Printer Paused");
                        if ((!ok) && (statuses.Count == 0))
                            statuses.push("Error: Unknown Error");
                        finishedFunction(statuses.join());
            }, printerError);
};
function hidePrintForm()
{
    $('#print_form').hide();
};
function showPrintForm()
{
    $('#print_form').show();
};
function showLoading(text)
{
    $('#loading_message').text(text);
    $('#printer_data_loading').show();
    hidePrintForm();
    $('#printer_details').hide();
    $('#printer_select').hide();
};
function printComplete()
{
    hideLoading();
    alert ("Printing complete");
}
function hideLoading()
{
    $('#printer_data_loading').hide();
    if(default_mode == true)
    {
        showPrintForm();
        $('#printer_details').show();
    }
    else
    {
        $('#printer_select').show();
        showPrintForm();
    }
};
function changePrinter()
{
    default_mode = false;
    selected_printer = null;
    $('#printer_details').hide();
    if(available_printers == null)
    {
        showLoading("Finding Printers...");
        $('#print_form').hide();
        setTimeout(changePrinter, 200);
        return;
    }
    $('#printer_select').show();
    onPrinterSelected();
}

function onPrinterSelected()
{
    selected_printer = available_printers[$('#printers')[0].selectedIndex];
}

function showErrorMessage(text)
{
    $('#main').hide();
    $('#error_div').show();
    $('#error_message').html(text);
}

function printerError(text)
{
    showErrorMessage("An error occurred while printing. Please try again." + text);
}

function trySetupAgain()
{
    $('#main').show();
    $('#error_div').hide();
    setup_web_print();
    //hideLoading();
}

在下面的函数中，我发送所需的参数以打印。
        selected_printer.send("^XA^FX^CFA,30^FO10,70^FDVisitorName:"+$("#user").val()+"^FS^FO10,120^FDCompany:"+$("#compName").val()+"^FS ^FO10,170^FDTo Meet:"+$("#toMeet").val()+"^FS ^FO10,220^FDPurpose:"+$("#reason").val()+"^FS ^FO10,270^FDAuthorise^FS ^FO10,320^FDto Carry:"+mob+" "+lap+"^FS^FO250,70^XG R:SAMPLE.GRF,1,1^FS^XZ");

在上述函数中，图像数据存储在^FO250,70^XG R:SAMPLE.GRF,1,1^FS中。
当我将数据发送到打印机时，所有文本都可以正确打印，但是图像打印的结果如第二张图片所示，而期望打印的图像应该像第一张图片一样。如果我在labelary网站硬编码转换图像，则可以打印第一张图片。如果我实时点击图片并打印，则会得到第二张图片。
https://www.zebra.com/us/en/support-downloads/knowledge-articles/using-the-zpl-command-dy-to-print-a-png-monochrome-graphic-on-a-label.html - Martin Zeitler
1个回答
0

看看这个库GDIndexedColorConverter，它是一个简单的库，可以将图像转换为索引颜色模式。

require 'GDIndexedColorConverter.php';

// create an image
$image = imagecreatefromjpeg('image.jpg');

// create a gd indexed color converter
$converter = new GDIndexedColorConverter();

// the color palette
$palette = array(
    array(0, 0, 0),
    array(255, 255, 255),
    array(0, 0, 0),
    array(0, 0, 0),
    array(0, 0, 0)
);

// convert the image to indexed color mode
$new_image = $converter->convertToIndexedColor($image, $palette, 0.25);

// save the new image
imagepng($new_image, 'example_indexed_color.png', 0);

这里是输入：

enter image description here

这是输出结果：

enter image description here

代码可以运行，但我希望将图像存储为GRF格式。可以看到第二段php代码将转换后的代码存储在R:SAMPLE.GRF中，使用它，我将使用javascript将其传递给打印机。 - Bhargav Venkatesh
看一下这个代码片段 https://gist.github.com/thomascube/9651d6fa916124a9c52cb0d4262f2c3f，我已经自己测试了之前的代码，但是对于这个我不太确定，但是无论如何也可以试试看.. 这不是常见的格式。 - Sherif Salah
只有在尝试了那段代码后，我才得到第二张图片作为输出。 - Bhargav Venkatesh
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