header={
  "recipe_version": "1.6",
  "title": "Make image background transparent",
  "description": "Convert images to a transparent background by using a color from one corner",
  "tags": "ImageMagick,image,transparent",
  "chef": "BeatRig",
  "dependencies": "identify,convert",
  "instructions": "Drop image files here and run this recipe to select the background detection settings",
  "type": "default",
  "os": "windows,macOS",
  "palette": "Mint Cream",
  "spice": "BQ==:G+Hy36kJcnQQYYavb/JV2Il6eCYr6h4hRJHCF9rRbhX5BcazL6cuTgUMdz0xA50VWA5PmmV0Q7aWkiUtNFtbk991l+t0e8IBXMReMIT1GNjnZZDv7n2YRAo0xcSQbY0ixjG6LLH4wGKnspKAoA/v69iLn6N2IH0XzIZwTGdHSo4=",
  "flavour": "5gnchER9IDp3Qba1ew9cEMnTc+pUXHxXhJg7iMtxZrEmHReJsUclezzYzLSoirkfGsOmvQOGPrV976j4i9uN/04nmzQXjeMYmQOLk2tvuwGSv9ht0tMYtIP+yuWwL6cUA7Qh11eJAIrOO04B7horG/krlUQJ68cMVZu7jB2vvhA=",
  "time": 1694301146,
  "core_version": "0.5.7",
  "magnetron_version": "1.0.261",
  "functions": "main,onAbout",
  "uuid": "7ebe4cd6eee6474c8c1190d380f4c630"
};

//----------------------------------------------------------------------------
// o7 based on https://github.com/hackerb9/mktrans/blob/master/mktrans

function main()
{
    CheckInstalled();

    var antialias_items = ["Anti-alias","Anti-alias (fast)","No anti-alias"];
    var corner_items = ["Top-Left","Top-Right","Bottom-Left","Bottom-Right"];
    
    var corner = corner_items[0];
    var fuzz = "20";
    var antialias = antialias_items[0];
    var tag = "-transparent";

    var files = getFiles();
    if (files.length <= 0)
        abort("drop a file to process first");

    for (var i = 0; i < files.length; i++)
    {
        filename = files[i].path;
        pathInfo = getPathInfo(filename);
        
        setMainMessage("processing " + pathInfo.basename);
        setProgress((i+0.5) / files.length * 100.);

        var dialog_width = 500;
        var form = {
            "mainlabel" : {
                "type" : "label",
                "label" : "Add transparancy from a specific background corner color to\n" + pathInfo.basename,
                "bounds" : {
                    "x" : 5,
                    "w" : dialog_width,
                    "h" : 60,
                    "y" : 5,
                }
            },
            "cornerlabel" : {
                "type" : "label",
                "label" : "The sample color corner",
                "bounds" : {
                    "x" : 5,
                    "w" : dialog_width/2,
                }
            },
            "corner" : {
                "type" : "combobox",
                "default" : corner,
                "items" : corner_items,
                "label" : "Sample color corner",
                "bounds" : {
                    "x" : dialog_width/2,
                    "y" : -1,
                    "w" : dialog_width/2,
                }
            },
            "fuzzlabel" : {
                "type" : "label",
                "label" : "Color tolerance",
                "bounds" : {
                    "x" : 5,
                    "w" : dialog_width/2
                }
            },
            "fuzz" : {
                "type" : "slider",
                "value": 30,
                "range" : { 
                    "min" : 0,
                    "max" : 100,
                    "interval" : 1,
                    "decimals": 0
                },
                "label" : "color % tolerance:",
                "bounds" : {
                    "x" : dialog_width/2,
                    "y" : -1,
                    "w" : dialog_width/2
                }
            },
            "antialiaslabel" : {
                "type" : "label",
                "label" : "anti-alias type",
                "bounds" : {
                    "x" : 5,
                    "w" : dialog_width/2
                }
            },
            "antialias" : {
                "type" : "combobox",
                "default" : antialias,
                "items" : antialias_items,
                "label" : "anti-alias types:",
                "bounds" : {
                    "x" : dialog_width/2,
                    "y" : -1,
                    "w" : dialog_width/2
                }
            },
            "tag" : {
                "type" : "textedit",
                "default" : tag,
                "label" : "add file name tag:",
                "bounds" : {
                    "x" : dialog_width/2,
                    "y" : -1,
                    "w" : dialog_width/2
                }
            },
            "okay" : {
                "type" : "button",
                "label" : "okay",
                "returns" : 1
            },
            "cancel" : {
                "type" : "button",
                "label" : "cancel",
                "returns" : 0
            }
        };

        form_out = dialog(form);
        if (form_out.cancel)
            abort("Cancelled");

        corner = form_out.corner;
        fuzz = form_out.fuzz;
        antialias = form_out.antialias;
        tag = form_out.tag;

        outfile = pathInfo.folder + pathInfo.sep + pathInfo.basename + form_out.tag + ".png";

        var wah = cmd("identify", ["-format", "%w,%h", filename]);
        var dimensions = wah.split(",");
        echo("dimensions:" + dimensions[0] + "x" + dimensions[1]);

        var x = 0;
        var y = 0;
        if (form_out.corner == corner_items[1])
            x = dimensions[0];
        if (form_out.corner == corner_items[2])
            y = dimensions[1];
        if (form_out.corner == corner_items[3])
        {
            x = dimensions[0];
            y = dimensions[1];
        }            
        pixelcomma = x + "," + y;
        pixelplus = "+" + x + "+" + y;

        var pflag = false; // false for 1 pixel border

        // Get color of pixel
        var color = cmd("convert", [filename, "-format", "%[pixel:p{" + pixelcomma + "}]", "info:-"]);
        // check if starts with rgba and ends with ,0)
        if (color.substring(0, 4) == "rgba" && color.substring(color.length - 3, color.length) == ",0)")
            color = color.substring(0, color.length - 3) + ",1)"; // if so replace end with ,1)
        if (color == "none")
            abort (filename + " pixel at " + pixelcomma + " completely transparent. Cannot floodfill");
        echo(color);

        var options=[filename];
        if (pflag == false) // Add a 1 pixel border so we'll fill from the bottom and sides as well.
	    {
            options.push("-bordercolor");
            options.push(color);
            options.push("-border");
            options.push("1");
        }

        // In a new stack, make a copy of the image
        options.push("(");
        options.push("+clone");
        
        // [copy] floodfill with transparency ("none") starting at top-left    
        options.push("-fuzz");
        options.push(form_out.fuzz + "%");
        options.push("-fill");
        options.push("none");
        options.push("-floodfill");
        options.push(pixelplus);
        options.push(color);
    
        // [copy] extract just the transparency (alpha channel)
        options.push("-alpha");
        options.push("extract");

        if (form_out.antialias != antialias_items[2])
        {
	        if (form_out.antialias == antialias_items[1])
            {
                // [copy] blow up the alpha channel so we can do sub-pixel morphology
                options.push("-geometry");
                options.push("200%");

                // [copy] blur the alpha channel to make it antialiased
                options.push("-blur");
                options.push("0x0.5");

                // [copy] shrink the region that is opaque by half a pixel.
                options.push("-morphology");
                options.push("erode");
                options.push("square:1");

                // [copy] scale the alpha channel back to normal size.
                options.push("-geometry");
                options.push("50%");
            }
	        else // speedy antialias
            {
                // [copy] blur the alpha channel to make it antialiased
                options.push("-blur");
                options.push("0x1");

                // [copy] only antialias inside the figure (<50% opacity becomes 0%)
                options.push("-level");
                options.push("50%,100%");
            }
        }

        // [copy] end the stack.
        options.push(")");

        // Compose the original image and the copy's alpha channel.
        options.push("-compose");
        options.push("CopyOpacity");
        options.push("-composite");

        if (pflag == false) // Remove the 1 pixel border we added
	    {
            options.push("-shave");
            options.push("1");
        }
        options.push(outfile);

        echo("convert " + objectToString(options));
        echo(cmd("convert", options));

        setProgress((i+1) / files.length * 100.);

        if (isCanceled())
            abort("Canceled");
    }
    setMainMessage("finished");
}

function onAbout()
{
    dialog(header.title, header.description, "i");
}

//----------------------------------------------------------------------------
function CheckInstalled()
{
    var cmds = header.dependencies.split(",");
    for (i = 0; i < cmds.length; i++)
    {
        var install_cmd = cmds[i];//"convert";
        var cmd_path = getAllowedApps(install_cmd);    
        if (cmd_path.length <= 0)
            abort("ImageMagick " + install_cmd + " not installed");
    }
}