Drawing rectangles on top of image R shiny

Question

I\'d like to elaborate on the accepted answer to this question.

I\'m looking at improving the minimal shiny app below (extracted from the accepted answer) with the follo

Answer 1

This solution uses kyamagu's bbox_annotator and is based on demo.html. I'm not familiar with JS, so it's not the prettiest. Limitations are:

1. Choosing a different image url will remove previous rectangles
2. I edited the JS a bit to change the rectangle/text color, so you won't be able to pull directly from the original repo
3. My changes probably broke input_method = "fixed" and "text", I only tested input_method = "select"

ui.R

# Adapted from https://github.com/kyamagu/bbox-annotator/
# Edited original JS to add color_list as an option
# ...should be the same length as labels
# ...and controls the color of the rectangle
# ...will probably be broken for input_method = "fixed" or "text"
# Also added color as a value in each rectangle entry
js <- '
    $(document).ready(function() {
       // define options to pass to bounding box constructor
        var options = {
          url: "https://www.r-project.org/logo/Rlogo.svg",
          input_method: "select", 
          labels: [""],
          color_list:  [""], 
          onchange: function(entries) {
                Shiny.onInputChange("rectCoord", JSON.stringify(entries, null, "  "));
          }
        };

        // Initialize the bounding-box annotator.
        var annotator = new BBoxAnnotator(options);

        // Initialize the reset button.
        $("#reset_button").click(function(e) {
            annotator.clear_all();
        })

        // define function to reset the bbox
        // ...upon choosing new label category or new url
        function reset_bbox(options) {
          document.getElementById("bbox_annotator").setAttribute("style", "display:inline-block");
          $(".image_frame").remove();
          annotator = new BBoxAnnotator(options);
        }

        // update image url from shiny
        Shiny.addCustomMessageHandler("change-img-url", function(url) {
          options.url = url;
          options.width = null;
          options.height = null;
          reset_bbox(options);
        });

        // update colors and categories from shiny
        Shiny.addCustomMessageHandler("update-category-list", function(vals) {
          options.labels = Object.values(vals);
          options.color_list = Object.keys(vals);
          reset_bbox(options);
        });

        // redraw rectangles based on list of entries
        Shiny.addCustomMessageHandler("redraw-rects", function(vals) {
          var arr = JSON.parse(vals);
          arr.forEach(function(rect){
             annotator.add_entry(rect);
          });
          if (annotator.onchange) {
             annotator.onchange(annotator.entries);
          }
        }); 
    });
'

ui <- fluidPage(
    tags$head(tags$script(HTML(js)),
              tags$head(
                  tags$script(src = "bbox_annotation.js")
              )),
    titlePanel("Bounding box annotator demo"),
    sidebarLayout(
        sidebarPanel(
            selectInput(
                "img_url",
                "URLs",
                c(
                    "https://www.r-project.org/logo/Rlogo.svg",
                    "https://github.githubassets.com/images/modules/logos_page/GitHub-Mark.png"
                )
            ),
            selectInput("category_type", "Label Category", c("animals", "fruits")),
            div(HTML(
                ''
            )),
            HTML(
                ''
            ),
            hr(),
            h4("Entries"),
            verbatimTextOutput("rectCoordOutput")
        ),
        mainPanel(div(id = "bbox_annotator", style = "display:inline-block"))
    )
)

server.R

server <- function(input, output, session) {
    # user choices
    output$rectCoordOutput <- renderPrint({
        if(!is.null(input$rectCoord)) {
            as.data.frame(jsonlite::fromJSON(input$rectCoord))
        }
    })
    # send chosen URL from shiny to JS
    observeEvent(input$img_url, {
        session$sendCustomMessage("change-img-url", input$img_url)
    })
    # send chosen category list from shiny to JS
    observeEvent(input$category_type, {
        vals <- switch(input$category_type, 
               fruits = list("yellow" = "banana", 
                          "orange" = "pineapple",
                          "pink" = "grapefruit"),
               animals = list("grey" = "raccoon",
                           "brown" = "dog",
                           "tan" = "cat")
               )
        # update category list
        session$sendCustomMessage("update-category-list", vals)
        # redraw rectangles
        session$sendCustomMessage("redraw-rects", input$rectCoord)
    })
}

www/bbox_annotation.js

// Generated by CoffeeScript 2.5.0
(function() {
  // https://github.com/kyamagu/bbox-annotator/blob/master/bbox_annotator.coffee
  // Use coffee-script compiler to obtain a javascript file.

  //    coffee -c bbox_annotator.coffee

  // See http://coffeescript.org/

  // BBox selection window.
  var BBoxSelector;

  BBoxSelector = class BBoxSelector {
    // Initializes selector in the image frame.
    constructor(image_frame, options) {
      if (options == null) {
        options = {};
      }
      options.input_method || (options.input_method = "text");
      this.image_frame = image_frame;
      this.border_width = options.border_width || 2;
      this.selector = $('
');
      this.selector.css({
        // rectangle color when dragging
        "border": this.border_width + "px dotted rgb(127,255,127)",
        "position": "absolute"
      });
      this.image_frame.append(this.selector);
      this.selector.css({
        "border-width": this.border_width
      });
      this.selector.hide();
      this.create_label_box(options);
    }

    // Initializes a label input box.
    create_label_box(options) {
      var i, label, len, ref;
      options.labels || (options.labels = ["object"]);
      this.label_box = $('
');
      this.label_box.css({
        "position": "absolute"
      });
      this.image_frame.append(this.label_box);
      switch (options.input_method) {
        case 'select':
          if (typeof options.labels === "string") {
            options.labels = [options.labels];
          }
          this.label_input = $('');
          this.label_box.append(this.label_input);
          this.label_input.append($('choose an item'));
          ref = options.labels;
          for (i = 0, len = ref.length; i < len; i++) {
            label = ref[i];
            this.label_input.append('' + label + '');
          }
          this.label_input.change(function(e) {
            return this.blur();
          });
          break;
        case 'text':
          if (typeof options.labels === "string") {
            options.labels = [options.labels];
          }
          this.label_input = $('');
          this.label_box.append(this.label_input);
          this.label_input.autocomplete({
            source: options.labels || [''],
            autoFocus: true
          });
          break;
        case 'fixed':
          if ($.isArray(options.labels)) {
            options.labels = options.labels[0];
          }
          this.label_input = $('');
          this.label_box.append(this.label_input);
          this.label_input.val(options.labels);
          break;
        default:
          throw 'Invalid label_input parameter: ' + options.input_method;
      }
      return this.label_box.hide();
    }

    // Crop x and y to the image size.
    crop(pageX, pageY) {
      var point;
      return point = {
        x: Math.min(Math.max(Math.round(pageX - this.image_frame.offset().left), 0), Math.round(this.image_frame.width() - 1)),
        y: Math.min(Math.max(Math.round(pageY - this.image_frame.offset().top), 0), Math.round(this.image_frame.height() - 1))
      };
    }

    // When a new selection is made.
    start(pageX, pageY) {
      this.pointer = this.crop(pageX, pageY);
      this.offset = this.pointer;
      this.refresh();
      this.selector.show();
      $('body').css('cursor', 'crosshair');
      return document.onselectstart = function() {
        return false;
      };
    }

    // When a selection updates.
    update_rectangle(pageX, pageY) {
      this.pointer = this.crop(pageX, pageY);
      return this.refresh();
    }

    // When starting to input label.
    input_label(options) {
      $('body').css('cursor', 'default');
      document.onselectstart = function() {
        return true;
      };
      this.label_box.show();
      return this.label_input.focus();
    }

    // Finish and return the annotation.
    finish(options) {
      var data;
      this.label_box.hide();
      this.selector.hide();
      data = this.rectangle();
      data.label = $.trim(this.label_input.val().toLowerCase());
      if (options.input_method !== 'fixed') {
        this.label_input.val('');
      }
      return data;
    }

    // Get a rectangle.
    rectangle() {
      var rect, x1, x2, y1, y2;
      x1 = Math.min(this.offset.x, this.pointer.x);
      y1 = Math.min(this.offset.y, this.pointer.y);
      x2 = Math.max(this.offset.x, this.pointer.x);
      y2 = Math.max(this.offset.y, this.pointer.y);
      return rect = {
        left: x1,
        top: y1,
        width: x2 - x1 + 1,
        height: y2 - y1 + 1
      };
    }

    // Update css of the box.
    refresh() {
      var rect;
      rect = this.rectangle();
      this.selector.css({
        left: (rect.left - this.border_width) + 'px',
        top: (rect.top - this.border_width) + 'px',
        width: rect.width + 'px',
        height: rect.height + 'px'
      });
      return this.label_box.css({
        left: (rect.left - this.border_width) + 'px',
        top: (rect.top + rect.height + this.border_width) + 'px'
      });
    }

    // Return input element.
    get_input_element() {
      return this.label_input;
    }

  };

  // Annotator object definition.
  this.BBoxAnnotator = class BBoxAnnotator {
    // Initialize the annotator layout and events.
    constructor(options) {
      var annotator, image_element;
      annotator = this;
      this.annotator_element = $(options.id || "#bbox_annotator");
      // allow us to access colors and labels in future steps
      this.color_list = options.color_list;
      this.label_list = options.labels;
      this.border_width = options.border_width || 2;
      this.show_label = options.show_label || (options.input_method !== "fixed");
      if (options.multiple != null) {
        this.multiple = options.multiple;
      } else {
        this.multiple = true;
      }
      this.image_frame = $('
');
      this.annotator_element.append(this.image_frame);
      if (options.guide) {
        annotator.initialize_guide(options.guide);
      }
      image_element = new Image();
      image_element.src = options.url;
      image_element.onload = function() {
        options.width || (options.width = image_element.width);
        options.height || (options.height = image_element.height);
        annotator.annotator_element.css({
          "width": (options.width + annotator.border_width) + 'px',
          "height": (options.height + annotator.border_width) + 'px',
          "padding-left": (annotator.border_width / 2) + 'px',
          "padding-top": (annotator.border_width / 2) + 'px',
          "cursor": "crosshair",
          "overflow": "hidden"
        });
        annotator.image_frame.css({
          "background-image": "url('" + image_element.src + "')",
          "width": options.width + "px",
          "height": options.height + "px",
          "position": "relative"
        });
        annotator.selector = new BBoxSelector(annotator.image_frame, options);
        return annotator.initialize_events(options);
      };
      image_element.onerror = function() {
        return annotator.annotator_element.text("Invalid image URL: " + options.url);
      };
      this.entries = [];
      this.onchange = options.onchange;
    }

    // Initialize events.
    initialize_events(options) {
      var annotator, selector, status;
      status = 'free';
      this.hit_menuitem = false;
      annotator = this;
      selector = annotator.selector;
      this.annotator_element.mousedown(function(e) {
        if (!annotator.hit_menuitem) {
          switch (status) {
            case 'free':
            case 'input':
              if (status === 'input') {
                selector.get_input_element().blur();
              }
              if (e.which === 1) { // left button
                selector.start(e.pageX, e.pageY);
                status = 'hold';
              }
          }
        }
        annotator.hit_menuitem = false;
        return true;
      });
      $(window).mousemove(function(e) {
        var offset;
        switch (status) {
          case 'hold':
            selector.update_rectangle(e.pageX, e.pageY);
        }
        if (annotator.guide_h) {
          offset = annotator.image_frame.offset();
          annotator.guide_h.css('top', Math.floor(e.pageY - offset.top) + 'px');
          annotator.guide_v.css('left', Math.floor(e.pageX - offset.left) + 'px');
        }
        return true;
      });
      $(window).mouseup(function(e) {
        switch (status) {
          case 'hold':
            selector.update_rectangle(e.pageX, e.pageY);
            selector.input_label(options);
            status = 'input';
            if (options.input_method === 'fixed') {
              selector.get_input_element().blur();
            }
        }
        return true;
      });
      selector.get_input_element().blur(function(e) {
        var data;
        switch (status) {
          case 'input':
            data = selector.finish(options);
            if (data.label) {
              // store color with the entry
              // ...so we can redraw the rectangle upon changing label category
              data.color = annotator.color_list[annotator.label_list.indexOf(data.label)];
              annotator.add_entry(data);
              if (annotator.onchange) {
                annotator.onchange(annotator.entries);
              }
            }
            status = 'free';
        }
        return true;
      });
      selector.get_input_element().keypress(function(e) {
        switch (status) {
          case 'input':
            if (e.which === 13) {
              selector.get_input_element().blur();
            }
        }
        return e.which !== 13;
      });
      selector.get_input_element().mousedown(function(e) {
        return annotator.hit_menuitem = true;
      });
      selector.get_input_element().mousemove(function(e) {
        return annotator.hit_menuitem = true;
      });
      selector.get_input_element().mouseup(function(e) {
        return annotator.hit_menuitem = true;
      });
      return selector.get_input_element().parent().mousedown(function(e) {
        return annotator.hit_menuitem = true;
      });
    }

    // Add a new entry.
    add_entry(entry) {
      var annotator, box_element, close_button, text_box;
      if (!this.multiple) {
        this.annotator_element.find(".annotated_bounding_box").detach();
        this.entries.splice(0);
      }
      this.entries.push(entry);
      box_element = $('
');
      box_element.appendTo(this.image_frame).css({
        // rectangle color -- when stopped dragging
        "border": this.border_width + "px solid " + entry.color,
        "position": "absolute",
        "top": (entry.top - this.border_width) + "px",
        "left": (entry.left - this.border_width) + "px",
        "width": entry.width + "px",
        "height": entry.height + "px",
        // text color when stopped dragging
        "color": entry.color,
        "font-family": "monospace",
        "font-size": "small"
      });
      close_button = $('
').appendTo(box_element).css({
        "position": "absolute",
        "top": "-8px",
        "right": "-8px",
        "width": "16px",
        "height": "0",
        "padding": "16px 0 0 0",
        "overflow": "hidden",
        "color": "#fff",
        "background-color": "#030",
        "border": "2px solid #fff",
        "-moz-border-radius": "18px",
        "-webkit-border-radius": "18px",
        "border-radius": "18px",
        "cursor": "pointer",
        "-moz-user-select": "none",
        "-webkit-user-select": "none",
        "user-select": "none",
        "text-align": "center"
      });
      $("
").appendTo(close_button).html('×').css({
        "display": "block",
        "text-align": "center",
        "width": "16px",
        "position": "absolute",
        "top": "-2px",
        "left": "0",
        "font-size": "16px",
        "line-height": "16px",
        "font-family": '"Helvetica Neue", Consolas, Verdana, Tahoma, Calibri, ' + 'Helvetica, Menlo, "Droid Sans", sans-serif'
      });
      text_box = $('
').appendTo(box_element).css({
        "overflow": "hidden"
      });
      if (this.show_label) {
        text_box.text(entry.label);
      }
      annotator = this;
      box_element.hover((function(e) {
        return close_button.show();
      }), (function(e) {
        return close_button.hide();
      }));
      close_button.mousedown(function(e) {
        return annotator.hit_menuitem = true;
      });
      close_button.click(function(e) {
        var clicked_box, index;
        clicked_box = close_button.parent(".annotated_bounding_box");
        index = clicked_box.prevAll(".annotated_bounding_box").length;
        clicked_box.detach();
        annotator.entries.splice(index, 1);
        return annotator.onchange(annotator.entries);
      });
      return close_button.hide();
    }

    // Clear all entries.
    clear_all(e) {
      this.annotator_element.find(".annotated_bounding_box").detach();
      this.entries.splice(0);
      return this.onchange(this.entries);
    }

    // Add crosshair guide.
    initialize_guide(options) {
      this.guide_h = $('
').appendTo(this.image_frame).css({
        "border": "1px dotted " + (options.color || '#000'),
        "height": "0",
        "width": "100%",
        "position": "absolute",
        "top": "0",
        "left": "0"
      });
      return this.guide_v = $('
').appendTo(this.image_frame).css({
        "border": "1px dotted " + (options.color || '#000'),
        "height": "100%",
        "width": "0",
        "position": "absolute",
        "top": "0",
        "left": "0"
      });
    }

  };

}).call(this);