13

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 following features:

  • 1) draw the rectangle + a text label. The label comes from R (input$foo), e.g., from a dropdown. To avoid the edge cases where the labels fall outside the images, labels should be placed inside their rectangles.
  • 2) use a different color for the rectangles and their labels depending on the label
  • 3) ability for the user to delete a rectangle by double-clicking inside it. In the case of multiple matches (overlap, nested), the rectangle with the smallest area should be deleted.

Brownie points for 1): the dropdown could appear next to the cursor like is done here (code here). If possible, the dropdown list should be passed from server.R and not be fixed/hardcoded. The reason is that depending on some user input, a different dropdown could be shown. E.g., we might have one dropdown for fruits c('banana','pineapple','grapefruit'), one dropdown for animals c('raccoon','dog','cat'), etc. 

# JS and CSS modified from: https://stackoverflow.com/a/17409472/8099834
css <- "
    #canvas {
        width:2000px;
        height:2000px;
        border: 10px solid transparent;
    }
    .rectangle {
        border: 5px solid #FFFF00;
        position: absolute;
    }
"

js <- 
"function initDraw(canvas) {
    var mouse = {
        x: 0,
        y: 0,
        startX: 0,
        startY: 0
    };
    function setMousePosition(e) {
        var ev = e || window.event; //Moz || IE
        if (ev.pageX) { //Moz
            mouse.x = ev.pageX + window.pageXOffset;
            mouse.y = ev.pageY + window.pageYOffset;
        } else if (ev.clientX) { //IE
            mouse.x = ev.clientX + document.body.scrollLeft;
            mouse.y = ev.clientY + document.body.scrollTop;
        }
    };

    var element = null;    
    canvas.onmousemove = function (e) {
        setMousePosition(e);
        if (element !== null) {
            element.style.width = Math.abs(mouse.x - mouse.startX) + 'px';
            element.style.height = Math.abs(mouse.y - mouse.startY) + 'px';
            element.style.left = (mouse.x - mouse.startX < 0) ? mouse.x + 'px' : mouse.startX + 'px';
            element.style.top = (mouse.y - mouse.startY < 0) ? mouse.y + 'px' : mouse.startY + 'px';
        }
    }

    canvas.onclick = function (e) {
        if (element !== null) {
           var coord = {
               left: element.style.left,
               top: element.style.top,
               width: element.style.width,
               height: element.style.height
            };
            Shiny.onInputChange('rectCoord', coord);
            element = null;
            canvas.style.cursor = \"default\";
        } else {
            mouse.startX = mouse.x;
            mouse.startY = mouse.y;
            element = document.createElement('div');
            element.className = 'rectangle'
            element.style.left = mouse.x + 'px';
            element.style.top = mouse.y + 'px';
            canvas.appendChild(element);
            canvas.style.cursor = \"crosshair\";
        }
    }
};
$(document).on('shiny:sessioninitialized', function(event) {
    initDraw(document.getElementById('canvas'));
});
"

library(shiny)

ui <- fluidPage(
  tags$head(
      tags$style(css),
      tags$script(HTML(js))
  ),
  fluidRow(
      column(width = 6, 
             # inline is necessary
             # ...otherwise we can draw rectangles over entire fluidRow
             uiOutput("canvas", inline = TRUE)),
      column(
          width = 6,
          verbatimTextOutput("rectCoordOutput")
          )
  )
)

server <- function(input, output, session) {
    output$canvas <- renderUI({
        tags$img(src = "https://www.r-project.org/logo/Rlogo.png")
    })
    output$rectCoordOutput <- renderPrint({
        input$rectCoord
    })

}

shinyApp(ui, server)
Antoine
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  • Would a modified version of the bbox-annotator demo work for you? i.e. use an "x" instead of double clicking to remove a rectangle – Hallie Swan Jan 31 '20 at 00:34
  • Whoah, I had replied to this comment shortly after you posted it 4 days ago, and now I see that it was not saved! Anyways, yes, what you propose would work very well for me, thank you. – Antoine Feb 04 '20 at 08:15

1 Answers1

8

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"

enter image description here

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(
                '<input id="reset_button" type="reset" />'
            )),
            HTML(
                '<input id="annotation_data" name="annotation_data" type="hidden" />'
            ),
            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 = $('<div class="bbox_selector"></div>');
      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 = $('<div class="label_box" style="z-index: 1000"></div>');
      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 = $('<select class="label_input" name="label"></select>');
          this.label_box.append(this.label_input);
          this.label_input.append($('<option value>choose an item</option>'));
          ref = options.labels;
          for (i = 0, len = ref.length; i < len; i++) {
            label = ref[i];
            this.label_input.append('<option value="' + label + '">' + label + '</option>');
          }
          this.label_input.change(function(e) {
            return this.blur();
          });
          break;
        case 'text':
          if (typeof options.labels === "string") {
            options.labels = [options.labels];
          }
          this.label_input = $('<input class="label_input" name="label" ' + 'type="text" value>');
          this.label_box.append(this.label_input);
          this.label_input.autocomplete({
            source: options.labels || [''],
            autoFocus: true
          });
          break;
        case 'fixed':
          if ($.isArray(options.labels)) {
            options.labels = options.labels[0];
          }
          this.label_input = $('<input class="label_input" name="label" type="text">');
          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 = $('<div class="image_frame"></div>');
      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 = $('<div class="annotated_bounding_box"></div>');
      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 = $('<div></div>').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"
      });
      $("<div></div>").appendTo(close_button).html('&#215;').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 = $('<div></div>').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 = $('<div class="guide_h"></div>').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 = $('<div class="guide_v"></div>').appendTo(this.image_frame).css({
        "border": "1px dotted " + (options.color || '#000'),
        "height": "100%",
        "width": "0",
        "position": "absolute",
        "top": "0",
        "left": "0"
      });
    }

  };

}).call(this);
Hallie Swan
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  • I let the bounty expire without awarding it, I'm the worst! Anyhow, I'll start a new bounty on the question to be able to award it to you, your answer well deserves it. I'll have to wait 24h though. In the meantime, do you know how to, given coordinates, programmatically draw a rectangle (like if the user was drawing it)? Since the coordinates of the boxes are accessible on the server side, we could store them somewhere (with the associated labels) and re-draw them automatically whenever the category changes. I think that would solve limitation 1). – Antoine Feb 05 '20 at 18:21
  • @Antoine No worries! Good call on using the coordinates from the server to redraw the rectangles -- I've updated the answer to use that method! Let me know if that works for you – Hallie Swan Feb 05 '20 at 22:51
  • Amazing, thank you so much! Your +100 bounty will definitely be well-deserved :) – Antoine Feb 06 '20 at 09:55
  • This answer works quite nicely. When drawing the bounding boxes, I found the `border_width` adjustments to bounding box locations in www/bbox_annotation.js to be a little off from what I expected. I added `2*this.border_width` to the width and the height in addition to moving the left and top columns out by `this.border_width`. – Josiah Yoder Jun 19 '20 at 19:28
  • @HallieSwan how to create 2 circles side by side on an existing canvas something like the [desired output on his SO question](https://stackoverflow.com/questions/65583493/gather-nodes-based-on-group-information) – user5249203 Jan 24 '21 at 06:25