删除 canvas 中上传的图片

Question

一旦我们点击图像，我们就会显示文件上传对话框。用户可以上传图片。

问题：

然后当我们点击"Remove"按钮时，它的清除整个canvas。

要求：

但我只需要删除上传的图片....

删除图片代码:

$("<br/><span id=\"" + newImageLoadedId + "\" class=\"remove\">Remove</span>").insertAfter(".masked-img" + newImageLoadedId).css({
                    "left": ImagePosition[newImageLoadedId].x + (ImagePosition[newImageLoadedId].width / 2) + "px",
                    "top": ImagePosition[newImageLoadedId].y + (ImagePosition[newImageLoadedId].height / 2 + 25) + "px"
                });

                $(".remove").click(function(event) {
                    const canvasId = "canvas#" + event.currentTarget.id;
                    // Delete the uploaded image & icon
                    const ctx = $("canvas")[event.currentTarget.id].getContext("2d");
                    ctx.fillStyle = "white"
                    ctx.fillRect(0, 0, 500, 500)
                    $('#container').data('image_set' + event.currentTarget.id, false)

                    // Delete the Remove button
                    $(this).remove();
                });

下面是代码片段：

var target;
const imageUrl = "";

let jsonData = {
    "layers": [{
        "x": 0,
        "height": 612,
        "layers": [{
            "x": 10,
            "src": "bW5RSFA.png",
            "y": 10,
            "height": 296,
            "width": 429,
            "name": "mask_1"
        }],
        "y": 0,
        "width": 612
    }]
};

const containerElement = $('#container');
const fileUp = $('#fileup');
let mask;

$(function() {

    // Upload image onclick mask image 

    containerElement.click(function(e) {
        var res = e.target;
        target = res.id;
        if (e.target.getContext) {
            // click only inside Non Transparent part 
            var pixel = e.target.getContext('2d').getImageData(e.offsetX, e.offsetY, 1, 1).data;
            if (pixel[3] === 255) {
                setTimeout(() => {
                    $('#fileup').click();
                }, 20);
            }
        }
    });

    // Fetch mask images from json file - IGNORE this code 

    function getAllSrc(layers) {
        let arr = [];
        layers.forEach(layer => {
            if (layer.src) {
                arr.push({
                    src: layer.src,
                    x: layer.x,
                    y: layer.y,
                    height: layer.height,
                    width: layer.width,
                    name: layer.name
                });
            } else if (layer.layers) {
                let newArr = getAllSrc(layer.layers);
                if (newArr.length > 0) {
                    newArr.forEach(({
                        src,
                        x,
                        y,
                        height,
                        width,
                        name
                    }) => {
                        arr.push({
                            src,
                            x: (layer.x + x),
                            y: (layer.y + y),
                            height,
                            width,
                            name: (name)
                        });
                    });
                }
            }
        });
        return arr;
    }

    function json(data) {
        var width = 0;
        var height = 0;

        let arr = getAllSrc(data.layers);
        let layer1 = data.layers;
        width = layer1[0].width;
        height = layer1[0].height;
        let counter = 0;
        let table = [];

        // container dimensions 
        containerElement.css('width', width + "px").css('height', height + "px").addClass('temp');
        //end 

        for (let {
                src,
                x,
                y,
                name
            } of arr) {

            //Get Height and width of mask image [ edit button ] 
            var ImagePosition = arr;
            //code end 

            var imageUrl1 = imageUrl;

            var mask = $(".container").mask({
                imageUrl: name.indexOf('mask_') !== -1 ? imageUrl1 : undefined,

                // Fetch Mask images 
                maskImageUrl: 'http://i.imgur.com/' + src,
                // end 

                onMaskImageCreate: function(img) {
                    // Mask image positions 
                    img.css({
                        "position": "absolute",
                        "left": x + "px",
                        "top": y + "px"
                    });
                    // end 

                },
                id: counter
            });
            // here 

            ImagePosition.map(function(cur, index) {
                var available = cur.name.includes('mask_');

                if (!available) {
                    $('.masked-img' + index).css('pointer-events', 'none');
                }
            });

            table.push(mask);
            fileup.onchange = function() {

                let mask2 = table[target];
                const newImageLoadedId = mask2.loadImage(URL.createObjectURL(fileup.files[0]));
                document.getElementById('fileup').value = "";

            //  Remove image

                $("<br/><span id=\"" + newImageLoadedId + "\" class=\"remove\">Remove</span>").insertAfter(".masked-img" + newImageLoadedId).css({
                    "left": ImagePosition[newImageLoadedId].x + (ImagePosition[newImageLoadedId].width / 2) + "px",
                    "top": ImagePosition[newImageLoadedId].y + (ImagePosition[newImageLoadedId].height / 2 + 25) + "px"
                });

                $(".remove").click(function(event) {
                    const canvasId = "canvas#" + event.currentTarget.id;
                    // Delete the uploaded image & icon
                    const ctx = $("canvas")[event.currentTarget.id].getContext("2d");
                    ctx.fillStyle = "white"
                    ctx.fillRect(0, 0, 500, 500)
                    $('#container').data('image_set' + event.currentTarget.id, false)
                    
                    // Delete the Remove button
                    $(this).remove();
                });

                // Remove image code end here....

            };
            counter++;
        }
        return mask;
    }
    mask = json(jsonData);
}); // end of function 

// Image code 

(function($) {
    window.JQmasks = [];
    $.fn.mask = function(options) {
        // This is the easiest way to have default options. 
        var settings = $.extend({
            // These are the defaults. 
            maskImageUrl: undefined,
            imageUrl: undefined,
            scale: 1,
            id: new Date().getUTCMilliseconds().toString(),
            x: 0, // image start position 
            y: 0, // image start position 
            onMaskImageCreate: function(div) {},
        }, options);

        // Create the image properties
        settings.maskImage = new Image
        settings.image = new Image

        // set the cross-origin attributes
        settings.maskImage.setAttribute('crossOrigin', 'anonymous');
        settings.image.setAttribute('crossOrigin', 'anonymous');

        settings.maskImage.onload = function() {
            // once the mask is loaded, load the image
            container.loadImage(settings.imageUrl)
            container.drawMask()
        }

        settings.image.onload = function() {
            // once the image is loaded, render to canvas

            container.drawImage()
        }

        var container = $(this);

        let prevX = 0,
            prevY = 0,
            draggable = false,
            img,
            canvas,
            context,
            image,
            timeout,
            initImage = false,
            startX = settings.x,
            startY = settings.y,
            div;

        container.mousePosition = function(event) {
            return {
                x: event.pageX || event.offsetX,
                y: event.pageY || event.offsetY
            };
        }


         container.selected = function(ev) {
            var pos = container.mousePosition(ev);
            var item = $(".masked-img canvas").filter(function() {
                var offset = $(this).offset()
                var x = pos.x - offset.left;
                var y = pos.y - offset.top;
                var d = this.getContext('2d').getImageData(x, y, 1, 1).data;
                return d[0] > 0
            });

            JQmasks.forEach(function(el) {
                var id = item.length > 0 ? $(item).attr("id") : "";
                if (el.id == id)
                    el.item.enable();
                else el.item.disable();
            });
        };

        container.enable = function() {
            draggable = true;
            $(canvas).attr("active", "true");
            div.css({
                "z-index": 2
            });
        }

        container.disable = function() {
            draggable = false;
            $(canvas).attr("active", "false");
            div.css({
                "z-index": 1
            });
        }      

        container.drawMask = function() {
            if (!settings.maskImage) return true;
            canvas.width = settings.maskImage.width;
            canvas.height = settings.maskImage.height;
            context.save();
            context.beginPath();
            context.globalCompositeOperation = "source-over";
            // draw the masked image after scaling 
            if (settings.maskImage) context.drawImage(settings.maskImage, 0, 0, settings.maskImage.width, settings.maskImage.height);
            context.restore()
        };

         container.drawImage = function() {
            const img = settings.image

            settings.x = settings.x == 0 && initImage ? (canvas.width - (img.width * settings.scale)) / 2 : settings.x;
            settings.y = settings.y == 0 && initImage ? (canvas.height - (img.height * settings.scale)) / 2 : settings.y;

            context.globalCompositeOperation = 'source-atop';
            context.save();
            context.translate(settings.x + img.width / 2, settings.y + img.height / 2);
            context.rotate(settings.rotate);
            context.scale(settings.scale, settings.scale);
            context.translate(-(settings.x + img.width / 2), -(settings.y + img.height / 2));
            let width = img.width,
                height = img.height;
            if (img)
                context.drawImage(img, settings.x, settings.y, width, height);
            context.restore();
            initImage = false;           
        }
  
        container.loadImage = function(imageUrl) {
            if (!imageUrl) return true;
            settings.y = startY;
            settings.x = startX;
            prevX = prevY = 0;

            initImage = true;

            settings.image.src = imageUrl; // CHANGED

            // sirpepole Add this 
            return settings.id;
        };

        container.loadMaskImage = function(imageUrl, from) {

            canvas = document.createElement("canvas");
            context = canvas.getContext('2d');
            canvas.setAttribute("draggable", "true");
            canvas.setAttribute("id", settings.id);
            // settings.maskImageUrl = imageUrl;
            settings.maskImage.src = imageUrl // CHANGED

            div = $("<div/>", {
                "class": "masked-img"
            }).append(canvas);

            // div.find("canvas").on('touchstart mousedown', function(event) 
            div.find("canvas").on('dragstart', function(event) {
                if (event.handled === false) return;
                event.handled = true;
                container.onDragStart(event);
            });

            div.find("canvas").on('touchend mouseup', function(event) {
                if (event.handled === false) return;
                event.handled = true;
                container.selected(event);
            });

            div.find("canvas").bind("dragover", container.onDragOver);

            container.append(div);
            if (settings.onMaskImageCreate)
                settings.onMaskImageCreate(div);

            // container.loadImage(settings.imageUrl);
            // Moved this to the settings.maskImage.onload
        };
        if (settings.maskImageUrl) {
            container.loadMaskImage(settings.maskImageUrl);
        }
        JQmasks.push({
            item: container,
            id: settings.id
        })
        // Edit image 
        div.addClass('masked-img' + settings.id);
        div.attr('data-id', settings.id);
        // ends 
        return container;
    };
}(jQuery));

.container {
 background: silver;
 position: relative;
}

.container img {
 position: absolute;
 top: 0;
 bottom: 250px;
 left: 0;
 right: 0;
 margin: auto;
 z-index: 999;
}

.masked-img {
 overflow: hidden;
 position: relative;
}

.pip {
 display: inline-block;
 margin: 0;
 position: absolute;
}

.remove {
 background: #444;
 border: 1px solid black;
 color: white;
 text-align: center;
 cursor: pointer;
 position: absolute;
 z-index: 3;
}

.remove:hover {
 background: white;
 color: black;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js">
</script>

<input id="fileup" name="fileup" type="file" style="display:none">

<div id="container" class="container">
</div>

这是Pastebin , Codepen , Fiddle

中的代码

Answer 1

更新脚本如下。这样在每次删除时，canvas 都是清晰的，然后是重新绘制的蒙版。

var container;
var target;
const imageUrl = "";

let jsonData = {
  "layers": [{
    "x": 0,
    "height": 612,
    "layers": [{
      "x": 10,
      "src": "bW5RSFA.png",
      "y": 10,
      "height": 296,
      "width": 429,
      "name": "mask_1"
    }],
    "y": 0,
    "width": 612
  }]
};

const containerElement = $('#container');
const fileUp = $('#fileup');
let mask;

$(function() {

  // Upload image onclick mask image 

  containerElement.click(function(e) {
    var res = e.target;
    target = res.id;
    if (e.target.getContext) {
      // click only inside Non Transparent part 
      var pixel = e.target.getContext('2d').getImageData(e.offsetX, e.offsetY, 1, 1).data;
      if (pixel[3] === 255) {
        setTimeout(() => {
          $('#fileup').click();
        }, 20);
      }
    }
  });

  // Fetch mask images from json file - IGNORE this code 

  function getAllSrc(layers) {
    let arr = [];
    layers.forEach(layer => {
      if (layer.src) {
        arr.push({
          src: layer.src,
          x: layer.x,
          y: layer.y,
          height: layer.height,
          width: layer.width,
          name: layer.name
        });
      } else if (layer.layers) {
        let newArr = getAllSrc(layer.layers);
        if (newArr.length > 0) {
          newArr.forEach(({
            src,
            x,
            y,
            height,
            width,
            name
          }) => {
            arr.push({
              src,
              x: (layer.x + x),
              y: (layer.y + y),
              height,
              width,
              name: (name)
            });
          });
        }
      }
    });
    return arr;
  }

  function json(data) {
    var width = 0;
    var height = 0;

    let arr = getAllSrc(data.layers);
    let layer1 = data.layers;
    width = layer1[0].width;
    height = layer1[0].height;
    let counter = 0;
    let table = [];

    // container dimensions 
    containerElement.css('width', width + "px").css('height', height + "px").addClass('temp');
    //end 

    for (let {
        src,
        x,
        y,
        name
      } of arr) {

      //Get Height and width of mask image [ edit button ] 
      var ImagePosition = arr;
      //code end 

      var imageUrl1 = imageUrl;

      var mask = $(".container").mask({
        imageUrl: name.indexOf('mask_') !== -1 ? imageUrl1 : undefined,

        // Fetch Mask images 
        maskImageUrl: 'http://i.imgur.com/' + src,
        // end 

        onMaskImageCreate: function(img) {
          // Mask image positions 
          img.css({
            "position": "absolute",
            "left": x + "px",
            "top": y + "px"
          });
          // end 

        },
        id: counter
      });
      // here 

      ImagePosition.map(function(cur, index) {
        var available = cur.name.includes('mask_');

        if (!available) {
          $('.masked-img' + index).css('pointer-events', 'none');
        }
      });

      table.push(mask);
      fileup.onchange = function() {

        let mask2 = table[target];
        const newImageLoadedId = mask2.loadImage(URL.createObjectURL(fileup.files[0]));
        document.getElementById('fileup').value = "";

        //  Remove image

        $("<br/><span id=\"" + newImageLoadedId + "\" class=\"remove\">Remove</span>").insertAfter(".masked-img" + newImageLoadedId).css({
          "left": ImagePosition[newImageLoadedId].x + (ImagePosition[newImageLoadedId].width / 2) + "px",
          "top": ImagePosition[newImageLoadedId].y + (ImagePosition[newImageLoadedId].height / 2 + 25) + "px"
        });

        $(".remove").click(function(event) {
          const canvasId = "canvas#" + event.currentTarget.id;
          // Delete the uploaded image & icon
          const ctx = $("canvas")[event.currentTarget.id].getContext("2d");

          ctx.clearRect(0, 0, 500, 500);
          $('#container').data('image_set' + event.currentTarget.id, false);
          container.drawMask();
          // Delete the Remove button
          $(this).remove();
        });

        // Remove image code end here....

      };
      counter++;
    }
    return mask;
  }
  mask = json(jsonData);
}); // end of function 

// Image code 

(function($) {
  window.JQmasks = [];
  $.fn.mask = function(options) {
    // This is the easiest way to have default options. 
    var settings = $.extend({
      // These are the defaults. 
      maskImageUrl: undefined,
      imageUrl: undefined,
      scale: 1,
      id: new Date().getUTCMilliseconds().toString(),
      x: 0, // image start position 
      y: 0, // image start position 
      onMaskImageCreate: function(div) {},
    }, options);

    // Create the image properties
    settings.maskImage = new Image
    settings.image = new Image

    // set the cross-origin attributes
    settings.maskImage.setAttribute('crossOrigin', 'anonymous');
    settings.image.setAttribute('crossOrigin', 'anonymous');

    settings.maskImage.onload = function() {
      // once the mask is loaded, load the image
      container.loadImage(settings.imageUrl)
      container.drawMask()
    }

    settings.image.onload = function() {
      // once the image is loaded, render to canvas

      container.drawImage()
    }

    container = $(this);

    let prevX = 0,
      prevY = 0,
      draggable = false,
      img,
      canvas,
      context,
      image,
      timeout,
      initImage = false,
      startX = settings.x,
      startY = settings.y,
      div;

    container.mousePosition = function(event) {
      return {
        x: event.pageX || event.offsetX,
        y: event.pageY || event.offsetY
      };
    }


    container.selected = function(ev) {
      var pos = container.mousePosition(ev);
      var item = $(".masked-img canvas").filter(function() {
        var offset = $(this).offset()
        var x = pos.x - offset.left;
        var y = pos.y - offset.top;
        var d = this.getContext('2d').getImageData(x, y, 1, 1).data;
        return d[0] > 0
      });

      JQmasks.forEach(function(el) {
        var id = item.length > 0 ? $(item).attr("id") : "";
        if (el.id == id)
          el.item.enable();
        else el.item.disable();
      });
    };

    container.enable = function() {
      draggable = true;
      $(canvas).attr("active", "true");
      div.css({
        "z-index": 2
      });
    }

    container.disable = function() {
      draggable = false;
      $(canvas).attr("active", "false");
      div.css({
        "z-index": 1
      });
    }

    container.drawMask = function() {
      if (!settings.maskImage) return true;
      canvas.width = settings.maskImage.width;
      canvas.height = settings.maskImage.height;
      context.save();
      context.beginPath();
      context.globalCompositeOperation = "source-over";
      // draw the masked image after scaling 
      if (settings.maskImage) context.drawImage(settings.maskImage, 0, 0, settings.maskImage.width, settings.maskImage.height);
      context.restore()
    };

    container.drawImage = function() {
      const img = settings.image

      settings.x = settings.x == 0 && initImage ? (canvas.width - (img.width * settings.scale)) / 2 : settings.x;
      settings.y = settings.y == 0 && initImage ? (canvas.height - (img.height * settings.scale)) / 2 : settings.y;

      context.globalCompositeOperation = 'source-atop';
      context.save();
      context.translate(settings.x + img.width / 2, settings.y + img.height / 2);
      context.rotate(settings.rotate);
      context.scale(settings.scale, settings.scale);
      context.translate(-(settings.x + img.width / 2), -(settings.y + img.height / 2));
      let width = img.width,
        height = img.height;
      if (img)
        context.drawImage(img, settings.x, settings.y, width, height);
      context.restore();
      initImage = false;
    }

    container.loadImage = function(imageUrl) {
      if (!imageUrl) return true;
      settings.y = startY;
      settings.x = startX;
      prevX = prevY = 0;

      initImage = true;

      settings.image.src = imageUrl; // CHANGED

      // sirpepole Add this 
      return settings.id;
    };

    container.loadMaskImage = function(imageUrl, from) {

      canvas = document.createElement("canvas");
      context = canvas.getContext('2d');
      canvas.setAttribute("draggable", "true");
      canvas.setAttribute("id", settings.id);
      // settings.maskImageUrl = imageUrl;
      settings.maskImage.src = imageUrl // CHANGED

      div = $("<div/>", {
        "class": "masked-img"
      }).append(canvas);

      // div.find("canvas").on('touchstart mousedown', function(event) 
      div.find("canvas").on('dragstart', function(event) {
        if (event.handled === false) return;
        event.handled = true;
        container.onDragStart(event);
      });

      div.find("canvas").on('touchend mouseup', function(event) {
        if (event.handled === false) return;
        event.handled = true;
        container.selected(event);
      });

      div.find("canvas").bind("dragover", container.onDragOver);

      container.append(div);
      if (settings.onMaskImageCreate)
        settings.onMaskImageCreate(div);

      // container.loadImage(settings.imageUrl);
      // Moved this to the settings.maskImage.onload
    };
    if (settings.maskImageUrl) {
      container.loadMaskImage(settings.maskImageUrl);
    }
    JQmasks.push({
      item: container,
      id: settings.id
    })
    // Edit image 
    div.addClass('masked-img' + settings.id);
    div.attr('data-id', settings.id);
    // ends 
    return container;
  };
}(jQuery));

.container {
  background: silver;
  position: relative;
}

.container img {
  position: absolute;
  top: 0;
  bottom: 250px;
  left: 0;
  right: 0;
  margin: auto;
  z-index: 999;
}

.masked-img {
  overflow: hidden;
  position: relative;
}

.pip {
  display: inline-block;
  margin: 0;
  position: absolute;
}

.remove {
  background: #444;
  border: 1px solid black;
  color: white;
  text-align: center;
  cursor: pointer;
  position: absolute;
  z-index: 3;
}

.remove:hover {
  background: white;
  color: black;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js">
</script>

<input id="fileup" name="fileup" type="file" style="display:none">

<div id="container" class="container">
</div>

删除 canvas 中上传的图片

Delete Uploaded image in canvas

javascript

jquery

image

delete-file