仅通过透明部分上传图像

Question

下面的蒙版图像有3个部分：

1.外部非透明部分

2.Border

3.Inside透明部分

现在当用户点击透明或非透明部分时，我允许用户上传图像....

要求：

当用户点击非透明部分时，不应显示上传图像的对话框....

这是https://codepen.io/kidsdial/pen/jJBVON

var mask;

let jsonData = {
    "path": " love shape\/",
    "info": {
        "author": "",
        "keywords": "",
        "file": "love shape",
        "date": "sRGB",
        "title": "",
        "description": "Normal",
        "generator": "Export Kit v1.2.8"
    },
    "name": "love shape",
    "layers": [{
        "x": 1,
        "height": 613,
        "layers": [{
                "x": 1,
                "color": "0xFFFFFF",
                "height": 612,
                "y": 30,
                "width": 612,
                "shapeType": "rectangle",
                "type": "shape",
                "name": "bg_rectangle_1"
            },
            {
                "x": 40,
                "height": 480,
                "layers": [{
                        "x": 10,
                        "height": 480,
                        "src": "ncdHNan.png",
                        "y": 10,
                        "width": 514,
                        "type": "image",
                        "name": "mask_image_1"
                    },
                    {
                        "radius": "27 \/ 27",
                        "color": "0xACACAC",
                        "x": 233,
                        "y": 205,
                        "height": 53,
                        "width": 53,
                        "shapeType": "ellipse",
                        "type": "shape",
                        "name": "useradd_ellipse1"
                    }
                ],
                "y": 1,
                "width": 514,
                "type": "group",
                "name": "user_image_1"
            }
        ],
        "y": 1,
        "width": 614,
        "type": "group",
        "name": "loveshape_18"
    }]
};

$(document).ready(function() {

    $('.container').click(function(e) {
        setTimeout(() => {
            $('#fileup').click();
        }, 20)
    });



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

        for (let {
                src,
                x,
                y
            } of arr) {
            $(".container").css('width', width + "px").css('height', height + "px").addClass('temp');

            var mask = $(".container").mask({
                maskImageUrl: 'https://i.imgur.com/' + src,
                onMaskImageCreate: function(img) {

                    img.css({
                        "position": "absolute",
                        "left": x + "px",
                        "top": y + "px"
                    });
                }
            });

            fileup.onchange = function() {
                mask.loadImage(URL.createObjectURL(fileup.files[0]));
            };
        }

    }
    json(jsonData);

}); // end of document ready

// jq plugin for mask
(function($) {
    var 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);


        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.onDragStart = function(evt) {
            container.selected(evt);
            prevX = evt.clientX;
            prevY = evt.clientY;
            var img = new Image();
            evt.originalEvent.dataTransfer.setDragImage(img, 10, 10);
            evt.originalEvent.dataTransfer.setData('text/plain', 'anything');
        };

        container.getImagePosition = function() {
            return {
                x: settings.x,
                y: settings.y,
                scale: settings.scale
            };
        };

        container.onDragOver = function(evt) {
            if (draggable && $(canvas).attr("active") === "true") {
                var x = settings.x + evt.clientX - prevX;
                var y = settings.y + evt.clientY - prevY;
                if (x == settings.x && y == settings.y)
                    return; // position has not changed
                settings.x += evt.clientX - prevX;
                settings.y += evt.clientY - prevY;
                prevX = evt.clientX;
                prevY = evt.clientY;
                container.updateStyle();
            }
        };

        container.updateStyle = function() {
            clearTimeout(timeout);
            timeout = setTimeout(function() {
                context.clearRect(0, 0, canvas.width, canvas.height);
                context.beginPath();
                context.globalCompositeOperation = "source-over";
                image = new Image();
                image.setAttribute('crossOrigin', 'anonymous');
                image.src = settings.maskImageUrl;
                image.onload = function() {
                    canvas.width = image.width;
                    canvas.height = image.height;
                    context.drawImage(image, 0, 0, image.width, image.height);
                    div.css({
                        "width": image.width,
                        "height": image.height
                    });
                };

                img = new Image();
                img.src = settings.imageUrl;
                img.setAttribute('crossOrigin', 'anonymous');
                img.onload = function() {
                    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.drawImage(img, settings.x, settings.y, img.width * settings.scale, img.height * settings.scale);
                    initImage = false;
                };
            }, 0);
        };

        // change the draggable image
        container.loadImage = function(imageUrl) {
            if (img)
                img.remove();
            // reset the code.
            settings.y = startY;
            settings.x = startX;
            prevX = prevY = 0;
            settings.imageUrl = imageUrl;
            initImage = true;
            container.updateStyle();
        };

        // change the masked Image
        container.loadMaskImage = function(imageUrl, from) {
            if (div)
                div.remove();
            canvas = document.createElement("canvas");
            context = canvas.getContext('2d');
            canvas.setAttribute("draggable", "true");
            canvas.setAttribute("id", settings.id);
            settings.maskImageUrl = imageUrl;
            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);
        };
        container.loadMaskImage(settings.maskImageUrl);
        JQmasks.push({
            item: container,
            id: settings.id
        })
        return container;
    };
}(jQuery));

.temp {
background: black;
}

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

.masked-img {
	overflow: hidden;
	margin-top: 30px;
	position: relative;
}

<script src="https://code.jquery.com/jquery-3.3.1.min.js"></script>

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

<div class="container">

</div>

Answer 1

在你的问题中，你说心脏是透明的，画布的其余部分是不透明的。但是，您的代码将心脏绘制为不透明，其余的画布保持透明。我将假设下面的情况。

由于您使用canvas元素进行实际绘制，我们可以利用它：

$('.container').click(function(e) {
  if(e.target.getContext) {
    var pixel = e.target.getContext('2d').getImageData(e.offsetX, e.offsetY, 1, 1).data;
    if(pixel[3] === 255) {
      setTimeout(() => {
          $('#fileup').click();
      }, 20);
    }
  }
});

e.target是实际被点击的元素。检查它是否具有属性getContext告诉我们它是否是画布。如果不是，则没有文件对话框。

如果它是画布，我们可以继续下一步。 getContext('2d')抓住画布的绘图环境，我们可以通过getImageData()从中提取原始像素数据。

来自事件的offsetX和offsetY是相对于被点击的元素的点击坐标。我们使用getImageData()中的那些来获取点击位置处的画布像素数据。

像素数据是交错的红色，蓝色，绿色和alpha（不透明度）值，每个值的范围从0到255。由于我们抓取了一个像素，它将有4个值，最后一个是alpha。然后我们可以使用它来确定我们是否触发文件对话框。