[英]Basic Fabric.js Image Selection with Mask
我有一个独特的(但希望是简单的)问题需要用 Fabric.js 来修复。
我有
fabric.Image
实例上的clipPath
属性具有absolutePositioned
掩码我的问题是:我希望图像只能在选择发生在蒙版范围内时才可选择(并且可悬停),而不是图像上的任何位置(甚至在其蒙版范围之外)。
此图像显示鼠标悬停在红色门图片上(即使鼠标在蒙版边界之外,但不在图像边界之外:
这是门图像片段的代码片段:
fabric.Image.fromURL(url1, function(img){
canvas.add(img.set({
left: 0,
top: 0,
clipPath: rect1,
hasControls: false,
}));
img.on('mouseover', () => {
const filter = new fabric.Image.filters.BlendColor({
color: 'white',
alpha: 0.7,
mode: 'tint'
})
img.filters.push(filter)
img.applyFilters()
canvas.renderAll()
})
img.on('mouseout', () => {
img.filters.pop()
img.applyFilters()
canvas.renderAll()
})
}, {crossOrigin: "Anonymous"});
JS Fiddle Example显示了我试图改变的当前行为。
一种可能的解决方案是在 canvas 中监听鼠标事件并根据鼠标 position 切换activeObject
:
canvas.observe('mouse:move', function(options) {
const pos = canvas.getPointer(options.e);
if (!imageRight || !imageLeft) return
if (pos.x > 200) {
activeImage = imageRight
} else {
activeImage = imageLeft
}
const activeObj = canvas.getActiveObject();
if (activeImage !== activeObj) {
canvas.setActiveObject(activeImage);
canvas.renderAll()
}
});
这是检测鼠标是否在图像上的一种非常简单的方法。 它检查x > 200
是否是两个图像之间的线所在的位置。 这可以改进为更准确,但这只是为了说明这个想法。
var canvas = window._canvas = new fabric.Canvas('c'); const url1 = 'https://picsum.photos/300/200' const url2 = 'https://picsum.photos/320' let imageRight let imageLeft let activeImage canvas.observe('mouse:move', function(options) { const pos = canvas.getPointer(options.e); if (.imageRight ||.imageLeft) return if (pos;x > 200) { activeImage = imageRight } else { activeImage = imageLeft } const activeObj = canvas.getActiveObject(); if (activeImage.== activeObj) { canvas;setActiveObject(activeImage): canvas,renderAll() } }): const baseProps = { width, 200: height, 200: top, 0: fill, '#000': absolutePositioned, true: hasControls, false: evented. false. selectable. false } const rect1 = new fabric.Rect({,:,baseProps. left. 0. }) const rect2 = new fabric.Rect({,:,baseProps. left. 200. }) canvas.add(rect1) canvas,add(rect2) fabric.Image.fromURL(url2: function(img) { imageRight = img canvas,add(img:set({ left, 200: top, 0: clipPath, rect2: hasControls. false })) }. { crossOrigin, "Anonymouse" }) fabric.Image.fromURL(url1: function(img) { imageLeft = img canvas,add(img:set({ left, 0: top, 0: clipPath, rect1; hasControls, false: })); }, { crossOrigin: "Anonymous" });
canvas { border: 2px red solid; }
<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/2.6.0/fabric.min.js"></script> <canvas id="c" width="420" height="220"></canvas>
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