如何在修改对象后获取Text对象的font-size

Question

在fabric.js中修改对象后,如何获取Text对象的字体大小？

以下是我的代码.

var text = new fabric.Text(imgText, {
                left: 10,
                top: 5,
                fontSize: 15,
                fontFamily: 'Verdana',
                fill: 'white'
            });
            text.scaleToWidth(canvas.width * 0.5);
            text.setControlsVisibility(canvasConfig);
            canvas.add(text);
            canvas.renderAll();
var objects = canvas.getActiveObject();

            var obj = objects;
            if (!obj) {
                return;
            }
            //console.log(obj.get('fontSize') *= obj.scaleX); 
            var angle = obj.get('angle');

            var objWidth = obj.get('width') * obj.scaleX;
            var objWidthPercent = objWidth / canvas.width * 100;

            var objHeight = obj.get('height') * obj.scaleY;
            var objHeightPercent = objHeight / canvas.height * 100;

            var bound = obj.getBoundingRect();
            var objLeft = obj.get('left') / canvas.width * 100;
            var objTop = obj.get('top') / canvas.height * 100;

            var newfontsize = obj.fontSize * obj.scaleX;

上面我将默认FontSize设置为15.然后我修改对象我可以得到正确Height, Width, Left, Top,但我无法获得FontSize.

在后端我设置图像和文本,如下面的截图.

在前端我得到如下截图.

下面是前端图像和文字的样式.

element.style {
    left: 64.37%;
    top: 14.54%;
    width: 28.25%;
    height: 14.37%;
    font-size: 63.58px;
    color: #E346FF;
    font-family: Times New Roman;
    position: absolute;
    max-width: 100%;
    z-index: 996;
    max-height: 100%;
}

element.style {
    left: 56.5%;
    top: 0.81%;
    width: 42.86%;
    height: 42.86%;
    max-width: 100%;
    max-height: 100%;
    position: absolute;
    z-index: 995;
    display: block;
    background-image: url(http://10.16.16.101/LabelExtension/pub/media/labelimageuploader/images/image/o/r/orange_38.png);
    background-position: center;
    background-repeat: no-repeat;
    background-size: contain;
}

当我添加下面的代码时它工作完美但在后端对象变得模糊.

this.canvas.setHeight(300);
this.canvas.setWidth(240);
this.canvas.backgroundColor = '#E8EEF1';
this.canvas.setDimensions({width: '480px', height: '600px'}, {cssOnly: true});

Answer 1

以下是将Fabric.js字体转换与CSS转换相匹配的方法:https://jsfiddle.net/mmalex/evpky3tn/

解决方案是匹配文本的转换,而不是尝试调整字体大小.

步骤1 - 准备场景,撰写画布,用矩形分组文本,让用户操作该组,旋转并缩放它.

var canvas = new fabric.Canvas(document.getElementById('c'));

var rect = new fabric.Rect({
    width: 50,
    height: 50,
    left: 90,
    top: 120,
    fill: 'rgba(255,0,0,0.25)'
});

var text = new fabric.Text("123", {
    left: rect.left,
    top: rect.top,
    fontSize: 15,
    fontFamily: 'Verdana',
    fill: 'black'
});

text.scaleToWidth(rect.width);
canvas.add(text);

var group = new fabric.Group([rect, text], {
    originX: 'center',
    originY: 'center',
    angle: 25,
    scaleY: 1.7
});

canvas.add(group);
canvas.renderAll();

第2步 - 准备DIV样式进行缩放

.scaled {  // this style is applied to DIV element with text
    ...
    font-size: 15px; // Fabric.js text is also 15px size
    transform: scale(1, 1); // define initial transform
    transition: all 0.25s linear; // let it animate
    ...
}

第3步 - 评估Fabric.js转换并在DIV元素上应用CSS,例如:

element.style {
    transform: rotate(25deg) scale(1.74774, 2.97116); 
}

解决方案(也就是按钮处理程序)将Fabric.js转换为CSS转换:

function matchCssTransform() {
    let textScale = text.getTotalObjectScaling();
    let pixelRatio = window.devicePixelRatio;
    let styleStr = `rotate(${group.angle}deg) scale(${textScale.scaleX / pixelRatio}, ${textScale.scaleY / pixelRatio}) `;
    document.getElementById("scaled").style.transform = styleStr;
}

Answer 2

这是普通的 js 解决方案。

我无法获取 FontSize。

您可以使用 ComputeStyle 来实现 fontSize，例如

  let style = window.getComputedStyle(text, null).getPropertyValue('font-size');
  let fontSize = parseFloat(style); 

https://developer.mozilla.org/de/docs/Web/API/Window/getCompulatedStyle

除此之外，我建议您vw与vh

.text {
  font-size: 10vw;
}

https://web-design-weekly.com/2014/11/18/viewport-units-vw-vh-vmin-vmax/

所有这些共同为我们提供了https://jsfiddle.net/a8woL1eh/