作为最终目标,我需要为 Canvas 创建经典的国际象棋背景来表示“透明”背景,并可以选择将其变为真正的透明并返回(在程序中,这里没有直接的用户交互) - 所以我对其他人持开放态度方法来做到这一点。
在当前状态下,我已经创建了或多或少正确的图案并将其添加到 Canvas 中,但我还有两个问题需要修复:
- 两个矩形之间以及矩形与背景之间的过渡是模糊的而不是清晰的。
- 将图案添加到 Canvas 时,它会根据页面加载时的页面视觉尺寸/缩放进行缩放,而不是图案和 Canvas 的编程尺寸。 (要检查缩放,然后再次啜饮)
代码:
// initialize fabric canvas and assign to global windows object for debug
var canvas = window._canvas = new fabric.Canvas('c');
const newTransparent = function() {
const chessStatic = new fabric.StaticCanvas();
chessStatic.setHeight(10);
chessStatic.setWidth(10);
chessStatic.renderAll();
chessStatic.setBackgroundColor('lightgrey');
const greyRect = new fabric.Rect({
width: 5,
height: 5,
left: 0,
top: 0,
// fill: 'grey',
strokeWidth: 0
});
greyRect.set('fill', 'rgba(150, 150, 150, 1)')
const lightGreyRect = new fabric.Rect({
width: 5,
height: 5,
left: 5,
top: 5,
// fill: 'grey',
strokeWidth: 0
});
lightGreyRect.set('fill', 'rgba(187, 187, 187, 1)')
chessStatic.add(greyRect);
chessStatic.add(lightGreyRect);
const greyRect2 = greyRect;
chessStatic.add(greyRect);
chessStatic.add(lightGreyRect);
chessStatic.calcOffset();
chessStatic.renderAll();
const transparentPattern = new fabric.Pattern({
source: function() {
return chessStatic.getElement();
},
repeat: 'repeat'
});
return transparentPattern;
}
canvas.setBackgroundColor(newTransparent(), canvas.renderAll.bind(canvas));
fabric.util.addListener(document.getElementById('toggle-repeat'), 'click', function () {
canvas.setBackgroundColor(newTransparent(), canvas.renderAll.bind(canvas));
const lightGreyRect = new fabric.Rect({
width: 5,
height: 5,
left: 5,
top: 5,
// fill: 'grey',
strokeWidth: 0
});
lightGreyRect.set('fill', 'rgba(187, 187, 187, 1)')
canvas.add(lightGreyRect);
canvas.renderAll();
});
fabric.util.addListener(document.getElementById('toggle-bgcolor'), 'click', function () {
if (canvas.backgroundColor instanceof fabric.Pattern) {
canvas.setBackgroundColor('rgba(0, 225, 64, 0.6)', canvas.renderAll.bind(canvas));
}
else {
canvas.setBackgroundColor({source: 'http://fabricjs.com/assets/escheresque_ste.png'}, canvas.renderAll.bind(canvas));
}
});
canvas {
border: 1px solid #999;
}
button {
margin-top: 20px;
}
<script src="https://rawgit.com/kangax/fabric.js/master/dist/fabric.js"></script>
<canvas id="c" width="400" height="400"></canvas>
<button id="toggle-repeat">Toggle repeat</button>
<button id="toggle-bgcolor">Toggle background</button>
最佳答案
页面缩放存储在同一窗口变量中,其中实际像素和虚拟像素之间的比率为(MacBook 的视网膜和手机的 hidpis)。
因此,当您想做一些不受页面缩放级别影响的操作时,请禁用 retinaScaling, Canvas 将停止考虑 devicepixelratio
的值。或者您也可以在初始化 Canvas 之前将其设置为最小整数。
fabric.devicePixelRatio = Math.max(Math.floor(fabric.devicePixelRatio), 1);
// initialize fabric canvas and assign to global windows object for debug
var canvas = window._canvas = new fabric.Canvas('c', { enableRetinaScaling: false });
const newTransparent = function() {
const chessStatic = new fabric.StaticCanvas(null, { enableRetinaScaling: false });
chessStatic.setHeight(10);
chessStatic.setWidth(10);
chessStatic.renderAll();
chessStatic.setBackgroundColor('lightgrey');
const greyRect = new fabric.Rect({
width: 5,
height: 5,
left: 0,
top: 0,
// fill: 'grey',
strokeWidth: 0
});
greyRect.set('fill', 'rgba(150, 150, 150, 1)')
const lightGreyRect = new fabric.Rect({
width: 5,
height: 5,
left: 5,
top: 5,
// fill: 'grey',
strokeWidth: 0
});
lightGreyRect.set('fill', 'rgba(187, 187, 187, 1)')
chessStatic.add(greyRect);
chessStatic.add(lightGreyRect);
const greyRect2 = greyRect;
chessStatic.add(greyRect);
chessStatic.add(lightGreyRect);
chessStatic.calcOffset();
chessStatic.renderAll();
const transparentPattern = new fabric.Pattern({
source: function() {
return chessStatic.getElement();
},
repeat: 'repeat'
});
return transparentPattern;
}
canvas.setBackgroundColor(newTransparent(), canvas.renderAll.bind(canvas));
fabric.util.addListener(document.getElementById('toggle-repeat'), 'click', function () {
canvas.setBackgroundColor(newTransparent(), canvas.renderAll.bind(canvas));
const lightGreyRect = new fabric.Rect({
width: 5,
height: 5,
left: 5,
top: 5,
// fill: 'grey',
strokeWidth: 0
});
lightGreyRect.set('fill', 'rgba(187, 187, 187, 1)')
canvas.add(lightGreyRect);
canvas.renderAll();
});
fabric.util.addListener(document.getElementById('toggle-bgcolor'), 'click', function () {
if (canvas.backgroundColor instanceof fabric.Pattern) {
canvas.setBackgroundColor('rgba(0, 225, 64, 0.6)', canvas.renderAll.bind(canvas));
}
else {
canvas.setBackgroundColor({source: 'http://fabricjs.com/assets/escheresque_ste.png'}, canvas.renderAll.bind(canvas));
}
});
canvas {
border: 1px solid #999;
}
button {
margin-top: 20px;
}
<script src="https://rawgit.com/kangax/fabric.js/master/dist/fabric.js"></script>
<canvas id="c" width="400" height="400"></canvas>
<button id="toggle-repeat">Toggle repeat</button>
<button id="toggle-bgcolor">Toggle background</button>
关于javascript - Fabric-js 模式 : How create pattern for canvas background from Rects without size depending on Zoom and blured Rects,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/60350747/