[英]Why does my drawing becomes invisible when I take my cursor out of the canvas?
我正在使用fabric.js
構建自定義的T恤設計面板。 我上傳了圖片,輸入了文字等選項,效果很好。 但是,當我從fabric.js
庫添加繪圖工具的JavaScript代碼時,遇到了一些問題:
繪制完所有內容后,如果我將光標移出畫布,則看不到該繪圖。 如果我在畫布上單擊回來,它是可見的。
如果我上傳圖像,則它在畫布中可見,但是當我單擊畫布時消失。
如果我注釋掉這部分代碼,所有問題都消失了,但是在畫布上繪制任何內容都是必不可少的!
var canvas = this.__canvas = new fabric.Canvas('tcanvas', {
isDrawingMode: false
});
我正在為繪圖工具添加圖像和JS代碼。
(function() {
var $ = function(id){return document.getElementById(id)};
var canvas = this.__canvas = new fabric.Canvas('tcanvas', {
isDrawingMode: true
});
fabric.Object.prototype.transparentCorners = false;
var drawingModeEl = $('drawing-mode'),
drawingOptionsEl = $('drawing-mode-options'),
drawingColorEl = $('drawing-color'),
drawingShadowColorEl = $('drawing-shadow-color'),
drawingLineWidthEl = $('drawing-line-width'),
drawingShadowWidth = $('drawing-shadow-width'),
drawingShadowOffset = $('drawing-shadow-offset'),
clearEl = $('clear-canvas');
clearEl.onclick = function() { canvas.clear() };
drawingModeEl.onclick = function() {
canvas.isDrawingMode = !canvas.isDrawingMode;
if (canvas.isDrawingMode) {
drawingModeEl.innerHTML = 'Cancel drawing mode';
drawingOptionsEl.style.display = '';
}
else {
drawingModeEl.innerHTML = 'Enter drawing mode';
drawingOptionsEl.style.display = 'none';
}
};
if (fabric.PatternBrush) {
var vLinePatternBrush = new fabric.PatternBrush(canvas);
vLinePatternBrush.getPatternSrc = function() {
var patternCanvas = fabric.document.createElement('canvas');
patternCanvas.width = patternCanvas.height = 10;
var ctx = patternCanvas.getContext('2d');
ctx.strokeStyle = this.color;
ctx.lineWidth = 5;
ctx.beginPath();
ctx.moveTo(0, 5);
ctx.lineTo(10, 5);
ctx.closePath();
ctx.stroke();
return patternCanvas;
};
var hLinePatternBrush = new fabric.PatternBrush(canvas);
hLinePatternBrush.getPatternSrc = function() {
var patternCanvas = fabric.document.createElement('canvas');
patternCanvas.width = patternCanvas.height = 10;
var ctx = patternCanvas.getContext('2d');
ctx.strokeStyle = this.color;
ctx.lineWidth = 5;
ctx.beginPath();
ctx.moveTo(5, 0);
ctx.lineTo(5, 10);
ctx.closePath();
ctx.stroke();
return patternCanvas;
};
var squarePatternBrush = new fabric.PatternBrush(canvas);
squarePatternBrush.getPatternSrc = function() {
var squareWidth = 10, squareDistance = 2;
var patternCanvas = fabric.document.createElement('canvas');
patternCanvas.width = patternCanvas.height = squareWidth + squareDistance;
var ctx = patternCanvas.getContext('2d');
ctx.fillStyle = this.color;
ctx.fillRect(0, 0, squareWidth, squareWidth);
return patternCanvas;
};
var diamondPatternBrush = new fabric.PatternBrush(canvas);
diamondPatternBrush.getPatternSrc = function() {
var squareWidth = 10, squareDistance = 5;
var patternCanvas = fabric.document.createElement('canvas');
var rect = new fabric.Rect({
width: squareWidth,
height: squareWidth,
angle: 45,
fill: this.color
});
var canvasWidth = rect.getBoundingRect().width;
patternCanvas.width = patternCanvas.height = canvasWidth + squareDistance;
rect.set({ left: canvasWidth / 2, top: canvasWidth / 2 });
var ctx = patternCanvas.getContext('2d');
rect.render(ctx);
return patternCanvas;
};
var img = new Image();
img.src = '../assets/honey_im_subtle.png';
var texturePatternBrush = new fabric.PatternBrush(canvas);
texturePatternBrush.source = img;
}
$('drawing-mode-selector').onchange = function() {
if (this.value === 'hline') {
canvas.freeDrawingBrush = vLinePatternBrush;
}
else if (this.value === 'vline') {
canvas.freeDrawingBrush = hLinePatternBrush;
}
else if (this.value === 'square') {
canvas.freeDrawingBrush = squarePatternBrush;
}
else if (this.value === 'diamond') {
canvas.freeDrawingBrush = diamondPatternBrush;
}
else if (this.value === 'texture') {
canvas.freeDrawingBrush = texturePatternBrush;
}
else {
canvas.freeDrawingBrush = new fabric[this.value + 'Brush'](canvas);
}
if (canvas.freeDrawingBrush) {
canvas.freeDrawingBrush.color = drawingColorEl.value;
canvas.freeDrawingBrush.width = parseInt(drawingLineWidthEl.value, 10) || 1;
canvas.freeDrawingBrush.shadow = new fabric.Shadow({
blur: parseInt(drawingShadowWidth.value, 10) || 0,
offsetX: 0,
offsetY: 0,
affectStroke: true,
color: drawingShadowColorEl.value,
});
}
};
drawingColorEl.onchange = function() {
canvas.freeDrawingBrush.color = this.value;
};
drawingShadowColorEl.onchange = function() {
canvas.freeDrawingBrush.shadow.color = this.value;
};
drawingLineWidthEl.onchange = function() {
canvas.freeDrawingBrush.width = parseInt(this.value, 10) || 1;
this.previousSibling.innerHTML = this.value;
};
drawingShadowWidth.onchange = function() {
canvas.freeDrawingBrush.shadow.blur = parseInt(this.value, 10) || 0;
this.previousSibling.innerHTML = this.value;
};
drawingShadowOffset.onchange = function() {
canvas.freeDrawingBrush.shadow.offsetX = parseInt(this.value, 10) || 0;
canvas.freeDrawingBrush.shadow.offsetY = parseInt(this.value, 10) || 0;
this.previousSibling.innerHTML = this.value;
};
if (canvas.freeDrawingBrush) {
canvas.freeDrawingBrush.color = drawingColorEl.value;
canvas.freeDrawingBrush.width = parseInt(drawingLineWidthEl.value, 10) || 1;
canvas.freeDrawingBrush.shadow = new fabric.Shadow({
blur: parseInt(drawingShadowWidth.value, 10) || 0,
offsetX: 0,
offsetY: 0,
affectStroke: true,
color: drawingShadowColorEl.value,
});
}
})();
繪圖模式存在一個已知的錯誤 ,即如果未觸發freeDrawingBrush.onMouseUp()事件,則剛才繪制的點不會轉換為路徑。
每當您從繪圖控件切換繪圖模式時,請確保調用
canvas.freeDrawingBrush.onMouseUp();
這是一個片段,可讓您切換該方法的調用。 關閉時,線路被擦除。 撥動打開時,線路將保留。
var canvas = new fabric.Canvas("c"); var toggleVal = 1; $('#toggle').on('click', function(e){ toggleVal = (toggleVal === 1 ? 0 : 1); $(this).html((toggleVal === 1 ? 'On' : 'Off')); $(this).val(toggleVal) clearTimeout(timer); reset(); }) var timer; function reset() { canvas.clear(); canvas.isDrawingMode = true; canvas.freeDrawingBrush.color = "green"; canvas.freeDrawingBrush.width = 4; timer = setTimeout(stop_drawing, 3000); } function stop_drawing() { canvas.isDrawingMode = false; if (toggleVal == 1){ canvas.freeDrawingBrush.onMouseUp(); } } reset();
div { background-color: silver; width: 600px; height: 300px; }
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/2.4.1/fabric.min.js"></script> <p>Click the canvas and draw a line. Shortly the timeout fires and drawing stops. Now click the canvas again.</p> <p>The toggle button toggles mouse-up catching - off makes your line dissapear on next canvas click,<br />whilst on works more intuitively <button id='toggle' >On</button></p> <div> <canvas id="c" width="600" height="300"></canvas> </div>
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