[英]Canvas doesn't draw IE 11
I have a canvas code to draw a signature. 我有一个画布代码来绘制签名。 The code works perfectly fine with chrome and Firefox but does not draw at all on IE 11.
该代码可与chrome和Firefox完美配合,但在IE 11上完全无法使用。
My canvas is: 我的画布是:
<canvas id="signitureCanvas" style="border: 3px solid #000; cursor:crosshair; background-color:white;"></canvas>
My code is as below: 我的代码如下:
var canvas = document.getElementById('signitureCanvas');
var ctx = canvas.getContext('2d');
var canvasWidth = 200;
var canvasLength = 120;
canvas.width = canvasWidth;
canvas.height = canvasLength;
var canvasx = $(canvas).offset().left;
var canvasy = $(canvas).offset().top;
var last_mousex = last_mousey = 0;
var mousex = mousey = 0;
var mousedown = false;
var tooltype = 'draw';
//Mousedown
$(canvas).on('mousedown', function (e) {
last_mousex = mousex = parseInt(e.clientX - canvasx);
last_mousey = mousey = parseInt(e.clientY - canvasy);
mousedown = true;
});
//Mouseup
$(canvas).on('mouseup', function (e) {
mousedown = false;
});
//Mousemove
$(canvas).on('mousemove', function (e) {
mousex = parseInt(e.clientX - canvasx);
mousey = parseInt(e.clientY - canvasy);
if (mousedown) {
ctx.beginPath();
if (tooltype == 'draw') {
ctx.globalCompositeOperation = 'source-over';
ctx.strokeStyle = 'black';
ctx.lineWidth = 3;
} else {
ctx.globalCompositeOperation = 'destination-out';
ctx.lineWidth = 10;
}
ctx.moveTo(last_mousex, last_mousey);
ctx.lineTo(mousex, mousey);
ctx.lineJoin = ctx.lineCap = 'round';
ctx.stroke();
}
last_mousex = mousex;
last_mousey = mousey;
});
function ClearCanvas() {
var canvas = document.getElementById('signitureCanvas');
var ctx = canvas.getContext('2d');
ctx.clearRect(0, 0, canvas.width, canvas.height);
}
Is IE 11 in particular having problems? IE 11特别有问题吗?
Edit: 编辑:
I figured out the problem is with my Iframe: 我发现问题出在我的iframe上:
When height and width are set to 300 everything works fine: 将高度和宽度设置为300时,一切正常:
<embed id="fred" type="application/pdf" style="border:1px solid #666CCC" title="PDF in an i-Frame" src="@Model.FilePath" frameborder="1" scrolling="yes" height="300" width="300" />
When I set it to 1000, it won't work: 当我将其设置为1000时,它将不起作用:
<embed id="fred" type="application/pdf" style="border:1px solid #666CCC" title="PDF in an i-Frame" src="@Model.FilePath" frameborder="1" scrolling="yes" height="1000" width="1000" />
I believe it's something with the offset but I can't figure how to fix it. 我相信这与偏移量有关,但我不知道如何解决。
any help? 有什么帮助吗?
For further knowledge to whom might ask: 要进一步了解谁可能会问:
I have found this piece of code that works on all browsers, layerX and layerY are different for firefox browsers: 我发现这段代码可在所有浏览器上使用,对于firefox浏览器,layerX和layerY是不同的:
var canvas = document.getElementById('signitureCanvas');
var ctx = canvas.getContext('2d');
var canvasWidth = 200;
var canvasLength = 120;
canvas.width = canvasWidth;
canvas.height = canvasLength;
var x = 0;
var y = 0;
function tool_pencil() {
var tool = this;
this.started = false;
// This is called when you start holding down the mouse button
// This starts the pencil drawing
this.mousedown = function (ev) {
ctx.beginPath();
ctx.strokeStyle = 'black';
ctx.lineWidth = 3;
ctx.lineJoin = ctx.lineCap = 'round';
ctx.moveTo(x, y);
tool.started = true;
};
// This function is called every time you move the mouse. Obviously, it only
// draws if the tool.started state is set to true (when you are holding down
// the mouse button)
this.mousemove = function (ev) {
if (tool.started) {
ctx.lineTo(x, y);
ctx.stroke();
}
};
// This is called when you release the mouse button
this.mouseup = function (ev) {
if (tool.started) {
tool.mousemove(ev);
tool.started = false;
}
};
}
// The general-purpose event handler. This function just determines
// the mouse position relative to the <canvas> element
function ev_canvas(ev) {
// Firefox
if (ev.offsetX || ev.offsetX == 0) {
x = ev.offsetX;
y = ev.offsetY;
// Opera
} else if (ev.layerX || ev.layerX == 0) {
x = ev.layerX;
y = ev.layerX;
}
// Call the event handler of the tool
var func = tool[ev.type];
if (func) {
func(ev);
}
}
function ClearCanvas() {
var canvas = document.getElementById('signitureCanvas');
var ctx = canvas.getContext('2d');
ctx.clearRect(0, 0, canvas.width, canvas.height);
}
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