我是 Html5 的新手。我正在上传图像，但它没有显示在画布中，如果我提供图像的直接来源，那么它将起作用。我从此链接获取帮助javascript：上传图像文件并将其绘制到画布中 https://stackoverflow.com/questions/22255580/javascript-upload-image-file-and-draw-it-into-a-canvas我会告诉你我的代码。
<style>
body {
padding:0px;
}
#canvas {
border:1px solid red;
}
</style>
<div id="bg">
<canvas id="canvas" style="margin-top:32px;margin-left:65px;" width=700 height=350></canvas>
</div>
<br>Click and drag the image or drag the dots to resize.
<br>
<!-- <br>Text:
<input type="textarea" id="words" value="" />-->
<input type="file" id="input" name="imageLoader" />
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<script>
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
// var Input = document.getElementById('words');
var x = 10;
var y = 30;
ctx.font = "bold 20px sans-serif";
ctx.fillStyle = "black";
// $('#words').keyup(function () {
// ctx.fillText($("#words").val(), x, y);
// });
var canvasOffset = $("#canvas").offset();
var offsetX = canvasOffset.left;
var offsetY = canvasOffset.top;
var startX;
var startY;
var isDown = false;
var pi2 = Math.PI * 2;
var resizerRadius = 3;
var rr = resizerRadius * resizerRadius;
var draggingResizer = {
x: 0,
y: 0
};
var imageX = 39;
var imageY = 15;
var imageWidth, imageHeight, imageRight, imageBottom;
var draggingImage = false;
var startX;
var startY;
var img = new Image();
img.onload = function () {
imageWidth = 165;
imageHeight = 125;
imageRight = imageX + imageWidth;
imageBottom = imageY + imageHeight
draw(true, false);
}
var b;
var input = document.getElementById('input');
input.addEventListener('change', handleFiles);
function handleFiles(e) {
var ctx = document.getElementById('canvas').getContext('2d');
var img = new Image;
b = URL.createObjectURL(e.target.files[0]);
console.log("jkfdhgjkdfhgjkdf " + b);
img.onload = function () {
ctx.drawImage(img, 60, 60);
}
}
img.src = "https://d3s16h6oq3j5fb.cloudfront.net/1.11.0/img/new-city-home/bang-img/cake3.jpg";
function draw(withAnchors, withBorders) {
// clear the canvas
ctx.clearRect(0, 0, canvas.width, canvas.height);
// draw the image
ctx.drawImage(img, 0, 0, img.width, img.height, imageX, imageY, imageWidth, imageHeight);
// optionally draw the draggable anchors
if (withAnchors) {
drawDragAnchor(imageX, imageY);
drawDragAnchor(imageRight, imageY);
drawDragAnchor(imageRight, imageBottom);
drawDragAnchor(imageX, imageBottom);
}
// optionally draw the connecting anchor lines
if (withBorders) {
ctx.beginPath();
ctx.moveTo(imageX, imageY);
ctx.lineTo(imageRight, imageY);
ctx.lineTo(imageRight, imageBottom);
ctx.lineTo(imageX, imageBottom);
ctx.closePath();
ctx.stroke();
}
}
function drawDragAnchor(x, y) {
ctx.beginPath();
ctx.arc(x, y, resizerRadius, 0, pi2, false);
ctx.closePath();
ctx.fill();
}
function anchorHitTest(x, y) {
var dx, dy;
// top-left
dx = x - imageX;
dy = y - imageY;
if (dx * dx + dy * dy <= rr) {
return (0);
}
// top-right
dx = x - imageRight;
dy = y - imageY;
if (dx * dx + dy * dy <= rr) {
return (1);
}
// bottom-right
dx = x - imageRight;
dy = y - imageBottom;
if (dx * dx + dy * dy <= rr) {
return (2);
}
// bottom-left
dx = x - imageX;
dy = y - imageBottom;
if (dx * dx + dy * dy <= rr) {
return (3);
}
return (-1);
}
function hitImage(x, y) {
return (x > imageX && x < imageX + imageWidth && y > imageY && y < imageY + imageHeight);
}
function handleMouseDown(e) {
startX = parseInt(e.clientX - offsetX);
startY = parseInt(e.clientY - offsetY);
draggingResizer = anchorHitTest(startX, startY);
draggingImage = draggingResizer < 0 && hitImage(startX, startY);
}
function handleMouseUp(e) {
draggingResizer = -1;
draggingImage = false;
draw(true, false);
}
function handleMouseOut(e) {
handleMouseUp(e);
}
function handleMouseMove(e) {
if (draggingResizer > -1) {
mouseX = parseInt(e.clientX - offsetX);
mouseY = parseInt(e.clientY - offsetY);
// resize the image
switch (draggingResizer) {
case 0:
//top-left
imageX = mouseX;
imageWidth = imageRight - mouseX;
imageY = mouseY;
imageHeight = imageBottom - mouseY;
break;
case 1:
//top-right
imageY = mouseY;
imageWidth = mouseX - imageX;
imageHeight = imageBottom - mouseY;
break;
case 2:
//bottom-right
imageWidth = mouseX - imageX;
imageHeight = mouseY - imageY;
break;
case 3:
//bottom-left
imageX = mouseX;
imageWidth = imageRight - mouseX;
imageHeight = mouseY - imageY;
break;
}
if (imageWidth < 25) {
imageWidth = 25;
}
if (imageHeight < 25) {
imageHeight = 25;
}
// set the image right and bottom
imageRight = imageX + imageWidth;
imageBottom = imageY + imageHeight;
// redraw the image with resizing anchors
draw(true, true);
} else if (draggingImage) {
imageClick = false;
mouseX = parseInt(e.clientX - offsetX);
mouseY = parseInt(e.clientY - offsetY);
// move the image by the amount of the latest drag
var dx = mouseX - startX;
var dy = mouseY - startY;
imageX += dx;
imageY += dy;
imageRight += dx;
imageBottom += dy;
// reset the startXY for next time
startX = mouseX;
startY = mouseY;
// redraw the image with border
draw(false, true);
}
}
$("#canvas").mousedown(function (e) {
handleMouseDown(e);
});
$("#canvas").mousemove(function (e) {
handleMouseMove(e);
});
$("#canvas").mouseup(function (e) {
handleMouseUp(e);
});
$("#canvas").mouseout(function (e) {
handleMouseOut(e);
});
</script>
In this screen shot image is resizable with (img.src="https://d3s16h6oq3j5fb.cloudfront.net/1.11.0/img/new-city-home/bang-img/cake3.jpg"). But i want this image upload in canvas by user. When i am upload image by user then it will not working.
I will give you one more screen shot.
我改变了现有代码中的一些想法。现在图像由用户上传。
<style>
body {
padding:0px;
}
#canvas {
border:1px solid red;
}
</style>
<div id="bg">
<canvas id="canvas" style="margin-top:32px;margin-left:65px;" width=700 height=350></canvas>
</div>
<br>Click and drag the image or drag the dots to resize.
<br>
<!-- <br>Text:
<input type="textarea" id="words" value="" />-->
<input type="file" id="input" name="imageLoader" />
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<script>
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
// var Input = document.getElementById('words');
var x = 10;
var y = 30;
ctx.font = "bold 20px sans-serif";
ctx.fillStyle = "black";
// $('#words').keyup(function () {
// ctx.fillText($("#words").val(), x, y);
// });
var canvasOffset = $("#canvas").offset();
var offsetX = canvasOffset.left;
var offsetY = canvasOffset.top;
var startX;
var startY;
var isDown = false;
var pi2 = Math.PI * 2;
var resizerRadius = 3;
var rr = resizerRadius * resizerRadius;
var draggingResizer = {
x: 0,
y: 0
};
var imageX = 39;
var imageY = 15;
var imageWidth, imageHeight, imageRight, imageBottom;
var draggingImage = false;
var startX;
var startY;
var img = new Image();
img.onload = function () {
imageWidth = 165;
imageHeight = 125;
imageRight = imageX + imageWidth;
imageBottom = imageY + imageHeight
draw(true, false);
}
var b;
var input = document.getElementById('input');
input.addEventListener('change', handleFiles);
function handleFiles(e) {
var ctx = document.getElementById('canvas').getContext('2d');
var img = new Image;
img.src = URL.createObjectURL(e.target.files[0]);
console.log("jkfdhgjkdfhgjkdf " + b);
img.onload = function draw(withAnchors, withBorders) {
// clear the canvas
ctx.clearRect(0, 0, canvas.width, canvas.height);
// draw the image
ctx.drawImage(img, 0, 0, img.width, img.height, imageX, imageY, imageWidth, imageHeight);
// optionally draw the draggable anchors
if (withAnchors) {
drawDragAnchor(imageX, imageY);
drawDragAnchor(imageRight, imageY);
drawDragAnchor(imageRight, imageBottom);
drawDragAnchor(imageX, imageBottom);
}
// optionally draw the connecting anchor lines
if (withBorders) {
ctx.beginPath();
ctx.moveTo(imageX, imageY);
ctx.lineTo(imageRight, imageY);
ctx.lineTo(imageRight, imageBottom);
ctx.lineTo(imageX, imageBottom);
ctx.closePath();
ctx.stroke();
}
}
function drawDragAnchor(x, y) {
ctx.beginPath();
ctx.arc(x, y, resizerRadius, 0, pi2, false);
ctx.closePath();
ctx.fill();
}
function anchorHitTest(x, y) {
var dx, dy;
// top-left
dx = x - imageX;
dy = y - imageY;
if (dx * dx + dy * dy <= rr) {
return (0);
}
// top-right
dx = x - imageRight;
dy = y - imageY;
if (dx * dx + dy * dy <= rr) {
return (1);
}
// bottom-right
dx = x - imageRight;
dy = y - imageBottom;
if (dx * dx + dy * dy <= rr) {
return (2);
}
// bottom-left
dx = x - imageX;
dy = y - imageBottom;
if (dx * dx + dy * dy <= rr) {
return (3);
}
return (-1);
}
function hitImage(x, y) {
return (x > imageX && x < imageX + imageWidth && y > imageY && y < imageY + imageHeight);
}
function handleMouseDown(e) {
startX = parseInt(e.clientX - offsetX);
startY = parseInt(e.clientY - offsetY);
draggingResizer = anchorHitTest(startX, startY);
draggingImage = draggingResizer < 0 && hitImage(startX, startY);
}
function handleMouseUp(e) {
draggingResizer = -1;
draggingImage = false;
draw(true, false);
}
function handleMouseOut(e) {
handleMouseUp(e);
}
function handleMouseMove(e) {
if (draggingResizer > -1) {
mouseX = parseInt(e.clientX - offsetX);
mouseY = parseInt(e.clientY - offsetY);
// resize the image
switch (draggingResizer) {
case 0:
//top-left
imageX = mouseX;
imageWidth = imageRight - mouseX;
imageY = mouseY;
imageHeight = imageBottom - mouseY;
break;
case 1:
//top-right
imageY = mouseY;
imageWidth = mouseX - imageX;
imageHeight = imageBottom - mouseY;
break;
case 2:
//bottom-right
imageWidth = mouseX - imageX;
imageHeight = mouseY - imageY;
break;
case 3:
//bottom-left
imageX = mouseX;
imageWidth = imageRight - mouseX;
imageHeight = mouseY - imageY;
break;
}
if (imageWidth < 25) {
imageWidth = 25;
}
if (imageHeight < 25) {
imageHeight = 25;
}
// set the image right and bottom
imageRight = imageX + imageWidth;
imageBottom = imageY + imageHeight;
// redraw the image with resizing anchors
draw(true, true);
} else if (draggingImage) {
imageClick = false;
mouseX = parseInt(e.clientX - offsetX);
mouseY = parseInt(e.clientY - offsetY);
// move the image by the amount of the latest drag
var dx = mouseX - startX;
var dy = mouseY - startY;
imageX += dx;
imageY += dy;
imageRight += dx;
imageBottom += dy;
// reset the startXY for next time
startX = mouseX;
startY = mouseY;
// redraw the image with border
draw(false, true);
}
}
}
$("#canvas").mousedown(function (e) {
handleMouseDown(e);
});
$("#canvas").mousemove(function (e) {
handleMouseMove(e);
});
$("#canvas").mouseup(function (e) {
handleMouseUp(e);
});
$("#canvas").mouseout(function (e) {
handleMouseOut(e);
});
img.src = "https://d3s16h6oq3j5fb.cloudfront.net/1.11.0/img/new-city-home/bang-img/cake3.jpg";
</script>
Till now image not rotate and draggable.
请告诉我如何在画布中拖动和移动该图像。
请分享您的想法。因为这对我来说非常重要。提前致谢。
var canvas = new fabric.Canvas('canvas');
document.getElementById('file').addEventListener("change", function (e) {
var file = e.target.files[0];
var reader = new FileReader();
reader.onload = function (f) {
var data = f.target.result;
fabric.Image.fromURL(data, function (img) {
var oImg = img.set({left: 0, top: 0, angle: 00,width:100, height:100}).scale(0.9);
canvas.add(oImg).renderAll();
var a = canvas.setActiveObject(oImg);
var dataURL = canvas.toDataURL({format: 'png', quality: 0.8});
});
};
reader.readAsDataURL(file);
});canvas{
border: 1px solid black;
}<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://rawgit.com/kangax/fabric.js/master/dist/fabric.min.js"></script>
<input type="file" id="file"><br />
<canvas id="canvas" width="450" height="450"></canvas>