我目前正在制作一个照片编辑器,我正处于将图像添加到图像并拖动它的位置的一部分,当你拖动它周围的文本时,它显示了你将它移动到的确切位置What It looks like when you move the text around
有关导致此问题的任何想法?或者任何修复方法?我已经玩了一段时间的代码并且无法解决这个问题。先感谢您! :)
HTML:
<input id="theText" type="text">
<button id="submit">Draw text on canvas</button><br>
<canvas id="canvas" width="300" height="300"></canvas>
<div id="image_div">
<h1> Choose an Image to Upload </h1>
<input type='file' name='img' id='uploadimage' />
</div>
图片上传脚本:
<script>
//Uploads Image from Input to Cavans :p //
function draw(ev) {
console.log(ev);
var ctx = document.getElementById('canvas').getContext('2d'),
img = new Image(),
f = document.getElementById("uploadimage").files[0],
url = window.URL || window.webkitURL,
src = url.createObjectURL(f);
img.src = src;
img.onload = function() {
ctx.drawImage(img, 0, 0);
url.revokeObjectURL(src);
}
}
document.getElementById("uploadimage").addEventListener("change", draw, false)
</script>
使Text Move Able的脚本:
<script>
// canvas related variables
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
// variables used to get mouse position on the canvas
var $canvas = $("#canvas");
var canvasOffset = $canvas.offset();
var offsetX = canvasOffset.left;
var offsetY = canvasOffset.top;
var scrollX = $canvas.scrollLeft();
var scrollY = $canvas.scrollTop();
// variables to save last mouse position
// used to see how far the user dragged the mouse
// and then move the text by that distance
var startX;
var startY;
// an array to hold text objects
var texts = [];
// this var will hold the index of the hit-selected text
var selectedText = -1;
// clear the canvas & redraw all texts ====
function draw() {
ctx.rect(0,0, canvas.width, canvas.height);
for (var i = 0; i < texts.length; i++) {
var text = texts[i];
ctx.fillStyle = "blue";
ctx.fillText(text.text, text.x, text.y);
}
}
// test if x,y is inside the bounding box of texts[textIndex]
function textHittest(x, y, textIndex) {
var text = texts[textIndex];
return (x >= text.x && x <= text.x + text.width && y >= text.y - text.height && y <= text.y);
}
// handle mousedown events
// iterate through texts[] and see if the user
// mousedown'ed on one of them
// If yes, set the selectedText to the index of that text
function handleMouseDown(e) {
e.preventDefault();
startX = parseInt(e.clientX - offsetX);
startY = parseInt(e.clientY - offsetY);
// Put your mousedown stuff here
for (var i = 0; i < texts.length; i++) {
if (textHittest(startX, startY, i)) {
selectedText = i;
}
}
}
// done dragging
function handleMouseUp(e) {
e.preventDefault();
selectedText = -1;
}
// also done dragging
function handleMouseOut(e) {
e.preventDefault();
selectedText = -1;
}
// handle mousemove events
// calc how far the mouse has been dragged since
// the last mousemove event and move the selected text
// by that distance
function handleMouseMove(e) {
if (selectedText < 0) {
return;
}
e.preventDefault();
mouseX = parseInt(e.clientX - offsetX);
mouseY = parseInt(e.clientY - offsetY);
// Put your mousemove stuff here
var dx = mouseX - startX;
var dy = mouseY - startY;
startX = mouseX;
startY = mouseY;
var text = texts[selectedText];
text.x += dx;
text.y += dy;
draw();
}
// listen for mouse events
$("#canvas").mousedown(function (e) {
handleMouseDown(e);
});
$("#canvas").mousemove(function (e) {
handleMouseMove(e);
});
$("#canvas").mouseup(function (e) {
handleMouseUp(e);
});
$("#canvas").mouseout(function (e) {
handleMouseOut(e);
});
$("#submit").click(function () {
// calc the y coordinate for this text on the canvas
var y = texts.length * 20 + 20;
// get the text from the input element
var text = {
text: $("#theText").val(),
x: 20,
y: y
};
// calc the size of this text for hit-testing purposes
ctx.font = "16px verdana";
text.width = ctx.measureText(text.text).width;
text.height = 16;
// put this new text in the texts array
texts.push(text);
// redraw everything
draw();
});
</script>
答案 0 :(得分:0)
draw()
方法
试。相关代码段
var drawnImage;
function drawImage(ev) {
console.log(ev);
var ctx = document.getElementById('canvas').getContext('2d'),
img = new Image(),
f = document.getElementById("uploadimage").files[0],
url = window.URL || window.webkitURL,
src = url.createObjectURL(f);
img.src = src;
img.onload = function () {
drawnImage = img;
ctx.drawImage(img, 0, 0);
url.revokeObjectURL(src);
}
}
document.getElementById("uploadimage").addEventListener("change", drawImage, false);
function redraw(){
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.drawImage(drawnImage,0,0);
draw();
}
function handleMouseMove(e) {
if (selectedText < 0) {
return;
}
e.preventDefault();
mouseX = parseInt(e.clientX - offsetX);
mouseY = parseInt(e.clientY - offsetY);
// Put your mousemove stuff here
var dx = mouseX - startX;
var dy = mouseY - startY;
startX = mouseX;
startY = mouseY;
var text = texts[selectedText];
text.x += dx;
text.y += dy;
redraw();
}
示例小提琴 - https://jsfiddle.net/rbkdLbcm/1/(图片上传无效)