Javascript HTML将图像从画布复制到另一画布
我想从第一个画布生成一个图像,然后在另一个画布中绘制,但我有一个问题,因为我不知道为什么在另一个画布中什么都看不到。这是我的密码:Javascript HTML将图像从画布复制到另一画布,javascript,html,canvas,Javascript,Html,Canvas,我想从第一个画布生成一个图像,然后在另一个画布中绘制,但我有一个问题,因为我不知道为什么在另一个画布中什么都看不到。这是我的密码: <canvas id="gameCanvas" width="704" height="608" /> <script type='text/javascript'> // prepaire our game canvas var canvas = document.getElementById("gameCanvas
<canvas id="gameCanvas" width="704" height="608" />
<script type='text/javascript'>
// prepaire our game canvas
var canvas = document.getElementById("gameCanvas");
var context = canvas.getContext("2d");
var ctx = document.createElement("canvas").getContext("2d");
ctx.canvas.width = 2048;
ctx.canvas.height = 2048;
var rows = 64;
var columns = 64;
this.image = new Image();
var imageObject = document.createElement("img");
var me = this;
/// need this as loading is async
imageObject.onload = function() {
for (var i = 0; i < rows; i++) {
for (var j=0; j <columns; j++) {
ctx.drawImage(this, i*32,j*32,32,32);
}
}
// store the generate map as this image texture
me.image.src = ctx.canvas.toDataURL("image/jpg");
}
imageObject.src='ground.jpg';
this.image.src = ctx.canvas.toDataURL("image/jpg");
context.drawImage(this.image, 0, 0, 300, 300, 0, 0, 300,300);
</script>
//为我们的游戏画布预先准备好
var canvas=document.getElementById(“gameCanvas”);
var context=canvas.getContext(“2d”);
var ctx=document.createElement(“canvas”).getContext(“2d”);
ctx.canvas.width=2048;
ctx.canvas.height=2048;
var行=64;
var列=64;
this.image=新图像();
var imageObject=document.createElement(“img”);
var me=这个;
///需要这个,因为加载是异步的
imageObject.onload=函数(){
对于(var i=0;i将画布转换为DataURL,然后将图像源设置为该DataURL,这是不必要的。这是因为context.drawImage
可以处理
,就像它可以处理This.image.src
画布的DataURL一样,然后将该图像用于e> 此时,画布可能仍然是空的,因此数据url也将是空图像的url
解决方案:将代码的最后一行放入onload函数
将画布转换为DataURL,然后将图像源设置为该DataURL,这是不必要的。这是因为context.drawImage
可以处理
,就像它可以处理This.image.src
画布的DataURL一样,然后将该图像用于e> 此时,画布可能仍然是空的,因此数据url也将是空图像的url
解决方案:将代码的最后一行放入onload函数。创建DOM元素后,应将其附加到另一个元素上以显示它
试试这个
脚本:
var canvas = document.getElementById("gameCanvas");
var ctx = canvas.getContext("2d");
var image=document.createElement("img");
image.onload=function(){
canvas.width = image.width;
canvas.height=image.height;
ctx.drawImage(image,0,0);
var tcanvas = document.createElement('canvas');
var tctx = tcanvas.getContext('2d');
tcanvas.width = 8*image.width;
tcanvas.height = 8*image.height;
for(var i=0;i<8;i++){
for(var j=0;j<8;j++){
tctx.drawImage(image, i*image.width,j*image.height);
document.body.appendChild(tcanvas);
}
}
}
image.src="https://lh4.googleusercontent.com/-L1cr04d6ONc/RsRykgOl9zI/AAAAAAAABIE/WqBGOdiJnys/s128/Finishes.Flooring.Tile.Square.Blue.bump.jpg";
var canvas=document.getElementById(“gameCanvas”);
var ctx=canvas.getContext(“2d”);
var image=document.createElement(“img”);
image.onload=function(){
canvas.width=image.width;
canvas.height=image.height;
ctx.drawImage(图像,0,0);
var tcanvas=document.createElement('canvas');
var tctx=tcanvas.getContext('2d');
tcanvas.width=8*image.width;
tcanvas.height=8*image.height;
对于(var i=0;i,在创建DOM元素之后,应该将它附加到另一个元素上以显示它
试试这个
脚本:
var canvas = document.getElementById("gameCanvas");
var ctx = canvas.getContext("2d");
var image=document.createElement("img");
image.onload=function(){
canvas.width = image.width;
canvas.height=image.height;
ctx.drawImage(image,0,0);
var tcanvas = document.createElement('canvas');
var tctx = tcanvas.getContext('2d');
tcanvas.width = 8*image.width;
tcanvas.height = 8*image.height;
for(var i=0;i<8;i++){
for(var j=0;j<8;j++){
tctx.drawImage(image, i*image.width,j*image.height);
document.body.appendChild(tcanvas);
}
}
}
image.src="https://lh4.googleusercontent.com/-L1cr04d6ONc/RsRykgOl9zI/AAAAAAAABIE/WqBGOdiJnys/s128/Finishes.Flooring.Tile.Square.Blue.bump.jpg";
var canvas=document.getElementById(“gameCanvas”);
var ctx=canvas.getContext(“2d”);
var image=document.createElement(“img”);
image.onload=function(){
canvas.width=image.width;
canvas.height=image.height;
ctx.drawImage(图像,0,0);
var tcanvas=document.createElement('canvas');
var tctx=tcanvas.getContext('2d');
tcanvas.width=8*image.width;
tcanvas.height=8*image.height;
对于(var i=0;i