drawImage 并调整大小为 Canvas-前端问题

drawImage and resize to Canvas(drawImage 并调整大小为 Canvas)

本文介绍了drawImage 并调整大小为 Canvas的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我有一个 1836 x 3264 的图像，我想 drawImage() 到画布上并将大小调整为 739 x 1162.

I have an image which is 1836 x 3264 I want to drawImage() to canvas and resize to 739 x 1162.

阅读文档后，我认为这可以通过以下方式完成:

After reading the documentation I thought this could be accomplished with the following:

ctx.drawImage(image, 0, 0, 739, 1162);

我也试过了:

ctx.drawImage(image, 0, 0, 1836, 3264, 0, 0, 739, 1162);

两者都只显示完整图像的一小部分，而不是缩小它.

Both show only a small part of the full image instead of shrinking it down.

如何传递值以从 1836 x 3264 -> 739 x 1162 调整大小?

How do I pass through the values to resize from 1836 x 3264 -> 739 x 1162 ?

推荐答案

你看到的东西是正确的，所以你可能会仔细检查某个地方的错字.

What you have looks correct, so you might double-check for a typo somewhere.

[额外的想法:你的图像真的是 1836x3264 而不是 3264x1836.]

[additional thought: Is your image really 1836x3264 and not 3264x1836.]

这是工作代码和小提琴:http://jsfiddle.net/m1erickson/MLGr4/

Here is working code and a Fiddle: http://jsfiddle.net/m1erickson/MLGr4/

<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="aHR0cDovL2NvZGUuanF1ZXJ5LmNvbS9qcXVlcnkubWluLmpz"></script>

<style>
    body{ background-color: ivory; }
    canvas{border:1px solid red;}
</style>

<script>
$(function(){

    var canvas=document.getElementById("canvas");
    var ctx=canvas.getContext("2d");

    img=new Image();
    img.onload=function(){
        canvas.width=400;
        canvas.height=300;
        ctx.drawImage(img,0,0,img.width,img.height,0,0,400,300);
    }
    img.src="aHR0cDovL3d3dy5vbmVzdG9wd2VibWFzdGVycy5jb20vd3AtY29udGVudC91cGxvYWRzLzIwMTEvMDYvZWl0YWktYnJpZGdlLmpwZw==";

}); // end $(function(){});
</script>

</head>

<body>
    <canvas id="canvas" width=100 height=100></canvas>
</body>
</html>

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