Phonegap相机在画布上绘制扭曲 [英] Phonegap camera draw on canvas distorted

问题描述

我正在使用Phonegap相机插件在画布上绘制捕获的图像。

I'm using Phonegap Camera Plugin to draw the captured image on a Canvas.

<canvas id="canvas"></canvas>

和JS：

            var canvas = document.getElementById('canvas');
            var context = canvas.getContext('2d');

            canvas.width = window.innerWidth;
            canvas.height = window.innerHeight;

            var x = 0;
            var y = 0;
            var width = window.innerWidth;
            var height = window.innerHeight;
            var imageObj = new Image();

            imageObj.onload = function() {
                context.drawImage(imageObj, x, y, width, height);
            };
            imageObj.src = imageURI;

投影图像看起来失真（拉长，宽度大于真实值）。

The projected images look distorted (streched, width is bigger than real).

如何确定图像的显示效果，例如css width：100％; height：auto？

How can I display the image ok, like in css width:100%; height:auto?

推荐答案

如果您的图片与屏幕的比例不同，则自您使用以来图片会被拉伸告诉它伸展到宽度和高度： context.drawImage（imageObj，x，y，width，height）; 。您可以尝试删除width，height参数。

If your image doesn't have the same ratio as your screen, it'll become stretched since you tell it to stretch to width and height: context.drawImage(imageObj, x, y, width, height);. You can try removing the width, height parameters.

您可能必须计算缩放比例：

You might have to calculate the scaling ratio:

var ratio;
if (imageObj.width>width) {
    ratio = width/imageObj.width;
}
else if (imageObj.height > height) {
    ratio = height/imageObj.height;
}
else {
    ratio = 1;
}
context.drawImage(imageObj, x, y, imageObj.width*ratio, imageObj.height*ratio);

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