[英]Javascript: Variable-sized image in fixed-sized canvas
我有一個尺寸為300x300的固定HTML5畫布。 我正在通過Javascript重新調整頁面上其他圖像的大小,使其最大寬度/高度為300px(取決於較大的尺寸)。
但是,這實際上並沒有調整源圖像的大小,並且當我在畫布上繪制它們時,將使用原始大小。
有沒有辦法:
和
(請考慮制作一個300x300 Photoshop文件,在其中放置各種圖像,然后它們會調整大小以適合)
Javascript / canvas甚至可能嗎?
編輯
這是我根據公認的答案最終使用的代碼:
var ssItems = [exampleUrls], //array of image paths
imgHolder = document.getElementById("img-holder");
for (var i = 0; i < ssItems.length; i++) {
var img = new Image(),
imgSrc = "/ItemImages/Large/" + ssItems[i] + ".jpg",
imgW,
imgH;
img.src = imgSrc;
img.onload = function () {
var canvas = document.createElement("canvas"),
ctx = canvas.getContext("2d");
canvas.setAttribute("class", "img-canvas");
canvas.setAttribute("width", "300");
canvas.setAttribute("height", "300");
imgHolder.appendChild(canvas);
imgW = (canvas.height * this.width) / this.height;
imgH = (canvas.width * this.height) / this.width;
if (this.height > this.width) {
ctx.drawImage(this, canvas.width / 2 - imgW / 2, 0, imgW, canvas.height);
} else {
ctx.drawImage(this, 0, canvas.height / 2 - imgH / 2, canvas.width, imgH);
}
}
我創建了試圖匹配上述情況的小提琴。
var canvas = document.getElementById('myCanvas');
var ctx = canvas.getContext("2d");
var image = new Image();
image.src = 'http://www.menucool.com/slider/jsImgSlider/images/image-slider-2.jpg';
// calculates width and height with respect to canvas
var width = (canvas.height * image.width) / image.height;
var height = (canvas.width * image.height) / image.width;
// takes width or height full choosing the larger value and centers the image
if(image.height > image.width){
ctx.drawImage(image, canvas.width / 2 - width / 2, 0, width, canvas.height);
}else{
ctx.drawImage(image, 0, canvas.height / 2 - height / 2, canvas.width, height);
}
您可以看看它: https : //jsfiddle.net/q8qodgmn/1/
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