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[英]By using HTML5 canvas, how to create infinite loop with time interval
[英]Need to create a loop using HTML5 canvas and JavaScript
我正在使用jQuery輪播顯示SVG大圖像的38個不同的放大率/位置。 理想情況下,我想使用某種循環遍歷所有不同的尺寸,繪制到單獨的canvas
然后在輪播中的每個li
放置一個。 誰能幫助我實現這一目標。 這是我嘗試過的:
function drawSlides() {
for (var i = 1; i <= 38; i++) {
var currentCanvas = 'myCanvas_' + slideNumber;
// initialise canvas element
var canvas_i = document.getElementById('' + currentCanvas + '');
var context = canvas_i.getContext('2d');
// position of SVG – these measurements are subject to change!
var destX_i = -6940;
var destY_i = -29240;
var destWidth_i = 9373;
var destHeight_i = 30000;
context.drawImage('/path/image.svg',
destX_i, destY_i, destWidth_i, destHeight_i);
// white rectangle background – these are constant
var topLeftCornerX_i = 453;
var topLeftCornerY_i = -10;
var width_i = 370;
var height_i = 480;
context.beginPath();
context.rect(topLeftCornerX_i, topLeftCornerY_i, width_i, height_i);
context.fillStyle = "rgba(255, 255, 255, 1)";
context.fill();
// orange vertical line – these elements are constant
context.moveTo(453, 0);
context.lineTo(453, 460);
context.lineWidth = 2;
context.strokeStyle = "#f5d7cb";
context.stroke();
//orange ball – these are constant
var centerX_ball_i = 453;
var centerY_ball_i = 323;
var radius = 99;
context.beginPath();
context.arc(centerX_ball_i, centerY_ball_i, radius, 0, 2 * Math.PI, false);
var grd_ball_i = context.createLinearGradient(224, 354, 422, 552);
grd_ball_i.addColorStop(0, "#f5d7cb"); // light orange
grd_ball_i.addColorStop(1, "#ff4900"); // dark orange
context.fillStyle = grd_ball_i;
context.fill();
}
};
drawSlides();
這應該使您感動:
var numCarouselItems = 38;
var myUL = document.getElementById('carousel');
var items = myUL.childNodes;
var img = new Image;
img.onload = function(){
for (var i=0;i<numCarouselItems;++i){
// Find the nth li, or create it
var li = items[i] || myUL.appendChild(document.createElement('li'));
// Find the nth canvas, or create it
var canvas = li.getElementsByTagName('canvas')[0] ||
li.appendChild(document.createElement('canvas'));
canvas.width = 1; // Erase the canvas, in case it existed
canvas.width = 320; // Set the width and height as desired
canvas.height = 240;
var ctx = canvas.getContext('2d');
// Use your actual calculations for the SVG size/position here
ctx.drawImage( img, 0, 0 );
}
}
// Be sure to set your image source after your load handler is in place
img.src = "foo.svg";
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