Html HTML5 画布背景图像重复
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HTML5 canvas background image repeat
提问by Sam Skirrow
I have a html5 canvas that draws a sound wave. I have set the background as an background image, however, I want this background image to repeat. Can anyone tell me how I would do this and what I need to add into my code:
我有一个绘制声波的 html5 画布。我已将背景设置为背景图像，但是，我希望此背景图像重复。谁能告诉我我将如何做到这一点以及我需要添加到我的代码中的内容：
var backgroundImage = new Image();
backgroundImage.src = 'http://www.samskirrow.com/client-kyra/images/main-bg.jpg';
var canvas;
var context;
function init(c) {
canvas = document.getElementById(c);
context = canvas.getContext("2d");
soundManager.onready(function() {
initSound(clientID, playlistUrl);
});
aniloop();
}
function aniloop() {
requestAnimFrame(aniloop);
drawWave();
}
function drawWave() {
var step = 10;
var scale = 60;
// clear
context.drawImage(backgroundImage, 0, 0);
// left wave
context.beginPath();
context.moveTo(0, 256);
for ( var i = 0; i < 256; i++) {
context.lineTo(6 * i, 257 + waveLeft[i] * 80.);
}
context.lineWidth = 1;
context.strokeStyle = "#000";
context.stroke();
// right wave
context.beginPath();
context.moveTo(0, 256);
for ( var i = 0; i < 256; i++) {
context.lineTo(6 * i, 256 + waveRight[i] * 80.);
}
context.lineWidth = 1;
context.strokeStyle = "#000";
context.stroke();
}
function updateWave(sound) {
waveLeft = sound.waveformData.left;
}
return {
init : init
};
})();
You can see this code in action here: http://www.samskirrow.com/client-kyra
您可以在此处查看此代码：http: //www.samskirrow.com/client-kyra
回答by Cerbrus
Use the canvas' createPatternfunction
使用画布的createPattern功能
var canvas = document.getElementById("canvas"),
context = canvas.getContext("2d"),
img = new Image();
img.src = 'https://www.google.nl/images/srpr/logo3w.png';
img.onload = function(){
// create pattern
var ptrn = context.createPattern(img, 'repeat'); // Create a pattern with this image, and set it to "repeat".
context.fillStyle = ptrn;
context.fillRect(0, 0, canvas.width, canvas.height); // context.fillRect(x, y, width, height);
}<canvas id="canvas" width="600px" height="600px"></canvas>(This is the fastestof the 2 samples).
（这是在最快的2个样品的）。
Or, try a manual implementation:
或者，尝试手动实现：
var canvas = document.getElementById("canvas"),
context = canvas.getContext("2d"),
img = new Image();
img.src = 'https://www.google.nl/images/srpr/logo3w.png';
img.onload = function(){
for (var w = 0; w < canvas.width; w += img.width) {
for (var h = 0; h < canvas.height; h += img.height) {
context.drawImage(img, w, h);
}
}
}<canvas id="canvas" width="600px" height="600px"></canvas>