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Detailed explanation of HTML5 canvas tiling code

黄舟
黄舟Original
2017-04-18 09:59:112784browse

I am working on a website project recently, and I use a lot of canvas. There is a need for drawImage to draw the picture in the canvas. The picture is relatively small, so I need Tile effect as background image. PS (the height and width of the background image are 10px, and the height and width of the canvas to be drawn are 200px)

Since it was drawn from drawImage at the beginning, the method one

var canvas = document.getElementById("canvasId");
var ctx = canvas.getContext("2d");
var img = new Image();
//需要平铺的图片
img.src = "test1_bg.jpg";
img.onload = function (){
    var can = document.createElement("canvas");
    can.width = 10;
    can.height = 10;
    var ctx2 = can.getContext("2d");
    ctx2.drawImage(img,0,0,10,10,0,0,10,10);
    ctx.fillStyle = ctx.createPattern(can,"repeat");
    ctx.fillRect(0,0,200,200);
}

was used The height and width of the background image are 10, which is a bit cumbersome. Why not do it in one step? So it was changed to this way

var canvas = document.getElementById("canvasId");
var ctx = canvas.getContext("2d");
var img = new Image();
//需要平铺的图片
img.src = "test1_bg.jpg";
img.onload = function (){
    var pat = ctx.createPattern(img,"repeat");
    ctx.rect(0,0,200,200);
    ctx.fillStyle = pat;
    ctx.fill();
}

GOOD!
Let’s reiterate the definition of createPattern

The createPattern() method repeats the specified element in the specified direction.
Elements can be images, videos, or other 5ba626b379994d53f7acf72a64f9b697 elements.
Repeated elements can be used to draw/fill rectangles, circles or lines, etc.

JavaScript Syntax:

context.createPattern(image,"repeat|repeat-x|repeat-y|no-repeat");

Parameters Description

#repeatDefault. Specifies the image, canvas, or video element to use. repeat-xThe pattern repeats horizontally only. repeat-yThe pattern repeats only in the vertical direction. no-repeatThis pattern is only displayed once (not repeated).


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