javascript+canvas制作九宫格小程序_javascript技巧

/*
 *canvasid:html canvas标签id
 *imageid:html img 标签id
 *gridcountX:x轴图片分割个数
 *gridcountY:y轴图片分割个数
 *gridspace:宫格空隙
 *offsetX：x*y宫格相对canvas（0，0）X坐标偏移量
 **offsetX：x*y宫格相对canvas（0，0）Y坐标偏移量
 *isanimat：是否启用动画显示
 */
function ImageGrid(canvasid, imageid, gridcountX, gridcountY, gridspace, offsetX, offsetY, isanimat) {
    var image = new Image();
    var g = document.getElementById(canvasid).getContext("2d");
    var img=document.getElementById(imageid);
    image.src=img.getAttribute("src");
    g.drawImage(image, 0, 0);
    var imagedata = g.getImageData(0, 0, image.width, image.height);
    var grid_width = imagedata.width / gridcountX;
    var grid_height = imagedata.height / gridcountY;
    //动画
    if (isanimat) {
        var x = 0,
            y = 0;
        var inter = setInterval(function() {
            g.putImageData(imagedata, gridspace * x + offsetX, gridspace * y + offsetY, grid_width * x, grid_height * y, grid_width, grid_height);
            x             if (x == 0) {
                y             }
        }, 200);
        y == gridcountY ? clearInterval(inter) : null;
    } else { //非动画
        for (var y = 0; y             for (var x = 0; x                 g.putImageData(imagedata, gridspace * x + offsetX, gridspace * y + offsetY, grid_width * x, grid_height * y, grid_width, grid_height);
            }
        }
    }
}

Canvas demo
 

//eg...
ImageGrid("canvas1", "image1", 3, 3, 2, 220, 0, true); //3*3
ImageGrid("canvas1", "image1", 4, 4, 2, 440, 0, true); //4*4
ImageGrid("canvas1", "image1", 3, 4, 2, 660, 0, false); //3*4