Viewports

Each Enabled Element has a Viewport which describes how the Image should be rendered.

Viewport描述了一个图像在canvas上的如何渲染的状态值，比如旋转，移动等参数。对于enabled element，可以通过 getViewport() 获取viewport信息， setViewport()接口设置viewport.

我们来看一个viewport参数的🌰

{
    "scale": 2, // 缩放
    "translation": { // 位移
        "x": 0,
        "y": 0
    },
    "voi": { // 窗宽窗位
        "windowWidth": 256,
        "windowCenter": 127
    },
    "pixelReplication": false,
    "rotation": 0, // 旋转
    "hflip": false, // 左右翻转
    "vflip": false, // 上下翻转
    "labelmap": false, // 标签
    "displayedArea": { //展示区域
        "tlhc": {
            "x": 1,
            "y": 1
        },
        "brhc": {
            "x": 256,
            "y": 256
        },
        "rowPixelSpacing": 0.8984375, // 像素行间距
        "columnPixelSpacing": 0.8984375, // 像素列间距
        "presentationSizeMode": "NONE"
    }
}