HTML5 Device Access (設備訪問)

camera api (含圖片預覽)

參考地址

• 主要爲利用input type=file, accept="image/*" 進行處理
• 圖片預覽方式（兩種）

const file = e.target.files[0]
// 方式1 
const url1 = window.URL.createObjectURL(file);
let url2

// 方式2
const reader = new FileReader();
reader.onload = (e) => {
    url2 = e.target.result;
};
reader.readAsDataURL(file);

touch events (觸屏事件)

參考地址

• touchstart
• touchend
• touchcancel 電話的接入或者彈出信息等比較高級的事件觸發，通常作保存操做
• touchmove

geolocation

參考地址

• 注意谷歌瀏覽器要https才能提供定位服務

if (navigator.geolocation){
        navigator.geolocation.getCurrentPosition((position) => {
            this.geolocation = `latitude:${position.coords.latitude},longitude:${position.coords.longitude}`
        }, (err) => {
            console.log(err);
        }, {
                enableHighAccuracy: true, 
                maximumAge        : 30000,  // buffer memory timre
                timeout           : 27000   // waiting time 
        })
    } else {
        alert('geolocation not supported!')
    }

device orientation and motion

參考地址

window.addEventListener('deviceorientation',(doe) => {
        this.absolute = doe.absolute //false 表示方向數據由設備自己座標系提供
        this.alpha = doe.alpha // 繞Z軸0-360 進入時手機水平正對的方向爲0或360
        this.beta = doe.beta // 繞X軸-180~180 描述由前向後旋轉
        this.gamma = doe.gamma // 繞Y軸-90~90 描述由左向右旋轉
    }, true)

    // chrome v65 只支持accelerationIncludingGravity和interval（應該由於一些限制沒有找到），其它瀏覽器最新版基本都支持
    window.addEventListener('devicemotion', (dme) => {
        this.acceleration = dme.acceleration
        this.accelerationIncludingGravity = dme.accelerationIncludingGravity
        this.rotationRate = dme.rotationRate
        this.interval  = dme.interval 
    }, false)

Pointer Lock(鼠標鎖定)

參考地址

<button onclick="lockPointer();">鎖住它!</button>
    <div id="pointer-lock-element" style="width:500px;height:500px;background-color: red"></div>

// 簡單示例，將鼠標鎖定在 pointer-lock-element 元素內
    let = document.getElementById("pointer-lock-element");
    
    document.addEventListener("mousemove", function(e) {
        var movementX = e.movementX 
            movementY = e.movementY

        // 打印鼠標移動的增量值。
        console.log("X=" + movementX, "Y=" + movementY);
    }, false);

    function lockPointer() {
        elem = document.getElementById("pointer-lock-element");
        elem.requestPointerLock = elem.requestPointerLock    ||
                            elem.mozRequestPointerLock ||
                            elem.webkitRequestPointerLock;
        elem.requestPointerLock();
    }