Retina Monitor’s Web Image Solution
什麼是Retina螢幕
今天來談談網頁圖片在視網膜（Retina）螢幕的顯示議題，首先必須來談談什麼是視網膜螢幕，其實他就是一種能在單位尺寸內顯示更多像素點的螢幕，且已經達到視網膜能辨識的極限，視網膜螢幕是由蘋果公司提出，賈伯斯在2010年iPhone 4的發表會中提到：「當你所拿的東西距離你10-12英寸（約25-30厘米）時，它的解析度只要達到300ppi這個『神奇數字』（每英寸300個像素點）以上，你的視網膜就無法分辨出像素點了。」
所以簡言之，視網膜螢幕比較一般非視網膜螢幕的不同處在於，能在同樣的範圍顯示更多的像素點，也就是PPI（Pixels Per Inch）比較高的螢幕，可參考下圖所示：
可以看到圖左在單位尺寸內顯示的像素點較少，圖右則能以更多的像素去呈現，在肉眼上就會覺得圖右會比較細緻。
接下來談談網頁圖片與視網膜螢幕之間的關係，先來看看同樣一張圖片在不同螢幕上顯示的效果。
當然在美觀的立場下，我們不會希望發生這樣的視覺差異，那網頁上要如何設置才可以做到讓圖形在視網膜螢幕下也能正常的顯示呢？以下提出一些解決方案：
方案1. 透過CSS針對不同的DPR (Device Pixel Ratio)設計顯示圖片
大家如果想知道自己螢幕的DPR，可以在Chrome的主控台輸入“window.devicePixelRatio”，就可以得知目前Chrome所在螢幕的DPR值。
可以觀察出來在兩個螢幕的DRP值是不同的，而透過CSS的樣式，可以針對這兩個不同的DPR設定顯示方式，可以參考下面的做法：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
.logo{
width: 190px;
height: 190px;
background-image: url("atd-icon.jpg");
background-size: contain;
}
@media (-webkit-min-device-pixel-ratio: 2){
.logo{
background-image: url("atd-icon@2x.jpg");
}
}
</style>
</head>
<body>
<div class="logo"></div>
</body>
</html>
<script>
</script>
這邊必須針對圖檔尺寸做個說明，其中atd-icon.jpg為190 x 190，而atd-icon@2x.jpg為380 x 380。
@media (-webkit-min-device-pixel-ratio: 2)的部分是在DPR兩倍下的Media Query。
透過這樣的方式去設定，當DPR為2的時候，螢幕上的圖片改變為atd-icon_2.jpg，剛好能夠滿足在兩倍像素狀況下的顯示需求，當然以此類推，也能去設定三倍或更高倍數下的顯示圖片。
方案二. 透過img標籤的srcset屬性
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<img src="atdIcon.jpg" srcset="atd-icon@2x.jpg x2">
</body>
</html>
<script>
</script>
其中srcset=”atd-icon@2x.jpg 2x”表示在DPR等於2的時候要去呈現的圖片。
以上兩個方法都可以解決圖片在Retina螢幕上面顯示的問題，但也要稍微注意一下支援程度：
可以看到在IE都是無法支援的狀態，但從Edge後就開始支援，當然也可以想想目前擁有Retina螢幕的使用者，用的瀏覽器都會是哪些？說不定你不會太在乎上面那兩張圖紅色的部分。
但若是一定要有IE瀏覽器的支援，大家應該也能從上述的文章了解，我們可以透過window.devicePixelRatio的數值自行寫script進行判斷，然後再給出適合DPR的圖片，不過這邊另外推薦一個JS Library可以協助你進行這方面的判斷。
方案三. 透過Retina.js輔助進行判斷
首先到Retina.js的網站下載他們所提供的js檔，接下來至網頁引入該JS，其實網站上也有詳細的使用方法，另外檔案大小僅有約4KB並不算很大，可以參考下面的Sample Code。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<script src="retina.min.js"></script>
</head>
<body>
<img src="atd-icon.jpg" />
</body>
</html>
可以看到在img標籤中僅使用了原始大小的atd-icon.jpg，但因為有引入retina.min.js，他會在螢幕DPR兩倍時，自動去搜尋符合倍率下的圖片，但要記得如果不加其他屬性去設定兩倍圖片的檔名，檔名就必須按照內建的規則，也就是atd-icon@2x.jpg，當然3x也依然支援，可以到官網看一下他的使用方式，但若是使用CSS設定的背景，依然沒辦法透過retina.js達到支援IE的效果。
以上三個方法提供目前在設計網頁時，對於Retina螢幕支援的做法，若在不考慮IE瀏覽器的情況下，其實方法1+方法2就已經可以解決所有情況，但若要支援IE則可以參考方法三的做法，也歡迎大家有問題可以留言進行討論。
方案四. 使用SVG圖檔
過往我們在網頁中使用的圖片僅有GIF、PNG、JPG這三種點陣圖格式，所以在高解析度（Retina）的螢幕中，我們需要輸入不同Size的圖片，來補足像素點不足的問題，現在有了另外一種解法“SVG”圖檔。
大家可以把SVG視為一種可以放在網頁上的向量圖檔，也就是說我們以前透過Illustrator或其他向量繪圖軟體（也包含Photoshop中向量工具）繪製出來的向量圖，本身放大就不會失真，但因為要放在網頁上，我們把它轉換成了前述的三種點陣格式，才導致圖檔放大後的失真，而SVG就是保留圖片原來的向量屬性，簡言之，就是把向量圖檔放在網頁上的意思。
感覺這個解決方案應該會比前幾項方便，但也有他必須要注意的地方：
- 在SVG檔案中匯入的點陣圖，在儲存成SVG時並不會被向量化，例如上圖中間的ASUS Design Logo就是匯入的點陣圖（放大後還是會模糊）。
- SVG字型可能會遺失，所以需要使用網路字型或是將文字轉成外框或形狀之後再轉存成SVG。
Melbet welcomes new players to a variety of bonuses. Melbet for today are bonus opportunities that the bookmaker itself gives. Today, many bookmakers offer such bonuses both for first-time registered users and for those who have been betting on sports for a long time. MelBet Promo Code Free – welcome bonus worth 130% up to €/$130. Welcome bonuses, free spins and freebets are equally available to all users, regardless of which gadget they use for the registration procedure or betting. Melbet often offers many exciting bonuses and offers that will make your time on the site more exciting and rewarding.
promo code for Melbet
Melbet is among the top operators offering a variety of sporting events and eSports. Claim top bonuses using our exclusive MelBet Promo Code and Welcome Bonuses, this is the best chance to join one of the most popular betting platforms and start winning with free bets and bonus money. Welcome bonuses and special promo codes will be perfect starters to help you enjoy our betting site with bonus money and free bets. Read the article to learn how to use one of the best betting bonus offers in India.
best Melbet promo codes
Melbet is among the top operators offering a variety of sporting events and eSports. Claim top bonuses using our exclusive MelBet Promo Code and Welcome Bonuses, this is the best chance to join one of the most popular betting platforms and start winning with free bets and bonus money. Welcome bonuses and special promo codes will be perfect starters to help you enjoy our betting site with bonus money and free bets. Read the article to learn how to use one of the best betting bonus offers in India.
Melbet promo code
http://7100.adminka.cc/
The Melbet bookmaker provides bonuses and promo codes, every bettor can receive bonuses. Get 130% off the current promo code for Melbet for free. New registration coupons every hour on the website. Melbet Promo Code 130 $ Fun layout for Android or iPhone applications. Since the promo code must be used upon sign-up, it can be claimed by new players registering with Melbet. Regarding the promotion, other offers from this bookmaker, it is proposed to users in adults. Registering with Melbet is easy to do in Nigeria with a Melbet promo code Nigeria players can use.
Melbet promo code 2023
Indian players are welcomed to join and bet on their favorite esports. To make things even more exciting. Melbet Promo Code India and learn about totaling up to 13.000 INR for sports betting and staggering € 1950 of free money for casino. Melbet WELCOME BONUS copy and enter the promo code upon registration. Yes, the Melbet bonus code is optimized for use on any device, including mobile phones. Melbet working promo code for today. When you first register, you get Melbet sign up promo code. Also known as voucher, bonus code, and discount, it allows you to receive exclusive bonuses or expand existing ones.
promo code for Melbet
Indian players are welcomed to join and bet on their favorite esports. To make things even more exciting. Melbet Promo Code India and learn about totaling up to 13.000 INR for sports betting and staggering € 1950 of free money for casino. Melbet WELCOME BONUS copy and enter the promo code upon registration. Yes, the Melbet bonus code is optimized for use on any device, including mobile phones. Melbet working promo code for today. When you first register, you get Melbet sign up promo code. Also known as voucher, bonus code, and discount, it allows you to receive exclusive bonuses or expand existing ones.
Melbet promo code Bahamas
How do I get Melbet promo code? You have to follow 3 easy steps to claim your bonus: Click on the action button (COPY). Melbet Promo Code India 2023 WELCOME BONUS copy and enter the promo code upon registration. We have an exclusive Melbet promo code for all new customers who love betting on sport events. Players in India can use this code when opening your account to get a bonus of up to ?10,400 or $/€130. It offers a promo code usually for its specific offers. For the welcome bonus, there is no Melbet promo code for Indian users.
Melbet promo code Palau
The bookmaker also takes bets on tv exhibits like Psychic Challenge, What? Pay a visit to the brand’s website to look into Melbet minimum deposit India. Melbet pays also a special attention to India residents and offers an exceptional welcome bonus of 9750 Indian rupees. Melbet Promo Code India Copy the About coupon code to get the first deposit bonus. Melbet is a popular betting site among Indians when it comes to making bets on Cricket or other sports, and they offer 100% bonus up to ?10400 for every India. Players can also enjoy the website in many other countries like Ghan
Melbet promo code
http://8217.adminka.cc/
Melbet allows its customers to receive exclusive bonuses if they enter melbet promo code upon registration. In this article, we will look at what a code is, how to use it, and what additional bonuses it gives. Now you have access to all machines, to all bonus programs and promotions. You can play directly from the site, or you can download a client program for yourself. Bonus points Melbet can be obtained by participating in loyalty programs. With its help, the bookmaker MelBet encourages customers who have been betting on the company’s website for a long time.
Melbet promo code Lesotho
The Melbet bookmaker provides bonuses and promo codes, every bettor can receive bonuses. Get 130% off the current promo code for Melbet for free. New registration coupons every hour on the website. Melbet Promo Code 130 $ Fun layout for Android or iPhone applications. Since the promo code must be used upon sign-up, it can be claimed by new players registering with Melbet. Regarding the promotion, other offers from this bookmaker, it is proposed to users in adults. Registering with Melbet is easy to do in Nigeria with a Melbet promo code Nigeria players can use.
Melbet promo code Madagascar
http://6847.adminka.cc/
The Melbet bookmaker provides bonuses and promo codes, every bettor can receive bonuses. Get 130% off the current promo code for Melbet for free. New registration coupons every hour on the website. Melbet Promo Code 130 $ Fun layout for Android or iPhone applications. Since the promo code must be used upon sign-up, it can be claimed by new players registering with Melbet. Regarding the promotion, other offers from this bookmaker, it is proposed to users in adults. Registering with Melbet is easy to do in Nigeria with a Melbet promo code Nigeria players can use.
Melbet promo code Gambia
https://pornobed.com/
http://3440.adminka.cc/
Many users, after reading the bookmaker’s bonus offers, want to know how to get melbet promo code. Melbet allows its customers to receive exclusive bonuses if they enter a promo code upon registration. In this article, we will look at what a Melbet Promo Code India is, how to use it, and what additional bonuses it gives. There is an opportunity to get the melbet bonus code from the site partners, on thematic forums. Also, melbet bonus is distributed by the casino administration during special events. The opportunity to make good money on such promotions is often mentioned in reviews of Melbet online casinos.
Melbet promo codes
https://pornoale.com/
https://datingtopreview.com/# free chat and dating online
http://4230.adminka.cc/
https://pornoait.com/
prices of cialis cialis professional cialis generic online
http://www.poxren.com/
https://www.pornoarka.com/
https://datingtopreview.com/# best dating websites
https://pornoshoy.com/
https://pornocell.com/
https://www.pornoazot.com/
beste dating site free dating sight