Gnome3的gnome-shell自帶自動切換桌布的功能。

1. 分析其自帶的桌布切換功能,可以發現是由2個檔案控制的 不想看的，直接點上面連結看下面第2步

• /usr/share/backgrounds/gnome/adwaita-timed.xml來宣告有哪些桌布，多久執行切換

<background>
  <starttime>
    <year>2011</year>
    <month>11</month>
    <day>24</day>
    <hour
 
>7</hour>
    <minute>00</minute>
    <second>00</second>
  </starttime>

<!-- This animation will start at 7 AM. -->

<!-- We start with sunrise at 7 AM. It will remain up for 1 hour. -->
<static>
<duration>3600.0</duration>
<file>/usr/share/backgrounds/gnome/adwaita-morning.jpg</file
 
>
</static>

<!-- Sunrise starts to transition to day at 8 AM. The transition lasts for 5 hours, ending at 1 PM. -->
<transition type="overlay">
<duration>18000.0</duration>
<from>/usr/share/backgrounds/gnome/adwaita-morning.jpg</from>
<to>/usr/share/backgrounds/gnome/adwaita-day.jpg</to
 
>
</transition>

<!-- It's 1 PM, we're showing the day image in full force now, for 5 hours ending at 6 PM. -->
<static>
<duration>18000.0</duration>
<file>/usr/share/backgrounds/gnome/adwaita-day.jpg</file>
</static>

<!-- It's 7 PM and it's going to start to get darker. This will transition for 6 hours up until midnight. -->
<transition type="overlay">
<duration>21600.0</duration>
<from>/usr/share/backgrounds/gnome/adwaita-day.jpg</from>
<to>/usr/share/backgrounds/gnome/adwaita-night.jpg</to>
</transition>

<!-- It's midnight. It'll stay dark for 5 hours up until 5 AM. -->
<static>
<duration>18000.0</duration>
<file>/usr/share/backgrounds/gnome/adwaita-night.jpg</file>
</static>

<!-- It's 5 AM. We'll start transitioning to sunrise for 2 hours up until 7 AM. -->
<transition type="overlay">
<duration>7200.0</duration>
<from>/usr/share/backgrounds/gnome/adwaita-night.jpg</from>
<to>/usr/share/backgrounds/gnome/adwaita-morning.jpg</to>
</transition>
</background>   

• /usr/share/gnome-background-properties/adwaita.xml來使宣告生效

<?xml version="1.0"?>
<!DOCTYPE wallpapers SYSTEM "gnome-wp-list.dtd">
<wallpapers>
  <wallpaper deleted="false">
    <name>Default Background</name>
    <filename>/usr/share/backgrounds/gnome/adwaita-timed.xml</filename>
    <options>zoom</options>
    <shade_type>solid</shade_type>
    <pcolor>#3465a4</pcolor>
    <scolor>#000000</scolor>
  </wallpaper>
</wallpapers>

2. 系統怎麼來，我們就怎麼來

• 編寫控制檔案switchBG.xml
  可以自己輸，不過圖片多就麻煩了，還是用指令碼吧有人發現這生成的檔案跟上面其實有點不同，其實這是我以前ubuntu中的格式，Gnome3也通用的

#!/bin/bash
files=`ls -U /home/mm/圖片/桌布/`                   //改成自己路徑，下同
last_file='emputy'

echo '<background>'
echo '  <starttime>'
echo '    <year>2018</year>'
echo '    <month>02</month>'
echo '    <day>04</day>'
echo '    <hour>00</hour>'
echo '    <minute>00</minute>'
echo '    <second>00</second>'
echo '  </starttime>'

for current_file in $files
do
        if [[ $last_file == 'emputy' ]]
        then
            echo '  <static>'
            echo '    <duration>300.0</duration>'
            echo "    <file>/home/mm/圖片/桌布/$current_file</file>"
            echo '  </static>'
            last_file=$current_file
        else
            echo '  <transition>'
            echo '    <duration>5.0</duration>'
            echo "    <from>/home/mm/圖片/桌布/$last_file</from>"
            echo "    <to>/home/mm/圖片/桌布/$current_file</to>"
            echo '  </transition>'
            echo '  <static>'
            echo '    <duration>300.0</duration>'
            echo "    <file>/home/mm/圖片/桌布/$current_file</file>"
            echo '  </static>'
            last_file=$current_file
        fi
done

echo '</background>'

• 複製到目錄sudo cp switchBG.xml /usr/share/backgrounds/（其實不復制也應該可以）
• 編寫生效檔案/usr/share/gnome-background-properties/xxx.xml

?xml version="1.0"?>
<!DOCTYPE wallpapers SYSTEM "gnome-wp-list.dtd">
<wallpapers>
  <wallpaper deleted="false">
    <name>Wifes</name>
    <filename>/usr/share/backgrounds/switchBG.xml</filename>   //剛才的路徑
    <options>zoom</options>
    <shade_type>solid</shade_type>
    <pcolor>#3465a4</pcolor>
    <scolor>#000000</scolor>
  </wallpaper>
</wallpapers>

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