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    <title>DEV Community: Boy Offi9</title>
    <description>The latest articles on DEV Community by Boy Offi9 (@boyoffi9).</description>
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      <title>DEV Community: Boy Offi9</title>
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      <title>I built a real, drop-in "Matrix rain" View for Android (not another Canvas tutorial)</title>
      <dc:creator>Boy Offi9</dc:creator>
      <pubDate>Fri, 04 Sep 2026 18:17:40 +0000</pubDate>
      <link>https://dev.to/boyoffi9/i-built-a-real-drop-in-matrix-rain-view-for-android-not-another-canvas-tutorial-25kp</link>
      <guid>https://dev.to/boyoffi9/i-built-a-real-drop-in-matrix-rain-view-for-android-not-another-canvas-tutorial-25kp</guid>
      <description>&lt;p&gt;I've built plenty of little effects and demos before, but this is the first thing I've shipped that's an actual &lt;em&gt;reusable library&lt;/em&gt; — not a gist, not a "here's how you'd do it" tutorial, not a GIF. Something you drop into a project with one line and it just works.&lt;/p&gt;

&lt;p&gt;It's called &lt;strong&gt;matrix-rain-view&lt;/strong&gt; — a configurable "digital rain" effect (the falling-glyph look from &lt;em&gt;The Matrix&lt;/em&gt;) as a real, custom Android &lt;code&gt;View&lt;/code&gt;.&lt;/p&gt;

&lt;h2&gt;
  
  
  Why not just another tutorial?
&lt;/h2&gt;

&lt;p&gt;Every Matrix-rain tutorial I found was the same: a &lt;code&gt;Canvas&lt;/code&gt;, a coroutine loop, some hardcoded green. Fine for a blog post, annoying to actually use — no lifecycle handling, no attribute API, speed tied to frame rate so it looks different on every device.&lt;/p&gt;

&lt;p&gt;So I built it properly instead:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;
&lt;strong&gt;Real lifecycle&lt;/strong&gt; — starts on attach, stops on detach. No leaks, no battery drain when it's off-screen.&lt;/li&gt;
&lt;li&gt;
&lt;strong&gt;Delta-time animation&lt;/strong&gt; — motion speed is consistent regardless of device refresh rate, instead of speeding up on 120Hz screens.&lt;/li&gt;
&lt;li&gt;
&lt;strong&gt;A real attribute API&lt;/strong&gt; — configurable via XML or code, not just a set of magic numbers buried in a &lt;code&gt;draw()&lt;/code&gt; method.&lt;/li&gt;
&lt;li&gt;
&lt;strong&gt;Custom glyph sets&lt;/strong&gt; — katakana, binary, alnum, or your own custom pool.&lt;/li&gt;
&lt;/ul&gt;

&lt;h2&gt;
  
  
  Install
&lt;/h2&gt;

&lt;p&gt;Add JitPack to &lt;code&gt;settings.gradle.kts&lt;/code&gt;:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight kotlin"&gt;&lt;code&gt;&lt;span class="nf"&gt;dependencyResolutionManagement&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="nf"&gt;repositories&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="nf"&gt;google&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
        &lt;span class="nf"&gt;mavenCentral&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
        &lt;span class="nf"&gt;maven&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="n"&gt;url&lt;/span&gt; &lt;span class="p"&gt;=&lt;/span&gt; &lt;span class="nf"&gt;uri&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s"&gt;"https://jitpack.io"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;
&lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Add the dependency:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight kotlin"&gt;&lt;code&gt;&lt;span class="nf"&gt;dependencies&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="nf"&gt;implementation&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s"&gt;"com.github.boy-offi9-inc:matrix-rain-view:1.0.1"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  Usage
&lt;/h2&gt;

&lt;p&gt;Full-screen effect:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight xml"&gt;&lt;code&gt;&lt;span class="nt"&gt;&amp;lt;com.boyoffi9.matrixrainview.MatrixRainView&lt;/span&gt;
    &lt;span class="na"&gt;android:layout_width=&lt;/span&gt;&lt;span class="s"&gt;"match_parent"&lt;/span&gt;
    &lt;span class="na"&gt;android:layout_height=&lt;/span&gt;&lt;span class="s"&gt;"match_parent"&lt;/span&gt;
    &lt;span class="na"&gt;app:rainColor=&lt;/span&gt;&lt;span class="s"&gt;"#00FF41"&lt;/span&gt;
    &lt;span class="na"&gt;app:rainSpeed=&lt;/span&gt;&lt;span class="s"&gt;"1.2"&lt;/span&gt;
    &lt;span class="na"&gt;app:rainDensity=&lt;/span&gt;&lt;span class="s"&gt;"1.0"&lt;/span&gt;
    &lt;span class="na"&gt;app:rainGlow=&lt;/span&gt;&lt;span class="s"&gt;"true"&lt;/span&gt; &lt;span class="nt"&gt;/&amp;gt;&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Or as a background behind real UI — just make sure it's the bottom child of a &lt;code&gt;FrameLayout&lt;/code&gt; (a &lt;code&gt;LinearLayout&lt;/code&gt; can't stack children):&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight xml"&gt;&lt;code&gt;&lt;span class="nt"&gt;&amp;lt;FrameLayout&lt;/span&gt;
    &lt;span class="na"&gt;android:layout_width=&lt;/span&gt;&lt;span class="s"&gt;"match_parent"&lt;/span&gt;
    &lt;span class="na"&gt;android:layout_height=&lt;/span&gt;&lt;span class="s"&gt;"match_parent"&lt;/span&gt;&lt;span class="nt"&gt;&amp;gt;&lt;/span&gt;

    &lt;span class="nt"&gt;&amp;lt;com.boyoffi9.matrixrainview.MatrixRainView&lt;/span&gt;
        &lt;span class="na"&gt;android:id=&lt;/span&gt;&lt;span class="s"&gt;"@+id/matrixRain"&lt;/span&gt;
        &lt;span class="na"&gt;android:layout_width=&lt;/span&gt;&lt;span class="s"&gt;"match_parent"&lt;/span&gt;
        &lt;span class="na"&gt;android:layout_height=&lt;/span&gt;&lt;span class="s"&gt;"match_parent"&lt;/span&gt; &lt;span class="nt"&gt;/&amp;gt;&lt;/span&gt;

    &lt;span class="nt"&gt;&amp;lt;LinearLayout&lt;/span&gt;
        &lt;span class="na"&gt;android:layout_width=&lt;/span&gt;&lt;span class="s"&gt;"match_parent"&lt;/span&gt;
        &lt;span class="na"&gt;android:layout_height=&lt;/span&gt;&lt;span class="s"&gt;"wrap_content"&lt;/span&gt;
        &lt;span class="na"&gt;android:layout_gravity=&lt;/span&gt;&lt;span class="s"&gt;"center"&lt;/span&gt;
        &lt;span class="na"&gt;android:orientation=&lt;/span&gt;&lt;span class="s"&gt;"vertical"&lt;/span&gt;&lt;span class="nt"&gt;&amp;gt;&lt;/span&gt;
        &lt;span class="c"&gt;&amp;lt;!-- your real UI --&amp;gt;&lt;/span&gt;
    &lt;span class="nt"&gt;&amp;lt;/LinearLayout&amp;gt;&lt;/span&gt;

&lt;span class="nt"&gt;&amp;lt;/FrameLayout&amp;gt;&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Everything's controllable at runtime too:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight kotlin"&gt;&lt;code&gt;&lt;span class="kd"&gt;val&lt;/span&gt; &lt;span class="py"&gt;rain&lt;/span&gt; &lt;span class="p"&gt;=&lt;/span&gt; &lt;span class="n"&gt;findViewById&lt;/span&gt;&lt;span class="p"&gt;&amp;lt;&lt;/span&gt;&lt;span class="nc"&gt;MatrixRainView&lt;/span&gt;&lt;span class="p"&gt;&amp;gt;(&lt;/span&gt;&lt;span class="nc"&gt;R&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;id&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;matrixRain&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="n"&gt;rain&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;rainColor&lt;/span&gt; &lt;span class="p"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;Color&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;parseColor&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s"&gt;"#00FFAA"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="n"&gt;rain&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;speed&lt;/span&gt; &lt;span class="p"&gt;=&lt;/span&gt; &lt;span class="mf"&gt;1.5f&lt;/span&gt;
&lt;span class="n"&gt;rain&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;density&lt;/span&gt; &lt;span class="p"&gt;=&lt;/span&gt; &lt;span class="mf"&gt;0.8f&lt;/span&gt;
&lt;span class="n"&gt;rain&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;charSet&lt;/span&gt; &lt;span class="p"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;MatrixRainView&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nc"&gt;CharSet&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nc"&gt;BINARY&lt;/span&gt;
&lt;span class="n"&gt;rain&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;glowEnabled&lt;/span&gt; &lt;span class="p"&gt;=&lt;/span&gt; &lt;span class="k"&gt;false&lt;/span&gt;

&lt;span class="n"&gt;rain&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;pause&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
&lt;span class="n"&gt;rain&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;resume&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  See it in action
&lt;/h2&gt;

&lt;p&gt;I put together a small demo app showing it running as a background behind real content, with a live settings panel wired to every property (color, speed, density, fade, glow, charset) — no restart needed, updates the running animation immediately.&lt;/p&gt;

&lt;p&gt;👉 &lt;a href="https://github.com/boy-offi9-inc/matrix-rain-demo" rel="noopener noreferrer"&gt;matrix-rain-demo&lt;/a&gt; — screenshots, a screen recording, and a CI-built debug APK from the Actions tab.&lt;/p&gt;

&lt;h2&gt;
  
  
  Try it
&lt;/h2&gt;

&lt;ul&gt;
&lt;li&gt;Library: &lt;a href="https://github.com/boy-offi9-inc/matrix-rain-view" rel="noopener noreferrer"&gt;github.com/boy-offi9-inc/matrix-rain-view&lt;/a&gt;
&lt;/li&gt;
&lt;li&gt;Demo: &lt;a href="https://github.com/boy-offi9-inc/matrix-rain-demo" rel="noopener noreferrer"&gt;github.com/boy-offi9-inc/matrix-rain-demo&lt;/a&gt;
&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;MIT licensed. If you use it or have thoughts, I'd love a star or an issue — this is my first real reusable Android lib, so feedback's very welcome.&lt;/p&gt;

</description>
      <category>android</category>
      <category>kotlin</category>
      <category>opensource</category>
      <category>androiddev</category>
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