https://saucewu.github.io/tags/cache/Recent content in Cache on Website of SauceWuHugo -- gohugo.iozhSun, 10 May 2020 15:00:00 +0000https://saucewu.github.io/posts/drawable%E7%9A%84%E7%BC%93%E5%AD%98%E6%9C%BA%E5%88%B6/Sun, 10 May 2020 15:00:00 +0000https://saucewu.github.io/posts/drawable%E7%9A%84%E7%BC%93%E5%AD%98%E6%9C%BA%E5%88%B6/<h1 id="从-settint-引发的drawable-的缓存问题">从 setTint 引发的Drawable 的缓存问题</h1> <p>这两天在做一个新需求是突然发现 DrawableCompat.setTint()更改drawable 渲染颜色的方法居然是全局生效的。变相说明getResource().getDrawable() 每次取出drawable的时候都是从一个缓存池里面出去的。</p> <h3 id="避免缓存的解决方案">避免缓存的解决方案</h3> <p>第一反应是clone一个新的对象出来进行修改 但是貌似drawable并没有实现Cloneable的借口0那看来得想想别的办法了</p> <p>看了一会源码果然google在drawable类中已经给我们提供了一个 mutate方法 看注释看似乎这个方法可以返回一个新的drawable对象</p> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-java" data-lang="java"><span style="display:flex;"><span> <span style="color:#75715e">/** </span></span></span><span style="display:flex;"><span><span style="color:#75715e"> * Make this drawable mutable. This operation cannot be reversed. A mutable </span></span></span><span style="display:flex;"><span><span style="color:#75715e"> * drawable is guaranteed to not share its state with any other drawable. </span></span></span><span style="display:flex;"><span><span style="color:#75715e"> * This is especially useful when you need to modify properties of drawables </span></span></span><span style="display:flex;"><span><span style="color:#75715e"> * loaded from resources. By default, all drawables instances loaded from </span></span></span><span style="display:flex;"><span><span style="color:#75715e"> * the same resource share a common state; if you modify the state of one </span></span></span><span style="display:flex;"><span><span style="color:#75715e"> * instance, all the other instances will receive the same modification. </span></span></span><span style="display:flex;"><span><span style="color:#75715e"> * </span></span></span><span style="display:flex;"><span><span style="color:#75715e"> * Calling this method on a mutable Drawable will have no effect. </span></span></span><span style="display:flex;"><span><span style="color:#75715e"> * </span></span></span><span style="display:flex;"><span><span style="color:#75715e"> * @return This drawable. </span></span></span><span style="display:flex;"><span><span style="color:#75715e"> * @see ConstantState </span></span></span><span style="display:flex;"><span><span style="color:#75715e"> * @see #getConstantState() </span></span></span><span style="display:flex;"><span><span style="color:#75715e"> */</span> </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">public</span> <span style="color:#a6e22e">@NonNull</span> Drawable <span style="color:#a6e22e">mutate</span>() { </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">return</span> <span style="color:#66d9ef">this</span>; </span></span><span style="display:flex;"><span> } </span></span></code></pre></div><p>最终的实现是根据不同的drawable类型有不同的实现方式 这里就用bitmapdrawable作为例子 不仅clone了的对象 还禁止了这个对象再次被复制 猜测是为了方式无限clone导致oom</p>