android.graphics.Canvas中使用的算法 [英] Algorithms used in android.graphics.Canvas

问题描述

我正在尝试找出什么绘制算法 android.graphics.Canvas 正在使用，尤其是drawLine和drawCircle.我设法找到了 Canvas_Delegate. Java ，但我无法理解每种情况下使用哪种算法.

I am trying to find out what drawing algorithms android.graphics.Canvas is using, and especialy for drawLine and drawCircle. I have managed to find Canvas_Delegate.java, but I cannot understand which algorithm is used in each occasion.

有什么主意吗?

推荐答案

总结评论:

• 绘图功能至少有两种实现，一种纯粹是在软件中实现( Skia库)，并且在 Skia实现是用C ++而不是Java编写的.由于必须考虑Paint功能(例如笔划宽度)，因此代码可能不会像

  The Skia implementation is written in C++, not Java. Because it has to take into account Paint features like stroke width, the code may not appear as straightforward as the classic implementation you found.

  使用C ++编写的给定算法的实现通常比使用Java编程语言编写的算法要快得多.这是一个宗教问题，定期发布各种基准以消除"Java缓慢"的概念.我认为C ++更具表现力，可以让您更准确地告诉编译器您想要执行的操作，尤其是在Android上，NDK C ++编译器明显优于Dalvik或Art编译器.

  The implementation of a given algorithm is often much faster when written in C++ than it is when written in the Java programming language. This is something of a religious issue, with various benchmarks periodically thrown around to dispel the "Java is slow" notion. I think C++ is a bit more expressive, allowing you to tell the compiler more exactly what you want it to do, and on Android in particular the NDK C++ compiler is significantly better than the Dalvik or Art compilers.

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