在android下移植了png库，实现在ndk层将一个BMP位图转换为PNG位图。java层代码仅做示例，ndk代码可以直接使用-Ported the android png library, a BMP bitmap in ndk layer will be converted to PNG bitmap. layer java code only as example, the the ndk code can be used directly

Java编写的Android简易计算器 文件 .settings assets bin gen libs res src .classpath .project AndroidManifest.xml ic_launcher-web.png proguard-project.txt project.properties-JAVA-Android simple calculating machine File： .settings