Android学习札记18：Drawable中的setDither()方法-优快云博客

本文介绍了Android中Drawable类及其子类BitmapDrawable的dither属性的作用，该属性决定在颜色位数较低的设备上绘制时是否使用抖动算法。抖动算法可以改善颜色显示效果，但可能会降低绘制速度。

4.0.4 r1.2中android.graphics.drawable.Drawable源代码

Set to true to have the drawable dither its colors when drawn to a device with fewer than 8-bits per 
color component. This can improve the look on those devices, but can also slow down the drawing a 
little.

public void setDither(boolean dither) {}

4.0.4 r1.2中android.graphics.drawable.BitmapDrawable源代码

@Override
public void setDither(boolean dither) {
	mBitmapState.mPaint.setDither(dither);
	invalidateSelf();
}

4.0.4 r1.2中android.graphics.Paint源代码

Helper for setFlags(), setting or clearing the DITHER_FLAG bit Dithering affects how colors that are 
higher precision than the device are down-sampled. No dithering is generally faster, but higher 
precision colors are just truncated down (e.g. 8888 -> 565). Dithering tries to distribute the error 
inherent in this process, to reduce the visual artifacts.

Parameters:
dither true to set the dithering bit in flags, false to clear it

public native void setDither(boolean dither);

最后调用本地类库进行处理。