Slate.java 文件源码

public void setPenColor(int color) {
            mPenColor = color;
            if (color == 0) {
                // eraser: DST_OUT
                mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
                mPaint.setColor(Color.BLACK);
            } else {
                mPaint.setXfermode(null);

                //mPaint.setColor(color); 
                mPaint.setColor(Color.BLACK); // or collor? or color & (mInkDensity << 24)?
                mPaint.setAlpha(mInkDensity);

//                mPaint.setColorFilter(new PorterDuffColorFilter(color, PorterDuff.Mode.SRC_IN));
                mPaint.setColorFilter(new PorterDuffColorFilter(color, PorterDuff.Mode.SRC_ATOP));
            }
        }