getInstance()메소드에 보면…
mAg = new AndroidGraphics2D(ctx, c, p);
이 부분이 이상하다고 하신것 같은데
이 라인은 3번째 함수인 private 생성자 메소드를 호출하므로 특별히 이상한것 같진 않네요..

public static AndroidGraphics2D getInstance() {
if (mAg == null) {
throw new RuntimeException(”AndroidGraphics2D not instantiated!”);
}
return mAg;
}

public static AndroidGraphics2D getInstance(Context ctx, Canvas c, Paint p) {
if (c == null || ctx == null) {
throw new RuntimeException(
“Illegal argument, Canvas cannot be null!”);
}
mAg = new AndroidGraphics2D(ctx, c, p);
return mAg;
}

private AndroidGraphics2D(Context ctx, Canvas c, Paint p) {
super();
mC = c;
mP = p;
mM = new Matrix();
mM.reset();
mM = mC.getMatrix();
Rect r = mC.getClipBounds();
int cl[] = {-1, r.top, r.left, -2, r.top, r.right, -2, r.bottom, r.right, -2, r.bottom, r.left};
mCurrClip = new Area(createShape(cl));
if(ctx != null) {
WindowManager wm = (WindowManager)ctx.getSystemService(Context.WINDOW_SERVICE);
Display d = wm.getDefaultDisplay();
displayWidth = d.getWidth();
displayHeight = d.getHeight();
}
blitter = new AndroidJavaBlitter(c);
cm = new DirectColorModel(32, 0xff0000, 0xff00, 0xff, 0xff000000);
sm = new SinglePixelPackedSampleModel(
DataBuffer.TYPE_INT, displayWidth, displayHeight, cm.getMasks());
wr = Raster.createWritableRaster(sm, null);
dstSurf = new ImageSurface(cm, wr);
}