关于foreground与background的区别

这时候我们给FrameLayout加上android:background=”@color/colorPrimary”效果如下

我们再给FrameLayout加上android:foreground=”@color/colorAccent”效果变成这样：

} foreground = drawable; if (drawable != null) { setWillNotDraw(false); lback(this); if (eful()) { te(getDrawableState()); } } else { setWillNotDraw(true); } requestLayout(); invalidate(); } } /** * Returns the drawable used as the foreground of this layout. The foreground drawable, * if non-null, is always drawn on top of the children. * * @return A Drawable or null if no foreground was set. */ public Drawable getForeground() { return foreground; } @Override protected void drawableStateChanged() { leStateChanged(); if (foreground != null && eful()) { te(getDrawableState()); } } @Override protected boolean verifyDrawable(Drawable who) { return Drawable(who) || (who == foreground); } @Override public void jumpDrawablesToCurrentState() { awablesToCurrentState(); if (foreground != null) { CurrentState(); } } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { Changed(w, h, oldw, oldh); foregroundBoundsChanged = true; } @Override public void draw(Canvas canvas) { (canvas); if (foreground != null) { final Drawable foreground = ound; if (foregroundBoundsChanged) { foregroundBoundsChanged = false;

final int w = getRight() - getLeft(); final int h = getBottom() - getTop(); if (foregroundPadding) { nds(, , w - , h - ); } else { nds(0, 0, w, h); } } (canvas); } } @TargetApi(N_OP) @Override public boolean onTouchEvent(MotionEvent e) { if (_INT >= N_OP) { if (ionMasked() == _DOWN) { if (foreground != null) { spot((), ()); } } } return hEvent(e); }}