ScrimInsetsFrameLayout.java

package moe.feng.bilinyan.view.internal;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.annotation.NonNull;
import android.support.v4.view.ViewCompat;
import android.support.v4.view.WindowInsetsCompat;
import android.util.AttributeSet;
import android.view.View;
import android.widget.FrameLayout;

import moe.feng.bilinyan.R;

public class ScrimInsetsFrameLayout extends FrameLayout {

	private Drawable mInsetForeground;
	private Rect mInsets;
	private Rect mTempRect;

	public ScrimInsetsFrameLayout(Context context) {
		this(context, null);
	}

	public ScrimInsetsFrameLayout(Context context, AttributeSet attrs) {
		this(context, attrs, 0);
	}

	public ScrimInsetsFrameLayout(Context context, AttributeSet attrs, int defStyleAttr) {
		super(context, attrs, defStyleAttr);
		this.mTempRect = new Rect();
		TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ScrimInsetsFrameLayout, defStyleAttr, R.style.Widget_Design_ScrimInsetsFrameLayout);
		this.mInsetForeground = a.getDrawable(R.styleable.ScrimInsetsFrameLayout_insetForeground);
		a.recycle();
		this.setWillNotDraw(true);
		ViewCompat.setOnApplyWindowInsetsListener(this, new android.support.v4.view.OnApplyWindowInsetsListener() {
			public WindowInsetsCompat onApplyWindowInsets(View v, WindowInsetsCompat insets) {
				if (null == ScrimInsetsFrameLayout.this.mInsets) {
					ScrimInsetsFrameLayout.this.mInsets = new Rect();
				}

				ScrimInsetsFrameLayout.this.mInsets.set(insets.getSystemWindowInsetLeft(), insets.getSystemWindowInsetTop(), insets.getSystemWindowInsetRight(), insets.getSystemWindowInsetBottom());
				ScrimInsetsFrameLayout.this.setWillNotDraw(ScrimInsetsFrameLayout.this.mInsets.isEmpty() || ScrimInsetsFrameLayout.this.mInsetForeground == null);
				ViewCompat.postInvalidateOnAnimation(ScrimInsetsFrameLayout.this);
				return insets.consumeSystemWindowInsets();
			}
		});
	}

	public void draw(@NonNull Canvas canvas) {
		super.draw(canvas);
		int width = this.getWidth();
		int height = this.getHeight();
		if (this.mInsets != null && this.mInsetForeground != null) {
			int sc = canvas.save();
			canvas.translate((float)this.getScrollX(), (float)this.getScrollY());
			this.mTempRect.set(0, 0, width, this.mInsets.top);
			this.mInsetForeground.setBounds(this.mTempRect);
			this.mInsetForeground.draw(canvas);
			this.mTempRect.set(0, height - this.mInsets.bottom, width, height);
			this.mInsetForeground.setBounds(this.mTempRect);
			this.mInsetForeground.draw(canvas);
			this.mTempRect.set(0, this.mInsets.top, this.mInsets.left, height - this.mInsets.bottom);
			this.mInsetForeground.setBounds(this.mTempRect);
			this.mInsetForeground.draw(canvas);
			this.mTempRect.set(width - this.mInsets.right, this.mInsets.top, width, height - this.mInsets.bottom);
			this.mInsetForeground.setBounds(this.mTempRect);
			this.mInsetForeground.draw(canvas);
			canvas.restoreToCount(sc);
		}

	}

	protected void onAttachedToWindow() {
		super.onAttachedToWindow();
		if (this.mInsetForeground != null) {
			this.mInsetForeground.setCallback(this);
		}

	}

	protected void onDetachedFromWindow() {
		super.onDetachedFromWindow();
		if (this.mInsetForeground != null) {
			this.mInsetForeground.setCallback(null);
		}
	}
}