Java tutorial
/* * Copyright 2015 Google Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package me.sweetll.tucao.widget; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.drawable.Drawable; import android.os.Build; import android.support.v4.view.ViewCompat; import android.util.AttributeSet; import android.view.ViewOutlineProvider; import android.widget.RelativeLayout; import me.sweetll.tucao.R; /** * An extension to {@link RelativeLayout} which has a foreground drawable. */ public class ForegroundRelativeLayout extends RelativeLayout { private Drawable foreground; public ForegroundRelativeLayout(Context context, AttributeSet attrs) { super(context, attrs); TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ForegroundView); final Drawable d = a.getDrawable(R.styleable.ForegroundView_android_foreground); if (d != null) { setForeground(d); } a.recycle(); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { setOutlineProvider(ViewOutlineProvider.BOUNDS); } } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); if (foreground != null) { foreground.setBounds(0, 0, w, h); } } @Override public boolean hasOverlappingRendering() { return false; } @Override protected boolean verifyDrawable(Drawable who) { return super.verifyDrawable(who) || (who == foreground); } @Override public void jumpDrawablesToCurrentState() { super.jumpDrawablesToCurrentState(); if (foreground != null) foreground.jumpToCurrentState(); } @Override protected void drawableStateChanged() { super.drawableStateChanged(); if (foreground != null && foreground.isStateful()) { foreground.setState(getDrawableState()); } } /** * Returns the drawable used as the foreground of this view. 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; } /** * Supply a Drawable that is to be rendered on top of all of the child * views within this layout. Any padding in the Drawable will be taken * into account by ensuring that the children are inset to be placed * inside of the padding area. * * @param drawable The Drawable to be drawn on top of the children. */ public void setForeground(Drawable drawable) { if (foreground != drawable) { if (foreground != null) { foreground.setCallback(null); unscheduleDrawable(foreground); } foreground = drawable; if (foreground != null) { foreground.setBounds(getLeft(), getTop(), getRight(), getBottom()); setWillNotDraw(false); foreground.setCallback(this); if (foreground.isStateful()) { foreground.setState(getDrawableState()); } } else { setWillNotDraw(true); } invalidate(); } } @Override public void draw(Canvas canvas) { super.draw(canvas); if (foreground != null) { foreground.draw(canvas); } } @Override public void drawableHotspotChanged(float x, float y) { super.drawableHotspotChanged(x, y); if (foreground != null) { foreground.setHotspot(x, y); } } }