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/*
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* Copyright (C) 2013 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.android.displayingbitmaps.ui;
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import android.content.Context;
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import android.graphics.drawable.Drawable;
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import android.graphics.drawable.LayerDrawable;
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import android.util.AttributeSet;
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import android.widget.ImageView;
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import com.example.android.displayingbitmaps.util.RecyclingBitmapDrawable;
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/**
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* Sub-class of ImageView which automatically notifies the drawable when it is
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* being displayed.
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*/
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public class RecyclingImageView extends ImageView {
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public RecyclingImageView(Context context) {
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super(context);
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}
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public RecyclingImageView(Context context, AttributeSet attrs) {
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super(context, attrs);
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}
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/**
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* @see android.widget.ImageView#onDetachedFromWindow()
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*/
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@Override
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protected void onDetachedFromWindow() {
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// This has been detached from Window, so clear the drawable
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setImageDrawable(null);
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super.onDetachedFromWindow();
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}
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/**
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* @see android.widget.ImageView#setImageDrawable(android.graphics.drawable.Drawable)
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*/
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@Override
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public void setImageDrawable(Drawable drawable) {
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// Keep hold of previous Drawable
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final Drawable previousDrawable = getDrawable();
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// Call super to set new Drawable
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super.setImageDrawable(drawable);
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// Notify new Drawable that it is being displayed
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notifyDrawable(drawable, true);
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// Notify old Drawable so it is no longer being displayed
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notifyDrawable(previousDrawable, false);
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}
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/**
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* Notifies the drawable that it's displayed state has changed.
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*
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* @param drawable
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* @param isDisplayed
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*/
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private static void notifyDrawable(Drawable drawable, final boolean isDisplayed) {
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if (drawable instanceof RecyclingBitmapDrawable) {
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// The drawable is a CountingBitmapDrawable, so notify it
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((RecyclingBitmapDrawable) drawable).setIsDisplayed(isDisplayed);
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} else if (drawable instanceof LayerDrawable) {
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// The drawable is a LayerDrawable, so recurse on each layer
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LayerDrawable layerDrawable = (LayerDrawable) drawable;
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for (int i = 0, z = layerDrawable.getNumberOfLayers(); i < z; i++) {
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notifyDrawable(layerDrawable.getDrawable(i), isDisplayed);
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}
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}
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}
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}