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NetworkImageView.javaAPI DocAndroid 5.1 API8150Thu Mar 12 22:22:56 GMT 2015com.android.volley.toolbox

NetworkImageView

public class NetworkImageView extends android.widget.ImageView
Handles fetching an image from a URL as well as the life-cycle of the associated request.

Fields Summary
private String
mUrl
The URL of the network image to load
private int
mDefaultImageId
Resource ID of the image to be used as a placeholder until the network image is loaded.
private int
mErrorImageId
Resource ID of the image to be used if the network response fails.
private ImageLoader
mImageLoader
Local copy of the ImageLoader.
private com.android.volley.toolbox.ImageLoader.ImageContainer
mImageContainer
Current ImageContainer. (either in-flight or finished)
Constructors Summary
public NetworkImageView(android.content.Context context)

        this(context, null);
public NetworkImageView(android.content.Context context, android.util.AttributeSet attrs)

        this(context, attrs, 0);
public NetworkImageView(android.content.Context context, android.util.AttributeSet attrs, int defStyle)

        super(context, attrs, defStyle);
Methods Summary
protected voiddrawableStateChanged()

        super.drawableStateChanged();
        invalidate();
voidloadImageIfNecessary(boolean isInLayoutPass)
Loads the image for the view if it isn't already loaded.

param
isInLayoutPass True if this was invoked from a layout pass, false otherwise.

        int width = getWidth();
        int height = getHeight();

        boolean wrapWidth = false, wrapHeight = false;
        if (getLayoutParams() != null) {
            wrapWidth = getLayoutParams().width == LayoutParams.WRAP_CONTENT;
            wrapHeight = getLayoutParams().height == LayoutParams.WRAP_CONTENT;
        }

        // if the view's bounds aren't known yet, and this is not a wrap-content/wrap-content
        // view, hold off on loading the image.
        boolean isFullyWrapContent = wrapWidth && wrapHeight;
        if (width == 0 && height == 0 && !isFullyWrapContent) {
            return;
        }

        // if the URL to be loaded in this view is empty, cancel any old requests and clear the
        // currently loaded image.
        if (TextUtils.isEmpty(mUrl)) {
            if (mImageContainer != null) {
                mImageContainer.cancelRequest();
                mImageContainer = null;
            }
            setDefaultImageOrNull();
            return;
        }

        // if there was an old request in this view, check if it needs to be canceled.
        if (mImageContainer != null && mImageContainer.getRequestUrl() != null) {
            if (mImageContainer.getRequestUrl().equals(mUrl)) {
                // if the request is from the same URL, return.
                return;
            } else {
                // if there is a pre-existing request, cancel it if it's fetching a different URL.
                mImageContainer.cancelRequest();
                setDefaultImageOrNull();
            }
        }

        // Calculate the max image width / height to use while ignoring WRAP_CONTENT dimens.
        int maxWidth = wrapWidth ? 0 : width;
        int maxHeight = wrapHeight ? 0 : height;

        // The pre-existing content of this view didn't match the current URL. Load the new image
        // from the network.
        ImageContainer newContainer = mImageLoader.get(mUrl,
                new ImageListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        if (mErrorImageId != 0) {
                            setImageResource(mErrorImageId);
                        }
                    }

                    @Override
                    public void onResponse(final ImageContainer response, boolean isImmediate) {
                        // If this was an immediate response that was delivered inside of a layout
                        // pass do not set the image immediately as it will trigger a requestLayout
                        // inside of a layout. Instead, defer setting the image by posting back to
                        // the main thread.
                        if (isImmediate && isInLayoutPass) {
                            post(new Runnable() {
                                @Override
                                public void run() {
                                    onResponse(response, false);
                                }
                            });
                            return;
                        }

                        if (response.getBitmap() != null) {
                            setImageBitmap(response.getBitmap());
                        } else if (mDefaultImageId != 0) {
                            setImageResource(mDefaultImageId);
                        }
                    }
                }, maxWidth, maxHeight);

        // update the ImageContainer to be the new bitmap container.
        mImageContainer = newContainer;
protected voidonDetachedFromWindow()

        if (mImageContainer != null) {
            // If the view was bound to an image request, cancel it and clear
            // out the image from the view.
            mImageContainer.cancelRequest();
            setImageBitmap(null);
            // also clear out the container so we can reload the image if necessary.
            mImageContainer = null;
        }
        super.onDetachedFromWindow();
protected voidonLayout(boolean changed, int left, int top, int right, int bottom)

        super.onLayout(changed, left, top, right, bottom);
        loadImageIfNecessary(true);
private voidsetDefaultImageOrNull()

        if(mDefaultImageId != 0) {
            setImageResource(mDefaultImageId);
        }
        else {
            setImageBitmap(null);
        }
public voidsetDefaultImageResId(int defaultImage)
Sets the default image resource ID to be used for this view until the attempt to load it completes.

        mDefaultImageId = defaultImage;
public voidsetErrorImageResId(int errorImage)
Sets the error image resource ID to be used for this view in the event that the image requested fails to load.

        mErrorImageId = errorImage;
public voidsetImageUrl(java.lang.String url, ImageLoader imageLoader)
Sets URL of the image that should be loaded into this view. Note that calling this will immediately either set the cached image (if available) or the default image specified by {@link NetworkImageView#setDefaultImageResId(int)} on the view. NOTE: If applicable, {@link NetworkImageView#setDefaultImageResId(int)} and {@link NetworkImageView#setErrorImageResId(int)} should be called prior to calling this function.

param
url The URL that should be loaded into this ImageView.
param
imageLoader ImageLoader that will be used to make the request.

        mUrl = url;
        mImageLoader = imageLoader;
        // The URL has potentially changed. See if we need to load it.
        loadImageIfNecessary(false);