Beware when implementing com.google.gwt.resources interfaces (whose
implementations are expected to be generated) that they might change and
break your code. GWT 2.6 will introduce a new isStandalone() method for
instance.
Also, BTW, you should probably use UriUtils.unsafeCastFromUntrustedString;
it works exactly the same as fromSafeConstants, it's just a matter of
"semantics": one says it's "safe" when the other clearly states that it's
"unsafe but necessary".
On Wednesday, August 21, 2013 7:45:04 PM UTC+2, Steve C wrote:
>
> I haven't sorted out in my mind the best approach for a few of the
> details, in particular making it reusable, but this works. Consider it
> more of a "proof of concept".
>
> You'd need to create red.png in the war directory, or could try out a data
> url (which per my tests works with this).
>
> For a bundle with more images, the asynchronicity gets to be a bigger
> issue, since you'd need to have something like a "master" callback once all
> of the individual image callbacks have completed. Also, there's no
> facility for sprites, although I think it could be implemented.
>
>
> public class DynamicResourcesDemo implements EntryPoint {
>
> private DynamicMenuBarResources resources;
> private MenuBar bar;
>
> public void onModuleLoad() {
>
> MenuBar.Resources defaultResources =
> GWT.create(MenuBar.Resources.class);
> MyImageResource imgres = new
> MyImageResource(defaultResources.menuBarSubMenuIcon());
> resources = new DynamicMenuBarResources(imgres);
>
> imgres.load("red.png", new Callback<Void, Throwable>() {
> @Override
> public void onSuccess(Void result) {
> showUi();
> }
>
> @Override
> public void onFailure(Throwable reason) {
> Window.alert("Error");
> }
> });
> }
>
> private void showUi() {
> MenuBar fileMenu = new MenuBar(true);
> fileMenu.addItem("Open", new Scheduler.ScheduledCommand() {
> @Override
> public void execute() {
> Window.alert("Open File");
> }
> });
> fileMenu.addItem("Exit", new Scheduler.ScheduledCommand() {
> @Override
> public void execute() {
> Window.alert("So long!");
> }
> });
> MenuBar actionsMenu = new MenuBar(true, resources);
> actionsMenu.addItem("File", fileMenu);
> bar = new MenuBar();
> bar.addItem("Actions", actionsMenu);
>
> RootPanel.get().add(bar);
> }
> }
>
> //-------------------------------------------------------------
>
> public class DynamicMenuBarResources implements Resources {
>
> private static Resources base = GWT.create(Resources.class);
> private ImageResource menuBarSubmenuIconResource;
>
> public DynamicMenuBarResources() {
> }
>
> public DynamicMenuBarResources(ImageResource
> menuBarSubmenuIconResource) {
> this.menuBarSubmenuIconResource = menuBarSubmenuIconResource;
> }
>
> @Override
> @ImageOptions(flipRtl = true)
> public ImageResource menuBarSubMenuIcon() {
> if (menuBarSubmenuIconResource != null) {
> return menuBarSubmenuIconResource;
> } else {
> return base.menuBarSubMenuIcon();
> }
> }
>
> }
>
> //----------------------------------------------------
>
> public class MyImageResource implements ImageResource {
>
> private Image image;
> private ImageResource defaultResource;
> private boolean imageValid = false;
>
> public MyImageResource(ImageResource defaultResource) {
> image = new Image();
> this.defaultResource = defaultResource;
> }
>
> public void load(String url, final Callback<Void, Throwable> callback)
> {
> image.setUrl(url);
> final Panel pnl = new SimplePanel();
> pnl.add(image);
> Style pnlStyle = pnl.getElement().getStyle();
> pnlStyle.setVisibility(Visibility.HIDDEN);
> pnlStyle.setPosition(Position.ABSOLUTE);
> image.addLoadHandler(new LoadHandler() {
> @Override
> public void onLoad(LoadEvent event) {
> RootPanel.get().remove(pnl);
> imageValid = true;
> if (callback != null) callback.onSuccess(null);
> }
> });
> image.addErrorHandler(new ErrorHandler() {
> @Override
> public void onError(ErrorEvent event) {
> RootPanel.get().remove(pnl);
> // this lets the resource fall back to the default
> if (callback != null) callback.onSuccess(null);
> // this would instead invoke the error handling for the
> callback
> //if (callback != null) callback.onFailure(new
> Exception("Image Resource Load Error"));
> }
> });
> RootPanel.get().add(pnl);
> }
>
> @Override
> public String getName() {
> return imageValid ? "" : defaultResource.getName(); // ???
> }
>
> @Override
> public int getHeight() {
> return imageValid ? image.getHeight() :
> defaultResource.getHeight();
> }
>
> @Override
> public int getLeft() {
> return imageValid ? 0 : defaultResource.getLeft();
> }
>
> @Override
> public SafeUri getSafeUri() {
> return imageValid ? UriUtils.fromSafeConstant(image.getUrl()) :
> defaultResource.getSafeUri();
> }
>
> @Override
> public int getTop() {
> return imageValid ? 0 : defaultResource.getTop();
> }
>
> @Override
> @Deprecated
> public String getURL() {
> return imageValid ? image.getUrl() : defaultResource.getURL();
> }
>
> @Override
> public int getWidth() {
> return imageValid ? image.getWidth() : defaultResource.getWidth();
> }
>
> @Override
> public boolean isAnimated() {
> return imageValid ? false : defaultResource.isAnimated(); // ???
> }
>
> }
>
>
> On Saturday, August 17, 2013 12:30:11 PM UTC-4, df wrote:
>>
>> Could you give some code?
>> Thanks
>>
>> W dniu czwartek, 15 sierpnia 2013 01:05:30 UTC+2 użytkownik Steve C
>> napisał:
>>>
>>> Thanks for asking that question - it led me to a solution to a problem
>>> that I've had, which is "skinning" an app using different versions of
>>> resources loaded asynchronously from the war directory as opposed to coded
>>> into a ClientBundle.
>>>
>>> I created a client bundle extending SimplePager.Resources, with sources
>>> that reference dummy placeholder images in my source tree, then created a
>>> separate class implementing that interface. In the constructor I populate
>>> it from the GWT.created bundle (since some of the resources aren't dynamic,
>>> and I can just delegate through to them) but then load my dynamic images
>>> into Image widgets. Those, in turn, are each given to an implementation of
>>> ImageResource that holds an Image widget, and obtains the width, height,
>>> url, etc. from it (wasn't sure what the heck to do with getName, or how to
>>> implement isAnimated). Those are the return values from the associated
>>> methods in my resource object. And then I give that to the pager
>>> constructor.
>>>
>>> The asychronicity turned out to be a bear, since I'm using a LoadHandler
>>> for each image to know when the size values will be available, and that
>>> won't do anything unless I actually add the Image to the document, so I had
>>> to create a hidden div to put them into. I haven't yet tested if that's
>>> necessary with a data: url. And a lot of layout tasks had to be pushed off
>>> into a callback.
>>>
>>> The concept works, but I suspect that unless I make all versions of a
>>> particular image the same size, I can't use any CssResource tricks based on
>>> the image. That's probably not a big deal - since the variations generally
>>> would all be the same size. Also, I don't think that there's any existing
>>> Resource class in the API with CSS resources that depend on the images, so
>>> it would only be an issue with custom resource classes.
>>>
>>> On Wednesday, August 14, 2013 3:42:34 AM UTC-4, df wrote:
>>>>
>>>> Hello. Is There any way to create ImageResource dynamically? For
>>>> example : I get images from WebService in base64 format and I don't have
>>>> opportunity to have all images on the server at compile time. Can i cast
>>>> Images to ImageResource? Or is there any other solution?
>>>> Thanks for help.
>>>>
>>>
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