Re: How to load images dynamically?
I can see a use case for dynamic ImageBundles. If you need to display a set
of images that are a function of user input, you transfer all of them as the
result of 1 HTTP request & then display them as appropriate using viewports.
This way you don't need to fetch a bunch of individual images, each
requiring 1 HTTP connection.
If you lay it out just like they are in the bundle, you can also get a cool
effect seeing the row by row of images fill up at once.
Of course ImageBundle is not the perfect idiom for this concept. You have
to generate the combined image & create image widgets with the correct
viewport.
One bad thing about the suggested RPC approach is that the browser won't
render the partial image as it is being downloaded. Another is that you're
bloating the transfer size & placing load on the server unnecessarily.
Simply transfer a raw byte array, & do the base64 encoding on the client
side. The added advantage is you don't actually need to write you're own
encoder & most versions of FF, Safari & provide a fast native one.
On Mon, Apr 20, 2009 at 8:57 PM, John Ivens wrote:
> There is a really good solution listed earlier using Image(url) where url
> looks like "data:
> // Example client code which uses an encoded base64 string passed from the
> server to the client:
>
> private void refreshImage() {
>
> // lazy initialization of service proxy
>
> if (ditherSvc == null) {
>
> ditherSvc = GWT.create(DitherService.class);
>
> }
>
>
> AsyncCallback callback = new AsyncCallback() {
>
> public void onFailure(Throwable caught) {
>
> // do something with errors
>
> }
>
>
> public void onSuccess(String result) {
>
> img.setUrl("data:image/png;base64," + result);
>
> }
>
> };
>
>
> // make the call to the dither service
>
>
> ditherSvc.getDither(steps, spiralDistance, magnitude, callback);
>
> }
>
>
> On the server side, you need to get a library which is available free for
> java on the web which encodes a string as base64... an example server side
> is:
>
>
> package edu.wiyn.odi.server;
>
>
> import java.io.File;
>
> import java.io.IOException;
>
> import java.util.Calendar;
>
> import java.util.Date;
>
> import java.util.Vector;
>
>
> import org.wiyn.odi.op2.application.DitherPatternCoverage;
>
> import org.wiyn.odi.op2.application.op2;
>
> import org.wiyn.odi.op2.otalib.otaMosaic;
>
>
> import com.google.gwt.core.client.GWT;
>
> import com.google.gwt.user.server.rpc.RemoteServiceServlet;
>
>
> import edu.wiyn.odi.client.DitherService;
>
>
> public class DitherServiceImpl extends RemoteServiceServlet implements
>
> DitherService {
>
>
> /**
>
> *
>
> */
>
> private static final long serialVersionUID = 1L;
>
>
> public String getDither(int steps, double spiralDistance, doublemagnitude) {
>
> // Read in a png file and make it into a byte array
>
> // Encode this file as a string and pass it to the client
>
> //System.out.println(System.getProperty("user.dir"));
>
> System.out.println("Steps: " + steps + ", spiralDistance: " +
> spiralDistance + ", magnitude: " + magnitude);
>
> String encoded = null;
>
> try {
>
>
> // BasicConfigurator.configure ();
>
> DitherPatternCoverage cover = new DitherPatternCoverage(800);
>
>
> op2.updateCatalog(120., 60.);
>
> Vector myDither = cover.generateDitherSequence(120., 60.,
>
> cover.getSpiralDither(steps, spiralDistance));
>
>
> long start = System.currentTimeMillis();
>
>
> cover.calculateCoverage(myDither);
>
>
> long end = System.currentTimeMillis();
>
>
> System.out.println("rendering took: " + (end - start) + "ms");
>
>
> cover.writeToDisk("./coveragetest.png");
>
> encoded = Base64.encodeFromFile("./coveragetest.png");
>
> } catch (IOException e) {
>
> e.printStackTrace();
>
> }
>
> return(encoded);
>
> }
>
>
> }
>
>
> The main lines are:
>
> cover.writeToDisk("./coveragetest.png");
>
> encoded = Base64.encodeFromFile("./coveragetest.png");
>
> return(encoded);
>
> I write to disk, but don't need to. If I kept this in a byte array it
> would be faster. There is also an encoding method which works with byte
> arrays.
>
>
> On Mon, Apr 20, 2009 at 5:43 PM, Chii wrote:
>
>>
>> The purpose of image bundles is to crunch the static images you have
>> into one big image - if you have multiple images that could be
>> submitted by a user and changes dynamically, then image bundles is not
>> the right solution. new Image(url) is quite a simple and easy
>> solution, why not use that?
>>
>> On Apr 19, 9:16 am, POLS wrote:
>> > Hi,
>> >
>> > I am using ImageBundle feature.
>> > I am using @Resource annotation, specifying image file location and
>> > image name.
>> > Its kind of a static behavior.
>> >
>> > I have details of images name and locations in the database.
>> > Can you please tell me, How to load the images?
>> >
>> > Thanks,
>> > POLS
>>
>>
>
> >
>
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To po
Re: How to load images dynamically?
There is a really good solution listed earlier using Image(url) where url
looks like "data:
// Example client code which uses an encoded base64 string passed from the
server to the client:
private void refreshImage() {
// lazy initialization of service proxy
if (ditherSvc == null) {
ditherSvc = GWT.create(DitherService.class);
}
AsyncCallback callback = new AsyncCallback() {
public void onFailure(Throwable caught) {
// do something with errors
}
public void onSuccess(String result) {
img.setUrl("data:image/png;base64," + result);
}
};
// make the call to the dither service
ditherSvc.getDither(steps, spiralDistance, magnitude, callback);
}
On the server side, you need to get a library which is available free for
java on the web which encodes a string as base64... an example server side
is:
package edu.wiyn.odi.server;
import java.io.File;
import java.io.IOException;
import java.util.Calendar;
import java.util.Date;
import java.util.Vector;
import org.wiyn.odi.op2.application.DitherPatternCoverage;
import org.wiyn.odi.op2.application.op2;
import org.wiyn.odi.op2.otalib.otaMosaic;
import com.google.gwt.core.client.GWT;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;
import edu.wiyn.odi.client.DitherService;
public class DitherServiceImpl extends RemoteServiceServlet implements
DitherService {
/**
*
*/
private static final long serialVersionUID = 1L;
public String getDither(int steps, double spiralDistance, double magnitude)
{
// Read in a png file and make it into a byte array
// Encode this file as a string and pass it to the client
//System.out.println(System.getProperty("user.dir"));
System.out.println("Steps: " + steps + ", spiralDistance: " + spiralDistance
+ ", magnitude: " + magnitude);
String encoded = null;
try {
// BasicConfigurator.configure ();
DitherPatternCoverage cover = new DitherPatternCoverage(800);
op2.updateCatalog(120., 60.);
Vector myDither = cover.generateDitherSequence(120., 60.,
cover.getSpiralDither(steps, spiralDistance));
long start = System.currentTimeMillis();
cover.calculateCoverage(myDither);
long end = System.currentTimeMillis();
System.out.println("rendering took: " + (end - start) + "ms");
cover.writeToDisk("./coveragetest.png");
encoded = Base64.encodeFromFile("./coveragetest.png");
} catch (IOException e) {
e.printStackTrace();
}
return(encoded);
}
}
The main lines are:
cover.writeToDisk("./coveragetest.png");
encoded = Base64.encodeFromFile("./coveragetest.png");
return(encoded);
I write to disk, but don't need to. If I kept this in a byte array it would
be faster. There is also an encoding method which works with byte arrays.
On Mon, Apr 20, 2009 at 5:43 PM, Chii wrote:
>
> The purpose of image bundles is to crunch the static images you have
> into one big image - if you have multiple images that could be
> submitted by a user and changes dynamically, then image bundles is not
> the right solution. new Image(url) is quite a simple and easy
> solution, why not use that?
>
> On Apr 19, 9:16 am, POLS wrote:
> > Hi,
> >
> > I am using ImageBundle feature.
> > I am using @Resource annotation, specifying image file location and
> > image name.
> > Its kind of a static behavior.
> >
> > I have details of images name and locations in the database.
> > Can you please tell me, How to load the images?
> >
> > Thanks,
> > POLS
> >
>
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Re: How to load images dynamically?
The purpose of image bundles is to crunch the static images you have into one big image - if you have multiple images that could be submitted by a user and changes dynamically, then image bundles is not the right solution. new Image(url) is quite a simple and easy solution, why not use that? On Apr 19, 9:16 am, POLS wrote: > Hi, > > I am using ImageBundle feature. > I am using �...@resource annotation, specifying image file location and > image name. > Its kind of a static behavior. > > I have details of images name and locations in the database. > Can you please tell me, How to load the images? > > Thanks, > POLS --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To post to this group, send email to Google-Web-Toolkit@googlegroups.com To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/Google-Web-Toolkit?hl=en -~--~~~~--~~--~--~---
Re: How to load images dynamically?
I thought you were stating an absolute (i.e. it's not possible at all to use the image bundle concept). My bad. On Sun, Apr 19, 2009 at 6:44 AM, Salvador Diaz wrote: > > > There isn't such a framework right now & it would take some effort to > write > > I imagine. > > So my remark stands true: ImageBundles cannot be generated dynamically > (and by that I meant: with the standard GWT distribution) > > > > > --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To post to this group, send email to Google-Web-Toolkit@googlegroups.com To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/Google-Web-Toolkit?hl=en -~--~~~~--~~--~--~---
Re: How to load images dynamically?
> There isn't such a framework right now & it would take some effort to write > I imagine. So my remark stands true: ImageBundles cannot be generated dynamically (and by that I meant: with the standard GWT distribution) --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To post to this group, send email to Google-Web-Toolkit@googlegroups.com To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/Google-Web-Toolkit?hl=en -~--~~~~--~~--~--~---
Re: How to load images dynamically?
Well, that's not technically true. You could potentially write a framework
that would get the GWT compiler to generate the bundles for you at runtime.
There isn't such a framework right now & it would take some effort to write
I imagine.
You could base it off the work that was done to recompile the code into JS
on the fly when the Java code changes (I forget by which project - it's in
the mailing list archives somewhere).
Something along the lines of - extract the images to disk, generate the code
for the image bundle, invoke the compiler, delete the original images (if
you really want to save space), & then return a map of image alias & the
parameters of the image (i.e. url of the bundle, offsets into the bundle,
size of the image).
On Sun, Apr 19, 2009 at 5:01 AM, Salvador Diaz wrote:
>
> Also note that ImageBundles cannot be generated dynamically as they're
> created by the GWT Compiler as a single image at compile time.
> For more information about ImageBundles and its intended purposes read
> this:
> http://code.google.com/webtoolkit/doc/1.6/DevGuideUserInterface.html#DevGuideImageBundles
>
> Cheers,
>
> Salvador
>
> On Apr 19, 1:50 am, Vitali Lovich wrote:
> > new Image("path to remote image file here");
> >
> > On Sat, Apr 18, 2009 at 7:16 PM, POLS
> wrote:
> >
> > > Hi,
> >
> > > I am using ImageBundle feature.
> > > I am using @Resource annotation, specifying image file location and
> > > image name.
> > > Its kind of a static behavior.
> >
> > > I have details of images name and locations in the database.
> > > Can you please tell me, How to load the images?
> >
> > > Thanks,
> > > POLS
> >
>
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Re: How to load images dynamically?
Also note that ImageBundles cannot be generated dynamically as they're
created by the GWT Compiler as a single image at compile time.
For more information about ImageBundles and its intended purposes read
this:
http://code.google.com/webtoolkit/doc/1.6/DevGuideUserInterface.html#DevGuideImageBundles
Cheers,
Salvador
On Apr 19, 1:50 am, Vitali Lovich wrote:
> new Image("path to remote image file here");
>
> On Sat, Apr 18, 2009 at 7:16 PM, POLS wrote:
>
> > Hi,
>
> > I am using ImageBundle feature.
> > I am using �...@resource annotation, specifying image file location and
> > image name.
> > Its kind of a static behavior.
>
> > I have details of images name and locations in the database.
> > Can you please tell me, How to load the images?
>
> > Thanks,
> > POLS
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Re: How to load images dynamically?
new Image("path to remote image file here");
On Sat, Apr 18, 2009 at 7:16 PM, POLS wrote:
>
> Hi,
>
> I am using ImageBundle feature.
> I am using �...@resource annotation, specifying image file location and
> image name.
> Its kind of a static behavior.
>
> I have details of images name and locations in the database.
> Can you please tell me, How to load the images?
>
>
> Thanks,
> POLS
>
> >
>
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How to load images dynamically?
Hi, I am using ImageBundle feature. I am using @Resource annotation, specifying image file location and image name. Its kind of a static behavior. I have details of images name and locations in the database. Can you please tell me, How to load the images? Thanks, POLS --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To post to this group, send email to Google-Web-Toolkit@googlegroups.com To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/Google-Web-Toolkit?hl=en -~--~~~~--~~--~--~---
