Page History

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1. #IRequestTargetUrlCodingStrategy which is mounted and returns the contextual image for a fixed path.
2. #Resource which wraps the image creation logic but where the URL is auto-generated by wicket.

Create custom IRequestTargetUrlCodingStrategy and bind it to the /surveyed-date.png Image

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IRequestTargetUrlCodingStrategyOverview:

1. mount the custom IRequestTargetUrlCodingStrategy in application.init();
   1. My custom strategy is hardcoded with the name of the image that it responds to: /surveyed-date.png
2. When ever a request is sent to that image the strategy will either returned a cached copy or generate a new image by stamping the current date onto a template image.
   1. The page that places the image will have an image link with the

      Code Block
      <img src="/surveyed-date.png" />

      HTML tag.

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The tripTimeService.getImageResource(surveyedDate, true) method is what does the work of converting the date into a particular format and then writing the text onto an image template.

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stampedImage stampedImage

How to create an image stamped with user specific context

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Code Block

public class TripTimeImageServiceImpl implements TripTimeImageService { private static final Logger log = Logger .getLogger(TripTimeImageServiceImpl.class); // spring resource that points at the template image private Resource baseTripTimeImageFile; private DateTimeFormatter dayOfWeekFormatter; private DateTimeFormatter dateFormatter; // Font to use to write the string version of the date onto the image template private static Font font = new Font( Font.SANS_SERIF, Font.BOLD, 14); // cache containing the created image for each private Map<String, BufferedDynamicImageResource> dateToImageMap = new LinkedHashMap<String, BufferedDynamicImageResource>(); private BufferedDynamicImageResource generateImage(DateTime surveyedDate, SurveyTime st, boolean cacheable) throws IOException { BufferedDynamicImageResource generatedImage = new BufferedDynamicImageResource( "png"); String dow = dayOfWeekFormatter.print(surveyedDate); String date = dateFormatter.print(surveyedDate); DateTime nextDay = surveyedDate.plusDays(1); String nextDow = dayOfWeekFormatter.print(nextDay); String nextDate = dateFormatter.print(nextDay); BufferedImage overlayImage = ImageIO.read(baseTripTimeImageFile.getFile()); int width = overlayImage.getWidth(); int height = overlayImage.getHeight(); Graphics2D overlayG2d = overlayImage.createGraphics(); overlayG2d.setFont(font); overlayG2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); overlayG2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON); overlayG2d.setPaint(Color.BLACK); /* * These offsets were calculated using a test case to repeatably place the details * and with the Gimp to locate viable insertion points. */ // day of week overlayG2d.drawString(dow, 32, 90); // date overlayG2d.drawString(date, 32, 107); // next day of week overlayG2d.drawString(nextDow, 332, 90); // next date overlayG2d.drawString(nextDate, 332, 107); BufferedImage target = new BufferedImage (width, height, BufferedImage.TYPE_INT_ARGB); Graphics2D targetG2d = target.createGraphics(); targetG2d.setFont(font); targetG2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); targetG2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON); targetG2d.setPaint(Color.white); targetG2d.fillRect(0, 0, width, height); targetG2d.setPaint(Color.RED); // fill with the background color (white) // targetG2d.fillRect(0, 0, width, height); // draw the overlay (the printed surveyedDate detail) onto the target. targetG2d.drawImage(overlayImage, 0, 0, null); // do the final setup on the BufferedDynamicImageResource that will contain this image // note that the generated image does not change the base image. generatedImage.setImage(target); generatedImage.setCacheable(cacheable); generatedImage.setFormat("png"); log.info("generated image"); return generatedImage; } public void setBaseTripTimeImageFile(Resource baseTripTimeImageFile) { this.baseTripTimeImageFile = baseTripTimeImageFile; } public TripTimeImageServiceImpl() { // e.g Wednesday dayOfWeekFormatter = DateTimeFormat.forPattern("EEEE"); // e.g. February 18, 2009 dateFormatter = DateTimeFormat.forPattern("MMMM dd, yyyy"); } @Override public org.apache.wicket.Resource getImageResource(DateTime surveyedDate, boolean cacheable) throws IOException { return getImageResource(surveyedDate, null, cacheable); } @Override public org.apache.wicket.Resource getImageResource(DateTime surveyedDate, SurveyTime previousDepartureTime, boolean cacheable) throws IOException { BufferedDynamicImageResource cachedImage = null; String cachedImageKey = TimeUtils.getInstance().getString( surveyedDate); cachedImage = this.dateToImageMap.get(cachedImageKey); if (cachedImage == null) { cachedImage = generateImage(surveyedDate, previousDepartureTime, cacheable); this.dateToImageMap.put(cachedImageKey, cachedImage); } return cachedImage; } }

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Resource Resource

Using Custom Resource to stamp the image.

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Overview:

The resource is aware of the current state and will adjust the image based upon it.

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