java/src/main/com/google/appengine/api/images/CompositeImpl.java

   1 // Copyright 2009 Google Inc. All Rights Reserved.
   2
   3 package com.google.appengine.api.images;
   4
   5 import java.util.Map;
   6
   7 import com.google.appengine.api.images.ImagesServicePb.ImagesCompositeRequest;
   8 import com.google.appengine.api.images.ImagesServicePb.CompositeImageOptions;
   9
  10 /**
  11  * Implementation of Composite using alpha blending.
  12  *
  13  */
  14 final class CompositeImpl extends Composite {
  15
  16   private final Image image;
  17   private final Anchor anchor;
  18   private final int xOffset;
  19   private final int yOffset;
  20   private final float opacity;
  21
  22   /**
  23    * Creates a compositing operation with the supplied parameters.
  24    * @param image Image to be placed onto the canvas.
  25    * @param xOffset X offset from anchor position.
  26    * @param yOffset X offset from anchor position.
  27    * @param opacity Opacity of the image as a float in range [0.0, 1.0].
  28    * @param anchor Anchor position of the image on the canvas.
  29    */
  30   CompositeImpl(Image image, int xOffset, int yOffset, float opacity,
  31                 Anchor anchor) {
  32     if (image == null) {
  33       throw new IllegalArgumentException("The image must not be null");
  34     }
  35     if (xOffset > ImagesService.MAX_RESIZE_DIMENSIONS
  36         || xOffset < -ImagesService.MAX_RESIZE_DIMENSIONS
  37         || yOffset > ImagesService.MAX_RESIZE_DIMENSIONS
  38         || yOffset < -ImagesService.MAX_RESIZE_DIMENSIONS) {
  39       throw new IllegalArgumentException("Images must fit on the canvas");
  40     }
  41     if (opacity < 0.0f || opacity > 1.0f) {
  42       throw new IllegalArgumentException("Opacity must be in range [0, 1]");
  43     }
  44     if (anchor == null) {
  45       throw new IllegalArgumentException("Anchor must not be null");
  46     }
  47     this.image = image;
  48     this.anchor = anchor;
  49     this.xOffset = xOffset;
  50     this.yOffset = yOffset;
  51     this.opacity = opacity;
  52   }
  53
  54   /** {@inheritDoc} */
  55   @Override
  56   void apply(ImagesCompositeRequest.Builder request, Map<Image, Integer> imageIndexMap) {
  57     if (!imageIndexMap.containsKey(image)) {
  58       imageIndexMap.put(image, request.build().getImageCount());
  59       request.addImage(ImagesServiceImpl.convertImageData(image));
  60     }
  61     CompositeImageOptions.Builder options = CompositeImageOptions.newBuilder();
  62     int sourceId = imageIndexMap.get(image);
  63     options.setSourceIndex(sourceId);
  64     options.setXOffset(xOffset);
  65     options.setYOffset(yOffset);
  66     options.setOpacity(opacity);
  67     options.setAnchor(convertAnchor(anchor));
  68     request.addOptions(options);
  69   }
  70
  71   static CompositeImageOptions.ANCHOR convertAnchor(Anchor anchor) {
  72     switch (anchor) {
  73       case TOP_LEFT:
  74         return CompositeImageOptions.ANCHOR.TOP_LEFT;
  75       case TOP_CENTER:
  76         return CompositeImageOptions.ANCHOR.TOP;
  77       case TOP_RIGHT:
  78         return CompositeImageOptions.ANCHOR.TOP_RIGHT;
  79       case CENTER_LEFT:
  80         return CompositeImageOptions.ANCHOR.LEFT;
  81       case CENTER_CENTER:
  82         return CompositeImageOptions.ANCHOR.CENTER;
  83       case CENTER_RIGHT:
  84         return CompositeImageOptions.ANCHOR.RIGHT;
  85       case BOTTOM_LEFT:
  86         return CompositeImageOptions.ANCHOR.BOTTOM_LEFT;
  87       case BOTTOM_CENTER:
  88         return CompositeImageOptions.ANCHOR.BOTTOM;
  89       case BOTTOM_RIGHT:
  90         return CompositeImageOptions.ANCHOR.BOTTOM_RIGHT;
  91     }
  92     throw new IllegalArgumentException("Unexpected anchor value: " + anchor);
  93   }
  94 }