Add cropAround element; Fixes #32

Author: glibas

src/main/java/com/assertthat/selenium_shutterbug/core/PageSnapshot.java

@@ -155,6 +155,23 @@ public PageSnapshot blurExcept(WebElement element) {
         return this;
     }
 
+    /**
+     * Crop the image around specified element with offset.
+     *
+     * @param element WebElement to crop around
+     * @param offsetX  offsetX around element in px
+     * @param offsetY offsetY around element in px
+     * @return instance of type PageSnapshot
+     */
+    public PageSnapshot cropAround(WebElement element, int offsetX, int offsetY) {
+        try{
+            image = ImageProcessor.cropAround(image, new Coordinates(element), offsetX, offsetY);
+        }catch(RasterFormatException rfe){
+            throw new ElementOutsideViewportException(ELEMENT_OUT_OF_VIEWPORT_EX_MESSAGE,rfe);
+        }
+        return this;
+    }
+
     @Override
     protected PageSnapshot self() {
         return this;

src/main/java/com/assertthat/selenium_shutterbug/utils/image/ImageProcessor.java

@@ -87,6 +87,11 @@ public static BufferedImage blurExceptArea(BufferedImage sourceImage, Coordinate
         return combined;
     }
 
+    public static BufferedImage cropAround(BufferedImage sourceImage, Coordinates coords, int offsetX, int offsetY) {
+        BufferedImage subImage = sourceImage.getSubimage(coords.getX()-offsetX, coords.getY()-offsetY, coords.getWidth()+offsetX*2, coords.getHeight()+offsetY*2);
+        return subImage;
+    }
+
     public static BufferedImage addTitle(BufferedImage sourceImage, String title, Color color, Font textFont) {
         int textOffset = 5;
         BufferedImage combined = new BufferedImage(sourceImage.getWidth(), sourceImage.getHeight() + textFont.getSize(), BufferedImage.TYPE_INT_ARGB);
@@ -186,14 +191,6 @@ public static boolean imagesAreEqualsWithDiff(BufferedImage image1, BufferedImag
         return pixelError == 0 || pixelError <= deviation;
     }
 
-    /**
-     * Gives back the pixel error set by imagesAreEqualsWithDiff. 'getPixelError' should be called after 'imagesAreEqualsWithDiff.'
-     * @return pixelError The pixel error
-     */
-    public static double getPixelError(){
-        return pixelError;
-    }
-
     public static BufferedImage scale(BufferedImage source, double ratio) {
         int w = (int) (source.getWidth() * ratio);
         int h = (int) (source.getHeight() * ratio);