add resize_to_fill operation

resolves #1

Author: chrylis

blitline-image-client/src/main/java/com/blitline/image/Blitline.java

@@ -36,6 +36,7 @@
 import com.blitline.image.functions.Rectangle;
 import com.blitline.image.functions.Resample;
 import com.blitline.image.functions.Resize;
+import com.blitline.image.functions.ResizeToFill;
 import com.blitline.image.functions.ResizeToFit;
 import com.blitline.image.functions.Rotate;
 import com.blitline.image.functions.RunExecutable;
@@ -51,12 +52,12 @@
 import com.blitline.image.functions.Watermark;
 
 public class Blitline {
-	
+
 	/**
 	 * The API version this library will invoke. 1.20 fixed error reporting.
 	 */
 	public static final String BLITLINE_API_VERSION = "1.20";
-	
+
 	private Blitline() {
 	}
 
@@ -162,7 +163,7 @@ public static Ellipse drawEllipse(int centerX, int centerY, int width, int heigh
 
 	/**
 	 * Invokes ImageMagick's {@code -enhance} option; most applications will prefer {@link #autoEnhance()}.
-	 * 
+	 *
 	 * @return the singleton instance of the {@link Enhance} function
 	 */
 	public static Enhance enhance() {
@@ -245,6 +246,10 @@ public static Resize resizeTo(int width, int height) {
 		return new Resize(width, height);
 	}
 
+	public static ResizeToFill resizeToFill(int width, int maxHeight) {
+		return new ResizeToFill(width, maxHeight);
+	}
+
 	public static ResizeToFit resizeToFit(int maxWidth, int maxHeight) {
 		return new ResizeToFit(maxWidth, maxHeight);
 	}

blitline-image-client/src/main/java/com/blitline/image/functions/ResizeToFill.java

@@ -0,0 +1,48 @@
+package com.blitline.image.functions;
+
+import com.blitline.image.functions.params.Gravity;
+
+public class ResizeToFill extends AbstractFunction {
+
+	private static final long serialVersionUID = 1L;
+
+	@Override
+	public String getName() {
+		return "resize_to_fill";
+	}
+
+	/**
+	 * Specify the maximum dimensions of the resized image. You may specify zero for one of the dimensions to leave it
+	 * unconstrained.
+	 *
+	 * @param width
+	 *            the maximum width of the resulting image, or zero for any width
+	 * @param maxHeight
+	 *            the maximum height of the resulting image, or zero for any height
+	 */
+	public ResizeToFill(int width, int maxHeight) {
+		if (width == 0)
+			throw new IllegalArgumentException("width must be specified");
+
+		params.put("width", width);
+
+		if (maxHeight > 0)
+			params.put("height", maxHeight);
+	}
+
+	/**
+	 * Do not upscale the image if the original is already smaller than the maximum dimensions. Sets the {@code only_shrink_larger}
+	 * JSON option.
+	 *
+	 * @return {@literal this}
+	 */
+	public ResizeToFill doNotUpscale() {
+		params.put("only_shrink_larger", Boolean.TRUE);
+		return this;
+	}
+
+	public ResizeToFill gravity(Gravity gravity) {
+		params.put("gravity", gravity);
+		return this;
+	}
+}