Quoting Rob Oxspring :

I was using the image task to create thumbnails and couldn't figure out
how to keep proportions of an image but keep it within a fixed size.
My solution was to change the keepproportions attribute to be a little cleverer.
The keepproportions attribute is no more and has been replaced by the proportions
attribute, which has been added with the following features:

proportions="ignore" - treat the dimensions independently (==keepproportions="false" and is default)
proportions="width" - keep proportions based on the width (==keepproportions="true")
proportions="height" - keep proportions based on the height
proportions="fit" - keep proportions and fit in the supplied dimensions
proportions="cover" - keep proportions and cover the supplied dimensions

Submitted by: Rob Oxspring (roxspring at imapmail dot org)


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@275127 13f79535-47bb-0310-9956-ffa450edef68

WHATSNEW

@@ -262,6 +262,9 @@ Other changes:
 
 * Added <image> task (requires JAI).
 
+* <image> task has now proportions attribute in the <scale/> nested element
+  instead of keepproportions (bringing in more functionality)
+
 * New condition <isreference>
 
 * <ftp> now has a preservelastmodified attribute to preserve the

docs/manual/OptionalTasks/image.html

@@ -138,11 +138,15 @@ ImageOperation can handle nested Rotate, Draw, Rectangle, Text and Scale objects
     <td valign="top"><b>Description</b></td>
     <td align="center" valign="top"><b>Required</b></td>
   </tr>
-  <tr>
-    <td valign="top"> keepproportions </td>
-    <td valign="top"> Boolean value. Sets whether the proportion heigth/width should be kept. </td>
-    <td align="center"> no (defaults to <i>false</i>) </td>
-  </tr>
+    <td valign="top"> proportions </td>
+    <td valign="top"> Sets which dimension to control proportions from. Valid values are:<ul>
+        <li>&quot;ignore&quot; -  treat the dimensions independently.</li>
+        <li>&quot;height&quot; - keep proportions based on the width.</li>
+        <li>&quot;width&quot; - keep proportions based on the height.</li>
+        <li>&quot;cover&quot; - keep proportions and fit in the supplied dimensions.</li>
+        <li>&quot;fit&quot; - keep proportions and cover the supplied dimensions.</li>
+    </ul></td>
++    <td align="center"> no (defaults to <i>ignore</i>) </td>
   <tr>
     <td valign="top"> width </td>
     <td valign="top"> Sets the width of the image, either as an integer or a %. </td>

src/etc/testcases/taskdefs/optional/image/image.xml

@@ -18,35 +18,35 @@
    	<!-- this should produce a single file in the dest dir -->
 	 	<target name="testSimpleScale" depends="init">
 			<image includes="*.jpg" srcdir="${src.dir}" destdir="${dest.dir}" overwrite="no" failonerror="no">
-				<scale width="300" keepproportions="true"/>
+				<scale width="300" proportions="width"/>
 			</image>   
 		</target>   
 
    	<!-- this should put some text in the log -->
 	 	<target name="testEchoToLog" depends="init">
 			<image includes="*.jpg" srcdir="${src.dir}" destdir="${dest.dir}" overwrite="no" failonerror="no">
-				<scale width="300" keepproportions="true"/>
+				<scale width="300" proportions="width"/>
 			</image>   
 		</target>   
 		
    	<!-- this should produce a single file in the dest dir -->
 	 	<target name="testFailOnError" depends="init">
 			<image includes="*.jpg" srcdir="${src.dir}" destdir="${dest.dir}" overwrite="no" failonerror="yes">
-				<scale width="300" keepproportions="true"/>
+				<scale width="300" proportions="width"/>
 			</image>   
 		</target>   		
 		
 		<!-- this should produce a single file in the dest dir, overwriting any existing file -->
 		<target name="testOverwriteTrue" depends="init">
 			<image includes="*.jpg" srcdir="${src.dir}" destdir="${dest.dir}" overwrite="true" failonerror="no">
-				<scale width="300" keepproportions="true"/>
+				<scale width="300" proportions="width"/>
 			</image>   
 		</target>   
 
 		<!-- this should not overwrite the existing file -->
 		<target name="testOverwriteFalse" depends="init">
 			<image includes="*.jpg" srcdir="${src.dir}" destdir="${dest.dir}" overwrite="false" failonerror="no">
-				<scale width="300" keepproportions="true"/>
+				<scale width="300" proportions="width"/>
 			</image>   
 		</target>   
    

src/main/org/apache/tools/ant/types/optional/image/Scale.java

@@ -53,26 +53,42 @@
  */
 package org.apache.tools.ant.types.optional.image;
 
+import org.apache.tools.ant.types.EnumeratedAttribute;
+
 import javax.media.jai.JAI;
 import javax.media.jai.PlanarImage;
+import javax.media.jai.InterpolationBilinear;
+import java.awt.RenderingHints;
 import java.awt.image.BufferedImage;
 import java.awt.image.renderable.ParameterBlock;
 
 /**
  *
  * @author <a href="mailto:kzgrey@ntplx.net">Kevin Z Grey</a>
+ * @author <a href="mailto:roxspring@imapmail.org">Rob Oxspring</a>
  * @see org.apache.tools.ant.taskdefs.optional.image.Image
  */
 public class Scale extends TransformOperation implements DrawOperation {
+
     private String width_str = "100%";
     private String height_str = "100%";
     private boolean x_percent = true;
     private boolean y_percent = true;
-    private boolean keep_proportions = false;
+    private String proportions = "ignore";
+
+    public static class ProportionsAttribute extends EnumeratedAttribute {
+        public String[] getValues() {
+            return new String[] {"ignore", "width", "height", "cover", "fit"};
+        }
+    }
 
-    public void setKeepproportions(boolean props) {
-        keep_proportions = props;
+    /**
+     *  Sets the behaviour regarding the image proportions.
+     */
+    public void setProportions(ProportionsAttribute pa){
+        proportions = pa.getValue();
     }
+
     /**
      *  Sets the width of the image, either as an integer or a %.  Defaults to 100%.
      */
@@ -117,19 +133,32 @@ public class Scale extends TransformOperation implements DrawOperation {
         pb.addSource(image);
         float x_fl = getWidth();
         float y_fl = getHeight();
+
         if (!x_percent) {
             x_fl = (x_fl / image.getWidth());
         }
         if (!y_percent) {
             y_fl = (y_fl / image.getHeight());
         }
-        if (keep_proportions) {
+
+        if("width".equals(proportions)){
             y_fl = x_fl;
         }
+        else if("height".equals(proportions)){
+            x_fl = y_fl;
+        }
+        else if("fit".equals(proportions)){
+            x_fl = y_fl = Math.min(x_fl,y_fl);
+        }
+        else if("cover".equals(proportions)){
+            x_fl = y_fl = Math.max(x_fl,y_fl);
+        }
+
         pb.add(new Float(x_fl));
         pb.add(new Float(y_fl));
 
-        log("\tScaling to " + x_fl + "% x " + y_fl + "%");
+        log("\tScaling to " + (x_fl*100) + "% x " + (y_fl*100)+ "%");
+
         return JAI.create("scale", pb);
     }