'imageWidth' and '..Height' formula functions

Author: kasemir

app/display/model/src/main/resources/examples/plots_image.bob

@@ -1,8 +1,8 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <display version="2.0.0">
   <name>Image Widget</name>
-  <width>1100</width>
-  <height>1200</height>
+  <width>1090</width>
+  <height>1430</height>
   <widget type="label" version="2.0.0">
     <name>Label</name>
     <class>TITLE</class>
@@ -322,11 +322,13 @@ For Channel Access, the waveform PV only provides pixels. The data width, height
 
 When "Limits from PV" is not set, the range of the X and Y axes can be configured independently from the image size. This allows for example a calibration of pixel positions in millimeters.
 The axis direction can be inverted by swapping the axis minimum and maximum limit.
+
+To set an axis limit relative to the image pixel size, one can use rules or scripts that take inputs from formula PVs '=imageWidth(`pva://...Image`)' or '=imageHeight(`pva://...Image`)' and then write for example the 'x_axis.maximum' or 'y_axis.minimum' property of the widget.
 </text>
-    <x>201</x>
+    <x>200</x>
     <y>1150</y>
-    <width>421</width>
-    <height>209</height>
+    <width>422</width>
+    <height>280</height>
   </widget>
   <widget type="label" version="2.0.0">
     <name>Label_10</name>

core/formula/src/main/java/org/csstudio/apputil/formula/areadetector/ImageHeightFunction.java

@@ -0,0 +1,34 @@
+/*******************************************************************************
+ * Copyright (c) 2022 Oak Ridge National Laboratory.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ ******************************************************************************/
+package org.csstudio.apputil.formula.areadetector;
+
+import org.epics.vtype.VImage;
+
+/** A formula function for fetching height of VImage
+ *  @author Kay Kasemir
+ */
+public class ImageHeightFunction extends ImageWidthFunction
+{
+    @Override
+    public String getName()
+    {
+        return "imageHeight";
+    }
+
+    @Override
+    public String getDescription()
+    {
+        return "Fetch height of image";
+    }
+
+    @Override
+    protected int getImageInfo(final VImage image)
+    {
+        return image.getHeight();
+    }
+}

core/formula/src/main/java/org/csstudio/apputil/formula/areadetector/ImageWidthFunction.java

@@ -0,0 +1,70 @@
+/*******************************************************************************
+ * Copyright (c) 2022 Oak Ridge National Laboratory.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ ******************************************************************************/
+package org.csstudio.apputil.formula.areadetector;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.csstudio.apputil.formula.spi.FormulaFunction;
+import org.epics.vtype.Display;
+import org.epics.vtype.VImage;
+import org.epics.vtype.VInt;
+import org.epics.vtype.VType;
+
+/** A formula function for fetching width of VImage
+ *  @author Kay Kasemir
+ */
+public class ImageWidthFunction implements FormulaFunction
+{
+    @Override
+    public String getCategory()
+    {
+        return "areaDetector";
+    }
+
+    @Override
+    public String getName()
+    {
+        return "imageWidth";
+    }
+
+    @Override
+    public String getDescription()
+    {
+        return "Fetch width of image";
+    }
+
+    @Override
+    public List<String> getArguments()
+    {
+        return List.of("image");
+    }
+
+    /** Fetch info (width, height, ...) from image
+     *
+     *  Subclass can override
+     *
+     *  @param image Image
+     *  @return info
+     */
+    protected int getImageInfo(final VImage image)
+    {
+        return image.getWidth();
+    }
+
+    @Override
+    public VType compute(final VType... args) throws Exception
+    {
+        if (args.length != 1 || ! (args[0] instanceof VImage))
+            throw new Exception("Function " + getName() +
+                    " takes VImage but received " + Arrays.toString(args));
+
+        final VImage image = (VImage) args[0];
+        return VInt.of(getImageInfo(image), image.getAlarm(), image.getTime(), Display.none());
+    }
+}

core/formula/src/main/resources/META-INF/services/org.csstudio.apputil.formula.spi.FormulaFunction

@@ -27,6 +27,8 @@ org.csstudio.apputil.formula.math.Pow
 # Other functions
 org.csstudio.apputil.formula.demo.Factorial
 org.csstudio.apputil.formula.areadetector.ADDataTypeMappingFunction
+org.csstudio.apputil.formula.areadetector.ImageWidthFunction
+org.csstudio.apputil.formula.areadetector.ImageHeightFunction
 
 # String
 org.csstudio.apputil.formula.string.StringFunction