Bugzilla #36067

Support for relative font sizes.
Submitted by: Manuel Mall <mm.at.arcus.com.au>

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@231198 13f79535-47bb-0310-9956-ffa450edef68

3 files changed, 197 insertions, 2 deletions

diff --git a/src/java/org/apache/fop/fo/FOPropertyMapping.java b/src/java/org/apache/fop/fo/FOPropertyMapping.java
index b90256632..5cf6d2bdc 100644
--- a/src/java/org/apache/fop/fo/FOPropertyMapping.java
+++ b/src/java/org/apache/fop/fo/FOPropertyMapping.java
@@ -32,6 +32,8 @@ import org.apache.fop.fo.properties.CondLengthProperty;
 import org.apache.fop.fo.properties.CorrespondingPropertyMaker;
 import org.apache.fop.fo.properties.DimensionPropertyMaker;
 import org.apache.fop.fo.properties.EnumProperty;
+import org.apache.fop.fo.properties.FontSizePropertyMaker;
+import org.apache.fop.fo.properties.FontStretchPropertyMaker;
 import org.apache.fop.fo.properties.GenericShorthandParser;
 import org.apache.fop.fo.properties.IndentPropertyMaker;
 import org.apache.fop.fo.properties.KeepProperty;
@@ -1081,7 +1083,7 @@ public class FOPropertyMapping implements Constants {
         addPropertyMaker("font-selection-strategy", m);
 
         // font-size
-        m  = new LengthProperty.Maker(PR_FONT_SIZE);
+        m  = new FontSizePropertyMaker(PR_FONT_SIZE);
         m.setInherited(true);
         m.setDefault("12pt");
         m.addKeyword("xx-small", "6.944pt");
@@ -1091,11 +1093,13 @@ public class FOPropertyMapping implements Constants {
         m.addKeyword("large", "14.4pt");
         m.addKeyword("x-large", "17.28pt");
         m.addKeyword("xx-large", "20.736pt");
+        m.addEnum("larger", getEnumProperty(EN_LARGER, "LARGER"));
+        m.addEnum("smaller", getEnumProperty(EN_SMALLER, "SMALLER"));
         m.setPercentBase(LengthBase.INH_FONTSIZE);
         addPropertyMaker("font-size", m);
 
         // font-stretch
-        m  = new EnumProperty.Maker(PR_FONT_STRETCH);
+        m  = new FontStretchPropertyMaker(PR_FONT_STRETCH);
         m.addEnum("normal", getEnumProperty(EN_NORMAL, "NORMAL"));
         m.addEnum("wider", getEnumProperty(EN_WIDER, "WIDER"));
         m.addEnum("narrower", getEnumProperty(EN_NARROWER, "NARROWER"));
diff --git a/src/java/org/apache/fop/fo/properties/FontSizePropertyMaker.java b/src/java/org/apache/fop/fo/properties/FontSizePropertyMaker.java
new file mode 100644
index 000000000..83379dfa4
--- /dev/null
+++ b/src/java/org/apache/fop/fo/properties/FontSizePropertyMaker.java
@@ -0,0 +1,96 @@
+/*
+ * Copyright 2005 The Apache Software Foundation.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* $Id: $ */
+
+package org.apache.fop.fo.properties;
+import org.apache.fop.fo.Constants;
+import org.apache.fop.fo.FObj;
+import org.apache.fop.fo.PropertyList;
+import org.apache.fop.fo.expr.PropertyException;
+
+/**
+ * This subclass of LengthProperty.Maker handles the special treatment of 
+ * relative font sizes described in 7.8.4.
+ */
+public class FontSizePropertyMaker 
+    extends LengthProperty.Maker implements Constants {
+
+    /** The default normal font size in mpt */
+    private static final int FONT_SIZE_NORMAL = 12000;
+    /** The factor to be applied when stepping font sizes upwards */
+    private static final double FONT_SIZE_GROWTH_FACTOR = 1.2;
+    
+    /**
+     * Create a length property which can handle relative font sizes 
+     * @param propId the font size property id.
+     */
+    public FontSizePropertyMaker(int propId) {
+        super(propId);
+    }
+    
+    /**
+     * @see PropertyMaker#convertProperty
+     * Implements the parts of 7.8.4 relevant to relative font sizes
+     */
+    public Property convertProperty(Property p,
+                                    PropertyList propertyList,
+                                    FObj fo) throws PropertyException {
+        if (p.getEnum() == EN_LARGER || p.getEnum() == EN_SMALLER) {
+            // get the corresponding property from parent
+            Property pp = propertyList.getFromParent(this.getPropId());
+            int baseFontSize = computeClosestAbsoluteFontSize(pp.getLength().getValue());
+            if (p.getEnum() == EN_LARGER) {
+                return new FixedLength((int)Math.round((baseFontSize * FONT_SIZE_GROWTH_FACTOR)));
+            } else {
+                return new FixedLength((int)Math.round((baseFontSize / FONT_SIZE_GROWTH_FACTOR)));
+            }
+        }
+        return super.convertProperty(p, propertyList, fo);
+    }
+    
+    /**
+     * Calculates the nearest absolute font size to the given
+     * font size.
+     * @param baseFontSize the font size in mpt of the parent fo
+     * @return the closest absolute font size
+     */
+    private int computeClosestAbsoluteFontSize(int baseFontSize) {
+        double scale = FONT_SIZE_GROWTH_FACTOR;
+        int lastStepFontSize = FONT_SIZE_NORMAL;
+        if (baseFontSize < FONT_SIZE_NORMAL) {
+            // Need to shrink the font sizes = scale downwards
+            scale = 1 / FONT_SIZE_GROWTH_FACTOR;
+        }
+        // Calculate the inital next step font size
+        int nextStepFontSize = (int)Math.round(lastStepFontSize * scale);
+        while (scale < 1 && nextStepFontSize > baseFontSize
+                || scale > 1 && nextStepFontSize < baseFontSize) {
+            // baseFontSize is still bigger (if we grow) or smaller (if we shrink)
+            // than the last caculated step
+            lastStepFontSize = nextStepFontSize;
+            nextStepFontSize = (int)Math.round(lastStepFontSize * scale);
+        }
+        // baseFontSize is between last and next step font size
+        // Return the step value closer to the baseFontSize
+        if (Math.abs(lastStepFontSize - baseFontSize) 
+                <= Math.abs(baseFontSize - nextStepFontSize)) {
+            return lastStepFontSize;
+        }
+        return nextStepFontSize;
+    }
+
+}
diff --git a/src/java/org/apache/fop/fo/properties/FontStretchPropertyMaker.java b/src/java/org/apache/fop/fo/properties/FontStretchPropertyMaker.java
new file mode 100644
index 000000000..825633206
--- /dev/null
+++ b/src/java/org/apache/fop/fo/properties/FontStretchPropertyMaker.java
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2005 The Apache Software Foundation.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* $Id: $ */
+
+package org.apache.fop.fo.properties;
+import org.apache.fop.fo.Constants;
+import org.apache.fop.fo.FObj;
+import org.apache.fop.fo.PropertyList;
+import org.apache.fop.fo.expr.PropertyException;
+
+/**
+ * This subclass of EnumProperty.Maker handles the special treatment of 
+ * relative font stretch values described in 7.8.5.
+ */
+public class FontStretchPropertyMaker 
+    extends EnumProperty.Maker implements Constants {
+    
+    /* Ordered list of absolute font stretch properties so we can easily find the next /
+     * previous one */
+    private Property[] orderedFontStretchValues = null;
+        
+    /**
+     * Create an enum property which can handle relative font stretches 
+     * @param propId the font size property id.
+     */
+    public FontStretchPropertyMaker(int propId) {
+        super(propId);
+    }
+    
+    /**
+     * @see PropertyMaker#convertProperty
+     * Implements the parts of 7.8.5 relevant to relative font stretches
+     */
+    public Property convertProperty(Property p,
+                                    PropertyList propertyList,
+                                    FObj fo) throws PropertyException {
+        // if it is a relative font stretch value get current parent value and step
+        // up or down accordingly
+        if (p.getEnum() == EN_NARROWER) {
+            return computeNextAbsoluteFontStretch(propertyList.getFromParent(this.getPropId()), -1);
+        } else if (p.getEnum() == EN_WIDER) {
+            return computeNextAbsoluteFontStretch(propertyList.getFromParent(this.getPropId()), 1);
+        }
+        return super.convertProperty(p, propertyList, fo);
+    }
+
+    /**
+     * Calculates the nearest absolute font stretch property to the given
+     * font stretch
+     * @param baseProperty the font stretch property as set on the parent fo
+     * @param direction should be -1 to get the next narrower value or +1 for the next wider value
+     */
+    private Property computeNextAbsoluteFontStretch(Property baseProperty, int direction) {
+        // Create the table entries the first time around
+        // @todo is this thread safe, do we need to worry about this here?
+        if (orderedFontStretchValues == null) {
+            orderedFontStretchValues = new Property[] {
+                checkEnumValues("ultra-condensed"),
+                checkEnumValues("extra-condensed"),
+                checkEnumValues("condensed"),
+                checkEnumValues("semi-condensed"),
+                checkEnumValues("normal"),
+                checkEnumValues("semi-expanded"),
+                checkEnumValues("expanded"),
+                checkEnumValues("extra-expanded"),
+                checkEnumValues("ultra-expanded")
+            };
+        }
+        int baseValue = baseProperty.getEnum();
+        for (int i = 0; i < orderedFontStretchValues.length; i++) {
+            if (baseValue == orderedFontStretchValues[i].getEnum()) {
+                // increment/decrement the index and make sure its within the array bounds
+                i = Math.min(Math.max(0, i + direction), orderedFontStretchValues.length - 1);
+                return orderedFontStretchValues[i];
+            }
+        }
+        // return the normal value
+        return orderedFontStretchValues[4];
+    }
+
+}