gnujpdf gradient transparency

libsrc/gnujpdf/src/gnu/jpdf/PDFGradientFunction3.java

@@ -0,0 +1,43 @@
+package gnu.jpdf;
+
+import java.awt.MultipleGradientPaint;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ *
+ * @author JPEXS
+ */
+public class PDFGradientFunction3 extends PDFObject {
+
+    private final MultipleGradientPaint fgrad;
+
+    private final List<String> functions2Refs;
+
+    public PDFGradientFunction3(MultipleGradientPaint fgrad, List<String> functions2Refs) {
+        super(null);
+        this.fgrad = fgrad;
+        this.functions2Refs = functions2Refs;
+    }
+
+    @Override
+    public void write(OutputStream os) throws IOException {
+        writeStart(os);
+        os.write(("/FunctionType 3 /Domain [0 1] /Functions [" + String.join(" ", functions2Refs) + "] ").getBytes());
+        int lastcols = fgrad.getColors().length - 1;
+        List<String> bounds = new ArrayList<>();
+        List<String> encode = new ArrayList<>();
+        for (int i = 1; i < fgrad.getColors().length; i++) {
+            if (i < lastcols) {
+                bounds.add("" + fgrad.getFractions()[i]);
+            }
+            encode.add("0 1");
+        }
+        os.write(("/Bounds [" + String.join(" ", bounds) + "] ").getBytes());
+        os.write(("/Encode [" + String.join(" ", encode) + "]\n").getBytes());
+        writeEnd(os);
+    }
+
+}