--- a/gnv-artifacts/ChangeLog	Wed Jun 09 17:11:54 2010 +0000
+++ b/gnv-artifacts/ChangeLog	Thu Jun 10 09:05:58 2010 +0000
@@ -1,3 +1,10 @@
+2010-06-10  Ingo Weinzierl <ingo.weinzierl@intevation.de>
+
+	  Issue290 - Centering of pdf exports
+
+	* src/main/java/de/intevation/gnv/exports/ChartExportHelper.java: PDF
+	  exports of charts are centered now.
+
 2010-06-09  Ingo Weinzierl <ingo.weinzierl@intevation.de>
 
 	* src/main/java/de/intevation/gnv/chart/VerticalProfileVectorChart.java,

--- a/gnv-artifacts/src/main/java/de/intevation/gnv/exports/ChartExportHelper.java	Wed Jun 09 17:11:54 2010 +0000
+++ b/gnv-artifacts/src/main/java/de/intevation/gnv/exports/ChartExportHelper.java	Thu Jun 10 09:05:58 2010 +0000
@@ -248,8 +248,8 @@
 
         // max size of the chart
         Rectangle page = PageSize.getRectangle(pageFormat);
-        int pageWidth  = (int) (page.getRight(marginRight) - page.getLeft(marginLeft));
-        int pageHeight = (int) (page.getTop(marginTop) - page.getBottom(marginBottom));
+        float pageWidth  = page.getWidth();
+        float pageHeight = page.getHeight();
 
         // the chart width
         int chartWidth  = (Integer) context.getContextValue("chart.width");
@@ -257,8 +257,8 @@
 
         boolean landscape = chartWidth > chartHeight ? true : false;
 
-        int width  = 0;
-        int height = 0;
+        float width  = 0;
+        float height = 0;
         if (landscape) {
             width  = pageHeight;
             height = pageWidth;
@@ -268,17 +268,19 @@
             height = pageHeight;
         }
 
-        if (chartWidth > width) {
+        float spaceX = width  - marginLeft - marginRight;
+        if (chartWidth > spaceX) {
             log.warn("Width of the chart is too big for pdf -> resize it now.");
-            double ratio = ((double)width) / chartWidth;
+            double ratio = ((double)spaceX) / chartWidth;
             chartWidth  *= ratio;
             chartHeight *= ratio;
             log.debug("Resized chart to " + chartWidth + "x" + chartHeight);
         }
 
-        if (chartHeight > height) {
+        float spaceY = height - marginTop  - marginBottom;
+        if (chartHeight > spaceY) {
             log.warn("Height of the chart is too big for pdf -> resize it now.");
-            double ratio = ((double)height) / chartHeight;
+            double ratio = ((double)spaceY) / chartHeight;
             chartWidth  *= ratio;
             chartHeight *= ratio;
             log.debug("Resized chart to " + chartWidth + "x" + chartHeight);
@@ -302,14 +304,19 @@
             PdfContentByte content  = writer.getDirectContent();
 
             PdfTemplate template = content.createTemplate(width, height);
-            Graphics2D  graphics = template.createGraphics(
+            Graphics2D  graphics = template.createGraphics(width, height);
+
+            double[] origin = getCenteredAnchor(
+                marginLeft, marginRight, marginBottom, marginTop,
+                width, height,
                 chartWidth, chartHeight);
+
             Rectangle2D area = new Rectangle2D.Double(
-                0.0D, 0.0D, chartWidth, chartHeight);
+                origin[0], origin[1], chartWidth, chartHeight);
 
             chart.draw(graphics, area);
             graphics.dispose();
-            content.addTemplate(template, marginLeft, marginBottom);
+            content.addTemplate(template, 0f, 0f);
         }
         catch (DocumentException de) {
             log.error("Error while exporting chart to pdf.", de);
@@ -431,5 +438,59 @@
             document.close();
         }
     }
+
+
+    /**
+     * This method returns the anchor of the chart so that the chart is centered
+     * according to the given parameters.
+     *
+     * @param mLeft Left margin
+     * @param mRight Right margin
+     * @param mBottom Bottom margin
+     * @param mTop Top margin
+     * @param width The complete width of the drawing area.
+     * @param height The complete height of the drawing area.
+     * @param chartWidth The width of the chart.
+     * @param chartHeight The height of the chart.
+     *
+     * @return an array that contains the anchor for a chart with the given
+     * parameters. The first value is the x point, the second value is the y
+     * point.
+     */
+    public static double[] getCenteredAnchor(
+        double mLeft,      double mRight,      double mBottom, double mTop,
+        double width,      double height,
+        double chartWidth, double chartHeight
+    ) {
+        if (log.isDebugEnabled()) {
+            log.debug("Calculate centered origin...");
+            log.debug("-> PDF width    : " + width);
+            log.debug("-> PDF height   : " + height);
+            log.debug("-> Chart width  : " + chartWidth);
+            log.debug("-> Chart height : " + chartHeight);
+            log.debug("-> margin left  : " + mLeft);
+            log.debug("-> margin right : " + mRight);
+            log.debug("-> margin bottom: " + mBottom);
+            log.debug("-> margin top   : " + mTop);
+        }
+
+        double[] origin = new double[2];
+
+        double centerX = width  / 2;
+        double centerY = height / 2;
+
+        origin[0] = centerX - chartWidth / 2;
+        origin[1] = centerY - chartHeight / 2;
+
+        origin[0] = origin[0] >= mLeft ? origin[0] : mLeft;
+        origin[1] = origin[1] >= mTop ? origin[1] : mTop;
+
+        if (log.isDebugEnabled()) {
+            log.debug("==> centered left origin: " + origin[0]);
+            log.debug("==> centered top  origin: " + origin[1]);
+        }
+
+        return origin;
+    }
 }
 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf-8 :