Feat/rasterizer update 21

This feature update adds logging to the current implementation of the rendering package. It also includes minor refactorings in the FunctionalRenderingBase and ImageRasterizer. (No changes in functionality) Please review.

src/main/java/de/tudresden/inf/mci/brailleplot/rendering/ImageRasterizer.java

 package de.tudresden.inf.mci.brailleplot.rendering;
 
 import de.tudresden.inf.mci.brailleplot.printabledata.MatrixData;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.awt.image.BufferedImage;
 
@@ -20,6 +22,8 @@ public class ImageRasterizer implements Rasterizer<Image> {
     // it is technically also possible to implement a rasterizer as a method independent from a class, as long
     // as it takes a renderable and a canvas as parameters.
 
+    private final Logger mLogger = LoggerFactory.getLogger(this.getClass());
+
     // Switches
     private boolean mPreventOverStretch;
     private boolean mPreserveAspectRatio;
@@ -27,16 +31,14 @@ public class ImageRasterizer implements Rasterizer<Image> {
 
     // Output threshold: A dot will be set for gray scale values below (darker than/equal) this threshold.
     private int mLowThreshold;
-    private final int mDefaultThreshold = 80;
+    private static final int DEFAULT_THRESHOLD = 80;
 
     /**
      * Constructor. Creates a new {@link Rasterizer} for instances of {@link Image} with default settings.
      */
     public ImageRasterizer() {
-        mPreventOverStretch = true;
-        mPreserveAspectRatio = true;
-        mQuantifiedPositions = true;
-        mLowThreshold = mDefaultThreshold;
+        this(true, true, true, DEFAULT_THRESHOLD);
+        mLogger.trace("ImageRasterizer has been setup with default settings");
     }
 
     /**
@@ -60,6 +62,8 @@ public class ImageRasterizer implements Rasterizer<Image> {
         mPreserveAspectRatio = preserveAspectRatio;
         mQuantifiedPositions = useQuantifiedPositions;
         mLowThreshold = threshold;
+        mLogger.trace("Created ImageRasterizer. Settings: preventOverStretch={}, preserveAspectRatio={}, useQuantifiedPositions={}, lowThreshold={}",
+                mPreventOverStretch, mPreserveAspectRatio, mQuantifiedPositions, mLowThreshold);
     }
 
     /**
@@ -83,6 +87,9 @@ public class ImageRasterizer implements Rasterizer<Image> {
         // the grey scale value of each pixel.
         // A more sophisticated implementation could utilize an edge finding algorithm.
 
+        mLogger.info("Rasterizing Image {}", imgData);
+
+        mLogger.trace("Retrieving buffered image");
         // First, a readable representation of the is retrieved.
         BufferedImage imgBuf = imgData.getBufferedImage();
 
@@ -98,6 +105,8 @@ public class ImageRasterizer implements Rasterizer<Image> {
 
     private void linearMapping(final BufferedImage imgBuf, final RasterCanvas canvas) {
 
+        mLogger.trace("Applying linear mapping algorithm");
+
         // A canvas is basically a wrapper for multiple representations of printable data, each representing a page.
         // These representations can be acquired by either requesting the current page or creating a new page.
         MatrixData<Boolean> data = canvas.getNewPage();
@@ -134,6 +143,7 @@ public class ImageRasterizer implements Rasterizer<Image> {
         // This can lead to distortions because the original pixel raster is equidistant, but the output raster
         // does not have to be equidistant.
 
+        mLogger.trace("Starting scanning through image pixel values...");
         // Scan through each pixel of the original image
         for (int x = 0; x < imgBuf.getWidth(); x++) {
             // Convert from original pixel x-position to braille dot x-position.
@@ -149,15 +159,19 @@ public class ImageRasterizer implements Rasterizer<Image> {
                 }
             }
         }
+        mLogger.trace("Finished scanning the image");
     }
 
     private void quantifiedPositionMapping(final BufferedImage imgBuf, final RasterCanvas canvas) {
 
+        mLogger.trace("Applying quantified position algorithm");
+
         MatrixData<Boolean> data = canvas.getNewPage();
 
         // Instead of using the dot rectangle a rectangle representing the target printing space in millimeters
         // is built from the canvas information.
         Rectangle availableArea = new Rectangle(0, 0, canvas.getPrintableWidth(), canvas.getPrintableHeight());
+        mLogger.trace("Determined available area (in mm): {}", availableArea);
 
         // Calculate the ratios between original image and target printable area. (mm / pixel)
         double hRatio =  (availableArea.getWidth() / imgBuf.getWidth());
@@ -179,6 +193,7 @@ public class ImageRasterizer implements Rasterizer<Image> {
         // In a second step, the calculated exact position is quantified to fit a dot position on the raster.
         // Distortions can still be introduced but are minimized.
 
+        mLogger.trace("Staring scanning through image pixel values...");
         // Scan through all pixels of the original image
         for (int x = 0; x < imgBuf.getWidth(); x++) {
             // Convert from original pixel x-position to printed dot x-position in millimeters.
@@ -197,6 +212,7 @@ public class ImageRasterizer implements Rasterizer<Image> {
                 }
             }
         }
+        mLogger.trace("Finished scanning the image");
     }