Proof-of-concept for auto-trimming of page margins

de.vonloesch.pdf4eclipse/OSGI-INF/l10n/bundle.properties

@@ -8,9 +8,11 @@ command.description.0 = Set the zoom level
 command.name.0 = Zoom
 commandParameter.name = zoomlevel
 command.name.1 = Toggle highlight
+command.name.2 = Toggle auto-trimming
 command.tooltip = Zoom out
 command.tooltip.0 = Fit page to window
 command.tooltip.1 = Fit page to window width
 command.tooltip.2 = Zoom in
 command.tooltip.3 = Toggle link highlighting
+command.tooltip.4 = Trim Page Margins
 context.name = PDF viewer

de.vonloesch.pdf4eclipse/plugin.xml

@@ -56,6 +56,27 @@
             </class>
          </state>
       </command>
+      <command
+            categoryId="de.vonloesch.pdf4Eclipse.category"
+            defaultHandler="de.vonloesch.pdf4eclipse.editors.handlers.ToggleAutoTrimHandler"
+            helpContextId="de.vonloesch.pdf4eclipse.annotationsToggleAutoTrim"
+            id="PDFViewer.command.ToggleAutoTrim"
+            name="%command.name.2">
+         <state
+               id="org.eclipse.ui.commands.toggleState">
+            <class
+                  class="org.eclipse.ui.handlers.RegistryToggleState">
+               <parameter
+                     name="persisted"
+                     value="true">
+               </parameter>
+               <parameter
+                     name="default"
+                     value="false">
+               </parameter>
+            </class>
+         </state>
+      </command>
       <category
             id="de.vonloesch.pdf4Eclipse.category"
             name="Pdf4Eclipse">
@@ -190,6 +211,18 @@
                   </reference>
                </visibleWhen>
             </command>
+            <command
+                  commandId="PDFViewer.command.ToggleAutoTrim"
+                  icon="icons/autotrim.png"
+                  style="toggle"
+                  tooltip="%command.tooltip.4">
+               <visibleWhen
+                     checkEnabled="false">
+                  <reference
+                        definitionId="PDFViewer.definitions.isPDFEditorActive">
+                  </reference>
+               </visibleWhen>
+            </command>
          </toolbar>
       </menuContribution>
    </extension>

de.vonloesch.pdf4eclipse/src/de/vonloesch/pdf4eclipse/PDFPageViewer.java

@@ -7,6 +7,7 @@
  * 
  * Contributors:
  *     Boris von Loesch - initial API and implementation
+ *     Robert Bamler - auto-trimming of page margins
  ******************************************************************************/
 package de.vonloesch.pdf4eclipse;
 
@@ -16,6 +17,7 @@
 import java.awt.geom.Rectangle2D.Double;
 import java.awt.image.BufferedImage;
 import java.awt.image.DataBufferByte;
+import java.awt.image.DataBufferInt;
 import java.awt.image.DirectColorModel;
 import java.awt.image.IndexColorModel;
 import java.awt.image.WritableRaster;
@@ -39,6 +41,7 @@
 import org.eclipse.swt.widgets.Display;
 
 import de.vonloesch.pdf4eclipse.editors.PDFEditor;
+import de.vonloesch.pdf4eclipse.editors.handlers.ToggleAutoTrimHandler;
 import de.vonloesch.pdf4eclipse.editors.handlers.ToggleLinkHighlightHandler;
 import de.vonloesch.pdf4eclipse.model.IPDFLinkAnnotation;
 import de.vonloesch.pdf4eclipse.model.IPDFPage;
@@ -72,6 +75,11 @@ public class PDFPageViewer extends Canvas implements PaintListener, IPreferenceC
 
     private float zoomFactor;
 
+    private boolean autoTrimOn = true;
+    private Point trimOffset = new Point(0, 0);
+    private float horizontalTrimFactor = 1.0f;
+    private float verticalTrimFactor = 1.0f;
+
     //private org.eclipse.swt.graphics.Image swtImage;
 
     /**
@@ -178,6 +186,7 @@ public void run() {
 		prefs.addPreferenceChangeListener(this);
 
 		highlightLinks = prefs.getBoolean(ToggleLinkHighlightHandler.PREF_LINKHIGHTLIGHT_ID, true);
+		autoTrimOn = prefs.getBoolean(ToggleAutoTrimHandler.PREF_AUTOTRIM_ID, false);
     }
 
 
@@ -299,13 +308,17 @@ public void showPage(IPDFPage page) {
     	highlight = null;
 
     	boolean resize = false;
-    	int newW = Math.round(zoomFactor*page.getWidth());
-    	int newH = Math.round(zoomFactor*page.getHeight());
+    	// always round _down_ so that the fit-to-screen commands work properly
+    	int newW = (int) (zoomFactor*page.getWidth());
+    	int newH = (int) (zoomFactor*page.getHeight());
 
     	Point sz = getSize();
 
     	if (sz.x == 0 || sz.y == 0) return;
     	currentImage = page.getImage(newH, newW);
+    	if (autoTrimOn) {
+    		trimCurrentImage();
+    	}
 
     	newW = currentImage.getWidth(null);
     	newH = currentImage.getHeight(null);
@@ -329,16 +342,97 @@ public void showPage(IPDFPage page) {
     	}
     }
 
+    private void trimCurrentImage() {
+    	if (currentImage==null)
+    		return;
+
+    	int origw = currentImage.getWidth(null);
+    	int origh = currentImage.getHeight(null);
+    	if (origw<1 || origh<1)
+    		return;
+
+    	BufferedImage img = new BufferedImage(origw, origh, BufferedImage.TYPE_INT_ARGB);
+    	img.getGraphics().drawImage(currentImage, 0, 0, origw, origh, 0, 0,	origw, origh, null);
+
+    	int[] srcbuf = ((DataBufferInt) img.getRaster().getDataBuffer()).getData();
+
+    	// detect upper margin
+    	int trimy1 = origh;
+    	int referenceColor = srcbuf[0];
+    	for (int i=0; i!=srcbuf.length; i++) {
+    		if (srcbuf[i] != referenceColor) {
+    			trimy1 = i/origw;
+    			break;
+    		}
+    	}
+
+    	// detect lower margin
+    	int trimy2 = 0;
+    	referenceColor = srcbuf[srcbuf.length-1];
+    	for (int i=srcbuf.length-1; i!=trimy1*origw-1; i--) {
+    		if (srcbuf[i] != referenceColor) {
+    			trimy2 = i/origw + 1;
+    			break;
+    		}
+    	}
+
+    	// detect left margin
+    	int trimx1 = 0;
+    	referenceColor = srcbuf[0];
+    	int offset = trimy1*origw;
+    	int end = trimy2*origw;
+    	trimx1loop:
+    		while (trimx1 != origw) {
+    			for (int i=offset+trimx1; i<end; i+=origw) {
+    				if (srcbuf[i] != referenceColor)
+    					break trimx1loop;
+    			}
+    			trimx1++;
+    		}
+
+    	// detect right margin
+    	int trimx2 = origw-1;
+    	referenceColor = srcbuf[srcbuf.length-1];
+    	trimx2loop:
+    		while (trimx2 != trimy1) {
+    			for (int i=offset+trimx2; i<end; i+=origw) {
+    				if (srcbuf[i] != referenceColor)
+    					break trimx2loop;
+    			}
+    			trimx2--;
+    		}
+    	trimx2++;
+
+    	// add some margin (2% of the smaller one of the two dimensions) 
+    	int margin = Math.min(trimx2-trimx1, trimy2-trimy1) / 50;
+    	trimx1 = Math.max(0, trimx1-margin);
+    	trimx2 = Math.min(origw, trimx2+margin);
+    	trimy1 = Math.max(0, trimy1-margin);
+    	trimy2 = Math.min(origh, trimy2+margin);
+
+    	// remember trim margins
+    	trimOffset .x = trimx1;
+    	trimOffset.y = trimy1;
+    	horizontalTrimFactor = 1.0f * (trimx2-trimx1) / origw;
+    	verticalTrimFactor = 1.0f * (trimy2-trimy1) / origh;
+
+    	// crop image
+    	currentImage = img.getSubimage(trimx1, trimy1, trimx2-trimx1, trimy2-trimy1);
+    }
+
     private Rectangle getRectangle(Rectangle2D r) {
     	return new Rectangle((int)Math.round(r.getX()), (int)Math.round(r.getY()), (int)Math.round(r.getWidth()), (int)Math.round(r.getHeight()));
     }
 
     public Rectangle2D convertPDF2ImageCoord(Rectangle2D r) {
-    	return currentPage.pdf2ImageCoordinates(r);
+    	Rectangle2D coord = currentPage.pdf2ImageCoordinates(r);
+    	coord.setRect(coord.getX()-trimOffset.x, coord.getY()-trimOffset.y, coord.getWidth(), coord.getHeight());
+    	return coord;
     }
 
     public Rectangle2D convertImage2PDFCoord(Rectangle2D r) {
-    	return currentPage.image2PdfCoordinates(r);
+    	java.awt.Rectangle coord = new java.awt.Rectangle((int)r.getX()+trimOffset.x, (int)r.getY()+trimOffset.y, (int)r.getWidth(), (int)r.getHeight());
+    	return currentPage.image2PdfCoordinates(coord);
     }
 
     /**
@@ -423,6 +517,15 @@ public void preferenceChange(PreferenceChangeEvent event) {
     	if (ToggleLinkHighlightHandler.PREF_LINKHIGHTLIGHT_ID.equals(event.getKey())) {
     		highlightLinks = Boolean.parseBoolean((String)(event.getNewValue()));
     		redraw();
+    	} else if (ToggleAutoTrimHandler.PREF_AUTOTRIM_ID.equals(event.getKey())) {
+    		autoTrimOn = Boolean.parseBoolean((String)(event.getNewValue()));
+    		if (!autoTrimOn) {
+    			trimOffset.x = 0;
+    			trimOffset.y = 0;
+    			horizontalTrimFactor = 1.0f;
+    			verticalTrimFactor = 1.0f;
+    		}
+    		showPage(currentPage);
     	}
     }
 
@@ -445,4 +548,14 @@ public void dispose() {
     	IEclipsePreferences prefs = (new InstanceScope()).getNode(de.vonloesch.pdf4eclipse.Activator.PLUGIN_ID);
     	prefs.removePreferenceChangeListener(this);
     }
+
+
+	public float getHorizontalTrimFactor() {
+		return horizontalTrimFactor;
+	}
+
+
+	public float getVerticalTrimFactor() {
+		return verticalTrimFactor;
+	}
 }

de.vonloesch.pdf4eclipse/src/de/vonloesch/pdf4eclipse/editors/PDFEditor.java

@@ -8,6 +8,7 @@
  * Contributors:
  *     Boris von Loesch - initial API and implementation
  *     MeisterYeti - pseudo-continuous scrolling and zooming by mouse wheel
+ *     Robert Bamler - auto-trimming of page margins
  ******************************************************************************/
 package de.vonloesch.pdf4eclipse.editors;
 
@@ -742,12 +743,12 @@ private void updateStatusLine() {
 
 	public void fitHorizontal() {
 		int w = sc.getClientArea().width;
-		pv.setZoomFactor((1.0f*w)/pv.getPage().getWidth());
+		pv.setZoomFactor((1.0f/pv.getHorizontalTrimFactor()*w)/pv.getPage().getWidth());
 	}
 
 	public void fit() {
-		float w = 1.f * sc.getClientArea().width;
-		float h = 1.f * sc.getClientArea().height;
+		float w = 1.f/pv.getHorizontalTrimFactor() * sc.getClientArea().width;
+		float h = 1.f/pv.getVerticalTrimFactor() * sc.getClientArea().height;
 		float pw = pv.getPage().getWidth();
 		float ph = pv.getPage().getHeight();
 		if (w/pw < h/ph) pv.setZoomFactor(w/pw);

de.vonloesch.pdf4eclipse/src/de/vonloesch/pdf4eclipse/editors/handlers/ToggleAutoTrimHandler.java

@@ -0,0 +1,65 @@
+/*******************************************************************************
+ * Copyright (c) 2011 Boris von Loesch.
+ * 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
+ * 
+ * Contributors:
+ *     Boris von Loesch - initial API and implementation
+ *     Robert Bamler - auto-trimming of page margins
+ ******************************************************************************/
+package de.vonloesch.pdf4eclipse.editors.handlers;
+
+import java.util.Map;
+
+import org.eclipse.core.commands.AbstractHandler;
+import org.eclipse.core.commands.Command;
+import org.eclipse.core.commands.ExecutionEvent;
+import org.eclipse.core.commands.ExecutionException;
+import org.eclipse.core.commands.State;
+import org.eclipse.core.runtime.preferences.IEclipsePreferences;
+import org.eclipse.core.runtime.preferences.InstanceScope;
+import org.eclipse.ui.PlatformUI;
+import org.eclipse.ui.commands.ICommandService;
+import org.eclipse.ui.commands.IElementUpdater;
+import org.eclipse.ui.handlers.RegistryToggleState;
+import org.eclipse.ui.menus.UIElement;
+import org.osgi.service.prefs.BackingStoreException;
+
+public class ToggleAutoTrimHandler extends AbstractHandler implements IElementUpdater{
+
+	public final static String PREF_AUTOTRIM_ID = "de.vonloesch.pdf4eclipse.preferences.autoTrim";
+
+	private final static String COMMAND_ID = "PDFViewer.command.ToggleAutoTrim";
+	private final static String STATE_ID = RegistryToggleState.STATE_ID;
+
+	@Override
+	public Object execute(ExecutionEvent event) throws ExecutionException {
+		Command command = event.getCommand();
+		State state = command.getState(STATE_ID);
+		state.setValue(!(Boolean) state.getValue());
+
+		ICommandService service =
+				(ICommandService) PlatformUI.getWorkbench().getService(ICommandService.class);
+		service.refreshElements(command.getId(), null);
+		IEclipsePreferences prefs = (new InstanceScope()).getNode(de.vonloesch.pdf4eclipse.Activator.PLUGIN_ID);
+		prefs.putBoolean(PREF_AUTOTRIM_ID, ((Boolean) state.getValue()).booleanValue());
+		try {
+			prefs.flush();
+		} catch (BackingStoreException e) {
+			//Do nothing
+		}
+		return null;
+	}	
+
+	@Override
+	public void updateElement(UIElement element, Map parameters) {
+		ICommandService service =
+				(ICommandService) PlatformUI.getWorkbench().getService(ICommandService.class);
+		Command command = service.getCommand(COMMAND_ID);
+		State state = command.getState(STATE_ID);
+		element.setChecked(((Boolean) state.getValue()).booleanValue());		
+	}
+
+}