From d0ba2d54ed60c67fb2ca91f1eb534d800e3d7e6c Mon Sep 17 00:00:00 2001
From: Jakob Heher <jakob.heher@iaik.tugraz.at>
Date: Thu, 3 Nov 2022 15:01:23 +0100
Subject: fix UX race condition in positioningpanel

cf. #129
---
 .../at/asit/pdfover/gui/composites/PositioningComposite.java  | 11 +++++++++--
 .../java/at/asit/pdfover/gui/composites/SignaturePanel.java   |  4 ++--
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/PositioningComposite.java b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/PositioningComposite.java
index 85b950a6..5be8a4c7 100644
--- a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/PositioningComposite.java
+++ b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/PositioningComposite.java
@@ -26,6 +26,7 @@ import java.awt.event.KeyEvent;
 import java.awt.event.KeyListener;
 import java.awt.event.MouseWheelEvent;
 import java.awt.event.MouseWheelListener;
+import java.awt.geom.Point2D;
 
 import org.apache.pdfbox.pdmodel.PDDocument;
 import org.eclipse.swt.SWT;
@@ -123,6 +124,8 @@ public class PositioningComposite extends StateComposite {
 		requestFocus();
 	}
 
+	@Override public void onDisplay() { if (this.viewer.getSigPagePos() == null) this.btnSign.setEnabled(false); }
+
 	/**
 	 * Set the PDF Document to display
 	 *
@@ -132,6 +135,7 @@ public class PositioningComposite extends StateComposite {
 	public void displayDocument(final PDDocument document) {
 		EventQueue.invokeLater(() -> {
 			this.viewer.setDocument(document);
+			getDisplay().asyncExec(() -> this.btnSign.setEnabled(true));
 		});
 
 		if (document != null)
@@ -333,9 +337,12 @@ public class PositioningComposite extends StateComposite {
 		if (this.currentPage == 0) {
 			this.position = new SignaturePosition();
 		} else {
+			Point2D pos = this.viewer.getSigPagePos();
+			if (pos == null) return;
+
 			this.position = new SignaturePosition(
-					this.viewer.getSigPageX(),
-					this.viewer.getSigPageY(),
+					pos.getX(),
+					pos.getY(),
 					this.currentPage);
 		}
 		PositioningComposite.this.state.updateStateMachine();
diff --git a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/SignaturePanel.java b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/SignaturePanel.java
index 72811050..6f4064bc 100644
--- a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/SignaturePanel.java
+++ b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/SignaturePanel.java
@@ -29,6 +29,7 @@ import java.awt.geom.Rectangle2D;
 import java.awt.image.BufferedImage;
 import java.io.IOException;
 
+import javax.annotation.CheckForNull;
 import javax.swing.JPanel;
 
 import org.apache.pdfbox.pdmodel.PDDocument;
@@ -110,8 +111,7 @@ public class SignaturePanel extends JPanel {
 	private int offY = 0;
 	/** The position of the top-left corner of the signature, in absolute page space */
 	private Point2D sigPagePos = null;
-	public double getSigPageX() { return this.sigPagePos.getX(); }
-	public double getSigPageY() { return this.sigPagePos.getY(); }
+	public @CheckForNull Point2D getSigPagePos() { return this.sigPagePos; }
 	/** The signature placeholder image */
 	private Image sigPlaceholder = null;
 	/** Width of the signature placeholder in page space */
-- 
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