Bugfix drawing zoom rectangle

1 files changed, 9 insertions, 1 deletions

diff --git a/Week11 Mandelbrot/src/com/camilstaps/mandelbrot/ZoomFrame.java b/Week11 Mandelbrot/src/com/camilstaps/mandelbrot/ZoomFrame.java
index 1a48926..b7b5a68 100644
--- a/Week11 Mandelbrot/src/com/camilstaps/mandelbrot/ZoomFrame.java
+++ b/Week11 Mandelbrot/src/com/camilstaps/mandelbrot/ZoomFrame.java
@@ -23,6 +23,7 @@ public class ZoomFrame extends JFrame implements MouseListener, MouseMotionListe
     private Graphics graphics;
     
     private int start_x, start_y, old_x, old_y;
+    private boolean dragging = false;
     
     public ZoomFrame(String s) {
         super(s);
@@ -85,6 +86,8 @@ public class ZoomFrame extends JFrame implements MouseListener, MouseMotionListe
         }
             
         mandelbrotController.redraw();
+        
+        dragging = false;
     }
 
     @Override
@@ -99,9 +102,12 @@ public class ZoomFrame extends JFrame implements MouseListener, MouseMotionListe
     public void mouseDragged(MouseEvent me) {
         Graphics g = getSafeGraphics();
         if (g != null) {
-            eraseZoombox();
+            if (dragging) {
+                eraseZoombox();
+            }
             g.drawRect(start_x, start_y, me.getX() - start_x, me.getX() - start_x);
             old_y = old_x = me.getX();
+            dragging = true;
         }
     }
     
@@ -114,6 +120,8 @@ public class ZoomFrame extends JFrame implements MouseListener, MouseMotionListe
     }
     
     private void eraseZoombox() {
+        if (start_x < 0 || start_y < 0 || old_x < 0 || old_y < 0)
+            return;
         Graphics g = getSafeGraphics();
         if (g != null)
             g.drawRect(start_x, start_y, old_x - start_x, old_y - start_x);