JAL-147 don't scroll up beyond startRes = 0

[jalview.git] / src / jalview / viewmodel / ViewportRanges.java

diff --git a/src/jalview/viewmodel/ViewportRanges.java b/src/jalview/viewmodel/ViewportRanges.java
index abbc24c..10cf583 100644 (file)
--- a/src/jalview/viewmodel/ViewportRanges.java
+++ b/src/jalview/viewmodel/ViewportRanges.java
@@ -135,9 +135,10 @@ public class ViewportRanges extends ViewportProperties
     /*
      * if not wrapped, don't leave white space at the right margin
      */
-    if (!wrappedMode && (start > getVisibleAlignmentWidth() - 1))
+    int lastColumn = getVisibleAlignmentWidth() - 1;
+    if (!wrappedMode && (start > lastColumn))
     {
-      startRes = Math.max(getVisibleAlignmentWidth() - 1, 0);
+      startRes = Math.max(lastColumn, 0);
     }
     else if (start < 0)
     {
@@ -153,9 +154,9 @@ public class ViewportRanges extends ViewportProperties
     {
       endRes = 0;
     }
-    else if (!wrappedMode && (end > getVisibleAlignmentWidth() - 1))
+    else if (!wrappedMode && (end > lastColumn))
     {
-      endRes = Math.max(getVisibleAlignmentWidth() - 1, 0);
+      endRes = Math.max(lastColumn, 0);
     }
     else
     {
@@ -172,30 +173,6 @@ public class ViewportRanges extends ViewportProperties
   }
 
   /**
-   * Set last residue visible in the viewport. Fires a property change event.
-   * 
-   * @param res
-   *          residue position
-   */
-  public void setEndRes(int res)
-  {
-    int startres = res;
-    int width = getViewportWidth();
-
-    /*
-     * if not wrapped, don't leave white space at the right margin
-     */
-    if (!wrappedMode)
-    {
-      if (startres + width - 1 > getVisibleAlignmentWidth() - 1)
-      {
-        startres = getVisibleAlignmentWidth() - width;
-      }
-    }
-    setStartEndRes(startres - width + 1, startres);
-  }
-
-  /**
    * Set the first sequence visible in the viewport, maintaining the height. If
    * the viewport would extend past the last sequence, sets the viewport so it
    * sits at the bottom of the alignment. Fires a property change event.
@@ -579,16 +556,20 @@ public class ViewportRanges extends ViewportProperties
     wrappedMode = wrapped;
   }
 
+  public boolean isWrappedMode()
+  {
+    return wrappedMode;
+  }
+
   /**
    * Answers the vertical scroll position (0..) to set, given the visible column
-   * that is at top left. Note that if called with the total visible width of
-   * the alignment, this gives the maximum cursor scroll value.
+   * that is at top left.
    * 
    * <pre>
    * Example:
    *    viewport width 40 columns (0-39, 40-79, 80-119...)
    *    column 0 returns scroll position 0
-   *    columns 0-40 return scroll position 1
+   *    columns 1-40 return scroll position 1
    *    columns 41-80 return scroll position 2
    *    etc
    * </pre>
@@ -605,8 +586,35 @@ public class ViewportRanges extends ViewportProperties
      * visible whole widths
      */
     int scroll = topLeftColumn / w;
+
+    /*
+     * add 1 for a part width if there is one
+     */
     scroll += topLeftColumn % w > 0 ? 1 : 0;
 
     return scroll;
   }
+
+  /**
+   * Answers the maximum wrapped vertical scroll value, given the column
+   * position (0..) to show at top left of the visible region.
+   * 
+   * @param topLeftColumn
+   * @return
+   */
+  public int getWrappedMaxScroll(int topLeftColumn)
+  {
+    int scrollPosition = getWrappedScrollPosition(topLeftColumn);
+
+    /*
+     * how many more widths could be drawn after this one?
+     */
+    int columnsRemaining = getVisibleAlignmentWidth() - topLeftColumn;
+    int width = getViewportWidth();
+    int widthsRemaining = columnsRemaining / width
+            + (columnsRemaining % width > 0 ? 1 : 0) - 1;
+    int maxScroll = scrollPosition + widthsRemaining;
+
+    return maxScroll;
+  }
 }