Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-6333318

JViewPort.scrollRectToVisible( Rectangle cr ) doesn't scroll if cr left or above

    Details

      Description

      A DESCRIPTION OF THE REQUEST :
      The JViewPort.positionAdjustment when called from JViewPort.scrollRectToVisible( ) doesn't account for the content being to the left or above the JViewPort's rectangle. It doesn't compute a delta value ( != 0 ) in this case causing the JViewPort.scrollRectToVisible( ) to do nothing. Requesting the logic be altered so that if my content rectangle is to left of above that it computes a non-zero delta value and scrolls the viewport.

      JUSTIFICATION :
      The end programmer shouldn't have to worry about the location of his rectangle only if it is somewhere outside the JViewPort's current rectangle ( JViewPort.getViewRect() ).

      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      I would like the JViewPort.scrollRectToVisible to move the viewport.
      ACTUAL -
      The viewport is not moved when the content rectangle falls to the left or above the viewport's current rectangle.

      ---------- BEGIN SOURCE ----------
      viewport's rectangle:
         x=0
         y=512
         width=846
         height=604

      content rectangle:
         x=409
         y=505
         width=12
         height=23


      The following method will return a delta of 0 on the first 'if' when the prior identified viewport and content rectangles are used:

          private int positionAdjustment(int parentWidth, int childWidth, int childAt)
          {

              // +-----+
              // | --- | No Change
              // +-----+
              if (childAt >= 0 && childWidth + childAt <= parentWidth)
              {
                  return 0;
              }
              .......
           }

      As you can see the content's rectangle falls outside the bounds of the viewport's rectangle because a zero delta value is returned from the method the following if inside JViewPort.scrollRectToVisible() leaves without scrolling.

                  if (dx != 0 || dy != 0)
                  {
                       .......
                  }


      ---------- END SOURCE ----------

      CUSTOMER SUBMITTED WORKAROUND :
         public void scrollRectToVisible( Rectangle contentRectangle )
         {
            // I had to right all this code because JViewPort's 'scrollRectToVisible()'
            // appears to have a bug. It won't scroll for you if your content area
            // ( rectangle ) is above or to the left of the viewport's rectangle??
            Rectangle viewportRectangle = scrollPane.getViewport().getViewRect();
            if ( !viewportRectangle.contains( contentRectangle ) )
            {
               int outCode = viewportRectangle.outcode( contentRectangle.getLocation() );
               if ( ( outCode & Rectangle2D.OUT_LEFT ) > 0 || ( outCode & Rectangle2D.OUT_TOP ) > 0 )
                  scrollPane.getViewport().setViewPosition( contentRectangle.getLocation() );
               else
               {
                  outCode = viewportRectangle.outcode( new Point( contentRectangle.x + contentRectangle.width, contentRectangle.y + contentRectangle.height ) );
                  if ( ( outCode & Rectangle2D.OUT_RIGHT ) > 0 || ( outCode & Rectangle2D.OUT_BOTTOM ) > 0 )
                     scrollPane.getViewport().scrollRectToVisible( contentRectangle );
               }
            }
         }

        Attachments

          Activity

            People

            • Assignee:
              Unassigned
              Reporter:
              ndcosta Nelson Dcosta (Inactive)
            • Votes:
              0 Vote for this issue
              Watchers:
              0 Start watching this issue

              Dates

              • Created:
                Updated:
                Imported:
                Indexed: