readme.clog2slog

MPICH是MPI的重要研究,提供了一系列的接口函数,为并行计算的实现提供了编程环境.

A.Chan, 4/20/99

Since the original Jumpshot has extremely poor documentation on
the variables and data structures used in the GUI.  This note is to 
document what has been done to allow ProgramCanvas to have non-zero 
initial starttime of the frame, i.e. for SLOG, and what is the current 
understanding of the data structures/variables used in ProgramCanvas.java 
and MyImage.java.  In the following notes, assume that the x-axis of user 
coordinates is measured in time.  And that of plot coordinates is measured
in pixel.

1, all the double variables in ProgramCanvas.java refer to time in
   user coordinates.

2, all plot coordinates are in pixels.  They include
   panePosX:  viewport origin relative to the 3 canvas images measured in pixel.
   sbPos:     Scroll bar position relative to the current canvas images,
              currImg.img, in pixel.  
   maxT:      the time difference between the frame beginning time and
              frame ending time.  It is measured in double.
              In slog, maxT = FrameEndTime - FrameBegTime.



Diagram for the main data structures used in the GUI code
---------------------------------------------------------

                    currImg.begT              currImg.endT
                           :       <  maxT >       :
                           :                       :
   |      img[prevH]       :        currImg        :       img[nextH]      |
   +-----------------------+-------*********-------+-----------------------+
   |                       |       *       *       |                       |
   |                       |       * vport *       |                       |
   |                       |       *       *       |                       |
   |                       |       *       *       |                       |
   |                       |       *       *       |                       |
   +-----------------------+-------*********-------+-----------------------+
   ^                       ^       ^ _xPix ^        
   !<------- _xPix ------->|       !<----->!       
   !                       |       !   3            
   !                       |       !                
   !                       +-sbPos-+
   !                               !
   !                               !
   !<-------- panePosX ----------->!



3, In ProgramCanvas.paintComponent(), the images are drawn in the order 
   of img[prevH], currImg, img[nextH].  And each of them is of _xPix 
   pixels in width.   Since the viewport should be in currImg, so 
   panePosX = _xPix + time2pixel( BegTimeOfViewport - currImg.begTime ),
   where the initial constant, _xPix, accounts for the 1st image in the
   3 images canvas, i.e. img[prevH] = "previous image".

4, The range of JScrollbar is between 0 and canvas.maxH in ClogDisplay, where
   canvas.maxH = time2pixel( maxT ) = time2pixel( FrameEndTime - FrameBegTime ) 
   In ClogDisplay.setHoriz(), the JScrollBar, hbar, has called its 
   setVisibleAmount() with 1/3 of a image length, i.e. 1/3 of _xPix pixels.  
   Here maxT in user coordinates is mapped to the "1/3 of _xPix pixels"
   in plot coordinates.

5, JViewport, vport, calls its setViewPosition() method with argument
   panePosX as its x-coordinate argument.  This is called in various locations 
   in ClogDisplay.java and ProgramCanvas.java.  Together with point 3 mentioned
   above, the viewport is set to be within the current image pointed to
   by currImg in ProgramCanvas.java.   As sbPos is updated, hence
   the hbar.setValue(), so the vport will be moved along the 3 images canvas.

6, sbPos can be bigger than _xPix during zoom operations.  But when it is
   bigger than _xPix, the pointer to current image, currImg will be updated
   through getCurrGridH().

7, The original Jumpshot written by Omer to handle CLOG basically 
   assumed the starttime for all logfiles is zero.  So the original code
   has zero time hardwired inside the code, expecially, ProgramCanvas.java.
   So to modify the GUI code for SLOG, one needs to generalize the original
   GUI code to allow non-zero starttime of the frame data.  In the code,
   maxT is endtime of the frame when the begintime is zero.  So one can 
   simply extend maxT to be the lenT, i.e. lenT = FrameEndTime - FrameBegTime.
   Also each viewport is NOT identified by begTime & endTime, instead the code
   carried begTime and maxT as identifiers to specify the time range of the
   viewport.  One needs to put in the FrameBegTime in all the lines that
   assume zero beginning Frame time.  In order to do that, one needs to 
   locate all the functions that convert the time variablaes in double 
   to pixel variables.  There are 3 functions, getW(), getEvtXCord()
   and getTime.   getW() is TimePair2PixelDistance() and getEvtXCord() 
   is time2pixel().  And getTime() is basically pixel2time().  And observe 
   all lines in ProgramCanvas.java that involve the three functions mentioned
   above.  For the time or pixel variable involed is used as a standalone 
   time, it implies the variable may have been assumed zero time.  Add
   or substract FrameBegTime in the appropriate places depending on the 
   context.