Bill,
Thanks for your reply. I am using TV to put an image in the window
prior to drawing the grid. To use the method you propose I will need
to scale the image into the plot axes. Rather than use TV as I've been
doing, I think that I'll have to futz around a bit. I have been trying
to use TV rather than some other image display wrapper because the
images I'm displaying are not static. I want the display part of my
program to work as fast as possible. In any case, what I'm doing might
not be as straightforward as I had originally hoped. Thanks for your
help.
Rob
On Oct 9, 1:53 pm, Bill Gallery <wogall...@comcast.net> wrote:
> On Tuesday, October 9, 2012 11:08:03 AM UTC-6, Rob wrote:
>> Hi,
>
>> It's been quite a while since I've programmed in IDL but I have a
>
>> problem with something very basic. I am drawing a grid using the PLOTS
>
>> command but the final lines are not being drawn (i.e. the top and
>
>> rightmost lines). I might use a hack to get it to look right (i.e.
>
>> enlarge the window by a few pixels) but it's not a very elegant
>
>> solution. Below I list a simple procedure that shows the issue. You
>
>> should see a window pop up with most of the grid except for lines
>
>> along the top and along the right. Any help on my pedestrian
>
>> problem? :o)
>
>> Thanks,
>
>> Rob
>
>> pro test_grid_win
>
>> ; Test program that writes out a PNG file that captures the screen
>
>> with
>
>> ; a grid drawn on it.
>
>> xsize = (ysize = 500)
>
>> device,decomposed = 0 & loadct,0,/silent
>
>> nx = 10
>
>> window,0,xsize = xsize,ysize = ysize
>
>> dx = 1./float(nx)
>
>> erase,255B
>
>> for j = 0,nx do plots,[j*dx,j*dx],[0.0,1.0],/normal,color = 0B
>
>> for j = 0,nx do plots,[0.0,1.0],[j*dx,j*dx],/normal,color = 0B
>
>> ;filename = 'e:\test.png'
>
>> ;WRITE_PNG, filename, TVRD(/TRUE)
>
>> end
>
> Rob,
>
> Try this version of your program. The comments explain what you need to change and why.
>
> Cheers,
> Bill Gallery
>
> pro test_grid_win
> ; Test program that writes out a PNG file that captures the screen with
> ; a grid drawn on it.
> xsize = (ysize = 500)
> device,decomposed = 0 & loadct,0,/silent
> nx = 10
> window,0,xsize = xsize,ysize = ysize
> dx = 1./float(nx)
> ;;erase,255B
> !p.BACKGROUND=255b ;set the default background color
> !p.COLOR=0 ;set the default color of plot axes, points, lines, ...
>
> ;;plots places points on an already specified grid
> ;;You need to first use plot (no s) to set up the scale of the plot and
> ;;to draw the axes
> ;;the x and y data set the scale of the plot to x=[0,1], y=[0,1]
> ;;xgrid=1 and ygrid=1 ensure that the x and y axes are exacty as specified and
> ;;not expanded
> ;;/nodata prevents data from actually being plotted
> plot, [0,1],[0,1], /nodata, xgrid=1, ygrid=1
>
> ;;use oplot to place the data on the existing plot (plots will also work)
> ;;/normal says that the data is in 'normal' coordinates which vary from
> ;;[0,0] at the lower left of the screen to [1,1] to the upper right:
> ;;this is not what you want. You want to draw on the existing data scale
> ;;which has been created with the plot command.
> ;;The color of the data has already been specified with !p.color
> for j = 0,nx do oplot,[j*dx,j*dx],[0.0,1.0] ;;,/normal,color = 0B
> for j = 0,nx do oplot,[0.0,1.0],[j*dx,j*dx] ;;,/normal,color = 0B
> ;filename = 'e:\test.png'
> ;WRITE_PNG, filename, TVRD(/TRUE)
> end
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