Re: pngcairo: suggestion for additional option

[Ethan A M. <merritt@u.washington.edu>]

On Thursday 22 November 2007 08:19, Allin Cottrell wrote:
> 
> I'm attaching a small patch to eval.c that implements 
> GPVAL_GRAPH_XMIN, GPVAL_GRAPH_XMAX, GPVAL_GRAPH_YMIN and 
> GPVAL_GRAPH_YMAX. In the context of bitmapped output, these values 
> should represent the pixel coordinates of the actual graph area.
> 
> Those more familiar than I with the gnuplot architecture will no 
> doubt be able to see if there's a better way of doing this.

>--- eval.c.orig	2007-11-22 10:16:05.000000000 -0500
>+++ eval.c	2007-11-22 11:05:46.000000000 -0500
>@@ -733,6 +733,39 @@
>     Gstring(&v->udv_value, gp_strdup(stringvalue));
> }
> 
>+static void update_plot_bounds (void)
>+{
>+    int xl = plot_bounds.xleft;
>+    int xr = plot_bounds.xright;
>+    int yb = plot_bounds.ybot;
>+    int yt = plot_bounds.ytop;

I think that has to be 

    unsigned int xl, xr, yb, yt;
    struct position bottom_left = {graph, graph, graph, 0., 0., 0.};
    struct position upper_right = {graph, graph, graph, 1., 1., 1.};

    map_position(&bottom_left, &xl, &yb, "");
    map_position(&upper_right, &xr, &yt, "");

>+    if (term != NULL && !strcmp(term->name, "pngcairo")) {
>+        /* convert to pixels */
>+	xl /= 20;
>+	xr /= 20;
>+	yb /= 20;
>+	yt /= 20;

Where did the magic number 20 come from?
If we need terminal-specific code in core routines, this approach isn't
going to work.  We would have to export addition information from the
terminals, probably from term->text().  But I'm not sure we need this at all.

-- 
Ethan A Merritt