[Plplot-cvs] SF.net SVN: plplot:[8841] trunk/drivers/cairo.c

[<ai...@us...>]

Revision: 8841
          http://plplot.svn.sourceforge.net/plplot/?rev=8841&view=rev
Author:   airwin
Date:     2008-09-30 22:01:47 +0000 (Tue, 30 Sep 2008)

Log Message:
-----------
Redo scaling code to be consistent in spirit with that used for gd.c and
svg.c by setting the downscale factor so internal coordinates will always be
PIXELS_X x PIXELS_Y = 32768x24576 regardless of the size of the external
dimensions.  The advantage of this technique is you cannot overflow the
internal coordinates (stored in a short).  That was possible for the old
cairo scaling technique (which simply multiplied external coordinates by 10
to derive internal coordinates) for large external geometry.  Also, the old
technique potentially gave low internal resolution and line hiding problems
for small external geometry.

Modified Paths:
--------------
    trunk/drivers/cairo.c

Modified: trunk/drivers/cairo.c
===================================================================
--- trunk/drivers/cairo.c	2008-09-30 20:44:11 UTC (rev 8840)
+++ trunk/drivers/cairo.c	2008-09-30 22:01:47 UTC (rev 8841)
@@ -63,7 +63,6 @@
  ---------------------------------------------------------------------*/
 
 #define DPI 72
-#define DOWNSCALE 0.1
 #define PLCAIRO_DEFAULT_X 720
 #define PLCAIRO_DEFAULT_Y 540
 
@@ -74,7 +73,7 @@
 static int text_anti_aliasing;
 static int graphics_anti_aliasing;
 static int external_drawable;
-
+static PLFLT downscale = 0.;
 static DrvOpt cairo_options[] = {{"text_clipping", DRV_INT, &text_clipping, "Use text clipping (text_clipping=0|1)"},
 				 {"text_anti_aliasing", DRV_INT, &text_anti_aliasing, "Set desired text anti-aliasing (text_anti_aliasing=0|1|2|3). The numbers are in the same order as the cairo_antialias_t enumeration documented at http://cairographics.org/manual/cairo-cairo-t.html#cairo-antialias-t)"},
 				 {"graphics_anti_aliasing", DRV_INT, &graphics_anti_aliasing, "Set desired graphics anti-aliasing (graphics_anti_aliasing=0|1|2|3). The numbers are in the same order as the cairo_antialias_t enumeration documented at http://cairographics.org/manual/cairo-cairo-t.html#cairo-antialias-t"},
@@ -253,8 +252,8 @@
 
   set_current_context(pls);
 
-  cairo_move_to(aStream->cairoContext, DOWNSCALE * (double) x1a, DOWNSCALE * (double) y1a);
-  cairo_line_to(aStream->cairoContext, DOWNSCALE * (double) x2a, DOWNSCALE * (double) y2a);
+  cairo_move_to(aStream->cairoContext, downscale * (double) x1a, downscale * (double) y1a);
+  cairo_line_to(aStream->cairoContext, downscale * (double) x2a, downscale * (double) y2a);
   cairo_stroke(aStream->cairoContext);
 }
 
@@ -405,12 +404,12 @@
 
   /* Set up the clipping region if we are doing text clipping */
   if(aStream->text_clipping){
-    cairo_rectangle(aStream->cairoContext, DOWNSCALE * pls->clpxmi, DOWNSCALE * pls->clpymi, DOWNSCALE * (pls->clpxma - pls->clpxmi), DOWNSCALE * (pls->clpyma - pls->clpymi));
+    cairo_rectangle(aStream->cairoContext, downscale * pls->clpxmi, downscale * pls->clpymi, downscale * (pls->clpxma - pls->clpxmi), downscale * (pls->clpyma - pls->clpymi));
     cairo_clip(aStream->cairoContext);
   }
 
   /* Move to the string reference point */
-  cairo_move_to(aStream->cairoContext, DOWNSCALE * (double) args->x, DOWNSCALE * (double) args->y);
+  cairo_move_to(aStream->cairoContext, downscale * (double) args->x, downscale * (double) args->y);
 
   /* Invert the coordinate system so that the text is drawn right side up */
   cairoTransformMatrix = (cairo_matrix_t *) malloc (sizeof(cairo_matrix_t));
@@ -667,13 +666,19 @@
   pls->dev_fill0 = 1;        /* Supports hardware solid fills */
   pls->plbuf_write = 1;      /* Activate plot buffer */
   
-  plP_setpxl(DPI/25.4/DOWNSCALE, DPI/25.4/DOWNSCALE);
   
   if (pls->xlength <= 0 || pls->ylength <= 0){
     pls->xlength = PLCAIRO_DEFAULT_X;
     pls->ylength = PLCAIRO_DEFAULT_Y;
   }
-  plP_setphy((PLINT) 0, (PLINT) pls->xlength / DOWNSCALE, (PLINT) 0, (PLINT) pls->ylength / DOWNSCALE);
+  /* Calculate ratio of (smaller) external coordinates used for cairo
+     devices to (larger) internal PLplot coordinates. */
+  if (pls->xlength > pls->ylength)
+    downscale = (PLFLT)pls->xlength/(PLFLT)PIXELS_X;
+  else
+    downscale = (PLFLT)pls->ylength/(PLFLT)PIXELS_Y;
+  plP_setphy((PLINT) 0, (PLINT) (pls->xlength / downscale), (PLINT) 0, (PLINT) (pls->ylength / downscale));
+  plP_setpxl(DPI/25.4/downscale, DPI/25.4/downscale);
 
   /* Initialize font table with either enviroment variables or defaults.
      This was copied from the psttf driver. */
@@ -758,9 +763,9 @@
 
   set_current_context(pls);
   
-  cairo_move_to(aStream->cairoContext, DOWNSCALE * (double) xa[0], DOWNSCALE * (double) ya[0]);
+  cairo_move_to(aStream->cairoContext, downscale * (double) xa[0], downscale * (double) ya[0]);
   for(i=1;i<npts;i++){
-    cairo_line_to(aStream->cairoContext, DOWNSCALE * (double) xa[i], DOWNSCALE * (double) ya[i]);
+    cairo_line_to(aStream->cairoContext, downscale * (double) xa[i], downscale * (double) ya[i]);
   }
 }
 
@@ -1070,8 +1075,8 @@
           &x, &y, &w, &h, &b, &d);
         pls->xlength = w;
         pls->ylength = h;
-        plP_setphy((PLINT) 0, (PLINT) pls->xlength / DOWNSCALE, (PLINT) 0, 
-          (PLINT) pls->ylength / DOWNSCALE);
+        plP_setphy((PLINT) 0, (PLINT) (pls->xlength / downscale), (PLINT) 0, 
+          (PLINT) (pls->ylength / downscale));
   
         /* Associate cairo with the supplied drawable */
         xcairo_init_cairo(pls);


This was sent by the SourceForge.net collaborative development platform, the world's largest Open Source development site.