Roughly clip glyphs into the X coordinate area to avoid wrap-around.

Fri Dec  6 23:07:58 2002  Owen Taylor  <otaylor@redhat.com>

        * pango/pangoxft-font.c (pango_xft_real_render)
          pango/pangox.c (pango_x_render): Roughly clip glyphs
        into the X coordinate area to avoid wrap-around. (#73199)

2 files changed, 44 insertions, 24 deletions

diff --git a/pango/pangox.c b/pango/pangox.c
index d45f9780..cca2e278 100644
--- a/pango/pangox.c
+++ b/pango/pangox.c
@@ -491,21 +491,35 @@ pango_x_render  (Display           *display,
   
   for (i=0; i<glyphs->num_glyphs; i++)
     {
-      if (glyphs->glyphs[i].glyph &
-          PANGO_X_UNKNOWN_FLAG)
+      PangoGlyph glyph = glyphs->glyphs[i].glyph;
+      int glyph_x = x + PANGO_PIXELS (x_off + glyphs->glyphs[i].geometry.x_offset);
+      int glyph_y = y + PANGO_PIXELS (glyphs->glyphs[i].geometry.y_offset);
+
+      /* Clip glyphs into the X coordinate range; we really
+       * want to clip glyphs with an ink rect outside the
+       * [0,32767] x [0,32767] rectangle but looking up
+       * the ink rect here would be a noticeable speed hit.
+       * This is close enough.
+       */
+      if (!(glyph &&
+	    glyph_x >= -16384 && glyph_x <= 32767 &&
+	    glyph_y >= -16384 && glyph_y <= 32767))
+	goto next_glyph;
+	      
+      if (glyph & PANGO_X_UNKNOWN_FLAG)
         {
           PangoFontMetrics *metrics = pango_font_get_metrics (font, NULL);
           int x1, y1, x2, y2; /* rectangle the character should go inside. */
           int baseline;
           gunichar wc;
           
-          x1 = x + (x_off + glyphs->glyphs[i].geometry.x_offset) / PANGO_SCALE;
-          y1 = y + (glyphs->glyphs[i].geometry.y_offset - metrics->ascent) / PANGO_SCALE;
-          x2 = x1 + glyphs->glyphs[i].geometry.width / PANGO_SCALE;
-          y2 = y1 + (metrics->ascent + metrics->descent) / PANGO_SCALE;
-          baseline = y1 + metrics->ascent / PANGO_SCALE;
+          x1 = glyph_x;
+          y1 = glyph_y - PANGO_PIXELS (metrics->ascent);
+          x2 = x1 + PANGO_PIXELS (glyphs->glyphs[i].geometry.width);
+          y2 = y1 + PANGO_PIXELS (metrics->ascent + metrics->descent);
+          baseline = glyph_y;
           
-          wc = glyphs->glyphs[i].glyph & (~PANGO_X_UNKNOWN_FLAG);
+          wc = glyph & (~PANGO_X_UNKNOWN_FLAG);
 
           switch (wc)
             {
@@ -576,10 +590,10 @@ pango_x_render  (Display           *display,
 
 	  pango_font_metrics_unref (metrics);
         }
-      else if (glyphs->glyphs[i].glyph)
+      else
 	{
-	  guint16 index = PANGO_X_GLYPH_INDEX (glyphs->glyphs[i].glyph);
-	  guint16 subfont_index = PANGO_X_GLYPH_SUBFONT (glyphs->glyphs[i].glyph);
+	  guint16 index = PANGO_X_GLYPH_INDEX (glyph);
+	  guint16 subfont_index = PANGO_X_GLYPH_SUBFONT (glyph);
 	  PangoXSubfontInfo *subfont;
       
 	  XChar2b c;
@@ -601,12 +615,12 @@ pango_x_render  (Display           *display,
 		}
 	      
 	      XDrawString16 (display, d, gc,
-			     x + (x_off + glyphs->glyphs[i].geometry.x_offset) / PANGO_SCALE,
-			     y + glyphs->glyphs[i].geometry.y_offset / PANGO_SCALE,
+			     glyph_x, glyph_y,
 			     &c, 1);
 	    }
 	}
 
+    next_glyph:
       x_off += glyphs->glyphs[i].geometry.width;
     }
 }
diff --git a/pango/pangoxft-font.c b/pango/pangoxft-font.c
index f2d799d0..addc27e4 100644
--- a/pango/pangoxft-font.c
+++ b/pango/pangoxft-font.c
@@ -281,18 +281,24 @@ pango_xft_real_render (Display          *display,
     }										\
   } G_STMT_END
 
-  /* Slow initial implementation. For speed, it should really
-   * collect the characters into runs, and draw multiple
-   * characters with each XftDrawString32 call.
-   */
   if (!display)
     _pango_xft_font_map_get_info (xfont->fontmap, &display, NULL);
-  
+
   for (i=0; i<glyphs->num_glyphs; i++)
     {
       PangoGlyph glyph = glyphs->glyphs[i].glyph;
-
-      if (glyph)
+      int glyph_x = x + PANGO_PIXELS (x_off + glyphs->glyphs[i].geometry.x_offset);
+      int glyph_y = y + PANGO_PIXELS (glyphs->glyphs[i].geometry.y_offset);
+
+      /* Clip glyphs into the X coordinate range; we really
+       * want to clip glyphs with an ink rect outside the
+       * [0,32767] x [0,32767] rectangle but looking up
+       * the ink rect here would be a noticeable speed hit.
+       * This is close enough.
+       */
+      if (glyph &&
+	  glyph_x >= -16384 && glyph_x <= 32767 &&
+	  glyph_y >= -16384 && glyph_y <= 32767)
 	{
 	  if (glyph & PANGO_XFT_UNKNOWN_FLAG)
 	    {
@@ -306,11 +312,11 @@ pango_xft_real_render (Display          *display,
       
 	      glyph &= ~PANGO_XFT_UNKNOWN_FLAG;
 	      
-	      ys[0] = y + PANGO_PIXELS (glyphs->glyphs[i].geometry.y_offset) - xft_font->ascent + (xft_font->ascent + xft_font->descent - xfont->mini_height * 2 - xfont->mini_pad * 5) / 2;
+	      ys[0] = glyph_y - xft_font->ascent + (xft_font->ascent + xft_font->descent - xfont->mini_height * 2 - xfont->mini_pad * 5) / 2;
 	      ys[1] = ys[0] + 2 * xfont->mini_pad + xfont->mini_height;
 	      ys[2] = ys[1] + xfont->mini_height + xfont->mini_pad;
 
-	      xs[0] = x + PANGO_PIXELS (x_off + glyphs->glyphs[i].geometry.x_offset); 
+	      xs[0] = glyph_x; 
 	      xs[1] = xs[0] + 2 * xfont->mini_pad;
 	      xs[2] = xs[1] + xfont->mini_width + xfont->mini_pad;
 	      
@@ -343,8 +349,8 @@ pango_xft_real_render (Display          *display,
 	      if (n_xft_glyph == N_XFT_LOCAL)
 		FLUSH_GLYPHS ();
 	      
-	      xft_glyphs[n_xft_glyph].x = x + PANGO_PIXELS (x_off + glyphs->glyphs[i].geometry.x_offset);
-	      xft_glyphs[n_xft_glyph].y = y + PANGO_PIXELS (glyphs->glyphs[i].geometry.y_offset);
+	      xft_glyphs[n_xft_glyph].x = glyph_x;
+	      xft_glyphs[n_xft_glyph].y = glyph_y;
 	      xft_glyphs[n_xft_glyph].glyph = glyph;
 	      n_xft_glyph++;
 	    }