X-Git-Url: https://git.libre-soc.org/?a=blobdiff_plain;f=src%2Fmesa%2Fswrast%2Fs_zoom.c;h=29b8df41b7e42dce1f393f8e4acf8e6a984d8877;hb=6aa62ba43f64f617c608e52b63c7eaa7aae16fb4;hp=3520fd506ac6a1a9812c490dd7f3d3219f2a39f0;hpb=e3a051e0538a605551f4d58294c94f5eb00ed07f;p=mesa.git

diff --git a/src/mesa/swrast/s_zoom.c b/src/mesa/swrast/s_zoom.c
index 3520fd506ac..29b8df41b7e 100644
--- a/src/mesa/swrast/s_zoom.c
+++ b/src/mesa/swrast/s_zoom.c
@@ -1,21 +1,19 @@
-/* $Id: s_zoom.c,v 1.1 2000/10/31 18:00:05 keithw Exp $ */
-
 /*
  * Mesa 3-D graphics library
- * Version:  3.5
- * 
- * Copyright (C) 1999-2000  Brian Paul   All Rights Reserved.
- * 
+ * Version:  6.5.2
+ *
+ * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
+ *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
- * 
+ *
  * The above copyright notice and this permission notice shall be included
  * in all copies or substantial portions of the Software.
- * 
+ *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
@@ -26,428 +24,442 @@
 
 #include "glheader.h"
 #include "macros.h"
+#include "imports.h"
+#include "colormac.h"
 
+#include "s_context.h"
 #include "s_span.h"
 #include "s_stencil.h"
 #include "s_zoom.h"
 
 
-
-/*
- * Write a span of pixels to the frame buffer while applying a pixel zoom.
- * This is only used by glDrawPixels and glCopyPixels.
- * Input:  n - number of pixels in input row
- *         x, y - destination of the span
- *         z - depth values for the span
- *         red, green, blue, alpha - array of colors
- *         y0 - location of first row in the image we're drawing.
+/**
+ * Compute the bounds of the region resulting from zooming a pixel span.
+ * The resulting region will be entirely inside the window/scissor bounds
+ * so no additional clipping is needed.
+ * \param imageX, imageY  position of the overall image being drawn
+ * \param spanX, spanY  position of span being drawing
+ * \param x0, x1  returned X bounds of zoomed region [x0, x1)
+ * \param y0, y1  returned Y bounds of zoomed region [y0, y1)
+ * \return GL_TRUE if any zoomed pixels visible, GL_FALSE if totally clipped
  */
-void
-gl_write_zoomed_rgba_span( GLcontext *ctx,
-                           GLuint n, GLint x, GLint y, const GLdepth z[],
-			   const GLfixed *fog,
-                           CONST GLchan rgba[][4], GLint y0 )
+static GLboolean
+compute_zoomed_bounds(GLcontext *ctx, GLint imageX, GLint imageY,
+                      GLint spanX, GLint spanY, GLint width,
+                      GLint *x0, GLint *x1, GLint *y0, GLint *y1)
 {
-   GLint m;
-   GLint r0, r1, row, r;
-   GLint i, j, skipcol;
-   GLchan zrgba[MAX_WIDTH][4];  /* zoomed pixel colors */
-   GLdepth zdepth[MAX_WIDTH];  /* zoomed depth values */
-   GLfixed zfog[MAX_WIDTH];  /* zoomed fog values */
-   GLint maxwidth = MIN2( ctx->DrawBuffer->Width, MAX_WIDTH );
-   const GLuint *srcRGBA32 = (const GLuint *) rgba;
-   GLuint *dstRGBA32 = (GLuint *) zrgba;
-
-   /* compute width of output row */
-   m = (GLint) ABSF( n * ctx->Pixel.ZoomX );
-   if (m==0) {
-      return;
-   }
-   if (ctx->Pixel.ZoomX<0.0) {
-      /* adjust x coordinate for left/right mirroring */
-      x = x - m;
-   }
-
-   /* compute which rows to draw */
-   row = y-y0;
-   r0 = y0 + (GLint) (row * ctx->Pixel.ZoomY);
-   r1 = y0 + (GLint) ((row+1) * ctx->Pixel.ZoomY);
-   if (r0==r1) {
-      return;
-   }
-   else if (r1<r0) {
-      GLint rtmp = r1;
+   const struct gl_framebuffer *fb = ctx->DrawBuffer;
+   GLint c0, c1, r0, r1;
+
+   ASSERT(spanX >= imageX);
+   ASSERT(spanY >= imageY);
+
+   /*
+    * Compute destination columns: [c0, c1)
+    */
+   c0 = imageX + (GLint) ((spanX - imageX) * ctx->Pixel.ZoomX);
+   c1 = imageX + (GLint) ((spanX + width - imageX) * ctx->Pixel.ZoomX);
+   if (c1 < c0) {
+      /* swap */
+      GLint tmp = c1;
+      c1 = c0;
+      c0 = tmp;
+   }
+   c0 = CLAMP(c0, fb->_Xmin, fb->_Xmax);
+   c1 = CLAMP(c1, fb->_Xmin, fb->_Xmax);
+   if (c0 == c1) {
+      return GL_FALSE; /* no width */
+   }
+
+   /*
+    * Compute destination rows: [r0, r1)
+    */
+   r0 = imageY + (GLint) ((spanY - imageY) * ctx->Pixel.ZoomY);
+   r1 = imageY + (GLint) ((spanY + 1 - imageY) * ctx->Pixel.ZoomY);
+   if (r1 < r0) {
+      /* swap */
+      GLint tmp = r1;
       r1 = r0;
-      r0 = rtmp;
+      r0 = tmp;
    }
-
-   /* return early if r0...r1 is above or below window */
-   if (r0<0 && r1<0) {
-      /* below window */
-      return;
-   }
-   if (r0>=ctx->DrawBuffer->Height && r1>=ctx->DrawBuffer->Height) {
-      /* above window */
-      return;
+   r0 = CLAMP(r0, fb->_Ymin, fb->_Ymax);
+   r1 = CLAMP(r1, fb->_Ymin, fb->_Ymax);
+   if (r0 == r1) {
+      return GL_FALSE; /* no height */
    }
 
-   /* check if left edge is outside window */
-   skipcol = 0;
-   if (x<0) {
-      skipcol = -x;
-      m += x;
-   }
-   /* make sure span isn't too long or short */
-   if (m>maxwidth) {
-      m = maxwidth;
-   }
-   else if (m<=0) {
-      return;
-   }
+   *x0 = c0;
+   *x1 = c1;
+   *y0 = r0;
+   *y1 = r1;
 
-   assert( m <= MAX_WIDTH );
+   return GL_TRUE;
+}
 
-   /* zoom the span horizontally */
-   if (ctx->Pixel.ZoomX==-1.0F) {
-      /* n==m */
-      for (j=0;j<m;j++) {
-         i = n - (j+skipcol) - 1;
-         dstRGBA32[j] = srcRGBA32[i];
-         zdepth[j] = z[i];
-      }
-      if (fog && ctx->Fog.Enabled) {
-	 for (j=0;j<m;j++) {
-	    i = n - (j+skipcol) - 1;
-	    zfog[j] = fog[i];
-	 }
-      }
-   }
-   else {
-      GLfloat xscale = 1.0F / ctx->Pixel.ZoomX;
-      for (j=0;j<m;j++) {
-         i = (GLint) ((j+skipcol) * xscale);
-         if (i<0)  i = n + i - 1;
-         dstRGBA32[j] = srcRGBA32[i];
-         zdepth[j] = z[i];
-      }
-      if (fog && ctx->Fog.Enabled) {
-	 for (j=0;j<m;j++) {
-	    i = (GLint) ((j+skipcol) * xscale);
-	    if (i<0)  i = n + i - 1;
-	    zfog[j] = fog[i];
-	 }
-      }
-   }
 
-   /* write the span */
-   for (r=r0; r<r1; r++) {
-      gl_write_rgba_span( ctx, m, x+skipcol, r, zdepth, 
-			  (fog ? zfog : 0),
-			  zrgba, GL_BITMAP );
-   }
+/**
+ * Can use this for unzooming X or Y values.
+ */
+static INLINE GLint
+unzoom_x(GLfloat zoomX, GLint imageX, GLint zx)
+{
+   /*
+   zx = imageX + (x - imageX) * zoomX;
+   zx - imageX = (x - imageX) * zoomX;
+   (zx - imageX) / zoomX = x - imageX;
+   */
+   GLint x = imageX + (GLint) ((zx - imageX) / zoomX);
+   return x;
 }
 
 
 
-void
-gl_write_zoomed_rgb_span( GLcontext *ctx,
-                          GLuint n, GLint x, GLint y, const GLdepth z[],
-			  const GLfixed *fog,
-                          CONST GLchan rgb[][3], GLint y0 )
+/**
+ * Helper function called from _swrast_write_zoomed_rgba/rgb/
+ * index/depth_span().
+ */
+static void
+zoom_span( GLcontext *ctx, GLint imgX, GLint imgY, const SWspan *span,
+           const GLvoid *src, GLenum format )
 {
-   GLint m;
-   GLint r0, r1, row, r;
-   GLint i, j, skipcol;
-   GLchan zrgba[MAX_WIDTH][4];  /* zoomed pixel colors */
-   GLdepth zdepth[MAX_WIDTH];  /* zoomed depth values */
-   GLfixed zfog[MAX_WIDTH];  /* zoomed fog values */
-   GLint maxwidth = MIN2( ctx->DrawBuffer->Width, MAX_WIDTH );
-
-   /* compute width of output row */
-   m = (GLint) ABSF( n * ctx->Pixel.ZoomX );
-   if (m==0) {
-      return;
-   }
-   if (ctx->Pixel.ZoomX<0.0) {
-      /* adjust x coordinate for left/right mirroring */
-      x = x - m;
-   }
-
-   /* compute which rows to draw */
-   row = y-y0;
-   r0 = y0 + (GLint) (row * ctx->Pixel.ZoomY);
-   r1 = y0 + (GLint) ((row+1) * ctx->Pixel.ZoomY);
-   if (r0==r1) {
-      return;
+   SWspan zoomed;
+   SWspanarrays zoomed_arrays;  /* this is big! */
+   GLint x0, x1, y0, y1;
+   GLint zoomedWidth;
+
+   if (!compute_zoomed_bounds(ctx, imgX, imgY, span->x, span->y, span->end,
+                              &x0, &x1, &y0, &y1)) {
+      return;  /* totally clipped */
+   }
+
+   zoomedWidth = x1 - x0;
+   ASSERT(zoomedWidth > 0);
+   ASSERT(zoomedWidth <= MAX_WIDTH);
+
+   /* no pixel arrays! must be horizontal spans. */
+   ASSERT((span->arrayMask & SPAN_XY) == 0);
+   ASSERT(span->primitive == GL_BITMAP);
+
+   INIT_SPAN(zoomed, GL_BITMAP, 0, 0, 0);
+   zoomed.x = x0;
+   zoomed.end = zoomedWidth;
+   zoomed.array = &zoomed_arrays;
+   zoomed_arrays.ChanType = span->array->ChanType;
+   /* XXX temporary */
+#if CHAN_TYPE == GL_UNSIGNED_BYTE
+   zoomed_arrays.rgba = zoomed_arrays.color.sz1.rgba;
+   zoomed_arrays.spec = zoomed_arrays.color.sz1.spec;
+#elif CHAN_TYPE == GL_UNSIGNED_SHORT
+   zoomed_arrays.rgba = zoomed_arrays.color.sz2.rgba;
+   zoomed_arrays.spec = zoomed_arrays.color.sz2.spec;
+#else
+   zoomed_arrays.rgba = zoomed_arrays.color.sz4.rgba;
+   zoomed_arrays.spec = zoomed_arrays.color.sz4.spec;
+#endif
+
+
+   /* copy fog interp info */
+   zoomed.fog = span->fog;
+   zoomed.fogStep = span->fogStep;
+   /* XXX copy texcoord info? */
+
+   if (format == GL_RGBA || format == GL_RGB) {
+      /* copy Z info */
+      zoomed.z = span->z;
+      zoomed.zStep = span->zStep;
+      /* we'll generate an array of colorss */
+      zoomed.interpMask = span->interpMask & ~SPAN_RGBA;
+      zoomed.arrayMask |= SPAN_RGBA;
+      ASSERT(span->arrayMask & SPAN_RGBA);
+   }
+   else if (format == GL_COLOR_INDEX) {
+      /* copy Z info */
+      zoomed.z = span->z;
+      zoomed.zStep = span->zStep;
+      /* we'll generate an array of color indexes */
+      zoomed.interpMask = span->interpMask & ~SPAN_INDEX;
+      zoomed.arrayMask |= SPAN_INDEX;
+      ASSERT(span->arrayMask & SPAN_INDEX);
+   }
+   else if (format == GL_DEPTH_COMPONENT) {
+      /* Copy color info */
+      zoomed.red = span->red;
+      zoomed.green = span->green;
+      zoomed.blue = span->blue;
+      zoomed.alpha = span->alpha;
+      zoomed.redStep = span->redStep;
+      zoomed.greenStep = span->greenStep;
+      zoomed.blueStep = span->blueStep;
+      zoomed.alphaStep = span->alphaStep;
+      /* we'll generate an array of depth values */
+      zoomed.interpMask = span->interpMask & ~SPAN_Z;
+      zoomed.arrayMask |= SPAN_Z;
+      ASSERT(span->arrayMask & SPAN_Z);
    }
-   else if (r1<r0) {
-      GLint rtmp = r1;
-      r1 = r0;
-      r0 = rtmp;
-   }
-
-   /* return early if r0...r1 is above or below window */
-   if (r0<0 && r1<0) {
-      /* below window */
-      return;
-   }
-   if (r0>=ctx->DrawBuffer->Height && r1>=ctx->DrawBuffer->Height) {
-      /* above window */
+   else {
+      _mesa_problem(ctx, "Bad format in zoom_span");
       return;
    }
 
-   /* check if left edge is outside window */
-   skipcol = 0;
-   if (x<0) {
-      skipcol = -x;
-      m += x;
+   /* zoom the span horizontally */
+   if (format == GL_RGBA) {
+      if (zoomed.array->ChanType == GL_UNSIGNED_BYTE) {
+         const GLubyte (*rgba)[4] = (const GLubyte (*)[4]) src;
+         GLint i;
+         for (i = 0; i < zoomedWidth; i++) {
+            GLint j = unzoom_x(ctx->Pixel.ZoomX, imgX, x0 + i) - span->x;
+            ASSERT(j >= 0);
+            ASSERT(j < span->end);
+            COPY_4UBV(zoomed.array->color.sz1.rgba[i], rgba[j]);
+         }
+      }
+      else if (zoomed.array->ChanType == GL_UNSIGNED_SHORT) {
+         const GLushort (*rgba)[4] = (const GLushort (*)[4]) src;
+         GLint i;
+         for (i = 0; i < zoomedWidth; i++) {
+            GLint j = unzoom_x(ctx->Pixel.ZoomX, imgX, x0 + i) - span->x;
+            ASSERT(j >= 0);
+            ASSERT(j < span->end);
+            COPY_4V(zoomed.array->color.sz2.rgba[i], rgba[j]);
+         }
+      }
+      else {
+         const GLfloat (*rgba)[4] = (const GLfloat (*)[4]) src;
+         GLint i;
+         for (i = 0; i < zoomedWidth; i++) {
+            GLint j = unzoom_x(ctx->Pixel.ZoomX, imgX, x0 + i) - span->x;
+            ASSERT(j >= 0);
+            ASSERT(j < span->end);
+            COPY_4V(zoomed.array->color.sz4.rgba[i], rgba[j]);
+         }
+      }
    }
-   /* make sure span isn't too long or short */
-   if (m>maxwidth) {
-      m = maxwidth;
+   else if (format == GL_RGB) {
+      if (zoomed.array->ChanType == GL_UNSIGNED_BYTE) {
+         const GLubyte (*rgb)[3] = (const GLubyte (*)[3]) src;
+         GLint i;
+         for (i = 0; i < zoomedWidth; i++) {
+            GLint j = unzoom_x(ctx->Pixel.ZoomX, imgX, x0 + i) - span->x;
+            ASSERT(j >= 0);
+            ASSERT(j < span->end);
+            zoomed.array->color.sz1.rgba[i][0] = rgb[j][0];
+            zoomed.array->color.sz1.rgba[i][1] = rgb[j][1];
+            zoomed.array->color.sz1.rgba[i][2] = rgb[j][2];
+            zoomed.array->color.sz1.rgba[i][3] = 0xff;
+         }
+      }
+      else if (zoomed.array->ChanType == GL_UNSIGNED_SHORT) {
+         const GLushort (*rgb)[3] = (const GLushort (*)[3]) src;
+         GLint i;
+         for (i = 0; i < zoomedWidth; i++) {
+            GLint j = unzoom_x(ctx->Pixel.ZoomX, imgX, x0 + i) - span->x;
+            ASSERT(j >= 0);
+            ASSERT(j < span->end);
+            zoomed.array->color.sz2.rgba[i][0] = rgb[j][0];
+            zoomed.array->color.sz2.rgba[i][1] = rgb[j][1];
+            zoomed.array->color.sz2.rgba[i][2] = rgb[j][2];
+            zoomed.array->color.sz2.rgba[i][3] = 0xffff;
+         }
+      }
+      else {
+         const GLfloat (*rgb)[3] = (const GLfloat (*)[3]) src;
+         GLint i;
+         for (i = 0; i < zoomedWidth; i++) {
+            GLint j = unzoom_x(ctx->Pixel.ZoomX, imgX, x0 + i) - span->x;
+            ASSERT(j >= 0);
+            ASSERT(j < span->end);
+            zoomed.array->color.sz4.rgba[i][0] = rgb[j][0];
+            zoomed.array->color.sz4.rgba[i][1] = rgb[j][1];
+            zoomed.array->color.sz4.rgba[i][2] = rgb[j][2];
+            zoomed.array->color.sz4.rgba[i][3] = 1.0F;
+         }
+      }
    }
-   else if (m<=0) {
-      return;
+   else if (format == GL_COLOR_INDEX) {
+      const GLuint *indexes = (const GLuint *) src;
+      GLint i;
+      for (i = 0; i < zoomedWidth; i++) {
+         GLint j = unzoom_x(ctx->Pixel.ZoomX, imgX, x0 + i) - span->x;
+         ASSERT(j >= 0);
+         ASSERT(j < span->end);
+         zoomed.array->index[i] = indexes[j];
+      }
    }
-
-   assert( m <= MAX_WIDTH );
-
-   /* zoom the span horizontally */
-   if (ctx->Pixel.ZoomX==-1.0F) {
-      /* n==m */
-      for (j=0;j<m;j++) {
-         i = n - (j+skipcol) - 1;
-         zrgba[j][0] = rgb[i][0];
-         zrgba[j][1] = rgb[i][1];
-         zrgba[j][2] = rgb[i][2];
-         zrgba[j][3] = CHAN_MAX;
-         zdepth[j] = z[i];
+   else if (format == GL_DEPTH_COMPONENT) {
+      const GLuint *zValues = (const GLuint *) src;
+      GLint i;
+      for (i = 0; i < zoomedWidth; i++) {
+         GLint j = unzoom_x(ctx->Pixel.ZoomX, imgX, x0 + i) - span->x;
+         ASSERT(j >= 0);
+         ASSERT(j < span->end);
+         zoomed.array->z[i] = zValues[j];
       }
-      if (fog && ctx->Fog.Enabled) {
-	 for (j=0;j<m;j++) {
-	    i = n - (j+skipcol) - 1;
-	    zfog[j] = fog[i];
-	 }
+      /* Now, fall into either the RGB or COLOR_INDEX path below */
+      format = ctx->Visual.rgbMode ? GL_RGBA : GL_COLOR_INDEX;
+   }
+
+   /* write the span in rows [r0, r1) */
+   if (format == GL_RGBA || format == GL_RGB) {
+      /* Writing the span may modify the colors, so make a backup now if we're
+       * going to call _swrast_write_zoomed_span() more than once.
+       * Also, clipping may change the span end value, so store it as well.
+       */
+      const GLint end = zoomed.end; /* save */
+      /* use specular color array for temp storage */
+      void *rgbaSave = zoomed.array->spec;
+      const GLint pixelSize =
+         (zoomed.array->ChanType == GL_UNSIGNED_BYTE) ? 4 * sizeof(GLubyte) :
+         ((zoomed.array->ChanType == GL_UNSIGNED_SHORT) ? 4 * sizeof(GLushort)
+          : 4 * sizeof(GLfloat));
+      if (y1 - y0 > 1) {
+         MEMCPY(rgbaSave, zoomed.array->rgba, zoomed.end * pixelSize);
+      }
+      for (zoomed.y = y0; zoomed.y < y1; zoomed.y++) {
+         _swrast_write_rgba_span(ctx, &zoomed);
+         zoomed.end = end;  /* restore */
+         if (y1 - y0 > 1) {
+            /* restore the colors */
+            MEMCPY(zoomed.array->rgba, rgbaSave, zoomed.end * pixelSize);
+         }
       }
    }
-   else {
-      GLfloat xscale = 1.0F / ctx->Pixel.ZoomX;
-      for (j=0;j<m;j++) {
-         i = (GLint) ((j+skipcol) * xscale);
-         if (i<0)  i = n + i - 1;
-         zrgba[j][0] = rgb[i][0];
-         zrgba[j][1] = rgb[i][1];
-         zrgba[j][2] = rgb[i][2];
-         zrgba[j][3] = CHAN_MAX;
-         zdepth[j] = z[i];
+   else if (format == GL_COLOR_INDEX) {
+      /* use specular color array for temp storage */
+      GLuint *indexSave = (GLuint *) zoomed.array->spec;
+      const GLint end = zoomed.end; /* save */
+      if (y1 - y0 > 1) {
+         MEMCPY(indexSave, zoomed.array->index, zoomed.end * sizeof(GLuint));
       }
-      if (fog && ctx->Fog.Enabled) {
-	 for (j=0;j<m;j++) {
-	    i = (GLint) ((j+skipcol) * xscale);
-	    if (i<0)  i = n + i - 1;
-	    zfog[j] = fog[i];
-	 }
+      for (zoomed.y = y0; zoomed.y < y1; zoomed.y++) {
+         _swrast_write_index_span(ctx, &zoomed);
+         zoomed.end = end;  /* restore */
+         if (y1 - y0 > 1) {
+            /* restore the colors */
+            MEMCPY(zoomed.array->index, indexSave, zoomed.end * sizeof(GLuint));
+         }
       }
    }
+}
 
-   /* write the span */
-   for (r=r0; r<r1; r++) {
-      gl_write_rgba_span( ctx, m, x+skipcol, r, zdepth, 
-			  (fog ? zfog : 0), zrgba, GL_BITMAP );
-   }
+
+void
+_swrast_write_zoomed_rgba_span(GLcontext *ctx, GLint imgX, GLint imgY,
+                               const SWspan *span, const GLvoid *rgba)
+{
+   zoom_span(ctx, imgX, imgY, span, rgba, GL_RGBA);
 }
 
 
+void
+_swrast_write_zoomed_rgb_span(GLcontext *ctx, GLint imgX, GLint imgY,
+                              const SWspan *span, const GLvoid *rgb)
+{
+   zoom_span(ctx, imgX, imgY, span, rgb, GL_RGB);
+}
+
 
-/*
- * As above, but write CI pixels.
- */
 void
-gl_write_zoomed_index_span( GLcontext *ctx,
-                            GLuint n, GLint x, GLint y, const GLdepth z[],
-			    const GLfixed *fog,
-                            const GLuint indexes[], GLint y0 )
+_swrast_write_zoomed_index_span(GLcontext *ctx, GLint imgX, GLint imgY,
+                                const SWspan *span)
 {
-   GLint m;
-   GLint r0, r1, row, r;
-   GLint i, j, skipcol;
-   GLuint zindexes[MAX_WIDTH];  /* zoomed color indexes */
-   GLdepth zdepth[MAX_WIDTH];  /* zoomed depth values */
-   GLfixed zfog[MAX_WIDTH];  /* zoomed fog values */
-   GLint maxwidth = MIN2( ctx->DrawBuffer->Width, MAX_WIDTH );
-
-   /* compute width of output row */
-   m = (GLint) ABSF( n * ctx->Pixel.ZoomX );
-   if (m==0) {
-      return;
-   }
-   if (ctx->Pixel.ZoomX<0.0) {
-      /* adjust x coordinate for left/right mirroring */
-      x = x - m;
-   }
+   zoom_span(ctx, imgX, imgY, span,
+             (const GLvoid *) span->array->index, GL_COLOR_INDEX);
+}
 
-   /* compute which rows to draw */
-   row = y-y0;
-   r0 = y0 + (GLint) (row * ctx->Pixel.ZoomY);
-   r1 = y0 + (GLint) ((row+1) * ctx->Pixel.ZoomY);
-   if (r0==r1) {
-      return;
-   }
-   else if (r1<r0) {
-      GLint rtmp = r1;
-      r1 = r0;
-      r0 = rtmp;
-   }
 
-   /* return early if r0...r1 is above or below window */
-   if (r0<0 && r1<0) {
-      /* below window */
-      return;
-   }
-   if (r0>=ctx->DrawBuffer->Height && r1>=ctx->DrawBuffer->Height) {
-      /* above window */
-      return;
-   }
+void
+_swrast_write_zoomed_depth_span(GLcontext *ctx, GLint imgX, GLint imgY,
+                                const SWspan *span)
+{
+   zoom_span(ctx, imgX, imgY, span,
+             (const GLvoid *) span->array->z, GL_DEPTH_COMPONENT);
+}
 
-   /* check if left edge is outside window */
-   skipcol = 0;
-   if (x<0) {
-      skipcol = -x;
-      m += x;
-   }
-   /* make sure span isn't too long or short */
-   if (m>maxwidth) {
-      m = maxwidth;
-   }
-   else if (m<=0) {
-      return;
+
+/**
+ * Zoom/write stencil values.
+ * No per-fragment operations are applied.
+ */
+void
+_swrast_write_zoomed_stencil_span(GLcontext *ctx, GLint imgX, GLint imgY,
+                                  GLint width, GLint spanX, GLint spanY,
+                                  const GLstencil stencil[])
+{
+   GLstencil zoomedVals[MAX_WIDTH];
+   GLint x0, x1, y0, y1, y;
+   GLint i, zoomedWidth;
+
+   if (!compute_zoomed_bounds(ctx, imgX, imgY, spanX, spanY, width,
+                              &x0, &x1, &y0, &y1)) {
+      return;  /* totally clipped */
    }
 
-   assert( m <= MAX_WIDTH );
+   zoomedWidth = x1 - x0;
+   ASSERT(zoomedWidth > 0);
+   ASSERT(zoomedWidth <= MAX_WIDTH);
 
    /* zoom the span horizontally */
-   if (ctx->Pixel.ZoomX==-1.0F) {
-      /* n==m */
-      for (j=0;j<m;j++) {
-         i = n - (j+skipcol) - 1;
-         zindexes[j] = indexes[i];
-         zdepth[j]   = z[i];
-      }
-      if (fog && ctx->Fog.Enabled) {
-	 for (j=0;j<m;j++) {
-	    i = n - (j+skipcol) - 1;
-	    zfog[j] = fog[i];
-	 }
-      }
-   }
-   else {
-      GLfloat xscale = 1.0F / ctx->Pixel.ZoomX;
-      for (j=0;j<m;j++) {
-         i = (GLint) ((j+skipcol) * xscale);
-         if (i<0)  i = n + i - 1;
-         zindexes[j] = indexes[i];
-         zdepth[j] = z[i];
-      }
-      if (fog && ctx->Fog.Enabled) {
-	 for (j=0;j<m;j++) {
-	    i = (GLint) ((j+skipcol) * xscale);
-	    if (i<0)  i = n + i - 1;
-	    zfog[j] = fog[i];
-	 }
-      }
+   for (i = 0; i < zoomedWidth; i++) {
+      GLint j = unzoom_x(ctx->Pixel.ZoomX, imgX, x0 + i) - spanX;
+      ASSERT(j >= 0);
+      ASSERT(j < width);
+      zoomedVals[i] = stencil[j];
    }
 
-   /* write the span */
-   for (r=r0; r<r1; r++) {
-      gl_write_index_span( ctx, m, x+skipcol, r, zdepth, 
-			   (fog ? zfog : 0), zindexes, GL_BITMAP );
+   /* write the zoomed spans */
+   for (y = y0; y < y1; y++) {
+      _swrast_write_stencil_span(ctx, zoomedWidth, x0, y, zoomedVals);
    }
 }
 
 
-
-/*
- * As above, but write stencil values.
+/**
+ * Zoom/write z values (16 or 32-bit).
+ * No per-fragment operations are applied.
  */
 void
-gl_write_zoomed_stencil_span( GLcontext *ctx,
-                              GLuint n, GLint x, GLint y,
-                              const GLstencil stencil[], GLint y0 )
+_swrast_write_zoomed_z_span(GLcontext *ctx, GLint imgX, GLint imgY,
+                            GLint width, GLint spanX, GLint spanY,
+                            const GLvoid *z)
 {
-   GLint m;
-   GLint r0, r1, row, r;
-   GLint i, j, skipcol;
-   GLstencil zstencil[MAX_WIDTH];  /* zoomed stencil values */
-   GLint maxwidth = MIN2( ctx->DrawBuffer->Width, MAX_WIDTH );
-
-   /* compute width of output row */
-   m = (GLint) ABSF( n * ctx->Pixel.ZoomX );
-   if (m==0) {
-      return;
-   }
-   if (ctx->Pixel.ZoomX<0.0) {
-      /* adjust x coordinate for left/right mirroring */
-      x = x - m;
-   }
-
-   /* compute which rows to draw */
-   row = y-y0;
-   r0 = y0 + (GLint) (row * ctx->Pixel.ZoomY);
-   r1 = y0 + (GLint) ((row+1) * ctx->Pixel.ZoomY);
-   if (r0==r1) {
-      return;
-   }
-   else if (r1<r0) {
-      GLint rtmp = r1;
-      r1 = r0;
-      r0 = rtmp;
-   }
-
-   /* return early if r0...r1 is above or below window */
-   if (r0<0 && r1<0) {
-      /* below window */
-      return;
-   }
-   if (r0>=ctx->DrawBuffer->Height && r1>=ctx->DrawBuffer->Height) {
-      /* above window */
-      return;
-   }
+   struct gl_renderbuffer *rb = ctx->DrawBuffer->_DepthBuffer;
+   GLushort zoomedVals16[MAX_WIDTH];
+   GLuint zoomedVals32[MAX_WIDTH];
+   GLint x0, x1, y0, y1, y;
+   GLint i, zoomedWidth;
 
-   /* check if left edge is outside window */
-   skipcol = 0;
-   if (x<0) {
-      skipcol = -x;
-      m += x;
-   }
-   /* make sure span isn't too long or short */
-   if (m>maxwidth) {
-      m = maxwidth;
-   }
-   else if (m<=0) {
-      return;
+   if (!compute_zoomed_bounds(ctx, imgX, imgY, spanX, spanY, width,
+                              &x0, &x1, &y0, &y1)) {
+      return;  /* totally clipped */
    }
 
-   assert( m <= MAX_WIDTH );
+   zoomedWidth = x1 - x0;
+   ASSERT(zoomedWidth > 0);
+   ASSERT(zoomedWidth <= MAX_WIDTH);
 
    /* zoom the span horizontally */
-   if (ctx->Pixel.ZoomX==-1.0F) {
-      /* n==m */
-      for (j=0;j<m;j++) {
-         i = n - (j+skipcol) - 1;
-         zstencil[j] = stencil[i];
+   if (rb->DataType == GL_UNSIGNED_SHORT) {
+      for (i = 0; i < zoomedWidth; i++) {
+         GLint j = unzoom_x(ctx->Pixel.ZoomX, imgX, x0 + i) - spanX;
+         ASSERT(j >= 0);
+         ASSERT(j < width);
+         zoomedVals16[i] = ((GLushort *) z)[j];
       }
+      z = zoomedVals16;
    }
    else {
-      GLfloat xscale = 1.0F / ctx->Pixel.ZoomX;
-      for (j=0;j<m;j++) {
-         i = (GLint) ((j+skipcol) * xscale);
-         if (i<0)  i = n + i - 1;
-         zstencil[j] = stencil[i];
+      ASSERT(rb->DataType == GL_UNSIGNED_INT);
+      for (i = 0; i < zoomedWidth; i++) {
+         GLint j = unzoom_x(ctx->Pixel.ZoomX, imgX, x0 + i) - spanX;
+         ASSERT(j >= 0);
+         ASSERT(j < width);
+         zoomedVals32[i] = ((GLuint *) z)[j];
       }
+      z = zoomedVals32;
    }
 
-   /* write the span */
-   for (r=r0; r<r1; r++) {
-      _mesa_write_stencil_span( ctx, m, x+skipcol, r, zstencil );
+   /* write the zoomed spans */
+   for (y = y0; y < y1; y++) {
+      rb->PutRow(ctx, rb, zoomedWidth, x0, y, z, NULL);
    }
 }