restored _mesa_rescale_teximage2d()

2 files changed, 78 insertions, 0 deletions

diff --git a/src/mesa/main/texstore.c b/src/mesa/main/texstore.c
index d0529b13c3e..3dae1929c4d 100644
--- a/src/mesa/main/texstore.c
+++ b/src/mesa/main/texstore.c
@@ -3209,3 +3209,74 @@ _mesa_generate_mipmap(GLcontext *ctx, GLenum target,
 
    } /* loop over mipmap levels */
 }
+
+
+/**
+ * Helper function for drivers which need to rescale texture images to
+ * certain aspect ratios.
+ * Nearest filtering only (for broken hardware that can't support
+ * all aspect ratios).  This can be made a lot faster, but I don't
+ * really care enough...
+ */
+void _mesa_rescale_teximage2d( GLuint bytesPerPixel, GLuint dstRowStride,
+			       GLint srcWidth, GLint srcHeight,
+			       GLint dstWidth, GLint dstHeight,
+			       const GLvoid *srcImage, GLvoid *dstImage )
+{
+   GLint row, col;
+
+#define INNER_LOOP( TYPE, HOP, WOP )					\
+   for ( row = 0 ; row < dstHeight ; row++ ) {				\
+      GLint srcRow = row HOP hScale;					\
+      for ( col = 0 ; col < dstWidth ; col++ ) {			\
+	 GLint srcCol = col WOP wScale;					\
+	 dst[col] = src[srcRow * srcWidth + srcCol];			\
+      }									\
+      dst = (TYPE *) ((GLubyte *) dst + dstRowStride);			\
+   }									\
+
+#define RESCALE_IMAGE( TYPE )						\
+do {									\
+   const TYPE *src = (const TYPE *)srcImage;				\
+   TYPE *dst = (TYPE *)dstImage;					\
+									\
+   if ( srcHeight <= dstHeight ) {					\
+      const GLint hScale = dstHeight / srcHeight;			\
+      if ( srcWidth <= dstWidth ) {					\
+	 const GLint wScale = dstWidth / srcWidth;			\
+	 INNER_LOOP( TYPE, /, / );					\
+      }									\
+      else {								\
+	 const GLint wScale = srcWidth / dstWidth;			\
+	 INNER_LOOP( TYPE, /, * );					\
+      }									\
+   }									\
+   else {								\
+      const GLint hScale = srcHeight / dstHeight;			\
+      if ( srcWidth <= dstWidth ) {					\
+	 const GLint wScale = dstWidth / srcWidth;			\
+	 INNER_LOOP( TYPE, *, / );					\
+      }									\
+      else {								\
+	 const GLint wScale = srcWidth / dstWidth;			\
+	 INNER_LOOP( TYPE, *, * );					\
+      }									\
+   }									\
+} while (0)
+
+   switch ( bytesPerPixel ) {
+   case 4:
+      RESCALE_IMAGE( GLuint );
+      break;
+
+   case 2:
+      RESCALE_IMAGE( GLushort );
+      break;
+
+   case 1:
+      RESCALE_IMAGE( GLubyte );
+      break;
+   default:
+      _mesa_problem(NULL,"unexpected bytes/pixel in _mesa_rescale_teximage2d");
+   }
+}
diff --git a/src/mesa/main/texstore.h b/src/mesa/main/texstore.h
index 47775a1bb81..d276ff94e47 100644
--- a/src/mesa/main/texstore.h
+++ b/src/mesa/main/texstore.h
@@ -225,4 +225,11 @@ _mesa_generate_mipmap(GLcontext *ctx, GLenum target,
                       const struct gl_texture_unit *texUnit,
                       struct gl_texture_object *texObj);
 
+
+extern void
+_mesa_rescale_teximage2d(GLuint bytesPerPixel, GLuint dstRowStride,
+                         GLint srcWidth, GLint srcHeight,
+                         GLint dstWidth, GLint dstHeight,
+                         const GLvoid *srcImage, GLvoid *dstImage);
+
 #endif