From c247268499d2bf387fee0397bd76e5fb889fc5a1 Mon Sep 17 00:00:00 2001
From: Brian Paul <brian.paul@tungstengraphics.com>
Date: Mon, 20 Mar 2006 02:17:15 +0000
Subject: [PATCH] added _mesa_clip_to_region()

---
 src/mesa/main/image.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
 src/mesa/main/image.h |  8 +++++++-
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/src/mesa/main/image.c b/src/mesa/main/image.c
index 0a117a967b6..263ce8ef64c 100644
--- a/src/mesa/main/image.c
+++ b/src/mesa/main/image.c
@@ -2,7 +2,7 @@
  * Mesa 3-D graphics library
  * Version:  6.5
  *
- * Copyright (C) 1999-2005  Brian Paul   All Rights Reserved.
+ * 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"),
@@ -4312,3 +4312,44 @@ _mesa_clip_readpixels(const GLcontext *ctx,
    return GL_TRUE;
 }
 
+
+/**
+ * Clip the rectangle defined by (x, y, width, height) against the bounds
+ * specified by [xmin, xmax) and [ymin, ymax).
+ * \return GL_FALSE if rect is totally clipped, GL_TRUE otherwise.
+ */
+GLboolean
+_mesa_clip_to_region(GLcontext *ctx,
+                     GLint xmin, GLint ymin,
+                     GLint xmax, GLint ymax,
+                     GLint *x, GLint *y,
+                     GLsizei *width, GLsizei *height )
+{
+   /* left clipping */
+   if (*x < xmin) {
+      *width -= (xmin - *x);
+      *x = xmin;
+   }
+
+   /* right clipping */
+   if (*x + *width > xmax)
+      *width -= (*x + *width - xmax - 1);
+
+   if (*width <= 0)
+      return GL_FALSE;
+
+   /* bottom (or top) clipping */
+   if (*y < ymin) {
+      *height -= (ymin - *y);
+      *y = ymin;
+   }
+
+   /* top (or bottom) clipping */
+   if (*y + *height > ymax)
+      *height -= (*y + *height - ymax - 1);
+
+   if (*height <= 0)
+      return GL_FALSE;
+
+   return GL_TRUE;
+}
diff --git a/src/mesa/main/image.h b/src/mesa/main/image.h
index e31959565af..7953192c52f 100644
--- a/src/mesa/main/image.h
+++ b/src/mesa/main/image.h
@@ -2,7 +2,7 @@
  * Mesa 3-D graphics library
  * Version:  6.5
  *
- * Copyright (C) 1999-2005  Brian Paul   All Rights Reserved.
+ * 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"),
@@ -216,5 +216,11 @@ _mesa_clip_readpixels(const GLcontext *ctx,
                       GLsizei *width, GLsizei *height,
                       struct gl_pixelstore_attrib *pack);
 
+extern GLboolean
+_mesa_clip_to_region(GLcontext *ctx,
+                     GLint xmin, GLint ymin,
+                     GLint xmax, GLint ymax,
+                     GLint *x, GLint *y,
+                     GLsizei *width, GLsizei *height );
 
 #endif