/*
 * Mesa 3-D graphics library
 * Version:  7.6
 *
 * Copyright (C) 2009  VMware, Inc.  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
 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

/**
 * Meta operations.  Some GL operations can be expressed in terms of
 * other GL operations.  For example, glBlitFramebuffer() can be done
 * with texture mapping and glClear() can be done with polygon rendering.
 *
 * \author Brian Paul
 */


#include "main/glheader.h"
#include "main/mtypes.h"
#include "main/imports.h"
#include "main/blend.h"
#include "main/bufferobj.h"
#include "main/buffers.h"
#include "main/context.h"
#include "main/depth.h"
#include "main/enable.h"
#include "main/feedback.h"
#include "main/formats.h"
#include "main/image.h"
#include "main/macros.h"
#include "main/matrix.h"
#include "main/pixel.h"
#include "main/polygon.h"
#include "main/readpix.h"
#include "main/scissor.h"
#include "main/state.h"
#include "main/stencil.h"
#include "main/texobj.h"
#include "main/texenv.h"
#include "main/texgetimage.h"
#include "main/teximage.h"
#include "main/texparam.h"
#include "main/texstate.h"
#include "main/varray.h"
#include "main/viewport.h"
#include "swrast/swrast.h"
#include "drivers/common/meta.h"


/** Return offset in bytes of the field within a vertex struct */
#define OFFSET(FIELD) ((void *) offsetof(struct vertex, FIELD))

/**
 * State which we may save/restore across meta ops.
 * XXX this may be incomplete...
 */
struct save_state
{
   GLbitfield SavedState;  /**< bitmask of MESA_META_* flags */

   /** MESA_META_ALPHA_TEST */
   GLboolean AlphaEnabled;
   GLenum AlphaFunc;
   GLclampf AlphaRef;

   /** MESA_META_BLEND */
   GLbitfield BlendEnabled;
   GLboolean ColorLogicOpEnabled;

   /** MESA_META_COLOR_MASK */
   GLubyte ColorMask[4];

   /** MESA_META_DEPTH_TEST */
   struct gl_depthbuffer_attrib Depth;

   /** MESA_META_FOG */
   GLboolean Fog;

   /** MESA_META_PIXEL_STORE */
   struct gl_pixelstore_attrib Pack, Unpack;

   /** MESA_META_PIXEL_TRANSFER */
   GLfloat RedBias, RedScale;
   GLfloat GreenBias, GreenScale;
   GLfloat BlueBias, BlueScale;
   GLfloat AlphaBias, AlphaScale;
   GLfloat DepthBias, DepthScale;
   GLboolean MapColorFlag;

   /** MESA_META_RASTERIZATION */
   GLenum FrontPolygonMode, BackPolygonMode;
   GLboolean PolygonOffset;
   GLboolean PolygonSmooth;
   GLboolean PolygonStipple;
   GLboolean PolygonCull;

   /** MESA_META_SCISSOR */
   struct gl_scissor_attrib Scissor;

   /** MESA_META_STENCIL_TEST */
   struct gl_stencil_attrib Stencil;

   /** MESA_META_TRANSFORM */
   GLenum MatrixMode;
   GLfloat ModelviewMatrix[16];
   GLfloat ProjectionMatrix[16];
   GLfloat TextureMatrix[16];

   /** MESA_META_CLIP */
   GLbitfield ClipPlanesEnabled;

   /** MESA_META_TEXTURE */
   struct gl_texture_object *CurrentTexture[NUM_TEXTURE_TARGETS];
   /** mask of TEXTURE_2D_BIT, etc */
   GLbitfield TexEnabled;
   GLbitfield TexGenEnabled;
   GLuint EnvMode;  /* unit[0] only */

   /** MESA_META_VIEWPORT */
   GLint ViewportX, ViewportY, ViewportW, ViewportH;
   GLclampd DepthNear, DepthFar;

   /** MESA_META_SELECT_FEEDBACK */
   GLenum RenderMode;
   struct gl_selection Select;
   struct gl_feedback Feedback;

   /** Miscellaneous (always disabled) */
   GLboolean Lighting;
   GLboolean RasterDiscard;
};


/**
 * State for glBlitFramebufer()
 */
struct blit_state
{
   GLuint ArrayObj;
   GLuint VBO;
   GLuint DepthFP;
};


/**
 * State for glClear()
 */
struct clear_state
{
   GLuint ArrayObj;
   GLuint VBO;
   GLint ColorLocation;

   GLint IntegerColorLocation;
};


/**
 * State for glCopyPixels()
 */
struct copypix_state
{
   GLuint ArrayObj;
   GLuint VBO;
};

#define MAX_META_OPS_DEPTH      8
/**
 * All per-context meta state.
 */
struct gl_meta_state
{
   /** Stack of state saved during meta-ops */
   struct save_state Save[MAX_META_OPS_DEPTH];
   /** Save stack depth */
   GLuint SaveStackDepth;

   struct copypix_state CopyPix;  /**< For _mesa_meta_CopyPixels() */
};

/**
 * Initialize meta-ops for a context.
 * To be called once during context creation.
 */
void
_mesa_meta_init(struct gl_context *ctx)
{
   ASSERT(!ctx->Meta);

   ctx->Meta = CALLOC_STRUCT(gl_meta_state);
}


/**
 * Free context meta-op state.
 * To be called once during context destruction.
 */
void
_mesa_meta_free(struct gl_context *ctx)
{
   GET_CURRENT_CONTEXT(old_context);
   _mesa_make_current(ctx, NULL, NULL);
   if (old_context)
      _mesa_make_current(old_context, old_context->WinSysDrawBuffer, old_context->WinSysReadBuffer);
   else
      _mesa_make_current(NULL, NULL, NULL);
   free(ctx->Meta);
   ctx->Meta = NULL;
}


/**
 * Enter meta state.  This is like a light-weight version of glPushAttrib
 * but it also resets most GL state back to default values.
 *
 * \param state  bitmask of MESA_META_* flags indicating which attribute groups
 *               to save and reset to their defaults
 */
void
_mesa_meta_begin(struct gl_context *ctx, GLbitfield state)
{
   struct save_state *save;

   /* hope MAX_META_OPS_DEPTH is large enough */
   assert(ctx->Meta->SaveStackDepth < MAX_META_OPS_DEPTH);

   save = &ctx->Meta->Save[ctx->Meta->SaveStackDepth++];
   memset(save, 0, sizeof(*save));
   save->SavedState = state;

   if (state & MESA_META_ALPHA_TEST) {
      save->AlphaEnabled = ctx->Color.AlphaEnabled;
      save->AlphaFunc = ctx->Color.AlphaFunc;
      save->AlphaRef = ctx->Color.AlphaRef;
      if (ctx->Color.AlphaEnabled)
         _mesa_set_enable(ctx, GL_ALPHA_TEST, GL_FALSE);
   }

   if (state & MESA_META_BLEND) {
      save->BlendEnabled = ctx->Color.BlendEnabled;
      if (ctx->Color.BlendEnabled) {
         _mesa_set_enable(ctx, GL_BLEND, GL_FALSE);
      }
      save->ColorLogicOpEnabled = ctx->Color.ColorLogicOpEnabled;
      if (ctx->Color.ColorLogicOpEnabled)
         _mesa_set_enable(ctx, GL_COLOR_LOGIC_OP, GL_FALSE);
   }

   if (state & MESA_META_COLOR_MASK) {
      memcpy(save->ColorMask, ctx->Color.ColorMask,
             sizeof(ctx->Color.ColorMask));
      if (!ctx->Color.ColorMask[0] ||
          !ctx->Color.ColorMask[1] ||
          !ctx->Color.ColorMask[2] ||
          !ctx->Color.ColorMask[3])
         _mesa_ColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
   }

   if (state & MESA_META_DEPTH_TEST) {
      save->Depth = ctx->Depth; /* struct copy */
      if (ctx->Depth.Test)
         _mesa_set_enable(ctx, GL_DEPTH_TEST, GL_FALSE);
   }

   if (state & MESA_META_FOG) {
      save->Fog = ctx->Fog.Enabled;
      if (ctx->Fog.Enabled)
         _mesa_set_enable(ctx, GL_FOG, GL_FALSE);
   }

   if (state & MESA_META_PIXEL_STORE) {
      save->Pack = ctx->Pack;
      save->Unpack = ctx->Unpack;
      ctx->Pack = ctx->DefaultPacking;
      ctx->Unpack = ctx->DefaultPacking;
   }

   if (state & MESA_META_PIXEL_TRANSFER) {
      save->RedScale = ctx->Pixel.RedScale;
      save->RedBias = ctx->Pixel.RedBias;
      save->GreenScale = ctx->Pixel.GreenScale;
      save->GreenBias = ctx->Pixel.GreenBias;
      save->BlueScale = ctx->Pixel.BlueScale;
      save->BlueBias = ctx->Pixel.BlueBias;
      save->AlphaScale = ctx->Pixel.AlphaScale;
      save->AlphaBias = ctx->Pixel.AlphaBias;
      save->MapColorFlag = ctx->Pixel.MapColorFlag;
      ctx->Pixel.RedScale = 1.0F;
      ctx->Pixel.RedBias = 0.0F;
      ctx->Pixel.GreenScale = 1.0F;
      ctx->Pixel.GreenBias = 0.0F;
      ctx->Pixel.BlueScale = 1.0F;
      ctx->Pixel.BlueBias = 0.0F;
      ctx->Pixel.AlphaScale = 1.0F;
      ctx->Pixel.AlphaBias = 0.0F;
      ctx->Pixel.MapColorFlag = GL_FALSE;
      /* XXX more state */
      ctx->NewState |=_NEW_PIXEL;
   }

   if (state & MESA_META_RASTERIZATION) {
      save->FrontPolygonMode = ctx->Polygon.FrontMode;
      save->BackPolygonMode = ctx->Polygon.BackMode;
      save->PolygonOffset = ctx->Polygon.OffsetFill;
      save->PolygonSmooth = ctx->Polygon.SmoothFlag;
      save->PolygonStipple = ctx->Polygon.StippleFlag;
      save->PolygonCull = ctx->Polygon.CullFlag;
      _mesa_PolygonMode(GL_FRONT_AND_BACK, GL_FILL);
      _mesa_set_enable(ctx, GL_POLYGON_OFFSET_FILL, GL_FALSE);
      _mesa_set_enable(ctx, GL_POLYGON_SMOOTH, GL_FALSE);
      _mesa_set_enable(ctx, GL_POLYGON_STIPPLE, GL_FALSE);
      _mesa_set_enable(ctx, GL_CULL_FACE, GL_FALSE);
   }

   if (state & MESA_META_SCISSOR) {
      save->Scissor = ctx->Scissor; /* struct copy */
      _mesa_set_enable(ctx, GL_SCISSOR_TEST, GL_FALSE);
   }

   if (state & MESA_META_STENCIL_TEST) {
      save->Stencil = ctx->Stencil; /* struct copy */
      if (ctx->Stencil.Enabled)
         _mesa_set_enable(ctx, GL_STENCIL_TEST, GL_FALSE);
      /* NOTE: other stencil state not reset */
   }

   if (state & MESA_META_TEXTURE) {
      GLuint tgt;

      save->EnvMode = ctx->Texture.Unit.EnvMode;

      /* Disable all texture units */
      save->TexEnabled = ctx->Texture.Unit.Enabled;
      save->TexGenEnabled = ctx->Texture.Unit.TexGenEnabled;
      if (ctx->Texture.Unit.Enabled ||
          ctx->Texture.Unit.TexGenEnabled) {
         _mesa_set_enable(ctx, GL_TEXTURE_1D, GL_FALSE);
         _mesa_set_enable(ctx, GL_TEXTURE_2D, GL_FALSE);
         if (ctx->Extensions.ARB_texture_cube_map)
            _mesa_set_enable(ctx, GL_TEXTURE_CUBE_MAP, GL_FALSE);
         _mesa_set_enable(ctx, GL_TEXTURE_GEN_S, GL_FALSE);
         _mesa_set_enable(ctx, GL_TEXTURE_GEN_T, GL_FALSE);
         _mesa_set_enable(ctx, GL_TEXTURE_GEN_R, GL_FALSE);
         _mesa_set_enable(ctx, GL_TEXTURE_GEN_Q, GL_FALSE);
      }

      /* save current texture objects for unit[0] only */
      for (tgt = 0; tgt < NUM_TEXTURE_TARGETS; tgt++) {
         _mesa_reference_texobj(&save->CurrentTexture[tgt],
                                ctx->Texture.Unit.CurrentTex[tgt]);
      }
      _mesa_TexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
   }

   if (state & MESA_META_TRANSFORM) {
      memcpy(save->ModelviewMatrix, ctx->ModelviewMatrixStack.Top->m,
             16 * sizeof(GLfloat));
      memcpy(save->ProjectionMatrix, ctx->ProjectionMatrixStack.Top->m,
             16 * sizeof(GLfloat));
      memcpy(save->TextureMatrix, ctx->TextureMatrixStack.Top->m,
             16 * sizeof(GLfloat));
      save->MatrixMode = ctx->Transform.MatrixMode;
      /* set 1:1 vertex:pixel coordinate transform */
      _mesa_MatrixMode(GL_TEXTURE);
      _mesa_LoadIdentity();
      _mesa_MatrixMode(GL_MODELVIEW);
      _mesa_LoadIdentity();
      _mesa_MatrixMode(GL_PROJECTION);
      _mesa_LoadIdentity();
      _mesa_Ortho(0.0, ctx->DrawBuffer->Width,
                  0.0, ctx->DrawBuffer->Height,
                  -1.0, 1.0);
   }

   if (state & MESA_META_CLIP) {
      save->ClipPlanesEnabled = ctx->Transform.ClipPlanesEnabled;
      if (ctx->Transform.ClipPlanesEnabled) {
         GLuint i;
         for (i = 0; i < ctx->Const.MaxClipPlanes; i++) {
            _mesa_set_enable(ctx, GL_CLIP_PLANE0 + i, GL_FALSE);
         }
      }
   }

   if (state & MESA_META_VIEWPORT) {
      /* save viewport state */
      save->ViewportX = ctx->Viewport.X;
      save->ViewportY = ctx->Viewport.Y;
      save->ViewportW = ctx->Viewport.Width;
      save->ViewportH = ctx->Viewport.Height;
      /* set viewport to match window size */
      if (ctx->Viewport.X != 0 ||
          ctx->Viewport.Y != 0 ||
          ctx->Viewport.Width != ctx->DrawBuffer->Width ||
          ctx->Viewport.Height != ctx->DrawBuffer->Height) {
         _mesa_set_viewport(ctx, 0, 0,
                            ctx->DrawBuffer->Width, ctx->DrawBuffer->Height);
      }
      /* save depth range state */
      save->DepthNear = ctx->Viewport.Near;
      save->DepthFar = ctx->Viewport.Far;
      /* set depth range to default */
      _mesa_DepthRange(0.0, 1.0);
   }

   if (state & MESA_META_SELECT_FEEDBACK) {
      save->RenderMode = ctx->RenderMode;
      if (ctx->RenderMode == GL_SELECT) {
	 save->Select = ctx->Select; /* struct copy */
	 _mesa_RenderMode(GL_RENDER);
      } else if (ctx->RenderMode == GL_FEEDBACK) {
	 save->Feedback = ctx->Feedback; /* struct copy */
	 _mesa_RenderMode(GL_RENDER);
      }
   }

   /* misc */
   {
      save->Lighting = ctx->Light.Enabled;
      if (ctx->Light.Enabled)
         _mesa_set_enable(ctx, GL_LIGHTING, GL_FALSE);
      save->RasterDiscard = ctx->RasterDiscard;
      if (ctx->RasterDiscard)
         _mesa_set_enable(ctx, GL_RASTERIZER_DISCARD, GL_FALSE);
   }
}


/**
 * Leave meta state.  This is like a light-weight version of glPopAttrib().
 */
void
_mesa_meta_end(struct gl_context *ctx)
{
   struct save_state *save = &ctx->Meta->Save[--ctx->Meta->SaveStackDepth];
   const GLbitfield state = save->SavedState;

   if (state & MESA_META_ALPHA_TEST) {
      if (ctx->Color.AlphaEnabled != save->AlphaEnabled)
         _mesa_set_enable(ctx, GL_ALPHA_TEST, save->AlphaEnabled);
      _mesa_AlphaFunc(save->AlphaFunc, save->AlphaRef);
   }

   if (state & MESA_META_BLEND) {
      if (ctx->Color.BlendEnabled != save->BlendEnabled) {
         _mesa_set_enable(ctx, GL_BLEND, (save->BlendEnabled & 1));
      }
      if (ctx->Color.ColorLogicOpEnabled != save->ColorLogicOpEnabled)
         _mesa_set_enable(ctx, GL_COLOR_LOGIC_OP, save->ColorLogicOpEnabled);
   }

   if (state & MESA_META_COLOR_MASK) {
      if (!TEST_EQ_4V(ctx->Color.ColorMask, save->ColorMask)) {
         _mesa_ColorMask(save->ColorMask[0], save->ColorMask[1],
                         save->ColorMask[2], save->ColorMask[3]);         
      }
   }

   if (state & MESA_META_DEPTH_TEST) {
      if (ctx->Depth.Test != save->Depth.Test)
         _mesa_set_enable(ctx, GL_DEPTH_TEST, save->Depth.Test);
      _mesa_DepthFunc(save->Depth.Func);
      _mesa_DepthMask(save->Depth.Mask);
   }

   if (state & MESA_META_FOG) {
      _mesa_set_enable(ctx, GL_FOG, save->Fog);
   }

   if (state & MESA_META_PIXEL_STORE) {
      ctx->Pack = save->Pack;
      ctx->Unpack = save->Unpack;
   }

   if (state & MESA_META_PIXEL_TRANSFER) {
      ctx->Pixel.RedScale = save->RedScale;
      ctx->Pixel.RedBias = save->RedBias;
      ctx->Pixel.GreenScale = save->GreenScale;
      ctx->Pixel.GreenBias = save->GreenBias;
      ctx->Pixel.BlueScale = save->BlueScale;
      ctx->Pixel.BlueBias = save->BlueBias;
      ctx->Pixel.AlphaScale = save->AlphaScale;
      ctx->Pixel.AlphaBias = save->AlphaBias;
      ctx->Pixel.MapColorFlag = save->MapColorFlag;
      /* XXX more state */
      ctx->NewState |=_NEW_PIXEL;
   }

   if (state & MESA_META_RASTERIZATION) {
      _mesa_PolygonMode(GL_FRONT, save->FrontPolygonMode);
      _mesa_PolygonMode(GL_BACK, save->BackPolygonMode);
      _mesa_set_enable(ctx, GL_POLYGON_STIPPLE, save->PolygonStipple);
      _mesa_set_enable(ctx, GL_POLYGON_OFFSET_FILL, save->PolygonOffset);
      _mesa_set_enable(ctx, GL_POLYGON_SMOOTH, save->PolygonSmooth);
      _mesa_set_enable(ctx, GL_CULL_FACE, save->PolygonCull);
   }

   if (state & MESA_META_SCISSOR) {
      _mesa_set_enable(ctx, GL_SCISSOR_TEST, save->Scissor.Enabled);
      _mesa_Scissor(save->Scissor.X, save->Scissor.Y,
                    save->Scissor.Width, save->Scissor.Height);
   }

   if (state & MESA_META_STENCIL_TEST) {
      const struct gl_stencil_attrib *stencil = &save->Stencil;

      _mesa_set_enable(ctx, GL_STENCIL_TEST, stencil->Enabled);
      _mesa_ClearStencil(stencil->Clear);
      _mesa_StencilFunc(stencil->Function,
                        stencil->Ref,
                        stencil->ValueMask);
      _mesa_StencilMask(stencil->WriteMask);
      _mesa_StencilOp(stencil->FailFunc, stencil->ZFailFunc, stencil->ZPassFunc);
   }

   if (state & MESA_META_TEXTURE) {
      GLuint tgt;

      /* restore texenv for unit[0] */
      _mesa_TexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, save->EnvMode);

      /* restore texture objects for unit[0] only */
      for (tgt = 0; tgt < NUM_TEXTURE_TARGETS; tgt++) {
	 if (ctx->Texture.Unit.CurrentTex[tgt] != save->CurrentTexture[tgt]) {
	    FLUSH_VERTICES(ctx, _NEW_TEXTURE);
	    _mesa_reference_texobj(&ctx->Texture.Unit.CurrentTex[tgt],
				   save->CurrentTexture[tgt]);
	 }
         _mesa_reference_texobj(&save->CurrentTexture[tgt], NULL);
      }

      /* Restore fixed function texture enables, texgen */
	 if (ctx->Texture.Unit.Enabled != save->TexEnabled) {
	    FLUSH_VERTICES(ctx, _NEW_TEXTURE);
	    ctx->Texture.Unit.Enabled = save->TexEnabled;
	 }

	 if (ctx->Texture.Unit.TexGenEnabled != save->TexGenEnabled) {
	    FLUSH_VERTICES(ctx, _NEW_TEXTURE);
	    ctx->Texture.Unit.TexGenEnabled = save->TexGenEnabled;
	 }
   }

   if (state & MESA_META_TRANSFORM) {
      _mesa_MatrixMode(GL_TEXTURE);
      _mesa_LoadMatrixf(save->TextureMatrix);

      _mesa_MatrixMode(GL_MODELVIEW);
      _mesa_LoadMatrixf(save->ModelviewMatrix);

      _mesa_MatrixMode(GL_PROJECTION);
      _mesa_LoadMatrixf(save->ProjectionMatrix);

      _mesa_MatrixMode(save->MatrixMode);
   }

   if (state & MESA_META_CLIP) {
      if (save->ClipPlanesEnabled) {
         GLuint i;
         for (i = 0; i < ctx->Const.MaxClipPlanes; i++) {
            if (save->ClipPlanesEnabled & (1 << i)) {
               _mesa_set_enable(ctx, GL_CLIP_PLANE0 + i, GL_TRUE);
            }
         }
      }
   }

   if (state & MESA_META_VIEWPORT) {
      if (save->ViewportX != ctx->Viewport.X ||
          save->ViewportY != ctx->Viewport.Y ||
          save->ViewportW != ctx->Viewport.Width ||
          save->ViewportH != ctx->Viewport.Height) {
         _mesa_set_viewport(ctx, save->ViewportX, save->ViewportY,
                            save->ViewportW, save->ViewportH);
      }
      _mesa_DepthRange(save->DepthNear, save->DepthFar);
   }

   /* misc */
   if (save->Lighting) {
      _mesa_set_enable(ctx, GL_LIGHTING, GL_TRUE);
   }
   if (save->RasterDiscard) {
      _mesa_set_enable(ctx, GL_RASTERIZER_DISCARD, GL_TRUE);
   }
}


/**
 * Determine whether Mesa is currently in a meta state.
 */
GLboolean
_mesa_meta_in_progress(struct gl_context *ctx)
{
   return ctx->Meta->SaveStackDepth != 0;
}


/**
 * Determine the GL data type to use for the temporary image read with
 * ReadPixels() and passed to Tex[Sub]Image().
 */
static GLenum
get_temp_image_type(struct gl_context *ctx, GLenum baseFormat)
{
   switch (baseFormat) {
   case GL_RGBA:
   case GL_RGB:
   case GL_RG:
   case GL_RED:
   case GL_ALPHA:
   case GL_LUMINANCE:
   case GL_LUMINANCE_ALPHA:
   case GL_INTENSITY:
      if (ctx->DrawBuffer->Visual.redBits <= 8)
         return GL_UNSIGNED_BYTE;
      else if (ctx->DrawBuffer->Visual.redBits <= 16)
         return GL_UNSIGNED_SHORT;
      else
         return GL_FLOAT;
   case GL_DEPTH_COMPONENT:
      return GL_UNSIGNED_INT;
   default:
      _mesa_problem(ctx, "Unexpected format %d in get_temp_image_type()",
		    baseFormat);
      return 0;
   }
}


/**
 * Helper for _mesa_meta_CopyTexSubImage1/2/3D() functions.
 * Have to be careful with locking and meta state for pixel transfer.
 */
static void
copy_tex_sub_image(struct gl_context *ctx,
                   GLuint dims,
                   struct gl_texture_image *texImage,
                   GLint xoffset, GLint yoffset, GLint zoffset,
                   struct gl_renderbuffer *rb,
                   GLint x, GLint y,
                   GLsizei width, GLsizei height)
{
   struct gl_texture_object *texObj = texImage->TexObject;
   const GLenum target = texObj->Target;
   GLenum format, type;
   GLint bpp;
   void *buf;

   /* Choose format/type for temporary image buffer */
   format = _mesa_get_format_base_format(texImage->TexFormat);
   if (format == GL_LUMINANCE ||
       format == GL_LUMINANCE_ALPHA ||
       format == GL_INTENSITY) {
      /* We don't want to use GL_LUMINANCE, GL_INTENSITY, etc. for the
       * temp image buffer because glReadPixels will do L=R+G+B which is
       * not what we want (should be L=R).
       */
      format = GL_RGBA;
   }

   if (_mesa_is_format_integer_color(texImage->TexFormat)) {
      _mesa_problem(ctx, "unsupported integer color copyteximage");
      return;
   }

   type = get_temp_image_type(ctx, format);
   bpp = _mesa_bytes_per_pixel(format, type);
   if (bpp <= 0) {
      _mesa_problem(ctx, "Bad bpp in meta copy_tex_sub_image()");
      return;
   }

   /*
    * Alloc image buffer (XXX could use a PBO)
    */
   buf = malloc(width * height * bpp);
   if (!buf) {
      _mesa_error(ctx, GL_OUT_OF_MEMORY, "glCopyTexSubImage%uD", dims);
      return;
   }

   _mesa_unlock_texture(ctx, texObj); /* need to unlock first */

   /*
    * Read image from framebuffer (disable pixel transfer ops)
    */
   _mesa_meta_begin(ctx, MESA_META_PIXEL_STORE | MESA_META_PIXEL_TRANSFER);
   ctx->Driver.ReadPixels(ctx, x, y, width, height,
			  format, type, &ctx->Pack, buf);
   _mesa_meta_end(ctx);

   _mesa_update_state(ctx); /* to update pixel transfer state */

   /*
    * Store texture data (with pixel transfer ops)
    */
   _mesa_meta_begin(ctx, MESA_META_PIXEL_STORE);
   if (target == GL_TEXTURE_1D) {
      ctx->Driver.TexSubImage1D(ctx, texImage,
                                xoffset, width,
                                format, type, buf, &ctx->Unpack);
   }
   else {
      ctx->Driver.TexSubImage2D(ctx, texImage,
                                xoffset, yoffset, width, height,
                                format, type, buf, &ctx->Unpack);
   }
   _mesa_meta_end(ctx);

   _mesa_lock_texture(ctx, texObj); /* re-lock */

   free(buf);
}


void
_mesa_meta_CopyTexSubImage1D(struct gl_context *ctx,
                             struct gl_texture_image *texImage,
                             GLint xoffset,
                             struct gl_renderbuffer *rb,
                             GLint x, GLint y, GLsizei width)
{
   copy_tex_sub_image(ctx, 1, texImage, xoffset, 0, 0,
                      rb, x, y, width, 1);
}


void
_mesa_meta_CopyTexSubImage2D(struct gl_context *ctx,
                             struct gl_texture_image *texImage,
                             GLint xoffset, GLint yoffset,
                             struct gl_renderbuffer *rb,
                             GLint x, GLint y,
                             GLsizei width, GLsizei height)
{
   copy_tex_sub_image(ctx, 2, texImage, xoffset, yoffset, 0,
                      rb, x, y, width, height);
}