s_drawpix.c

Mesa is an open-source implementation of the OpenGL specification - a system for rendering interacti

            }
            return GL_TRUE;
         }
      }
   }

   /* can't handle this pixel format and/or data type */
   return GL_FALSE;
}



/*
 * Draw color index image.
 */
static void
draw_index_pixels( GLcontext *ctx, GLint x, GLint y,
                   GLsizei width, GLsizei height,
                   GLenum type,
                   const struct gl_pixelstore_attrib *unpack,
                   const GLvoid *pixels )
{
   const GLint imgX = x, imgY = y;
   const GLboolean zoom = ctx->Pixel.ZoomX!=1.0 || ctx->Pixel.ZoomY!=1.0;
   GLint row, skipPixels;
   SWspan span;

   INIT_SPAN(span, GL_BITMAP);
   span.arrayMask = SPAN_INDEX;
   _swrast_span_default_attribs(ctx, &span);

   /*
    * General solution
    */
   skipPixels = 0;
   while (skipPixels < width) {
      const GLint spanWidth = MIN2(width - skipPixels, MAX_WIDTH);
      ASSERT(spanWidth <= MAX_WIDTH);
      for (row = 0; row < height; row++) {
         const GLvoid *source = _mesa_image_address2d(unpack, pixels,
                                                      width, height,
                                                      GL_COLOR_INDEX, type,
                                                      row, skipPixels);
         _mesa_unpack_index_span(ctx, spanWidth, GL_UNSIGNED_INT,
                                 span.array->index, type, source, unpack,
                                 ctx->_ImageTransferState);

         /* These may get changed during writing/clipping */
         span.x = x + skipPixels;
         span.y = y + row;
         span.end = spanWidth;
         
         if (zoom)
            _swrast_write_zoomed_index_span(ctx, imgX, imgY, &span);
         else
            _swrast_write_index_span(ctx, &span);
      }
      skipPixels += spanWidth;
   }
}



/*
 * Draw stencil image.
 */
static void
draw_stencil_pixels( GLcontext *ctx, GLint x, GLint y,
                     GLsizei width, GLsizei height,
                     GLenum type,
                     const struct gl_pixelstore_attrib *unpack,
                     const GLvoid *pixels )
{
   const GLboolean zoom = ctx->Pixel.ZoomX != 1.0 || ctx->Pixel.ZoomY != 1.0;
   GLint skipPixels;

   /* if width > MAX_WIDTH, have to process image in chunks */
   skipPixels = 0;
   while (skipPixels < width) {
      const GLint spanX = x + skipPixels;
      const GLint spanWidth = MIN2(width - skipPixels, MAX_WIDTH);
      GLint row;
      for (row = 0; row < height; row++) {
         const GLint spanY = y + row;
         GLstencil values[MAX_WIDTH];
         GLenum destType = (sizeof(GLstencil) == sizeof(GLubyte))
                         ? GL_UNSIGNED_BYTE : GL_UNSIGNED_SHORT;
         const GLvoid *source = _mesa_image_address2d(unpack, pixels,
                                                      width, height,
                                                      GL_COLOR_INDEX, type,
                                                      row, skipPixels);
         _mesa_unpack_stencil_span(ctx, spanWidth, destType, values,
                                   type, source, unpack,
                                   ctx->_ImageTransferState);
         if (zoom) {
            _swrast_write_zoomed_stencil_span(ctx, x, y, spanWidth,
                                              spanX, spanY, values);
         }
         else {
            _swrast_write_stencil_span(ctx, spanWidth, spanX, spanY, values);
         }
      }
      skipPixels += spanWidth;
   }
}


/*
 * Draw depth image.
 */
static void
draw_depth_pixels( GLcontext *ctx, GLint x, GLint y,
                   GLsizei width, GLsizei height,
                   GLenum type,
                   const struct gl_pixelstore_attrib *unpack,
                   const GLvoid *pixels )
{
   const GLboolean scaleOrBias
      = ctx->Pixel.DepthScale != 1.0 || ctx->Pixel.DepthBias != 0.0;
   const GLboolean zoom = ctx->Pixel.ZoomX != 1.0 || ctx->Pixel.ZoomY != 1.0;
   SWspan span;

   INIT_SPAN(span, GL_BITMAP);
   span.arrayMask = SPAN_Z;
   _swrast_span_default_attribs(ctx, &span);

   if (type == GL_UNSIGNED_SHORT
       && ctx->DrawBuffer->Visual.depthBits == 16
       && !scaleOrBias
       && !zoom
       && ctx->Visual.rgbMode
       && width <= MAX_WIDTH
       && !unpack->SwapBytes) {
      /* Special case: directly write 16-bit depth values */
      GLint row;
      for (row = 0; row < height; row++) {
         const GLushort *zSrc = (const GLushort *)
            _mesa_image_address2d(unpack, pixels, width, height,
                                  GL_DEPTH_COMPONENT, type, row, 0);
         GLint i;
         for (i = 0; i < width; i++)
            span.array->z[i] = zSrc[i];
         span.x = x;
         span.y = y + row;
         span.end = width;
         _swrast_write_rgba_span(ctx, &span);
      }
   }
   else if (type == GL_UNSIGNED_INT
            && !scaleOrBias
            && !zoom
            && ctx->Visual.rgbMode
            && width <= MAX_WIDTH
            && !unpack->SwapBytes) {
      /* Special case: shift 32-bit values down to Visual.depthBits */
      const GLint shift = 32 - ctx->DrawBuffer->Visual.depthBits;
      GLint row;
      for (row = 0; row < height; row++) {
         const GLuint *zSrc = (const GLuint *)
            _mesa_image_address2d(unpack, pixels, width, height,
                                  GL_DEPTH_COMPONENT, type, row, 0);
         if (shift == 0) {
            _mesa_memcpy(span.array->z, zSrc, width * sizeof(GLuint));
         }
         else {
            GLint col;
            for (col = 0; col < width; col++)
               span.array->z[col] = zSrc[col] >> shift;
         }
         span.x = x;
         span.y = y + row;
         span.end = width;
         _swrast_write_rgba_span(ctx, &span);
      }
   }
   else {
      /* General case */
      const GLuint depthMax = ctx->DrawBuffer->_DepthMax;
      GLint skipPixels = 0;

      /* in case width > MAX_WIDTH do the copy in chunks */
      while (skipPixels < width) {
         const GLint spanWidth = MIN2(width - skipPixels, MAX_WIDTH);
         GLint row;
         ASSERT(span.end <= MAX_WIDTH);
         for (row = 0; row < height; row++) {
            const GLvoid *zSrc = _mesa_image_address2d(unpack,
                                                      pixels, width, height,
                                                      GL_DEPTH_COMPONENT, type,
                                                      row, skipPixels);

            /* Set these for each row since the _swrast_write_* function may
             * change them while clipping.
             */
            span.x = x + skipPixels;
            span.y = y + row;
            span.end = spanWidth;

            _mesa_unpack_depth_span(ctx, spanWidth,
                                    GL_UNSIGNED_INT, span.array->z, depthMax,
                                    type, zSrc, unpack);
            if (zoom) {
               _swrast_write_zoomed_depth_span(ctx, x, y, &span);
            }
            else if (ctx->Visual.rgbMode) {
               _swrast_write_rgba_span(ctx, &span);
            }
            else {
               _swrast_write_index_span(ctx, &span);
            }
         }
         skipPixels += spanWidth;
      }
   }
}



/**
 * Draw RGBA image.
 */
static void
draw_rgba_pixels( GLcontext *ctx, GLint x, GLint y,
                  GLsizei width, GLsizei height,
                  GLenum format, GLenum type,
                  const struct gl_pixelstore_attrib *unpack,
                  const GLvoid *pixels )
{
   const GLint imgX = x, imgY = y;
   const GLboolean zoom = ctx->Pixel.ZoomX!=1.0 || ctx->Pixel.ZoomY!=1.0;
   GLfloat *convImage = NULL;
   GLbitfield transferOps = ctx->_ImageTransferState;
   SWspan span;

   /* Try an optimized glDrawPixels first */
   if (fast_draw_rgba_pixels(ctx, x, y, width, height, format, type,
                             unpack, pixels)) {
      return;
   }

   INIT_SPAN(span, GL_BITMAP);
   _swrast_span_default_attribs(ctx, &span);
   span.arrayMask = SPAN_RGBA;
   span.arrayAttribs = FRAG_BIT_COL0; /* we're fill in COL0 attrib values */

   if (ctx->Pixel.Convolution2DEnabled || ctx->Pixel.Separable2DEnabled) {
      /* Convolution has to be handled specially.  We'll create an
       * intermediate image, applying all pixel transfer operations
       * up to convolution.  Then we'll convolve the image.  Then
       * we'll proceed with the rest of the transfer operations and
       * rasterize the image.
       */
      GLint row;
      GLfloat *dest, *tmpImage;

      tmpImage = (GLfloat *) _mesa_malloc(width * height * 4 * sizeof(GLfloat));
      if (!tmpImage) {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glDrawPixels");
         return;
      }
      convImage = (GLfloat *) _mesa_malloc(width * height * 4 * sizeof(GLfloat));
      if (!convImage) {
         _mesa_free(tmpImage);
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glDrawPixels");
         return;
      }

      /* Unpack the image and apply transfer ops up to convolution */
      dest = tmpImage;
      for (row = 0; row < height; row++) {
         const GLvoid *source = _mesa_image_address2d(unpack,
                                  pixels, width, height, format, type, row, 0);
         _mesa_unpack_color_span_float(ctx, width, GL_RGBA, (GLfloat *) dest,
                                     format, type, source, unpack,
                                     transferOps & IMAGE_PRE_CONVOLUTION_BITS);
         dest += width * 4;
      }

      /* do convolution */
      if (ctx->Pixel.Convolution2DEnabled) {
         _mesa_convolve_2d_image(ctx, &width, &height, tmpImage, convImage);
      }
      else {
         ASSERT(ctx->Pixel.Separable2DEnabled);
         _mesa_convolve_sep_image(ctx, &width, &height, tmpImage, convImage);
      }
      _mesa_free(tmpImage);

      /* continue transfer ops and draw the convolved image */
      unpack = &ctx->DefaultPacking;
      pixels = convImage;
      format = GL_RGBA;
      type = GL_FLOAT;
      transferOps &= IMAGE_POST_CONVOLUTION_BITS;
   }
   else if (ctx->Pixel.Convolution1DEnabled) {
      /* we only want to apply 1D convolution to glTexImage1D */
      transferOps &= ~(IMAGE_CONVOLUTION_BIT |
                       IMAGE_POST_CONVOLUTION_SCALE_BIAS);
   }

   if (ctx->DrawBuffer->_NumColorDrawBuffers > 0 &&
       ctx->DrawBuffer->_ColorDrawBuffers[0]->DataType != GL_FLOAT &&
       ctx->Color.ClampFragmentColor != GL_FALSE) {
      /* need to clamp colors before applying fragment ops */
      transferOps |= IMAGE_CLAMP_BIT;
   }

   /*
    * General solution
    */
   {
      const GLboolean sink = (ctx->Pixel.MinMaxEnabled && ctx->MinMax.Sink)
         || (ctx->Pixel.HistogramEnabled && ctx->Histogram.Sink);