static GLboolean fast_draw_rgba_pixels	(	GLcontext *	ctx,
		GLint	x,
		GLint	y,
		GLsizei	width,
		GLsizei	height,
		GLenum	format,
		GLenum	type,
		const struct gl_pixelstore_attrib *	userUnpack,
		const GLvoid *	pixels
	)		`[static]`
Try to do a fast and simple RGB(a) glDrawPixels. Return: GL_TRUE if success, GL_FALSE if slow path must be used instead
Definition at line 48 of file s_drawpix.c.
Referenced by draw_rgba_pixels().
{
   const GLint imgX = x, imgY = y;
   struct gl_renderbuffer *rb = ctx->DrawBuffer->_ColorDrawBuffers[0];
   GLenum rbType;
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   SWspan span;
   GLboolean simpleZoom;
   GLint yStep;  /* +1 or -1 */
   struct gl_pixelstore_attrib unpack;
   GLint destX, destY, drawWidth, drawHeight; /* post clipping */

   if (!rb)
      return GL_TRUE; /* no-op */

   rbType = rb->DataType;

   if ((swrast->_RasterMask & ~CLIP_BIT) ||
       ctx->Texture._EnabledCoordUnits ||
       userUnpack->SwapBytes ||
       ctx->_ImageTransferState) {
      /* can't handle any of those conditions */
      return GL_FALSE;
   }

   INIT_SPAN(span, GL_BITMAP);
   span.arrayMask = SPAN_RGBA;
   span.arrayAttribs = FRAG_BIT_COL0;
   _swrast_span_default_attribs(ctx, &span);

   /* copy input params since clipping may change them */
   unpack = *userUnpack;
   destX = x;
   destY = y;
   drawWidth = width;
   drawHeight = height;

   /* check for simple zooming and clipping */
   if (ctx->Pixel.ZoomX == 1.0F &&
       (ctx->Pixel.ZoomY == 1.0F || ctx->Pixel.ZoomY == -1.0F)) {
      if (!_mesa_clip_drawpixels(ctx, &destX, &destY,
                                 &drawWidth, &drawHeight, &unpack)) {
         /* image was completely clipped: no-op, all done */
         return GL_TRUE;
      }
      simpleZoom = GL_TRUE;
      yStep = (GLint) ctx->Pixel.ZoomY;
      ASSERT(yStep == 1 || yStep == -1);
   }
   else {
      /* non-simple zooming */
      simpleZoom = GL_FALSE;
      yStep = 1;
      if (unpack.RowLength == 0)
         unpack.RowLength = width;
   }

   /*
    * Ready to draw!
    */

   if (format == GL_RGBA && type == rbType) {
      const GLubyte *src
         = (const GLubyte *) _mesa_image_address2d(&unpack, pixels, width,
                                                   height, format, type, 0, 0);
      const GLint srcStride = _mesa_image_row_stride(&unpack, width,
                                                     format, type);
      if (simpleZoom) {
         GLint row;
         for (row = 0; row < drawHeight; row++) {
            rb->PutRow(ctx, rb, drawWidth, destX, destY, src, NULL);
            src += srcStride;
            destY += yStep;
         }
      }
      else {
         /* with zooming */
         GLint row;
         for (row = 0; row < drawHeight; row++) {
            span.x = destX;
            span.y = destY + row;
            span.end = drawWidth;
            span.array->ChanType = rbType;
            _swrast_write_zoomed_rgba_span(ctx, imgX, imgY, &span, src);
            src += srcStride;
         }
         span.array->ChanType = CHAN_TYPE;
      }
      return GL_TRUE;
   }

   if (format == GL_RGB && type == rbType) {
      const GLubyte *src
         = (const GLubyte *) _mesa_image_address2d(&unpack, pixels, width,
                                                   height, format, type, 0, 0);
      const GLint srcStride = _mesa_image_row_stride(&unpack, width,
                                                     format, type);
      if (simpleZoom) {
         GLint row;
         for (row = 0; row < drawHeight; row++) {
            rb->PutRowRGB(ctx, rb, drawWidth, destX, destY, src, NULL);
            src += srcStride;
            destY += yStep;
         }
      }
      else {
         /* with zooming */
         GLint row;
         for (row = 0; row < drawHeight; row++) {
            span.x = destX;
            span.y = destY;
            span.end = drawWidth;
            span.array->ChanType = rbType;
            _swrast_write_zoomed_rgb_span(ctx, imgX, imgY, &span, src);
            src += srcStride;
            destY++;
         }
         span.array->ChanType = CHAN_TYPE;
      }
      return GL_TRUE;
   }

   /* Remaining cases haven't been tested with alignment != 1 */
   if (userUnpack->Alignment != 1)
      return GL_FALSE;

   if (format == GL_LUMINANCE && type == CHAN_TYPE && rbType == CHAN_TYPE) {
      const GLchan *src = (const GLchan *) pixels
         + (unpack.SkipRows * unpack.RowLength + unpack.SkipPixels);
      if (simpleZoom) {
         /* no zooming */
         GLint row;
         ASSERT(drawWidth <= MAX_WIDTH);
         for (row = 0; row < drawHeight; row++) {
            GLchan rgb[MAX_WIDTH][3];
            GLint i;
            for (i = 0;i<drawWidth;i++) {
               rgb[i][0] = src[i];
               rgb[i][1] = src[i];
               rgb[i][2] = src[i];
            }
            rb->PutRowRGB(ctx, rb, drawWidth, destX, destY, rgb, NULL);
            src += unpack.RowLength;
            destY += yStep;
         }
      }
      else {
         /* with zooming */
         GLint row;
         ASSERT(drawWidth <= MAX_WIDTH);
         for (row = 0; row < drawHeight; row++) {
            GLchan rgb[MAX_WIDTH][3];
            GLint i;
            for (i = 0;i<drawWidth;i++) {
               rgb[i][0] = src[i];
               rgb[i][1] = src[i];
               rgb[i][2] = src[i];
            }
            span.x = destX;
            span.y = destY;
            span.end = drawWidth;
            _swrast_write_zoomed_rgb_span(ctx, imgX, imgY, &span, rgb);
            src += unpack.RowLength;
            destY++;
         }
      }
      return GL_TRUE;
   }

   if (format == GL_LUMINANCE_ALPHA && type == CHAN_TYPE && rbType == CHAN_TYPE) {
      const GLchan *src = (const GLchan *) pixels
         + (unpack.SkipRows * unpack.RowLength + unpack.SkipPixels)*2;
      if (simpleZoom) {
         GLint row;
         ASSERT(drawWidth <= MAX_WIDTH);
         for (row = 0; row < drawHeight; row++) {
            GLint i;
            const GLchan *ptr = src;
            for (i = 0;i<drawWidth;i++) {
               span.array->rgba[i][0] = *ptr;
               span.array->rgba[i][1] = *ptr;
               span.array->rgba[i][2] = *ptr++;
               span.array->rgba[i][3] = *ptr++;
            }
            rb->PutRow(ctx, rb, drawWidth, destX, destY,
                       span.array->rgba, NULL);
            src += unpack.RowLength*2;
            destY += yStep;
         }
      }
      else {
         /* with zooming */
         GLint row;
         ASSERT(drawWidth <= MAX_WIDTH);
         for (row = 0; row < drawHeight; row++) {
            const GLchan *ptr = src;
            GLint i;
            for (i = 0;i<drawWidth;i++) {
               span.array->rgba[i][0] = *ptr;
               span.array->rgba[i][1] = *ptr;
               span.array->rgba[i][2] = *ptr++;
               span.array->rgba[i][3] = *ptr++;
            }
            span.x = destX;
            span.y = destY;
            span.end = drawWidth;
            _swrast_write_zoomed_rgba_span(ctx, imgX, imgY, &span,
                                           span.array->rgba);
            src += unpack.RowLength*2;
            destY++;
         }
      }
      return GL_TRUE;
   }

   if (format == GL_COLOR_INDEX && type == GL_UNSIGNED_BYTE) {
      const GLubyte *src = (const GLubyte *) pixels
         + unpack.SkipRows * unpack.RowLength + unpack.SkipPixels;
      if (ctx->Visual.rgbMode && rbType == GL_UNSIGNED_BYTE) {
         /* convert ubyte/CI data to ubyte/RGBA */
         if (simpleZoom) {
            GLint row;
            for (row = 0; row < drawHeight; row++) {
               ASSERT(drawWidth <= MAX_WIDTH);
               _mesa_map_ci8_to_rgba8(ctx, drawWidth, src,
                                      span.array->rgba8);
               rb->PutRow(ctx, rb, drawWidth, destX, destY,
                          span.array->rgba8, NULL);
               src += unpack.RowLength;
               destY += yStep;
            }
         }
         else {
            /* ubyte/CI to ubyte/RGBA with zooming */
            GLint row;
            for (row = 0; row < drawHeight; row++) {
               ASSERT(drawWidth <= MAX_WIDTH);
               _mesa_map_ci8_to_rgba8(ctx, drawWidth, src,
                                      span.array->rgba8);
               span.x = destX;
               span.y = destY;
               span.end = drawWidth;
               _swrast_write_zoomed_rgba_span(ctx, imgX, imgY, &span,
                                              span.array->rgba8);
               src += unpack.RowLength;
               destY++;
            }
         }
         return GL_TRUE;
      }
      else if (!ctx->Visual.rgbMode && rbType == GL_UNSIGNED_INT) {
         /* write CI data to CI frame buffer */
         GLint row;
         if (simpleZoom) {
            for (row = 0; row < drawHeight; row++) {
               GLuint index32[MAX_WIDTH];
               GLint col;
               for (col = 0; col < drawWidth; col++)
                  index32[col] = src[col];
               rb->PutRow(ctx, rb, drawWidth, destX, destY, index32, NULL);
               src += unpack.RowLength;
               destY += yStep;
            }
            return GL_TRUE;
         }
      }
   }

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