501 lines
17 KiB
C++
501 lines
17 KiB
C++
//----------------------------------------------------------------------------
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// Anti-Grain Geometry - Version 2.4
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// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
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//
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// Permission to copy, use, modify, sell and distribute this software
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// is granted provided this copyright notice appears in all copies.
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// This software is provided "as is" without express or implied
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// warranty, and with no claim as to its suitability for any purpose.
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//
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//----------------------------------------------------------------------------
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// Contact: mcseem@antigrain.com
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// mcseemagg@yahoo.com
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// http://www.antigrain.com
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//----------------------------------------------------------------------------
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//
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// Adaptation for 32-bit screen coordinates (scanline32_u) has been sponsored by
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// Liberty Technology Systems, Inc., visit http://lib-sys.com
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//
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// Liberty Technology Systems, Inc. is the provider of
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// PostScript and PDF technology for software developers.
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//
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//----------------------------------------------------------------------------
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#ifndef AGG_SCANLINE_U_INCLUDED
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#define AGG_SCANLINE_U_INCLUDED
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#include <cstring>
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#include "agg_array.h"
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namespace agg
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{
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//=============================================================scanline_u8
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//
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// Unpacked scanline container class
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//
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// This class is used to transfer data from a scanline rasterizer
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// to the rendering buffer. It's organized very simple. The class stores
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// information of horizontal spans to render it into a pixel-map buffer.
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// Each span has staring X, length, and an array of bytes that determine the
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// cover-values for each pixel.
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// Before using this class you should know the minimal and maximal pixel
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// coordinates of your scanline. The protocol of using is:
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// 1. reset(min_x, max_x)
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// 2. add_cell() / add_span() - accumulate scanline.
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// When forming one scanline the next X coordinate must be always greater
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// than the last stored one, i.e. it works only with ordered coordinates.
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// 3. Call finalize(y) and render the scanline.
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// 3. Call reset_spans() to prepare for the new scanline.
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//
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// 4. Rendering:
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//
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// Scanline provides an iterator class that allows you to extract
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// the spans and the cover values for each pixel. Be aware that clipping
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// has not been done yet, so you should perform it yourself.
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// Use scanline_u8::iterator to render spans:
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//-------------------------------------------------------------------------
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//
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// int y = sl.y(); // Y-coordinate of the scanline
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//
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// ************************************
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// ...Perform vertical clipping here...
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// ************************************
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//
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// scanline_u8::const_iterator span = sl.begin();
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//
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// unsigned char* row = m_rbuf->row(y); // The address of the beginning
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// // of the current row
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//
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// unsigned num_spans = sl.num_spans(); // Number of spans. It's guaranteed that
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// // num_spans is always greater than 0.
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//
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// do
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// {
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// const scanline_u8::cover_type* covers =
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// span->covers; // The array of the cover values
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//
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// int num_pix = span->len; // Number of pixels of the span.
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// // Always greater than 0, still it's
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// // better to use "int" instead of
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// // "unsigned" because it's more
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// // convenient for clipping
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// int x = span->x;
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//
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// **************************************
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// ...Perform horizontal clipping here...
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// ...you have x, covers, and pix_count..
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// **************************************
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//
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// unsigned char* dst = row + x; // Calculate the start address of the row.
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// // In this case we assume a simple
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// // grayscale image 1-byte per pixel.
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// do
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// {
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// *dst++ = *covers++; // Hypotetical rendering.
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// }
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// while(--num_pix);
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//
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// ++span;
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// }
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// while(--num_spans); // num_spans cannot be 0, so this loop is quite safe
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//------------------------------------------------------------------------
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//
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// The question is: why should we accumulate the whole scanline when we
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// could render just separate spans when they're ready?
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// That's because using the scanline is generally faster. When is consists
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// of more than one span the conditions for the processor cash system
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// are better, because switching between two different areas of memory
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// (that can be very large) occurs less frequently.
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//------------------------------------------------------------------------
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class scanline_u8
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{
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public:
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typedef scanline_u8 self_type;
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typedef int8u cover_type;
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typedef int16 coord_type;
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//--------------------------------------------------------------------
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struct span
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{
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coord_type x;
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coord_type len;
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cover_type* covers;
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};
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typedef span* iterator;
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typedef const span* const_iterator;
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//--------------------------------------------------------------------
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scanline_u8() :
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m_min_x(0),
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m_last_x(0x7FFFFFF0),
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m_cur_span(0)
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{}
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//--------------------------------------------------------------------
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void reset(int min_x, int max_x)
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{
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unsigned max_len = max_x - min_x + 2;
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if(max_len > m_spans.size())
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{
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m_spans.resize(max_len);
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m_covers.resize(max_len);
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}
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m_last_x = 0x7FFFFFF0;
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m_min_x = min_x;
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m_cur_span = &m_spans[0];
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}
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//--------------------------------------------------------------------
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void add_cell(int x, unsigned cover)
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{
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x -= m_min_x;
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m_covers[x] = (cover_type)cover;
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if(x == m_last_x+1)
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{
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m_cur_span->len++;
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}
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else
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{
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m_cur_span++;
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m_cur_span->x = (coord_type)(x + m_min_x);
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m_cur_span->len = 1;
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m_cur_span->covers = &m_covers[x];
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}
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m_last_x = x;
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}
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//--------------------------------------------------------------------
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void add_cells(int x, unsigned len, const cover_type* covers)
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{
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x -= m_min_x;
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std::memcpy(&m_covers[x], covers, len * sizeof(cover_type));
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if(x == m_last_x+1)
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{
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m_cur_span->len += (coord_type)len;
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}
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else
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{
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m_cur_span++;
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m_cur_span->x = (coord_type)(x + m_min_x);
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m_cur_span->len = (coord_type)len;
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m_cur_span->covers = &m_covers[x];
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}
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m_last_x = x + len - 1;
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}
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//--------------------------------------------------------------------
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void add_span(int x, unsigned len, unsigned cover)
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{
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x -= m_min_x;
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std::memset(&m_covers[x], cover, len);
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if(x == m_last_x+1)
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{
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m_cur_span->len += (coord_type)len;
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}
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else
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{
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m_cur_span++;
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m_cur_span->x = (coord_type)(x + m_min_x);
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m_cur_span->len = (coord_type)len;
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m_cur_span->covers = &m_covers[x];
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}
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m_last_x = x + len - 1;
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}
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//--------------------------------------------------------------------
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void finalize(int y)
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{
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m_y = y;
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}
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//--------------------------------------------------------------------
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void reset_spans()
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{
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m_last_x = 0x7FFFFFF0;
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m_cur_span = &m_spans[0];
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}
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//--------------------------------------------------------------------
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int y() const { return m_y; }
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unsigned num_spans() const { return unsigned(m_cur_span - &m_spans[0]); }
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const_iterator begin() const { return &m_spans[1]; }
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iterator begin() { return &m_spans[1]; }
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private:
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scanline_u8(const self_type&);
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const self_type& operator = (const self_type&);
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private:
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int m_min_x;
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int m_last_x;
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int m_y;
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pod_array<cover_type> m_covers;
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pod_array<span> m_spans;
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span* m_cur_span;
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};
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//==========================================================scanline_u8_am
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//
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// The scanline container with alpha-masking
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//
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//------------------------------------------------------------------------
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template<class AlphaMask>
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class scanline_u8_am : public scanline_u8
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{
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public:
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typedef scanline_u8 base_type;
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typedef AlphaMask alpha_mask_type;
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typedef base_type::cover_type cover_type;
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typedef base_type::coord_type coord_type;
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scanline_u8_am() : base_type(), m_alpha_mask(0) {}
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scanline_u8_am(AlphaMask& am) : base_type(), m_alpha_mask(&am) {}
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//--------------------------------------------------------------------
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void finalize(int span_y)
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{
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base_type::finalize(span_y);
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if(m_alpha_mask)
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{
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typename base_type::iterator span = base_type::begin();
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unsigned count = base_type::num_spans();
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do
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{
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m_alpha_mask->combine_hspan(span->x,
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base_type::y(),
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span->covers,
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span->len);
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++span;
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}
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while(--count);
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}
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}
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private:
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AlphaMask* m_alpha_mask;
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};
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//===========================================================scanline32_u8
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class scanline32_u8
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{
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public:
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typedef scanline32_u8 self_type;
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typedef int8u cover_type;
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typedef int32 coord_type;
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//--------------------------------------------------------------------
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struct span
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{
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span() {}
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span(coord_type x_, coord_type len_, cover_type* covers_) :
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x(x_), len(len_), covers(covers_) {}
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coord_type x;
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coord_type len;
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cover_type* covers;
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};
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typedef pod_bvector<span, 4> span_array_type;
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//--------------------------------------------------------------------
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class const_iterator
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{
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public:
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const_iterator(const span_array_type& spans) :
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m_spans(spans),
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m_span_idx(0)
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{}
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const span& operator*() const { return m_spans[m_span_idx]; }
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const span* operator->() const { return &m_spans[m_span_idx]; }
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void operator ++ () { ++m_span_idx; }
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private:
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const span_array_type& m_spans;
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unsigned m_span_idx;
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};
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//--------------------------------------------------------------------
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class iterator
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{
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public:
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iterator(span_array_type& spans) :
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m_spans(spans),
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m_span_idx(0)
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{}
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span& operator*() { return m_spans[m_span_idx]; }
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span* operator->() { return &m_spans[m_span_idx]; }
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void operator ++ () { ++m_span_idx; }
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private:
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span_array_type& m_spans;
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unsigned m_span_idx;
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};
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//--------------------------------------------------------------------
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scanline32_u8() :
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m_min_x(0),
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m_last_x(0x7FFFFFF0),
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m_covers()
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{}
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//--------------------------------------------------------------------
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void reset(int min_x, int max_x)
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{
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unsigned max_len = max_x - min_x + 2;
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if(max_len > m_covers.size())
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{
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m_covers.resize(max_len);
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}
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m_last_x = 0x7FFFFFF0;
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m_min_x = min_x;
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m_spans.remove_all();
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}
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//--------------------------------------------------------------------
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void add_cell(int x, unsigned cover)
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{
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x -= m_min_x;
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m_covers[x] = cover_type(cover);
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if(x == m_last_x+1)
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{
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m_spans.last().len++;
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}
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else
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{
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m_spans.add(span(coord_type(x + m_min_x), 1, &m_covers[x]));
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}
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m_last_x = x;
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}
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//--------------------------------------------------------------------
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void add_cells(int x, unsigned len, const cover_type* covers)
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{
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x -= m_min_x;
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std::memcpy(&m_covers[x], covers, len * sizeof(cover_type));
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if(x == m_last_x+1)
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{
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m_spans.last().len += coord_type(len);
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}
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else
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{
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m_spans.add(span(coord_type(x + m_min_x),
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coord_type(len),
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&m_covers[x]));
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}
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m_last_x = x + len - 1;
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}
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//--------------------------------------------------------------------
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void add_span(int x, unsigned len, unsigned cover)
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{
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x -= m_min_x;
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std::memset(&m_covers[x], cover, len);
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if(x == m_last_x+1)
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{
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m_spans.last().len += coord_type(len);
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}
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else
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{
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m_spans.add(span(coord_type(x + m_min_x),
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coord_type(len),
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&m_covers[x]));
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}
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m_last_x = x + len - 1;
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}
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//--------------------------------------------------------------------
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void finalize(int y)
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{
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m_y = y;
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}
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//--------------------------------------------------------------------
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void reset_spans()
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{
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m_last_x = 0x7FFFFFF0;
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m_spans.remove_all();
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}
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//--------------------------------------------------------------------
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int y() const { return m_y; }
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unsigned num_spans() const { return m_spans.size(); }
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const_iterator begin() const { return const_iterator(m_spans); }
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iterator begin() { return iterator(m_spans); }
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private:
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scanline32_u8(const self_type&);
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const self_type& operator = (const self_type&);
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private:
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int m_min_x;
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int m_last_x;
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int m_y;
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pod_array<cover_type> m_covers;
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span_array_type m_spans;
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};
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//========================================================scanline32_u8_am
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//
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// The scanline container with alpha-masking
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//
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//------------------------------------------------------------------------
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template<class AlphaMask>
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class scanline32_u8_am : public scanline32_u8
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{
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public:
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typedef scanline32_u8 base_type;
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typedef AlphaMask alpha_mask_type;
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typedef base_type::cover_type cover_type;
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typedef base_type::coord_type coord_type;
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scanline32_u8_am() : base_type(), m_alpha_mask(0) {}
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scanline32_u8_am(AlphaMask& am) : base_type(), m_alpha_mask(&am) {}
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//--------------------------------------------------------------------
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void finalize(int span_y)
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{
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base_type::finalize(span_y);
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if(m_alpha_mask)
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{
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typename base_type::iterator span = base_type::begin();
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unsigned count = base_type::num_spans();
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do
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{
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m_alpha_mask->combine_hspan(span->x,
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base_type::y(),
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span->covers,
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span->len);
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++span;
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}
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while(--count);
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}
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}
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private:
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AlphaMask* m_alpha_mask;
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};
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}
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#endif
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