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+//----------------------------------------------------------------------------
+// Anti-Grain Geometry - Version 2.3
+// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
+//
+// Permission to copy, use, modify, sell and distribute this software
+// is granted provided this copyright notice appears in all copies.
+// This software is provided "as is" without express or implied
+// warranty, and with no claim as to its suitability for any purpose.
+//
+//----------------------------------------------------------------------------
+// Contact: mcseem@antigrain.com
+// mcseemagg@yahoo.com
+// http://www.antigrain.com
+//----------------------------------------------------------------------------
+
+#ifndef AGG_SCANLINE_U_INCLUDED
+#define AGG_SCANLINE_U_INCLUDED
+
+#include <string.h>
+#include "agg_basics.h"
+
+namespace agg
+{
+ //==============================================================scanline_u
+ //
+ // Unpacked scanline container class
+ //
+ // This class is used to transfer data from a scanline rastyerizer
+ // to the rendering buffer. It's organized very simple. The class stores
+ // information of horizontal spans to render it into a pixel-map buffer.
+ // Each span has staring X, length, and an array of bytes that determine the
+ // cover-values for each pixel.
+ // Before using this class you should know the minimal and maximal pixel
+ // coordinates of your scanline. The protocol of using is:
+ // 1. reset(min_x, max_x)
+ // 2. add_cell() / add_span() - accumulate scanline.
+ // When forming one scanline the next X coordinate must be always greater
+ // than the last stored one, i.e. it works only with ordered coordinates.
+ // 3. Call finalize(y) and render the scanline.
+ // 3. Call reset_spans() to prepare for the new scanline.
+ //
+ // 4. Rendering:
+ //
+ // Scanline provides an iterator class that allows you to extract
+ // the spans and the cover values for each pixel. Be aware that clipping
+ // has not been done yet, so you should perform it yourself.
+ // Use scanline_u8::iterator to render spans:
+ //-------------------------------------------------------------------------
+ //
+ // int y = sl.y(); // Y-coordinate of the scanline
+ //
+ // ************************************
+ // ...Perform vertical clipping here...
+ // ************************************
+ //
+ // scanline_u8::const_iterator span = sl.begin();
+ //
+ // unsigned char* row = m_rbuf->row(y); // The the address of the beginning
+ // // of the current row
+ //
+ // unsigned num_spans = sl.num_spans(); // Number of spans. It's guaranteed that
+ // // num_spans is always greater than 0.
+ //
+ // do
+ // {
+ // const scanline_u8::cover_type* covers =
+ // span->covers; // The array of the cover values
+ //
+ // int num_pix = span->len; // Number of pixels of the span.
+ // // Always greater than 0, still it's
+ // // better to use "int" instead of
+ // // "unsigned" because it's more
+ // // convenient for clipping
+ // int x = span->x;
+ //
+ // **************************************
+ // ...Perform horizontal clipping here...
+ // ...you have x, covers, and pix_count..
+ // **************************************
+ //
+ // unsigned char* dst = row + x; // Calculate the start address of the row.
+ // // In this case we assume a simple
+ // // grayscale image 1-byte per pixel.
+ // do
+ // {
+ // *dst++ = *covers++; // Hypotetical rendering.
+ // }
+ // while(--num_pix);
+ //
+ // ++span;
+ // }
+ // while(--num_spans); // num_spans cannot be 0, so this loop is quite safe
+ //------------------------------------------------------------------------
+ //
+ // The question is: why should we accumulate the whole scanline when we
+ // could render just separate spans when they're ready?
+ // That's because using the scaline is generally faster. When is consists
+ // of more than one span the conditions for the processor cash system
+ // are better, because switching between two different areas of memory
+ // (that can be very large) occures less frequently.
+ //------------------------------------------------------------------------
+ template<class T> class scanline_u
+ {
+ public:
+ typedef T cover_type;
+
+ //--------------------------------------------------------------------
+ struct span
+ {
+ int16 x;
+ int16 len;
+ cover_type* covers;
+ };
+
+ typedef span* iterator;
+ typedef const span* const_iterator;
+
+ //--------------------------------------------------------------------
+ ~scanline_u();
+ scanline_u();
+
+ void reset(int min_x, int max_x);
+ void add_cell(int x, unsigned cover);
+ void add_cells(int x, unsigned len, const T* covers);
+ void add_span(int x, unsigned len, unsigned cover);
+ void finalize(int y) { m_y = y; }
+ void reset_spans();
+
+ int y() const { return m_y; }
+ unsigned num_spans() const { return unsigned(m_cur_span - m_spans); }
+ const_iterator begin() const { return m_spans + 1; }
+ iterator begin() { return m_spans + 1; }
+
+ private:
+ scanline_u<T>(const scanline_u<T>&);
+ const scanline_u<T>& operator = (const scanline_u<T>&);
+
+ private:
+ int m_min_x;
+ unsigned m_max_len;
+ int m_last_x;
+ int m_y;
+ cover_type* m_covers;
+ span* m_spans;
+ span* m_cur_span;
+ };
+
+
+
+ //------------------------------------------------------------------------
+ template<class T> scanline_u<T>::~scanline_u()
+ {
+ delete [] m_spans;
+ delete [] m_covers;
+ }
+
+
+ //------------------------------------------------------------------------
+ template<class T> scanline_u<T>::scanline_u() :
+ m_min_x(0),
+ m_max_len(0),
+ m_last_x(0x7FFFFFF0),
+ m_covers(0),
+ m_spans(0),
+ m_cur_span(0)
+ {
+ }
+
+
+ //------------------------------------------------------------------------
+ template<class T> void scanline_u<T>::reset(int min_x, int max_x)
+ {
+ unsigned max_len = max_x - min_x + 2;
+ if(max_len > m_max_len)
+ {
+ delete [] m_spans;
+ delete [] m_covers;
+ m_covers = new cover_type [max_len];
+ m_spans = new span [max_len];
+ m_max_len = max_len;
+ }
+ m_last_x = 0x7FFFFFF0;
+ m_min_x = min_x;
+ m_cur_span = m_spans;
+ }
+
+
+ //------------------------------------------------------------------------
+ template<class T> inline void scanline_u<T>::reset_spans()
+ {
+ m_last_x = 0x7FFFFFF0;
+ m_cur_span = m_spans;
+ }
+
+
+ //------------------------------------------------------------------------
+ template<class T> inline void scanline_u<T>::add_cell(int x, unsigned cover)
+ {
+ x -= m_min_x;
+ m_covers[x] = (unsigned char)cover;
+ if(x == m_last_x+1)
+ {
+ m_cur_span->len++;
+ }
+ else
+ {
+ m_cur_span++;
+ m_cur_span->x = (int16)(x + m_min_x);
+ m_cur_span->len = 1;
+ m_cur_span->covers = m_covers + x;
+ }
+ m_last_x = x;
+ }
+
+
+ //------------------------------------------------------------------------
+ template<class T> void scanline_u<T>::add_cells(int x, unsigned len, const T* covers)
+ {
+ x -= m_min_x;
+ memcpy(m_covers + x, covers, len * sizeof(T));
+ if(x == m_last_x+1)
+ {
+ m_cur_span->len += (int16)len;
+ }
+ else
+ {
+ m_cur_span++;
+ m_cur_span->x = (int16)(x + m_min_x);
+ m_cur_span->len = (int16)len;
+ m_cur_span->covers = m_covers + x;
+ }
+ m_last_x = x + len - 1;
+ }
+
+
+ //------------------------------------------------------------------------
+ template<class T> void scanline_u<T>::add_span(int x, unsigned len, unsigned cover)
+ {
+ x -= m_min_x;
+ memset(m_covers + x, cover, len);
+ if(x == m_last_x+1)
+ {
+ m_cur_span->len += (int16)len;
+ }
+ else
+ {
+ m_cur_span++;
+ m_cur_span->x = (int16)(x + m_min_x);
+ m_cur_span->len = (int16)len;
+ m_cur_span->covers = m_covers + x;
+ }
+ m_last_x = x + len - 1;
+ }
+
+
+ //=============================================================scanline_u8
+ typedef scanline_u<int8u> scanline_u8;
+
+ //============================================================scanline_u16
+ typedef scanline_u<int16u> scanline_u16;
+
+ //============================================================scanline_u32
+ typedef scanline_u<int32u> scanline_u32;
+
+
+ //=============================================================scanline_am
+ //
+ // The scanline container with alpha-masking
+ //
+ //------------------------------------------------------------------------
+ template<class AlphaMask, class CoverT>
+ class scanline_am : public scanline_u<CoverT>
+ {
+ public:
+ typedef AlphaMask alpha_mask_type;
+ typedef CoverT cover_type;
+ typedef scanline_u<CoverT> scanline_type;
+
+ scanline_am() : scanline_type(), m_alpha_mask(0) {}
+ scanline_am(const AlphaMask& am) : scanline_type(), m_alpha_mask(&am) {}
+
+ //--------------------------------------------------------------------
+ void finalize(int span_y)
+ {
+ scanline_u<CoverT>::finalize(span_y);
+ if(m_alpha_mask)
+ {
+ typename scanline_type::iterator span = scanline_type::begin();
+ unsigned count = scanline_type::num_spans();
+ do
+ {
+ m_alpha_mask->combine_hspan(span->x,
+ scanline_type::y(),
+ span->covers,
+ span->len);
+ ++span;
+ }
+ while(--count);
+ }
+ }
+
+ private:
+ const AlphaMask* m_alpha_mask;
+ };
+
+
+ //==========================================================scanline_u8_am
+ template<class AlphaMask>
+ class scanline_u8_am : public scanline_am<AlphaMask, int8u>
+ {
+ public:
+ typedef AlphaMask alpha_mask_type;
+ typedef int8u cover_type;
+ typedef scanline_am<alpha_mask_type, cover_type> self_type;
+
+ scanline_u8_am() : self_type() {}
+ scanline_u8_am(const AlphaMask& am) : self_type(am) {}
+ };
+
+}
+
+#endif
+