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git-svn-id: file:///srv/svn/repos/haiku/trunk/current@9933 a95241bf-73f2-0310-859d-f6bbb57e9c96
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DarkWyrm
2004-11-12 02:02:58 +00:00
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headers/libs/agg/agg_scanline_u.h
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//----------------------------------------------------------------------------
// Anti-Grain Geometry - Version 2.2
// Copyright (C) 2002-2004 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: [email protected]
// [email protected]
// 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