//---------------------------------------------------------------------------- // 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: mcseem@antigrain.com // mcseemagg@yahoo.com // http://www.antigrain.com //---------------------------------------------------------------------------- #ifndef AGG_SCANLINE_U_INCLUDED #define AGG_SCANLINE_U_INCLUDED #include #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 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(const scanline_u&); const scanline_u& operator = (const scanline_u&); 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 scanline_u::~scanline_u() { delete [] m_spans; delete [] m_covers; } //------------------------------------------------------------------------ template scanline_u::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 void scanline_u::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 inline void scanline_u::reset_spans() { m_last_x = 0x7FFFFFF0; m_cur_span = m_spans; } //------------------------------------------------------------------------ template inline void scanline_u::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 void scanline_u::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 void scanline_u::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 scanline_u8; //============================================================scanline_u16 typedef scanline_u scanline_u16; //============================================================scanline_u32 typedef scanline_u scanline_u32; //=============================================================scanline_am // // The scanline container with alpha-masking // //------------------------------------------------------------------------ template class scanline_am : public scanline_u { public: typedef AlphaMask alpha_mask_type; typedef CoverT cover_type; typedef scanline_u 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::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 scanline_u8_am : public scanline_am { public: typedef AlphaMask alpha_mask_type; typedef int8u cover_type; typedef scanline_am self_type; scanline_u8_am() : self_type() {} scanline_u8_am(const AlphaMask& am) : self_type(am) {} }; } #endif