Public API Reference

csplugincommon/canvas/draw_text.h

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/*
    Copyright (C) 2004 by Jorrit Tyberghein
              (C) 2004 by Frank Richter

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#ifndef __CS_CSPLUGINCOMMON_CANVAS_DRAW_TEXT_H__
#define __CS_CSPLUGINCOMMON_CANVAS_DRAW_TEXT_H__

#include "csplugincommon/canvas/draw_common.h"
#include "csplugincommon/canvas/softfontcache.h"
#include "csutil/csuctransform.h"

template<class Tpixel, class Tpixmixer1, class Tpixmixer2, class Tpixmixer3>
class csG2DDrawText
{
public:
  static void DrawText (csSoftFontCache* cache, iFont* font, int pen_x, int pen_y,
    Tpixel fg, uint8 alphaFG, Tpixel bg, uint8 alphaBG, const void* text, 
    bool isWide, uint flags)
  {
    csGraphics2D* G2D = cache->G2D;
    const int ClipX1 = cache->ClipX1, ClipY1 = cache->ClipY1, 
      ClipX2 = cache->ClipX2, ClipY2 = cache->ClipY2;
    Tpixmixer1 mixerFG (G2D, fg, alphaFG);
    Tpixmixer2 mixerBG (G2D, bg, alphaBG);
    
    if (!font)
      return;
    
    if (!(flags & CS_WRITE_BASELINE)) pen_y += font->GetAscent ();
  
    csSoftFontCache::KnownFont* knownFont = cache->GetCachedFont (font);
    if (knownFont == 0) knownFont = cache->CacheFont (font);
  
    size_t textLen = isWide ? wcslen ((wchar_t*)text) : strlen ((char*)text);
    int charW, charH, advance = 0;
    bool firstchar = true;
    while (textLen > 0)
    {
      utf32_char glyph;
      if (isWide)
      {
        int skip = csUnicodeTransform::Decode ((wchar_t*)text, textLen, glyph, 0);
        if (skip == 0) break;
  
        text = ((wchar_t*)text + skip);
        textLen -= skip;
      }
      else
      {
        int skip = csUnicodeTransform::UTF8Decode ((utf8_char*)text, textLen, glyph, 0);
        if (skip == 0) break;
  
        text = ((utf8_char*)text + skip);
        textLen -= skip;
      }
  
      csSoftFontCache::SoftGlyphCacheData* cacheData = 
        (csSoftFontCache::SoftGlyphCacheData*)cache->CacheGlyph (knownFont, 
        glyph, flags);
      if (!cacheData->hasGlyph) 
      {
        // fall back to the default glyph (CS_FONT_DEFAULT_GLYPH)
        cacheData = (csSoftFontCache::SoftGlyphCacheData*)cache->CacheGlyph (
          knownFont, CS_FONT_DEFAULT_GLYPH, flags);
        if (!cacheData->hasGlyph) continue;
      }
  
      csBitmapMetrics* bmetrics;
      if (cacheData->glyphAlphaDataBuf.IsValid())
      {
        bmetrics = &cacheData->alphaMetrics;
      }
      else if (cacheData->glyphDataBuf.IsValid())
      {
        bmetrics = &cacheData->bitmapMetrics;
      }
      else
        continue;

      register uint8 *CharImageAlpha = cacheData->glyphAlphaData;
      register uint8 *CharImage = cacheData->glyphData;
  
      charW = bmetrics->width;
      charH = bmetrics->height;
      
      int y = pen_y - bmetrics->top;
      
      // If we are advancing more than the last char was wide, we have to
      // fill the 'gap' with bg.
      
      int x = pen_x - (advance > 0 ? advance : 0) + (bmetrics->left < 0 ? bmetrics->left : 0);
      advance += bmetrics->left;
      
      // Hack: in case the first char has a negative left bitmap offset,
      // some of the background isn't drawn. Fix that.
      if (firstchar)
      {
        if (advance < 0)
        {
          advance = 0;
        }
        firstchar = false;
      }
     
      if (alphaBG != 0)
      {
        while (advance > 0)
        {
          if (x >= ClipX2)
            return;
    
          int cury = y;
          for (int i = 0; i < charH; i++, cury++)
          {
            if ((cury < ClipY1) || (cury >= ClipY2)) continue;
            register Tpixel *VRAM = (Tpixel*)G2D->GetPixelAt (x, cury);
            if (x >= ClipX1) mixerBG.Mix (*VRAM);
          }
          x++; advance--;
        }
      }
      else
      {
        if (advance > 0)
        {
          x += advance;
          advance = 0;
        }
      }
  
      if (x >= ClipX2)
        return;
  
      // If character is completely outside the clipping rectangle, continue
      if (!((x + charW <= ClipX1) || (x >= ClipX2)
       || (y + charH <= ClipY1) || (y >= ClipY2)))
      {
        int cury = y;
    
        int oldAdvance = advance;
        // If character should not be clipped, go the fast path
        if ((x < ClipX1) || (x + charW >= ClipX2)
         || (y < ClipY1) || (y + charH >= ClipY2))
        {
          // Perform full clipping
          int lX = x < ClipX1 ? ClipX1 - x : 0;
          int rX = x + charW >= ClipX2 ? ClipX2 - x : charW;
          int lBytes = CharImageAlpha ? lX : lX >> 3;
          int shiftX = CharImageAlpha ? 0 : lX & 7;
          int bbl = CharImageAlpha ? charW : (charW + 7) / 8; // bytes per line
          int lAbsX = x + lX;
          uint8 *p = CharImageAlpha ? CharImageAlpha - bbl : CharImage - bbl;
          
          if (CharImageAlpha)
          {
            for (int i = 0; i < charH; i++, cury++)
            {
              advance = oldAdvance;
              p += bbl;
              if ((cury < ClipY1) || (cury >= ClipY2)) 
              {
                if (advance < 0) advance = MIN(0, advance + (rX - lX));
                continue;
              }
              CharImageAlpha = p + lBytes;
              register uint8 CharLine = (*CharImageAlpha++) << shiftX;
              register Tpixel* VRAM = (Tpixel*)G2D->GetPixelAt (lAbsX, cury);
              // If we are advancing less than the last char was wide, the current
              // and last chars overlap. So we can't draw opaque, but have to draw
              // transparent instead.
              if (advance >= 0)
              {
                for (int j = lX; j < rX; j++)
                {
                  if (CharLine == 0xff)
                  {
                    mixerFG.Mix (*VRAM);
                  }
                  else if (CharLine == 0x00)
                  {
                    mixerBG.Mix (*VRAM);
                  }
                  else
                  {
                    // @@@ Could be more optimal, probably.
                    Tpixel mixedFG = *VRAM;
                    mixerFG.Mix (mixedFG);
                    mixerBG.Mix (*VRAM);
                    
                    Tpixmixer3 mixer (G2D, mixedFG, CharLine);
                    mixer.Mix (*VRAM);
                  }
                  VRAM++;
                  if (j < rX-1) CharLine = (*CharImageAlpha++);
                } /* endfor */
              }
              else
              {
                for (int j = lX; j < rX; j++)
                {
                  if (CharLine == 0xff)
                  {
                    mixerFG.Mix (*VRAM);
                  }
                  else if (CharLine != 0x00)
                  {
                    // @@@ Could be more optimal, probably.
                    Tpixel mixedFG = *VRAM;
                    mixerFG.Mix (mixedFG);
                    
                    Tpixmixer3 mixer (G2D, mixedFG, CharLine);
                    mixer.Mix (*VRAM);
                  }
                  VRAM++;
                  if (j < rX-1) CharLine = (*CharImageAlpha++);
                } /* endfor */
                if (advance < 0) advance++;
              }
            }
          }
          else if (CharImage)
          {
            for (int i = 0; i < charH; i++, cury++)
            {
              advance = oldAdvance;
              p += bbl;
              if ((cury < ClipY1) || (cury >= ClipY2))
              {
                if (advance < 0) advance = MIN(0, advance + (rX - lX));
                continue;
              }
              CharImage = p + lBytes;
              register uint8 CharLine = (*CharImage++) << shiftX;
              register Tpixel* VRAM = (Tpixel*)G2D->GetPixelAt (lAbsX, cury);
              for (int j = lX; j < rX; j++)
              {
                if (advance >= 0)
                {
                  if (CharLine & 0x80)
                    mixerFG.Mix (*VRAM++);
                  else
                    mixerBG.Mix (*VRAM++);
                }
                else
                {
                  if (CharLine & 0x80)
                    mixerFG.Mix (*VRAM++);
                  else
                    VRAM++;
                  advance++;
                }
                if ((j & 7) == 7)
                  CharLine = (*CharImage++);
                else
                  CharLine += CharLine;
              } /* endfor */
            }
          }
        }
        else
        {
          // no clipping
          if (CharImageAlpha)
          {
            for (int i = 0; i < charH; i++, cury++)
            {
              advance = oldAdvance;
              register Tpixel* VRAM = (Tpixel*)G2D->GetPixelAt (x, cury);
              register unsigned pixW = charW;
              register int pix;
              for (pix = pixW; pix > 0; pix--)
              {
                register uint8 CharLine = (*CharImageAlpha++);
                if (advance < 0)
                {
                  if (CharLine == 0xff)
                  {
                    mixerFG.Mix (*VRAM);
                  }
                  else if (CharLine != 0x00)
                  {
                    // @@@ Could be more optimal, probably.
                    Tpixel mixedFG = *VRAM;
                    mixerFG.Mix (mixedFG);
                    
                    Tpixmixer3 mixer (G2D, mixedFG, CharLine);
                    mixer.Mix (*VRAM);
                  }
                }
                else
                {
                  if (CharLine == 0xff)
                  {
                    mixerFG.Mix (*VRAM);
                  }
                  else if (CharLine == 0x00)
                  {
                    mixerBG.Mix (*VRAM);
                  }
                  else
                  {
                    // @@@ Could be more optimal, probably.
                    Tpixel mixedFG = *VRAM;
                    mixerFG.Mix (mixedFG);
                    mixerBG.Mix (*VRAM);
                    
                    Tpixmixer3 mixer (G2D, mixedFG, CharLine);
                    mixer.Mix (*VRAM);
                  }
                }
                if (advance < 0) advance++;
                VRAM++;
              }
            }
          }
          else if (CharImage)
          {
            for (int i = 0; i < charH; i++, cury++)
            {
              register Tpixel* VRAM = (Tpixel*)G2D->GetPixelAt (x, cury);
              register unsigned pixW = charW;
              while (pixW)
              {
                register unsigned char CharLine = *CharImage++;
                register int pix;
                for (pix = pixW < 8 ? pixW : 8, pixW -= pix; CharLine && pix; pix--)
                {
                  if (advance < 0)
                  {
                    if (CharLine & 0x80)
                      mixerFG.Mix (*VRAM++);
                    else
                      VRAM++;
                    // Addition is faster than shift, at least on i586+
                    CharLine += CharLine;
                  }
                  else
                  {
                    if (CharLine & 0x80)
                      mixerFG.Mix (*VRAM++);
                    else
                      mixerBG.Mix (*VRAM++);
                    // Addition is faster than shift, at least on i586+
                    CharLine += CharLine;
                  }
                  if (advance < 0) advance++;
                } /* endfor */
                if (advance < 0)
                {
                  VRAM -= advance;
                  pix += advance;
                }
                while (pix--)
                  mixerBG.Mix (*VRAM++);
              } 
            } 
          }
        } /* endif */
      }
  
      pen_x += cacheData->glyphMetrics.advance;
      advance += cacheData->glyphMetrics.advance - (charW + bmetrics->left);
    }
    cache->PurgeEmptyPlanes ();
    
  }
};

#endif // __CS_CSPLUGINCOMMON_CANVAS_DRAW_TEXT_H___

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