occt/src/OpenGl/OpenGl_Font.cxx

// Created on: 2013-01-29
// Created by: Kirill GAVRILOV
// Copyright (c) 2013-2014 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

#include <OpenGl_Font.hxx>

#include <OpenGl_Context.hxx>
#include <Font_FTFont.hxx>
#include <Graphic3d_TextureParams.hxx>
#include <Standard_Assert.hxx>
#include <TCollection_ExtendedString.hxx>

IMPLEMENT_STANDARD_RTTIEXT(OpenGl_Font,OpenGl_Resource)

// =======================================================================
// function : OpenGl_Font
// purpose  :
// =======================================================================
OpenGl_Font::OpenGl_Font (const Handle(Font_FTFont)&     theFont,
                          const TCollection_AsciiString& theKey)
: myKey  (theKey),
  myFont (theFont),
  myAscender (0.0f),
  myDescender (0.0f),
  myTileSizeY (0),
  myLastTileId (-1),
  myTextureFormat (GL_ALPHA)
{
  memset (&myLastTilePx, 0, sizeof(myLastTilePx));
}

// =======================================================================
// function : ~OpenGl_Font
// purpose  :
// =======================================================================
OpenGl_Font::~OpenGl_Font()
{
  Release (NULL);
}

// =======================================================================
// function : Release
// purpose  :
// =======================================================================
void OpenGl_Font::Release (OpenGl_Context* theCtx)
{
  if (myTextures.IsEmpty())
  {
    return;
  }

  for (Standard_Integer anIter = 0; anIter < myTextures.Length(); ++anIter)
  {
    Handle(OpenGl_Texture)& aTexture = myTextures.ChangeValue (anIter);
    if (aTexture->IsValid())
    {
      // application can not handle this case by exception - this is bug in code
      Standard_ASSERT_RETURN (theCtx != NULL,
        "OpenGl_Font destroyed without GL context! Possible GPU memory leakage...",);
    }

    aTexture->Release (theCtx);
    aTexture.Nullify();
  }
  myTextures.Clear();
}

// =======================================================================
// function : EstimatedDataSize
// purpose  :
// =======================================================================
Standard_Size OpenGl_Font::EstimatedDataSize() const
{
  Standard_Size aSize = 0;
  for (NCollection_Vector<Handle(OpenGl_Texture)>::Iterator aTexIter (myTextures); aTexIter.More(); aTexIter.Next())
  {
    aSize += aTexIter.Value()->EstimatedDataSize();
  }
  return aSize;
}

// =======================================================================
// function : Init
// purpose  :
// =======================================================================
bool OpenGl_Font::Init (const Handle(OpenGl_Context)& theCtx)
{
  Release (theCtx.operator->());
  if (myFont.IsNull() || !myFont->IsValid())
  {
    return false;
  }

  myAscender  = myFont->Ascender();
  myDescender = myFont->Descender();
  myTileSizeY = myFont->GlyphMaxSizeY (true);

  myLastTileId = -1;
  if (!createTexture (theCtx))
  {
    Release (theCtx.operator->());
    return false;
  }
  return true;
}

// =======================================================================
// function : createTexture
// purpose  :
// =======================================================================
bool OpenGl_Font::createTexture (const Handle(OpenGl_Context)& theCtx)
{
  // Single font might define very wide range of symbols, with very few of them actually used in text.
  // Limit single texture with circa 4096 glyphs.
  static const Standard_Integer THE_MAX_GLYPHS_PER_TEXTURE = 4096;

  myTileSizeY = myFont->GlyphMaxSizeY (true);
  const Standard_Integer aGlyphsNb = Min (THE_MAX_GLYPHS_PER_TEXTURE, myFont->GlyphsNumber (true) - myLastTileId + 1);
  const Standard_Integer aMaxTileSizeX = myFont->GlyphMaxSizeX (true);
  const Standard_Integer aMaxSize      = theCtx->MaxTextureSize();
  const Standard_Integer aTextureSizeX = OpenGl_Context::GetPowerOfTwo (aGlyphsNb * aMaxTileSizeX, aMaxSize);
  const Standard_Integer aTilesPerRow  = aTextureSizeX / aMaxTileSizeX;
  const Standard_Integer aTextureSizeY = OpenGl_Context::GetPowerOfTwo (GLint((aGlyphsNb / aTilesPerRow) + 1) * myTileSizeY, aMaxSize);

  memset (&myLastTilePx, 0, sizeof(myLastTilePx));
  myLastTilePx.Bottom = myTileSizeY;

  Handle(Graphic3d_TextureParams) aParams = new Graphic3d_TextureParams();
  aParams->SetModulate    (Standard_False);
  aParams->SetRepeat      (Standard_False);
  aParams->SetFilter      (Graphic3d_TOTF_BILINEAR);
  aParams->SetAnisoFilter (Graphic3d_LOTA_OFF);

  myTextures.Append (new OpenGl_Texture (myKey + "_texture" + myTextures.Size(), aParams));
  Handle(OpenGl_Texture)& aTexture = myTextures.ChangeLast();

  Image_PixMap aBlackImg;
  if (!aBlackImg.InitZero (Image_Format_Alpha, Standard_Size(aTextureSizeX), Standard_Size(aTextureSizeY))
   || !aTexture->Init (theCtx, aBlackImg, Graphic3d_TOT_2D, true)) // myTextureFormat
  {
    theCtx->PushMessage (GL_DEBUG_SOURCE_APPLICATION, GL_DEBUG_TYPE_ERROR, 0, GL_DEBUG_SEVERITY_HIGH,
                         TCollection_AsciiString ("New texture initialization of size ")
                       + aTextureSizeX + "x" + aTextureSizeY + " for textured font has failed.");
    return false;
  }

  return true;
}

// =======================================================================
// function : renderGlyph
// purpose  :
// =======================================================================
bool OpenGl_Font::renderGlyph (const Handle(OpenGl_Context)& theCtx,
                               const Standard_Utf32Char      theChar)
{
  if (!myFont->RenderGlyph (theChar))
  {
    return false;
  }

  Handle(OpenGl_Texture)& aTexture = myTextures.ChangeLast();
  if (aTexture.IsNull()
  || !aTexture->IsValid())
  {
    return false;
  }

  const Image_PixMap& anImg = myFont->GlyphImage();
  const Standard_Integer aTileId = myLastTileId + 1;
  myLastTilePx.Left  = myLastTilePx.Right + 3;
  myLastTilePx.Right = myLastTilePx.Left + (Standard_Integer )anImg.SizeX();
  if (myLastTilePx.Right > aTexture->SizeX()
   || (Standard_Integer )anImg.SizeY() > myTileSizeY)
  {
    myTileSizeY = myFont->GlyphMaxSizeY (true);

    myLastTilePx.Left    = 0;
    myLastTilePx.Right   = (Standard_Integer )anImg.SizeX();
    myLastTilePx.Top    += myTileSizeY;
    myLastTilePx.Bottom += myTileSizeY;

    if (myLastTilePx.Bottom > aTexture->SizeY()
     || myLastTilePx.Right  > aTexture->SizeX())
    {
      if (!createTexture (theCtx))
      {
        return false;
      }
      return renderGlyph (theCtx, theChar);
    }
  }

  aTexture->Bind (theCtx);
#if !defined(GL_ES_VERSION_2_0)
  glPixelStorei (GL_UNPACK_LSB_FIRST,  GL_FALSE);
  glPixelStorei (GL_UNPACK_ROW_LENGTH, 0);
#endif
  glPixelStorei (GL_UNPACK_ALIGNMENT,  1);

  glTexSubImage2D (GL_TEXTURE_2D, 0,
                   myLastTilePx.Left, myLastTilePx.Top, (GLsizei )anImg.SizeX(), (GLsizei )anImg.SizeY(),
                   aTexture->GetFormat(), GL_UNSIGNED_BYTE, anImg.Data());

  OpenGl_Font::Tile aTile;
  aTile.uv.Left   = GLfloat(myLastTilePx.Left)                / GLfloat(aTexture->SizeX());
  aTile.uv.Right  = GLfloat(myLastTilePx.Right)               / GLfloat(aTexture->SizeX());
  aTile.uv.Top    = GLfloat(myLastTilePx.Top)                 / GLfloat(aTexture->SizeY());
  aTile.uv.Bottom = GLfloat(myLastTilePx.Top + anImg.SizeY()) / GLfloat(aTexture->SizeY());
  aTile.texture   = aTexture->TextureId();
  myFont->GlyphRect (aTile.px);

  myLastTileId = aTileId;
  myTiles.Append (aTile);
  return true;
}

// =======================================================================
// function : RenderGlyph
// purpose  :
// =======================================================================
bool OpenGl_Font::RenderGlyph (const Handle(OpenGl_Context)& theCtx,
                               const Standard_Utf32Char      theUChar,
                               Tile&                         theGlyph)
{
  Standard_Integer aTileId = 0;
  if (!myGlyphMap.Find (theUChar,aTileId))
  {
    if (renderGlyph (theCtx, theUChar))
    {
      aTileId = myLastTileId;
    }
    else
    {
      return false;
    }

    myGlyphMap.Bind (theUChar, aTileId);
  }

  const OpenGl_Font::Tile& aTile = myTiles.Value (aTileId);
  theGlyph.px      = aTile.px;
  theGlyph.uv      = aTile.uv;
  theGlyph.texture = aTile.texture;

  return true;
}