#include "textureViewer.h"

#include <qimage.h>
#include <qfiledialog.h>

using namespace qglviewer;
using namespace std;

void Viewer::init()
{
  restoreFromFile();
  
  // Enable GL textures
  glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
  glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
  glEnable( GL_TEXTURE_2D );

  // Nice texture coordinate interpolation
  glHint( GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST );

  u_max = 1.0;
  v_max = 1.0;
  ratio = 1.0;
  
  loadImage();
  help();
}


void Viewer::draw()
{
  // Display the quad
  glNormal3f(0.0, 0.0, 1.0);
  glBegin(GL_QUADS);
  glTexCoord2f(0.0,   1.0-v_max);	glVertex2f(-u_max*ratio,-v_max);
  glTexCoord2f(0.0,   1.0);		glVertex2f(-u_max*ratio, v_max);
  glTexCoord2f(u_max, 1.0);		glVertex2f( u_max*ratio, v_max);
  glTexCoord2f(u_max, 1.0-v_max);	glVertex2f( u_max*ratio,-v_max);
  glEnd();
}


void Viewer::loadImage()
{
  QString name = QFileDialog::getOpenFileName(".", "Images (*.png *.xpm *.jpg)", this, "Choose", "Select an image");
  
  // In case of Cancel
  if (name.isEmpty())
    return;

  QImage img(name);
  
  if (img.isNull())
    {
      cerr << "Unable to load " << name << ", unsupported file format" << endl;
      return;
    }

  cout << "Loading " << name << ", " << img.width() << "x" << img.height() << " pixels" << endl;

  // 1E-3 needed. Just try with width=128 and see !
  int newWidth  = 1<<(int)(1+log(img.width() -1+1E-3) / log(2.0));
  int newHeight = 1<<(int)(1+log(img.height()-1+1E-3) / log(2.0));

  u_max = img.width()  / (float)newWidth;
  v_max = img.height() / (float)newHeight;
  
  if ((img.width()!=newWidth) || (img.height()!=newHeight))
    {
      cout << "Image size set to " << newWidth << "x" << newHeight << " pixels" << endl;
      img = img.copy(0, 0, newWidth, newHeight);
    }

  ratio = newWidth / (float)newHeight;
  
  QImage glImg = QGLWidget::convertToGLFormat(img);  // flipped 32bit RGBA

  // Bind the img texture...
  glTexImage2D(GL_TEXTURE_2D, 0, 4, glImg.width(), glImg.height(), 0,
	       GL_RGBA, GL_UNSIGNED_BYTE, glImg.bits());
}


void Viewer::keyPressEvent(QKeyEvent *e)
{
  switch (e->key())
    {
    case Qt::Key_L : loadImage(); break;
    default:         QGLViewer::keyPressEvent(e);
    }
}

QString Viewer::helpString() const
{
  QString text("<h2>T e x t u r e V i e w e r</h2>");
  text += "This pedagogical example illustrates how to texture map a polygon.<br>";
  text += "The Qt <i>QImage</i> class and its <i>convertToGLFormat()</i> function are used ";
  text += "to load an image in any format. The image is resized so that its dimensions ";
  text += "are powers of two if needed. Feel free to cut and paste.<br>";
  text += "Press <b>L</b>(oad) to load a new image.";
  return text;
}