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isfinkcanvas.cpp
/***************************************************************************
 *   Copyright (C) 2009 by Valerio Pilo                                    *
 *   valerio@kmess.org                                                     *
 *                                                                         *
 *   Copyright (C) 2009 by Adam Goossens                                   *
 *   adam@kmess.org                                                        *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU Lesser General Public License as        *
 *   published by the Free Software Foundation; either version 2.1 of the  *
 *   License, or (at your option) any later version.                       *
 *                                                                         *
 *   This program 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 General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU Lesser General Public      *
 *   License along with this program; if not, write to the                 *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/

#include "isfqt-internal.h"

#include "isfinkcanvas.h"
#include "isfqtdrawing.h"

#include <QMouseEvent>
#include <QPainter>
#include <QPen>
#include <QDebug>


using namespace Isf;



/**
 * Create a new InkCanvas widget.
 *
 * @param parent The parent widget.
 */
00044 InkCanvas:: InkCanvas( QWidget* parent )
: QWidget( parent )
, erasingImage_( false )
, drawing_( 0 )
, scribbling_( false )
, currentStroke_( 0 )
, drawingDirty_( true )
{
#ifdef ISFQT_DEBUG_VERBOSE
  qDebug() << "** Created new InkCanvas:" << this << "**";
#endif

  setCanvasColor( Qt::white );
  setPenColor( Qt::black );
  setPenSize( 4 );

  setAttribute( Qt::WA_StaticContents, true );      // only give us paint events for the parts of us that become visible on resize.

  setAutoFillBackground( true );

  clear();

  // prepare the buffer
  clearBuffer();

  // create a custom cursor
  updateCursor();

  // start with a drawing pen by default.
  setPenType( DrawingPen );
}



/**
 * Destructor.
 *
 * There are no members on stack, so it's currently not used.
 */
00083 InkCanvas::~InkCanvas()
{
#ifdef ISFQT_DEBUG_VERBOSE
  qDebug() << "** Destroyed InkCanvas:" << this << "**";
#endif
}



/**
 * Returns the drawing's ISF representation.
 *
 * @return A QByteArray filled with ISF data.
 */
00097 QByteArray InkCanvas::bytes()
{
  return Isf::Stream::writer( *drawing_ );
}



/**
 * Clears the current image, discarding all drawn strokes.
 *
 * Stroke attributes such as pen size, pen type and color are not cleared.
 *
 */
00110 void InkCanvas::clear()
{
  if ( drawing_ == 0 )
  {
    drawing_ = &initialDrawing_;
  }

  drawing_->clear();
  drawingDirty_ = true;

  update();

  emit inkChanged();
}



/**
 * Clear the internal pixmap buffer.
 *
 * The buffer used to quickly render on the widget painting area
 * the new and old strokes: every new stroke is saved here.
 * This allows to avoid repainting all strokes at every paint event.
 */
00134 void InkCanvas::clearBuffer()
{
  bufferPixmap_ = QPixmap( size() );
  bufferPixmap_.fill( Qt::transparent );
}



/**
 * Retrieve the Isf::Drawing instance that the canvas is currently manipulating.
 *
 * Beware: if you have not set your own Isf::Drawing instance via setDrawing(), you must not delete
 * the object that this method returns. In this case this method returns a pointer to an internal
 * Isf::Drawing instance that must not be deleted. If you have previously used setDrawing() then you
 * are free to do whatever you like with this pointer.
 *
 * \code
 * InkCanvas* canvas = new InkCanvas( this );
 *
 * Isf::Drawing* drawing = canvas->drawing();
 * delete drawing; // bad! deleting an object internal to InkCanvas.
 *
 * canvas->setDrawing( existingIsfDrawingInstance );
 *
 * drawing = canvas->drawing();
 * delete drawing; // good - drawing points to existingIsfDrawingInstance.
 * \endcode
 *
 *
 * @see setDrawing()
 * @return The current Isf::Drawing instance.
 */
00166 Isf::Drawing* InkCanvas::drawing()
{
  return drawing_;
}



/**
 * Draw a line from the current point to an ending point.
 *
 * The current point is initially set in mousePressEvent();
 * then it's set here.
 *
 * @see mousePressEvent()
 * @param endPoint Final point of the line
 */
00182 void InkCanvas::drawLineTo( const QPoint& endPoint )
{
  Q_ASSERT_X( drawing_, "drawLineTo", "Drawing is null" );

  // draw the "in progress" strokes on the buffer.
  QPainter painter( &bufferPixmap_ );
  painter.setRenderHints( QPainter::Antialiasing | QPainter::SmoothPixmapTransform, true );

  QColor color = color_;
  if( erasingImage_ )
  {
    color = QColor( "white" );
  }

  painter.setPen( QPen( color, penSize_, Qt::SolidLine, Qt::RoundCap,
                  Qt::RoundJoin ) );

  // QPainter::drawLine() doesn't draw anything if the two points are the same
  if( lastPoint_ == endPoint )
  {
    painter.drawPoint( endPoint );
  }
  else
  {
    painter.drawLine( lastPoint_, endPoint );
  }

  int rad = (1 / 2) + 2;
  update( QRect( lastPoint_, endPoint ).normalized()
          .adjusted( -rad, -rad, +rad, +rad ) );

  lastPoint_ = endPoint;

  // Refresh the widget with the new stroke
  update();
}



/**
 * Renders the ink drawing to a QImage and returns it.
 *
 * @return A QImage containing the rendered Ink.
 */
00226 QImage InkCanvas::image()
{
  return drawing_->pixmap( Qt::white ).toImage();
}



/**
 * Get whether the drawing is empty (i.e., contains no strokes).
 *
 * @return True if the Ink image is empty, false otherwise
 */
00238 bool InkCanvas::isEmpty()
{
  return drawing_->isNull();
}



/**
 * Start drawing a new stroke.
 *
 * Look at mouseMoveEvent() and mouseReleaseEvent() for more
 * information on how drawing is done.
 *
 * This method is usually called by Qt.
 *
 * @see mouseMoveEvent()
 * @see mouseReleaseEvent()
 * @param event The mouse button press event
 */
00257 void InkCanvas::mousePressEvent( QMouseEvent* event )
{
  Q_ASSERT_X( drawing_, "mousePressEvent", "Drawing is null" );

  if( event->button() != Qt::LeftButton )
  {
    return;
  }

  scribbling_ = true;

  if ( penType_ == EraserPen )
  {
    // is there a stroke here?
    QPoint point = event->pos();
    Stroke* s = drawing_->strokeAtPoint( point );
    if ( s != 0 )
    {
      drawing_->deleteStroke( s );
      drawingDirty_ = true;
      update();
    }

    return;
  }

  lastPoint_ = event->pos();

  // If there already is a stroke, add it
  if( currentStroke_ )
  {
    currentStroke_->finalize();
    drawing_->addStroke( currentStroke_ );
    currentStroke_ = 0;
  }

  currentStroke_ = new Isf::Stroke();
  currentStroke_->addPoint( lastPoint_ );
  currentStroke_->setColor( color_ );
  currentStroke_->setPenSize( QSizeF( (qreal)penSize_, (qreal)penSize_ ) );
  currentStroke_->setFlag( FitToCurve, true );

  // Draw the initial point
  drawLineTo( lastPoint_ );
}



/**
 * Continue drawing the current stroke.
 *
 * As the cursor moves across the canvas we continue drawing the stroke started in
 * mousePressEvent(). A line is drawn between the last point and the current point
 * as given by QMouseEvent::pos().
 *
 * Once the mouse button is released, drawing ends.
 *
 * @see mousePressEvent()
 * @see mouseReleaseEvent()
 * @param event The mouse move event
 */
00318 void InkCanvas::mouseMoveEvent( QMouseEvent* event )
{
  if( ! ( event->buttons() & Qt::LeftButton ) || ! scribbling_ )
  {
    return;
  }

  Q_ASSERT_X( drawing_, "mouseMoveEvent", "Drawing is null" );

  if ( penType_ == EraserPen )
  {
    // is there a stroke here?
    QPoint point = event->pos();
    Stroke* s = drawing_->strokeAtPoint( point );
    if ( s != 0 )
    {
      drawing_->deleteStroke( s );
      drawingDirty_ = true;
      update();
    }

    return;
  }

  QPoint position( event->pos() );

  // Don't add duplicate points. Mainly useful when drawing dots.
  if( lastPoint_ == position )
  {
    return;
  }

  drawLineTo( position );

  Q_ASSERT_X( currentStroke_, "mouseMoveEvent", "currentStroke_ is null" );

  // Add the new point to the stroke
  currentStroke_->addPoint( lastPoint_ );
}



/**
 * Finish drawing the current stroke.
 *
 * Adds this stroke, with the correct attributes, to the Isf::Drawing strokes collection.
 *
 * @see mousePressEvent()
 * @see mouseMoveEvent()
 * @param event The mouse release event
 */
00369 void InkCanvas::mouseReleaseEvent( QMouseEvent* event )
{
  Q_ASSERT_X( drawing_, "mouseReleaseEvent", "Drawing is null" );

  if( event->button() != Qt::LeftButton || ! scribbling_ )
  {
    return;
  }

  if ( penType_ == EraserPen )
  {
    return;
  }

  QPoint position = event->pos();

  // Don't redraw already drawn points or lines
  if( lastPoint_ != position )
  {
    drawLineTo( position );
  }

  Q_ASSERT_X( currentStroke_, "mouseReleaseEvent", "currentStroke_ is null" );

#ifdef KMESSDEBUG_INKEDIT_GENERAL
  qDebug() << "Finishing up stroke";
#endif

  // Don't add duplicate points. Mainly useful when drawing dots.
  if( lastPoint_ != position )
  {
    currentStroke_->addPoint( lastPoint_ );
  }

  currentStroke_->finalize();
  drawing_->addStroke( currentStroke_ );

  currentStroke_ = 0;

  drawingDirty_ = true;

  // clear the buffer.
  clearBuffer();

  // update
  update();

  scribbling_ = false;
  emit inkChanged();
}



/**
 * Repaints the ink canvas.
 *
 * For performance reasons an internal buffer is used to ensure that
 * the entire Ink drawing is not re-rendered on each paintEvent call.
 * This buffer is invalidated only when a stroke is added or removed, the
 * drawing is changed or the canvas cleared.
 *
 *
 * @param event The paint event from Qt.
 */
00433 void InkCanvas::paintEvent( QPaintEvent* event )
{
  Q_UNUSED( event );

  QPainter painter( this );

  Q_ASSERT_X( drawing_, "paintEvent", "Drawing is null" );

  // draw the ISF first, then the buffer over the top.
  // buffer has a transparent background.
  QPixmap isfPixmap( drawingDirty_
                       ? drawing_->pixmap( Qt::transparent )
                       : isfCachePixmap_ );

  if ( drawingDirty_ )
  {
#ifdef ISFQT_DEBUG
    qDebug() << "ISF pixmap cache dirty; re-caching.";
#endif
    isfCachePixmap_ = isfPixmap;
    drawingDirty_ = false;
  }

  QRect boundingRect = drawing_->boundingRect();

  // draw the pixmap starting at the boundingRect_ top left corner.
  painter.drawPixmap( boundingRect.topLeft(), isfPixmap );

  // draw the buffer from 0,0.
  painter.drawPixmap( event->rect(), bufferPixmap_, event->rect() );

  QWidget::paintEvent( event );
}



/**
 * Get the current pen color.
 *
 * @return The current pen color.
 */
00474 QColor InkCanvas::penColor()
{
  return color_;
}



/**
 * Get the current pen type.
 *
 * @return The current pen type.
 */
00486 int InkCanvas::penSize()
{
  return penSize_;
}



/**
 * Get the current pen type.
 *
 * See the PenType enum for details.
 *
 * @see PenType
 * @return The current pen type.
 */
00501 InkCanvas::PenType InkCanvas::penType()
{
  return penType_;
}



/**
 * The widget has changed size, re-draw everything.
 *
 * @param event The resizing event.
 */
00513 void InkCanvas::resizeEvent( QResizeEvent* event )
{
  // need to resize the buffer pixmap.
  clearBuffer();

  update();

  QWidget::resizeEvent( event );
}



/**
 * Save the current ISF drawing to a QIODevice.
 *
 * If the base64 param is true, then the drawing will be written base64-encoded.
 * This is helpful for transmission over binary-unfriendly media.
 *
 * @param dev The QIODevice to save to.
 * @param base64 If true, the drawing is written encoded with base64.
 */

00535 void InkCanvas::save( QIODevice &dev, bool base64 )
{
  dev.write( Isf::Stream::writer( *drawing_, base64 ) );
}



/**
 * Set the canvas colour (i.e., the background colour of the InkCanvas control)
 *
 * Note: this is not saved with the Ink data. This is only used for colouring the canvas.
 *
 * @param newColor The new canvas color.
 */
00549 void InkCanvas::setCanvasColor( QColor newColor )
{
#ifdef ISFQT_DEBUG
  qDebug() << "Setting new canvas color:" << newColor.name();
#endif
  canvasColor_ = newColor;

  QPalette p = palette();
  p.setColor( QPalette::Window, newColor );
  setPalette( p );
  update();
}



/**
 * Changes the currently displayed Ink to the one supplied.
 *
 * Note: InkCanvas does not take ownership of Isf::Drawing instances supplied here.
 * You are still responsible of ensuring they are deleted appropriately.
 *
 * @param drawing The new Ink drawing to display.
 */
00572 void InkCanvas::setDrawing( Isf::Drawing* drawing )
{
  drawing_ = drawing;

  // try to resize of the widget to accommodate the
  // drawing.
  QRect boundingRect = drawing_->boundingRect();
  boundingRect.setTopLeft( QPoint( 0, 0 ) );

  resize( boundingRect.width(), boundingRect.height() );

  drawingDirty_ = true;

  updateGeometry();
  update();
}



/**
 * Change the color of the pen used to draw on the Ink canvas.
 *
 * @param newColor The new color for the pen.
 */
00596 void InkCanvas::setPenColor( QColor newColor )
{
#ifdef ISFQT_DEBUG
  qDebug() << "Setting new pen color:" << newColor.name();
#endif

  color_ = newColor;

  updateCursor();
}



/**
 * Change the size of the pen. This value is in pixels.
 *
 * @param pixels The size of the pen, in pixels
 */
00614 void InkCanvas::setPenSize( int pixels )
{
#ifdef ISFQT_DEBUG
  qDebug() << "Setting new pen size:" << pixels;
#endif
  penSize_ = pixels;

  updateCursor();
}



/**
 * Change the pen type.
 *
 * Currently, only PenType::EraserPen and PenType::DrawingPen are supported. See the PenType
 * enum for more information.
 *
 * @see PenType
 * @param type The new pen type
 */
00635 void InkCanvas::setPenType( PenType type )
{
#ifdef ISFQT_DEBUG
  qDebug() << "Setting new pen type:" << type;
#endif

  penType_ = type;

  updateCursor();
}



/**
 * Return the suggested size for the canvas.
 *
 * The actual size hint will depend on the size of the drawing on the canvas. By default,
 * the size hint is 300x300 pixels.
 */
00654 QSize InkCanvas::sizeHint() const
{
  if ( drawing_->isNull() )
  {
    return QSize( 300, 300 );
  }
  else
  {
    QRect boundingRect = drawing_->boundingRect();
    boundingRect.setTopLeft( QPoint( 0, 0 ) );
    return boundingRect.size();
  }
}



/**
 * Creates a QCursor displayed when the mouse pointer moves over the widget.
 *
 * The cursor becomes a point, drawn with the current stroke colour and pen size.
 */
00675 void InkCanvas::updateCursor()
{
  if ( cursorPixmap_.isNull() )
  {
    cursorPixmap_ = QPixmap( QSize( 32, 32 ) );
  }

  if ( penType_ == EraserPen )
  {
    cursorPixmap_ = QPixmap( ":pics/draw-eraser.png" );
    cursor_ = QCursor( cursorPixmap_, 0, cursorPixmap_.height() );
  }
  else
  {
    cursorPixmap_.fill( Qt::transparent );

    QPainter painter( &cursorPixmap_ );

    painter.setRenderHints( QPainter::Antialiasing | QPainter::SmoothPixmapTransform, true );
    painter.setPen( QPen( color_, penSize_, Qt::SolidLine, Qt::RoundCap,
                          Qt::RoundJoin ) );

    // now draw a point.
    painter.drawPoint( QPoint( cursorPixmap_.size().width() / 2, cursorPixmap_.size().height() / 2 ) );

    cursor_ = QCursor( cursorPixmap_ );
  }

  // create our cursor.
  setCursor( cursor_ );
}



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