--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Toolbox/ViewportGeometry.cpp	Fri Oct 14 15:34:11 2016 +0200
@@ -0,0 +1,217 @@
+/**
+ * Stone of Orthanc
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * In addition, as a special exception, the copyright holders of this
+ * program give permission to link the code of its release with the
+ * OpenSSL project's "OpenSSL" library (or with modified versions of it
+ * that use the same license as the "OpenSSL" library), and distribute
+ * the linked executables. You must obey the GNU General Public License
+ * in all respects for all of the code used other than "OpenSSL". If you
+ * modify file(s) with this exception, you may extend this exception to
+ * your version of the file(s), but you are not obligated to do so. If
+ * you do not wish to do so, delete this exception statement from your
+ * version. If you delete this exception statement from all source files
+ * in the program, then also delete it here.
+ * 
+ * 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 General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+
+#include "ViewportGeometry.h"
+
+#include "../Orthanc/Core/Logging.h"
+#include "../Orthanc/Core/OrthancException.h"
+
+#include <boost/math/special_functions/round.hpp>
+
+namespace OrthancStone
+{
+  void ViewportGeometry::ComputeTransform()
+  {
+    // The following lines must be read in reverse order!
+    cairo_matrix_t tmp;
+    
+    // Bring the center of the scene to the center of the view
+    cairo_matrix_init_translate(&transform_, 
+                                panX_ + static_cast<double>(width_) / 2.0, 
+                                panY_ + static_cast<double>(height_) / 2.0);
+
+    // Apply the zoom around (0,0)
+    cairo_matrix_init_scale(&tmp, zoom_, zoom_);
+    cairo_matrix_multiply(&transform_, &tmp, &transform_);
+
+    // Bring the center of the scene to (0,0)
+    cairo_matrix_init_translate(&tmp, -(x1_ + x2_) / 2.0, -(y1_ + y2_) / 2.0);
+    cairo_matrix_multiply(&transform_, &tmp, &transform_);
+  }
+
+
+  ViewportGeometry::ViewportGeometry()
+  {
+    x1_ = 0;
+    y1_ = 0;
+    x2_ = 0;
+    y2_ = 0;
+
+    width_ = 0;
+    height_ = 0;
+
+    zoom_ = 1;
+    panX_ = 0;
+    panY_ = 0;
+
+    ComputeTransform();
+  }
+
+
+  void ViewportGeometry::SetDisplaySize(unsigned int width,
+                                        unsigned int height)
+  {
+    if (width_ != width ||
+        height_ != height)
+    {
+      LOG(INFO) << "New display size: " << width << "x" << height;
+
+      width_ = width;
+      height_ = height;
+
+      ComputeTransform();
+    }
+  }
+
+
+  void ViewportGeometry::SetSceneExtent(double x1,
+                                        double y1,
+                                        double x2,
+                                        double y2)
+  {
+    if (x1 == x1_ &&
+        y1 == y1_ &&
+        x2 == x2_ &&
+        y2 == y2_)
+    {
+      return;
+    }
+    else if (x1 > x2 || 
+             y1 > y2)
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_ParameterOutOfRange);
+    }
+    else
+    {
+      LOG(INFO) << "New scene extent: (" << x1 << "," << y1 << ") => (" << x2 << "," << y2 << ")";
+
+      x1_ = x1;
+      y1_ = y1;
+      x2_ = x2;
+      y2_ = y2;
+
+      ComputeTransform();
+    }
+  }
+
+
+  void ViewportGeometry::GetSceneExtent(double& x1,
+                                        double& y1,
+                                        double& x2,
+                                        double& y2) const
+  {
+    x1 = x1_;
+    y1 = y1_;
+    x2 = x2_;
+    y2 = y2_;
+  }
+
+
+  void ViewportGeometry::MapDisplayToScene(double& sceneX /* out */,
+                                           double& sceneY /* out */,
+                                           double x,
+                                           double y) const
+  {
+    cairo_matrix_t transform = transform_;
+
+    if (cairo_matrix_invert(&transform) != CAIRO_STATUS_SUCCESS)
+    {
+      LOG(ERROR) << "Cannot invert singular matrix";
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
+    }
+
+    sceneX = x;
+    sceneY = y;
+    cairo_matrix_transform_point(&transform, &sceneX, &sceneY);
+  }
+
+
+  void ViewportGeometry::MapSceneToDisplay(int& displayX /* out */,
+                                           int& displayY /* out */,
+                                           double x,
+                                           double y) const
+  {
+    cairo_matrix_transform_point(&transform_, &x, &y);
+
+    displayX = static_cast<int>(boost::math::iround(x));
+    displayY = static_cast<int>(boost::math::iround(y));
+  }
+
+
+  void ViewportGeometry::SetDefaultView()
+  {
+    if (width_ > 0 &&
+        height_ > 0 &&
+        x2_ > x1_ + 10 * std::numeric_limits<double>::epsilon() &&
+        y2_ > y1_ + 10 * std::numeric_limits<double>::epsilon())
+    {
+      double zoomX = static_cast<double>(width_) / (x2_ - x1_);
+      double zoomY = static_cast<double>(height_) / (y2_ - y1_);
+      zoom_ = zoomX < zoomY ? zoomX : zoomY;
+
+      panX_ = 0;
+      panY_ = 0;
+
+      ComputeTransform();
+    }
+  }
+
+
+  void ViewportGeometry::ApplyTransform(CairoContext& context) const
+  {
+    cairo_set_matrix(context.GetObject(), &transform_);
+  }
+
+
+  void ViewportGeometry::GetPan(double& x,
+                                double& y) const
+  {
+    x = panX_;
+    y = panY_;
+  }
+
+
+  void ViewportGeometry::SetPan(double x,
+                                double y)
+  {
+    panX_ = x;
+    panY_ = y;
+    ComputeTransform();
+  }
+
+
+  void ViewportGeometry::SetZoom(double zoom)
+  {
+    zoom_ = zoom;
+    ComputeTransform();
+  }
+}