--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OrthancStone/Sources/Scene2D/Internals/OpenGLInfoPanelRenderer.cpp	Tue Jul 07 16:21:02 2020 +0200
@@ -0,0 +1,117 @@
+/**
+ * Stone of Orthanc
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2020 Osimis S.A., Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU Affero General Public License
+ * as published by the Free Software Foundation, either version 3 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
+ * Affero General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+
+#include "OpenGLInfoPanelRenderer.h"
+
+namespace OrthancStone
+{
+  namespace Internals
+  {
+    void OpenGLInfoPanelRenderer::LoadTexture(const InfoPanelSceneLayer& layer)
+    {
+      if (!context_.IsContextLost())
+      {
+        context_.MakeCurrent();
+        texture_.reset(new OpenGL::OpenGLTexture(context_));
+        texture_->Load(layer.GetTexture(), layer.IsLinearInterpolation());
+        applySceneRotation_ = layer.ShouldApplySceneRotation();
+        anchor_ = layer.GetAnchor();
+      }
+    }
+
+    OpenGLInfoPanelRenderer::OpenGLInfoPanelRenderer(OpenGL::IOpenGLContext& context,
+                                                     OpenGLColorTextureProgram& program,
+                                                     const InfoPanelSceneLayer& layer) :
+      context_(context),
+      program_(program),
+      anchor_(BitmapAnchor_TopLeft),
+      applySceneRotation_(false)
+    {
+      LoadTexture(layer);
+    }
+    
+    void OpenGLInfoPanelRenderer::Render(const AffineTransform2D& transform,
+                                         unsigned int canvasWidth,
+                                         unsigned int canvasHeight)
+    {
+      if (!context_.IsContextLost() && texture_.get() != NULL)
+      {
+        int dx = 0, dy = 0;
+        InfoPanelSceneLayer::ComputeAnchorLocation(
+          dx, dy, anchor_, texture_->GetWidth(), texture_->GetHeight(),
+          canvasWidth, canvasHeight);
+
+        // The position of this type of layer is layer: Ignore the
+        // "transform" coming from the scene
+        AffineTransform2D actualTransform = 
+          AffineTransform2D::CreateOffset(dx, dy);
+
+        if (applySceneRotation_)
+        {
+          // the transformation is as follows:
+          // - originally, the image is aligned so that its top left corner
+          // is at 0,0
+          // - first, we translate the image by -w/2,-h/2 
+          // - then we rotate it, so that the next rotation will make the  
+          //   image rotate around its center.
+          // - then, we translate the image by +w/2,+h/2 to put it
+          //   back in place
+          // - the fourth and last transform is the one that brings the 
+          //   image to its desired anchored location.
+
+          int32_t halfWidth = 
+            static_cast<int32_t>(0.5 * texture_->GetWidth());
+
+          int32_t halfHeight=
+            static_cast<int32_t>(0.5 * texture_->GetHeight());
+
+          AffineTransform2D translation1 =
+            AffineTransform2D::CreateOffset(-halfWidth, -halfHeight);
+
+          const Matrix& sceneTransformM = transform.GetHomogeneousMatrix();
+          Matrix r;
+          Matrix q;
+          LinearAlgebra::RQDecomposition3x3(r, q, sceneTransformM);
+
+          // counterintuitively, q is the rotation and r is the upper
+          // triangular
+          AffineTransform2D rotation(q);
+
+          AffineTransform2D translation2 =
+            AffineTransform2D::CreateOffset(halfWidth, halfHeight);
+
+          // please note that the last argument is the 1st applied 
+          // transformation (rationale: if arguments are a, b and c, then
+          // the resulting matrix is a*b*c:
+          // x2 = (a*b*c)*x1 = (a*(b*(c*x1))) (you can see that the result
+          // of c*x1 is transformed by b, and the result of b*c*x1 is trans-
+          // formed by a)
+          actualTransform = AffineTransform2D::Combine(actualTransform,
+                                                       translation2,
+                                                       rotation,
+                                                       translation1);
+        }
+
+        program_.Apply(*texture_, actualTransform, true);
+      }
+    }
+  }
+}