[drape] device-independent viewport

drape_frontend/viewport.cpp

@@ -0,0 +1,46 @@
+#include "viewport.hpp"
+#include "../drape/glfunctions.hpp"
+
+namespace df
+{
+  Viewport::Viewport(float pixelRatio,
+                     uint32_t x0, uint32_t y0,
+                     uint32_t w, uint32_t h)
+    : m_pixelRatio(pixelRatio)
+    , m_zero(x0, y0)
+    , m_size(w, h)
+  {
+  }
+
+  void Viewport::SetViewport(uint32_t x0, uint32_t y0, uint32_t w, uint32_t h)
+  {
+    m_zero = m2::PointU(x0 ,y0);
+    m_size = m2::PointU(w, h);
+  }
+
+  uint32_t Viewport::GetX0() const
+  {
+    return m_zero.x;
+  }
+
+  uint32_t Viewport::GetY0() const
+  {
+    return m_zero.y;
+  }
+
+  uint32_t Viewport::GetWidth() const
+  {
+    return m_size.x;
+  }
+
+  uint32_t Viewport::GetHeight() const
+  {
+    return m_size.y;
+  }
+
+  void Viewport::Apply() const
+  {
+    GLFunctions::glViewport(m_zero.x * m_pixelRatio, m_zero.y * m_pixelRatio,
+                            m_size.x * m_pixelRatio, m_size.y * m_pixelRatio);
+  }
+}

drape_frontend/viewport.hpp

@@ -0,0 +1,35 @@
+#pragma once
+
+#include "../geometry/point2d.hpp"
+
+namespace df
+{
+  // Pixel ratio independent viewport implementation
+  // pixelRatio is ratio between physical pixels and device-independent
+  // pixels for the window. On retina displays pixelRation equal 2.0, In common equal 1.0
+  class Viewport
+  {
+  public:
+    // x0, y0, w, h is device-independent pixels
+    Viewport(float pixelRatio,
+             uint32_t x0, uint32_t y0,
+             uint32_t w, uint32_t h);
+
+    ///@{ Device-independent pixels
+    void SetViewport(uint32_t x0, uint32_t y0, uint32_t w, uint32_t h);
+    uint32_t GetX0() const;
+    uint32_t GetY0() const;
+    uint32_t GetWidth() const;
+    uint32_t GetHeight() const;
+    ///@}
+
+    // Apply viewport to graphics pipeline
+    // with convert start poin and size to physical pixels
+    void Apply() const;
+
+  private:
+    float m_pixelRatio;
+    m2::PointU m_zero;
+    m2::PointU m_size;
+  };
+}