2 files changed, 75 insertions, 7 deletions

diff --git a/src/common/emu_window.cpp b/src/common/emu_window.cpp
index 48bb35db5..1082ae26d 100644
--- a/src/common/emu_window.cpp
+++ b/src/common/emu_window.cpp
@@ -3,6 +3,7 @@
 // Refer to the license.txt file included.
 
 #include "emu_window.h"
+#include "video_core/video_core.h"
 
 void EmuWindow::KeyPressed(KeyMap::HostDeviceKey key) {
     Service::HID::PadState mapped_key = KeyMap::GetPadKey(key);
@@ -15,3 +16,52 @@ void EmuWindow::KeyReleased(KeyMap::HostDeviceKey key) {
 
     Service::HID::PadButtonRelease(mapped_key);
 }
+
+EmuWindow::FramebufferLayout EmuWindow::FramebufferLayout::DefaultScreenLayout(int width, int height) {
+    ASSERT(width > 0);
+    ASSERT(height > 0);
+
+    EmuWindow::FramebufferLayout res = { width, height, {}, {} };
+
+    float window_aspect_ratio = static_cast<float>(height) / width;
+    float emulation_aspect_ratio = static_cast<float>(VideoCore::kScreenTopHeight * 2) /
+        VideoCore::kScreenTopWidth;
+
+    if (window_aspect_ratio > emulation_aspect_ratio) {
+        // Window is narrower than the emulation content => apply borders to the top and bottom
+        int viewport_height = static_cast<int>(std::round(emulation_aspect_ratio * width));
+
+        res.top_screen.left = 0;
+        res.top_screen.right = res.top_screen.left + width;
+        res.top_screen.top = (height - viewport_height) / 2;
+        res.top_screen.bottom = res.top_screen.top + viewport_height / 2;
+
+        int bottom_width = static_cast<int>((static_cast<float>(VideoCore::kScreenBottomWidth) /
+            VideoCore::kScreenTopWidth) * (res.top_screen.right - res.top_screen.left));
+        int bottom_border = ((res.top_screen.right - res.top_screen.left) - bottom_width) / 2;
+
+        res.bottom_screen.left = bottom_border;
+        res.bottom_screen.right = res.bottom_screen.left + bottom_width;
+        res.bottom_screen.top = res.top_screen.bottom;
+        res.bottom_screen.bottom = res.bottom_screen.top + viewport_height / 2;
+    } else {
+        // Otherwise, apply borders to the left and right sides of the window.
+        int viewport_width = static_cast<int>(std::round(height / emulation_aspect_ratio));
+
+        res.top_screen.left = (width - viewport_width) / 2;
+        res.top_screen.right = res.top_screen.left + viewport_width;
+        res.top_screen.top = 0;
+        res.top_screen.bottom = res.top_screen.top + height / 2;
+
+        int bottom_width = static_cast<int>((static_cast<float>(VideoCore::kScreenBottomWidth) /
+            VideoCore::kScreenTopWidth) * (res.top_screen.right - res.top_screen.left));
+        int bottom_border = ((res.top_screen.right - res.top_screen.left) - bottom_width) / 2;
+
+        res.bottom_screen.left = res.top_screen.left + bottom_border;
+        res.bottom_screen.right = res.bottom_screen.left + bottom_width;
+        res.bottom_screen.top = res.top_screen.bottom;
+        res.bottom_screen.bottom = res.bottom_screen.top + height / 2;
+    }
+
+    return res;
+}
diff --git a/src/common/emu_window.h b/src/common/emu_window.h
index 1ad4b82a3..b6862030e 100644
--- a/src/common/emu_window.h
+++ b/src/common/emu_window.h
@@ -8,6 +8,7 @@
 #include "common/scm_rev.h"
 #include "common/string_util.h"
 #include "common/key_map.h"
+#include "common/math_util.h"
 
 /**
  * Abstraction class used to provide an interface between emulation code and the frontend
@@ -38,6 +39,23 @@ public:
         std::pair<unsigned,unsigned> min_client_area_size;
     };
 
+    /// Describes the layout of the window framebuffer (size and top/bottom screen positions)
+    struct FramebufferLayout {
+
+        /**
+         * Factory method for constructing a default FramebufferLayout
+         * @param width Window framebuffer width in pixels
+         * @param height Window framebuffer height in pixels
+         * @return Newly created FramebufferLayout object with default screen regions initialized
+         */
+        static FramebufferLayout DefaultScreenLayout(int width, int height);
+
+        unsigned width;
+        unsigned height;
+        MathUtil::Rectangle<unsigned> top_screen;
+        MathUtil::Rectangle<unsigned> bottom_screen;
+    };
+
     /// Swap buffers to display the next frame
     virtual void SwapBuffers() = 0;
 
@@ -75,11 +93,11 @@ public:
     }
 
     /**
-      * Gets the framebuffer size in pixels.
+      * Gets the framebuffer layout (width, height, and screen regions)
       * @note This method is thread-safe
       */
-    const std::pair<unsigned,unsigned> GetFramebufferSize() const {
-        return framebuffer_size;
+    const FramebufferLayout& GetFramebufferLayout() const {
+        return framebuffer_layout;
     }
 
     /**
@@ -118,11 +136,11 @@ protected:
     }
 
     /**
-     * Update internal framebuffer size with the given parameter.
+     * Update framebuffer layout with the given parameter.
      * @note EmuWindow implementations will usually use this in window resize event handlers.
      */
-    void NotifyFramebufferSizeChanged(const std::pair<unsigned,unsigned>& size) {
-        framebuffer_size = size;
+    void NotifyFramebufferLayoutChanged(const FramebufferLayout& layout) {
+        framebuffer_layout = layout;
     }
 
     /**
@@ -143,7 +161,7 @@ private:
         // By default, ignore this request and do nothing.
     }
 
-    std::pair<unsigned,unsigned> framebuffer_size;
+    FramebufferLayout framebuffer_layout; ///< Current framebuffer layout
 
     unsigned client_area_width;    ///< Current client width, should be set by window impl.
     unsigned client_area_height;   ///< Current client height, should be set by window impl.