4 files changed, 215 insertions, 1 deletions

diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index b19335fe1..d9618c40c 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -32,6 +32,7 @@ set(SRCS
             frontend/camera/factory.cpp
             frontend/camera/interface.cpp
             frontend/emu_window.cpp
+            frontend/framebuffer_layout.cpp
             frontend/motion_emu.cpp
             gdbstub/gdbstub.cpp
             hle/config_mem.cpp
@@ -216,6 +217,7 @@ set(HEADERS
             frontend/camera/factory.h
             frontend/camera/interface.h
             frontend/emu_window.h
+            frontend/framebuffer_layout.h
             frontend/input.h
             frontend/motion_emu.h
             gdbstub/gdbstub.h
diff --git a/src/core/frontend/emu_window.h b/src/core/frontend/emu_window.h
index 36f2667fa..9414123a4 100644
--- a/src/core/frontend/emu_window.h
+++ b/src/core/frontend/emu_window.h
@@ -8,8 +8,8 @@
 #include <tuple>
 #include <utility>
 #include "common/common_types.h"
-#include "common/framebuffer_layout.h"
 #include "common/math_util.h"
+#include "core/frontend/framebuffer_layout.h"
 
 /**
  * Abstraction class used to provide an interface between emulation code and the frontend
diff --git a/src/core/frontend/framebuffer_layout.cpp b/src/core/frontend/framebuffer_layout.cpp
new file mode 100644
index 000000000..f3815170d
--- /dev/null
+++ b/src/core/frontend/framebuffer_layout.cpp
@@ -0,0 +1,157 @@
+// Copyright 2016 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <cmath>
+
+#include "common/assert.h"
+#include "core/frontend/framebuffer_layout.h"
+#include "core/settings.h"
+#include "video_core/video_core.h"
+
+namespace Layout {
+
+static const float TOP_SCREEN_ASPECT_RATIO =
+    static_cast<float>(VideoCore::kScreenTopHeight) / VideoCore::kScreenTopWidth;
+static const float BOT_SCREEN_ASPECT_RATIO =
+    static_cast<float>(VideoCore::kScreenBottomHeight) / VideoCore::kScreenBottomWidth;
+
+// Finds the largest size subrectangle contained in window area that is confined to the aspect ratio
+template <class T>
+static MathUtil::Rectangle<T> maxRectangle(MathUtil::Rectangle<T> window_area,
+                                           float screen_aspect_ratio) {
+    float scale = std::min(static_cast<float>(window_area.GetWidth()),
+                           window_area.GetHeight() / screen_aspect_ratio);
+    return MathUtil::Rectangle<T>{0, 0, static_cast<T>(std::round(scale)),
+                                  static_cast<T>(std::round(scale * screen_aspect_ratio))};
+}
+
+FramebufferLayout DefaultFrameLayout(unsigned width, unsigned height, bool swapped) {
+    ASSERT(width > 0);
+    ASSERT(height > 0);
+
+    FramebufferLayout res{width, height, true, true, {}, {}};
+    // Default layout gives equal screen sizes to the top and bottom screen
+    MathUtil::Rectangle<unsigned> screen_window_area{0, 0, width, height / 2};
+    MathUtil::Rectangle<unsigned> top_screen =
+        maxRectangle(screen_window_area, TOP_SCREEN_ASPECT_RATIO);
+    MathUtil::Rectangle<unsigned> bot_screen =
+        maxRectangle(screen_window_area, BOT_SCREEN_ASPECT_RATIO);
+
+    float window_aspect_ratio = static_cast<float>(height) / width;
+    // both screens height are taken into account by multiplying by 2
+    float emulation_aspect_ratio = TOP_SCREEN_ASPECT_RATIO * 2;
+
+    if (window_aspect_ratio < emulation_aspect_ratio) {
+        // Apply borders to the left and right sides of the window.
+        top_screen =
+            top_screen.TranslateX((screen_window_area.GetWidth() - top_screen.GetWidth()) / 2);
+        bot_screen =
+            bot_screen.TranslateX((screen_window_area.GetWidth() - bot_screen.GetWidth()) / 2);
+    } else {
+        // Window is narrower than the emulation content => apply borders to the top and bottom
+        // Recalculate the bottom screen to account for the width difference between top and bottom
+        screen_window_area = {0, 0, width, top_screen.GetHeight()};
+        bot_screen = maxRectangle(screen_window_area, BOT_SCREEN_ASPECT_RATIO);
+        bot_screen = bot_screen.TranslateX((top_screen.GetWidth() - bot_screen.GetWidth()) / 2);
+        if (swapped) {
+            bot_screen = bot_screen.TranslateY(height / 2 - bot_screen.GetHeight());
+        } else {
+            top_screen = top_screen.TranslateY(height / 2 - top_screen.GetHeight());
+        }
+    }
+    // Move the top screen to the bottom if we are swapped.
+    res.top_screen = swapped ? top_screen.TranslateY(height / 2) : top_screen;
+    res.bottom_screen = swapped ? bot_screen : bot_screen.TranslateY(height / 2);
+    return res;
+}
+
+FramebufferLayout SingleFrameLayout(unsigned width, unsigned height, bool swapped) {
+    ASSERT(width > 0);
+    ASSERT(height > 0);
+    // The drawing code needs at least somewhat valid values for both screens
+    // so just calculate them both even if the other isn't showing.
+    FramebufferLayout res{width, height, !swapped, swapped, {}, {}};
+
+    MathUtil::Rectangle<unsigned> screen_window_area{0, 0, width, height};
+    MathUtil::Rectangle<unsigned> top_screen =
+        maxRectangle(screen_window_area, TOP_SCREEN_ASPECT_RATIO);
+    MathUtil::Rectangle<unsigned> bot_screen =
+        maxRectangle(screen_window_area, BOT_SCREEN_ASPECT_RATIO);
+
+    float window_aspect_ratio = static_cast<float>(height) / width;
+    float emulation_aspect_ratio = (swapped) ? BOT_SCREEN_ASPECT_RATIO : TOP_SCREEN_ASPECT_RATIO;
+
+    if (window_aspect_ratio < emulation_aspect_ratio) {
+        top_screen =
+            top_screen.TranslateX((screen_window_area.GetWidth() - top_screen.GetWidth()) / 2);
+        bot_screen =
+            bot_screen.TranslateX((screen_window_area.GetWidth() - bot_screen.GetWidth()) / 2);
+    } else {
+        top_screen = top_screen.TranslateY((height - top_screen.GetHeight()) / 2);
+        bot_screen = bot_screen.TranslateY((height - bot_screen.GetHeight()) / 2);
+    }
+    res.top_screen = top_screen;
+    res.bottom_screen = bot_screen;
+    return res;
+}
+
+FramebufferLayout LargeFrameLayout(unsigned width, unsigned height, bool swapped) {
+    ASSERT(width > 0);
+    ASSERT(height > 0);
+
+    FramebufferLayout res{width, height, true, true, {}, {}};
+    // Split the window into two parts. Give 4x width to the main screen and 1x width to the small
+    // To do that, find the total emulation box and maximize that based on window size
+    float window_aspect_ratio = static_cast<float>(height) / width;
+    float emulation_aspect_ratio =
+        swapped
+            ? VideoCore::kScreenBottomHeight * 4 /
+                  (VideoCore::kScreenBottomWidth * 4.0f + VideoCore::kScreenTopWidth)
+            : VideoCore::kScreenTopHeight * 4 /
+                  (VideoCore::kScreenTopWidth * 4.0f + VideoCore::kScreenBottomWidth);
+    float large_screen_aspect_ratio = swapped ? BOT_SCREEN_ASPECT_RATIO : TOP_SCREEN_ASPECT_RATIO;
+    float small_screen_aspect_ratio = swapped ? TOP_SCREEN_ASPECT_RATIO : BOT_SCREEN_ASPECT_RATIO;
+
+    MathUtil::Rectangle<unsigned> screen_window_area{0, 0, width, height};
+    MathUtil::Rectangle<unsigned> total_rect =
+        maxRectangle(screen_window_area, emulation_aspect_ratio);
+    MathUtil::Rectangle<unsigned> large_screen =
+        maxRectangle(total_rect, large_screen_aspect_ratio);
+    MathUtil::Rectangle<unsigned> fourth_size_rect = total_rect.Scale(.25f);
+    MathUtil::Rectangle<unsigned> small_screen =
+        maxRectangle(fourth_size_rect, small_screen_aspect_ratio);
+
+    if (window_aspect_ratio < emulation_aspect_ratio) {
+        large_screen =
+            large_screen.TranslateX((screen_window_area.GetWidth() - total_rect.GetWidth()) / 2);
+    } else {
+        large_screen = large_screen.TranslateY((height - total_rect.GetHeight()) / 2);
+    }
+    // Shift the small screen to the bottom right corner
+    small_screen =
+        small_screen.TranslateX(large_screen.right)
+            .TranslateY(large_screen.GetHeight() + large_screen.top - small_screen.GetHeight());
+    res.top_screen = swapped ? small_screen : large_screen;
+    res.bottom_screen = swapped ? large_screen : small_screen;
+    return res;
+}
+
+FramebufferLayout CustomFrameLayout(unsigned width, unsigned height) {
+    ASSERT(width > 0);
+    ASSERT(height > 0);
+
+    FramebufferLayout res{width, height, true, true, {}, {}};
+
+    MathUtil::Rectangle<unsigned> top_screen{
+        Settings::values.custom_top_left, Settings::values.custom_top_top,
+        Settings::values.custom_top_right, Settings::values.custom_top_bottom};
+    MathUtil::Rectangle<unsigned> bot_screen{
+        Settings::values.custom_bottom_left, Settings::values.custom_bottom_top,
+        Settings::values.custom_bottom_right, Settings::values.custom_bottom_bottom};
+
+    res.top_screen = top_screen;
+    res.bottom_screen = bot_screen;
+    return res;
+}
+}
diff --git a/src/core/frontend/framebuffer_layout.h b/src/core/frontend/framebuffer_layout.h
new file mode 100644
index 000000000..f1df5c55a
--- /dev/null
+++ b/src/core/frontend/framebuffer_layout.h
@@ -0,0 +1,55 @@
+// Copyright 2016 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/math_util.h"
+namespace Layout {
+/// Describes the layout of the window framebuffer (size and top/bottom screen positions)
+struct FramebufferLayout {
+    unsigned width;
+    unsigned height;
+    bool top_screen_enabled;
+    bool bottom_screen_enabled;
+    MathUtil::Rectangle<unsigned> top_screen;
+    MathUtil::Rectangle<unsigned> bottom_screen;
+};
+
+/**
+ * Factory method for constructing a default FramebufferLayout
+ * @param width Window framebuffer width in pixels
+ * @param height Window framebuffer height in pixels
+ * @param is_swapped if true, the bottom screen will be displayed above the top screen
+ * @return Newly created FramebufferLayout object with default screen regions initialized
+ */
+FramebufferLayout DefaultFrameLayout(unsigned width, unsigned height, bool is_swapped);
+
+/**
+ * Factory method for constructing a FramebufferLayout with only the top or bottom screen
+ * @param width Window framebuffer width in pixels
+ * @param height Window framebuffer height in pixels
+ * @param is_swapped if true, the bottom screen will be displayed (and the top won't be displayed)
+ * @return Newly created FramebufferLayout object with default screen regions initialized
+ */
+FramebufferLayout SingleFrameLayout(unsigned width, unsigned height, bool is_swapped);
+
+/**
+ * Factory method for constructing a Frame with the a 4x size Top screen with a 1x size bottom
+ * screen on the right
+ * This is useful in particular because it matches well with a 1920x1080 resolution monitor
+ * @param width Window framebuffer width in pixels
+ * @param height Window framebuffer height in pixels
+ * @param is_swapped if true, the bottom screen will be the large display
+ * @return Newly created FramebufferLayout object with default screen regions initialized
+ */
+FramebufferLayout LargeFrameLayout(unsigned width, unsigned height, bool is_swapped);
+
+/**
+ * Factory method for constructing a custom 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
+ */
+FramebufferLayout CustomFrameLayout(unsigned width, unsigned height);
+}