From 221a9b023d8c9ca55c093823e9efd6d13d0a54a2 Mon Sep 17 00:00:00 2001
From: Kevin Hartman <kevin@hart.mn>
Date: Fri, 29 Aug 2014 22:23:12 -0700
Subject: Viewport scaling and display density independence

The view is scaled to be as large as possible, without changing the aspect, within the bounds of the window.
On "retina" displays, or other displays where window units != pixels, the view should no longer draw incorrectly.
---
 src/video_core/renderer_opengl/renderer_opengl.cpp | 36 +++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

(limited to 'src/video_core/renderer_opengl/renderer_opengl.cpp')

diff --git a/src/video_core/renderer_opengl/renderer_opengl.cpp b/src/video_core/renderer_opengl/renderer_opengl.cpp
index 8483f79be..3757482db 100644
--- a/src/video_core/renderer_opengl/renderer_opengl.cpp
+++ b/src/video_core/renderer_opengl/renderer_opengl.cpp
@@ -191,7 +191,8 @@ void RendererOpenGL::DrawSingleScreenRotated(const TextureInfo& texture, float x
  * Draws the emulated screens to the emulator window.
  */
 void RendererOpenGL::DrawScreens() {
-    glViewport(0, 0, resolution_width, resolution_height);
+    UpdateViewportExtent();
+    glViewport(viewport_extent.x, viewport_extent.y, viewport_extent.width, viewport_extent.height);
     glClear(GL_COLOR_BUFFER_BIT);
 
     glUseProgram(program_id);
@@ -228,6 +229,39 @@ void RendererOpenGL::SetWindow(EmuWindow* window) {
     render_window = window;
 }
 
+void RendererOpenGL::UpdateViewportExtent() {
+    int width_in_pixels;
+    int height_in_pixels;
+
+    render_window->GetFramebufferSize(&width_in_pixels, &height_in_pixels);
+
+    // No update needed if framebuffer size hasn't changed
+    if (width_in_pixels == framebuffer_size.width && height_in_pixels == framebuffer_size.height) {
+        return;
+    }
+
+    framebuffer_size.width = width_in_pixels;
+    framebuffer_size.height = height_in_pixels;
+
+    float window_aspect_ratio = static_cast<float>(height_in_pixels) / width_in_pixels;
+    float emulation_aspect_ratio = static_cast<float>(resolution_height) / resolution_width;
+
+    if (window_aspect_ratio > emulation_aspect_ratio) {
+        // If the window is more narrow than the emulation content, borders are applied on the
+        // top and bottom of the window.
+        viewport_extent.width = width_in_pixels;
+        viewport_extent.height = emulation_aspect_ratio * viewport_extent.width;
+        viewport_extent.x = 0;
+        viewport_extent.y = (height_in_pixels - viewport_extent.height) / 2;
+    } else {
+        // Otherwise, borders are applied on the left and right sides of the window.
+        viewport_extent.height = height_in_pixels;
+        viewport_extent.width = (1 / emulation_aspect_ratio) * viewport_extent.height;
+        viewport_extent.x = (width_in_pixels - viewport_extent.width) / 2;
+        viewport_extent.y = 0;
+    }
+}
+
 /// Initialize the renderer
 void RendererOpenGL::Init() {
     render_window->MakeCurrent();
-- 
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