From 0ec94906518a54082e3363f68841d8b6838ccc55 Mon Sep 17 00:00:00 2001
From: CobaltXII <40343339+CobaltXII@users.noreply.github.com>
Date: Tue, 22 Jan 2019 10:50:58 -0500
Subject: [PATCH] Implemented high-DPI support

---
 vga.cc | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/vga.cc b/vga.cc
index cd89cbc..d0d63ae 100644
--- a/vga.cc
+++ b/vga.cc
@@ -120,6 +120,12 @@ namespace
     } } xterm256init;
     #undef Make16
 
+    // CobaltXII: These two variables retain the
+    // scaling factor for high-dpi monitors.
+
+    int xr_factor;
+    int yr_factor;
+
     SDL_Window*   window   = nullptr;
     SDL_Renderer* renderer = nullptr;
     SDL_Texture*  texture  = nullptr;
@@ -154,7 +160,14 @@ namespace
             window = SDL_CreateWindow("editor",
                 SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
                 pixels_width, pixels_height,
-                SDL_WINDOW_RESIZABLE);
+                SDL_WINDOW_RESIZABLE|
+
+                // HIGH DPI SUPPORT!
+                SDL_WINDOW_ALLOW_HIGHDPI);
+
+            // This is not really required but it may be of use for
+            // people with strange monitors. It prevents antialiasing.
+            SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY,0);
         }
         else
         {
@@ -178,6 +191,18 @@ namespace
                 textureheight = bufpixels_height);
         }
 
+        // Get size of OpenGL drawable. This will be larger than the pixels_width and
+        // pixels_height defined by Bisqwit (on high dpi monitors, only!). 
+        int gl_xr;
+        int gl_yr;
+        SDL_GL_GetDrawableSize(window,&gl_xr, &gl_yr);
+
+        // Find the Scaling factors. This is done by dividing the GL resolution by the
+        // resolution defined by Bisqwit. If no high-dpi, this will be 1. Otherwise it
+        // will probably be 2 or rarely 3.
+        xr_factor = gl_xr / pixels_width;
+        yr_factor = gl_yr / pixels_height;
+
         pixbuf.resize(bufpixels_width*bufpixels_height);
         cursor_old=~0u;
         //fprintf(stderr, "resized\n");
@@ -207,6 +232,9 @@ namespace
                 trect.w = (rect.x + rect.w) * w / bufpixels_width - trect.x;
                 trect.h = (rect.y + rect.h) * h / bufpixels_height - trect.y;
 
+                trect.w *= xr_factor;
+                trect.h *= yr_factor;
+
                 if(SDL_UpdateTexture(texture, &rect,
                                      pixbuf.data() + rect.y*bufpixels_width,
                                      bufpixels_width*sizeof(pixbuf[0]))) ++errors;