Add integer scaling.

Author: jyetcv

config_spec.yml

@@ -181,7 +181,7 @@ display:
       default: true
     fit:
       type: enum
-      values: [center, scale, stretch]
+      values: [center, scale, integer, stretch]
       default: scale
     aspect_ratio:
       type: enum

ui/xui/gl-helpers.cc

@@ -949,6 +949,15 @@ void RenderFramebuffer(GLint tex, int width, int height, bool flip)
         float t_ratio = GetDisplayAspectRatio(tw, th);
         scale[0] = t_ratio*(float)th/(float)width;
         scale[1] = (float)th/(float)height;
+    } else if (g_config.display.ui.fit == CONFIG_DISPLAY_UI_FIT_INTEGER) {
+        // Integer scaling
+        float t_ratio = GetDisplayAspectRatio(tw, th);
+        int s_factor = (float)width/(float)tw;
+        int s_height = (float)height/(float)th;
+        if (s_height < s_factor) s_factor = s_height;
+        if (s_factor < 1) s_factor = 1;
+            scale[0] = s_factor*t_ratio*(int)th/(float)width;
+            scale[1] = s_factor*(int)th/(float)height;
     } else {
         float t_ratio = GetDisplayAspectRatio(tw, th);
         float w_ratio = (float)width/(float)height;

ui/xui/menubar.cc

@@ -195,7 +195,7 @@ void ShowMainMenu()
             }
 
             ImGui::Combo("Display Mode", &g_config.display.ui.fit,
-                         "Center\0Scale\0Stretch\0");
+                         "Center\0Scale\0Integer\0Stretch\0");
             ImGui::SameLine();
             HelpMarker("Controls how the rendered content should be scaled "
                        "into the window");