# HG changeset patch
# User hmk <sdl@guu.fi>
# Date 1569873256 -10800
#      Mon Sep 30 22:54:16 2019 +0300
# Node ID bb6ade3c7daef8e93582aea6789e9509731e07e8
# Parent  57c63adfdad172f03e53b182e3a4455bd9d0d04a
add a hint for toggling relative scaling

diff --git a/include/SDL_hints.h b/include/SDL_hints.h
--- a/include/SDL_hints.h
+++ b/include/SDL_hints.h
@@ -289,6 +289,17 @@ extern "C" {
 #define SDL_HINT_MOUSE_RELATIVE_SPEED_SCALE    "SDL_MOUSE_RELATIVE_SPEED_SCALE"
 
 /**
+ *  \brief  A variable controlling whether relative mouse motion is affected by renderer scaling
+ *
+ *  This variable can be set to the following values:
+ *    "0"       - Relative motion is unaffected by DPI or renderer's logical size
+ *    "1"       - Relative motion is scaled according to DPI scaling and logical size
+ *
+ *  By default relative mouse deltas are affected by DPI and renderer scaling
+ */
+#define SDL_HINT_MOUSE_RELATIVE_SCALING "SDL_MOUSE_RELATIVE_SCALING"
+
+/**
  *  \brief  A variable controlling whether relative mouse mode is implemented using mouse warping
  *
  *  This variable can be set to the following values:
diff --git a/src/render/SDL_render.c b/src/render/SDL_render.c
--- a/src/render/SDL_render.c
+++ b/src/render/SDL_render.c
@@ -654,13 +654,13 @@ SDL_RendererEventWatch(void *userdata, S
                 event->motion.y -= (int)(viewport.y * renderer->dpi_scale.y);
                 event->motion.x = (int)(event->motion.x / (scale.x * renderer->dpi_scale.x));
                 event->motion.y = (int)(event->motion.y / (scale.y * renderer->dpi_scale.y));
-                if (event->motion.xrel != 0) {
+                if (event->motion.xrel != 0 && renderer->relative_scaling) {
                     float rel = renderer->xrel + event->motion.xrel / (scale.x * renderer->dpi_scale.x);
                     float trunc = truncf(rel);
                     renderer->xrel = rel - trunc;
                     event->motion.xrel = trunc;
                 }
-                if (event->motion.yrel != 0) {
+                if (event->motion.yrel != 0 && renderer->relative_scaling) {
                     float rel = renderer->yrel + event->motion.yrel / (scale.y * renderer->dpi_scale.y);
                     float trunc = truncf(rel);
                     renderer->yrel = rel - trunc;
@@ -865,6 +865,8 @@ SDL_CreateRenderer(SDL_Window * window, 
         }
     }
 
+    renderer->relative_scaling = SDL_GetHintBoolean(SDL_HINT_MOUSE_RELATIVE_SCALING, SDL_TRUE);
+
     if (SDL_GetWindowFlags(window) & (SDL_WINDOW_HIDDEN|SDL_WINDOW_MINIMIZED)) {
         renderer->hidden = SDL_TRUE;
     } else {
diff --git a/src/render/SDL_sysrender.h b/src/render/SDL_sysrender.h
--- a/src/render/SDL_sysrender.h
+++ b/src/render/SDL_sysrender.h
@@ -194,6 +194,9 @@ struct SDL_Renderer
     /* The pixel to point coordinate scale */
     SDL_FPoint dpi_scale;
 
+    /* Whether or not to scale relative mouse motion */
+    SDL_bool relative_scaling;
+
     /* Remainder from scaled relative motion */
     float xrel;
     float yrel;