hidpiscale

app/meson.build

@@ -8,6 +8,7 @@ src = [
     'src/device.c',
     'src/fpscounter.c',
     'src/frames.c',
+    'src/hidpi.c',
     'src/inputmanager.c',
     'src/lockutil.c',
     'src/net.c',

app/src/convert.c

@@ -136,6 +136,7 @@ SDL_bool input_key_from_sdl_to_android(const SDL_KeyboardEvent *from,
 
 SDL_bool mouse_button_from_sdl_to_android(const SDL_MouseButtonEvent *from,
                                           struct size screen_size,
+                                          struct hidpi_scale *hidpi_scale,
                                           struct control_event *to) {
     to->type = CONTROL_EVENT_TYPE_MOUSE;
 
@@ -145,21 +146,30 @@ SDL_bool mouse_button_from_sdl_to_android(const SDL_MouseButtonEvent *from,
 
     to->mouse_event.buttons = convert_mouse_buttons(SDL_BUTTON(from->button));
     to->mouse_event.position.screen_size = screen_size;
-    to->mouse_event.position.point.x = (Uint16) from->x;
-    to->mouse_event.position.point.y = (Uint16) from->y;
+
+    Sint32 x = from->x;
+    Sint32 y = from->y;
+    hidpi_unscale_coordinates(hidpi_scale, &x, &y);
+    to->mouse_event.position.point.x = (Uint16) x;
+    to->mouse_event.position.point.y = (Uint16) y;
 
     return SDL_TRUE;
 }
 
 SDL_bool mouse_motion_from_sdl_to_android(const SDL_MouseMotionEvent *from,
                                           struct size screen_size,
+                                          struct hidpi_scale *hidpi_scale,
                                           struct control_event *to) {
     to->type = CONTROL_EVENT_TYPE_MOUSE;
     to->mouse_event.action = AMOTION_EVENT_ACTION_MOVE;
     to->mouse_event.buttons = convert_mouse_buttons(from->state);
     to->mouse_event.position.screen_size = screen_size;
-    to->mouse_event.position.point.x = from->x;
-    to->mouse_event.position.point.y = from->y;
+
+    Sint32 x = from->x;
+    Sint32 y = from->y;
+    hidpi_unscale_coordinates(hidpi_scale, &x, &y);
+    to->mouse_event.position.point.x = (Uint16) x;
+    to->mouse_event.position.point.y = (Uint16) y;
 
     return SDL_TRUE;
 }

app/src/convert.h

@@ -3,7 +3,10 @@
 
 #include <SDL2/SDL_stdinc.h>
 #include <SDL2/SDL_events.h>
+
+#include "common.h"
 #include "controlevent.h"
+#include "hidpi.h"
 
 struct complete_mouse_motion_event {
     SDL_MouseMotionEvent *mouse_motion_event;
@@ -19,12 +22,14 @@ SDL_bool input_key_from_sdl_to_android(const SDL_KeyboardEvent *from,
                                        struct control_event *to);
 SDL_bool mouse_button_from_sdl_to_android(const SDL_MouseButtonEvent *from,
                                           struct size screen_size,
+                                          struct hidpi_scale *hidpi_scale,
                                           struct control_event *to);
 
 // the video size may be different from the real device size, so we need the size
 // to which the absolute position apply, to scale it accordingly
 SDL_bool mouse_motion_from_sdl_to_android(const SDL_MouseMotionEvent *from,
                                           struct size screen_size,
+                                          struct hidpi_scale *hidpi_scale,
                                           struct control_event *to);
 
 // on Android, a scroll event requires the current mouse position

app/src/hidpi.c

@@ -0,0 +1,16 @@
+#include "hidpi.h"
+
+void hidpi_get_scale(struct screen *screen, struct hidpi_scale *scale) {
+    SDL_GL_GetDrawableSize(screen->window, &scale->horizontal.num, &scale->vertical.num);
+    SDL_GetWindowSize(screen->window, &scale->horizontal.div, &scale->vertical.div);
+}
+
+void hidpi_unscale_coordinates(struct hidpi_scale *scale, Sint32 *x, Sint32 *y) {
+    // to unscale, we devide by the ratio (so num and div are reversed)
+    if (scale->horizontal.num) {
+        *x = ((Sint64) *x) * scale->horizontal.div / scale->horizontal.num;
+    }
+    if (scale->vertical.num) {
+        *y = ((Sint64) *y) * scale->vertical.div / scale->vertical.num;
+    }
+}

app/src/hidpi.h

@@ -0,0 +1,24 @@
+#ifndef HIDPI_H
+#define HIDPI_H
+
+#include "common.h"
+#include "screen.h"
+
+// rational number p/q
+struct rational {
+    int num;
+    int div;
+};
+
+struct hidpi_scale {
+    struct rational horizontal; // drawable.width / window.width
+    struct rational vertical; // drawable.height / window.height
+};
+
+void hidpi_get_scale(struct screen *screen, struct hidpi_scale *hidpi_scale);
+
+// mouse location need to be "unscaled" if hidpi is enabled
+// <https://nlguillemot.wordpress.com/2016/12/11/high-dpi-rendering/>
+void hidpi_unscale_coordinates(struct hidpi_scale *hidpi_scale, Sint32 *x, Sint32 *y);
+
+#endif

app/src/inputmanager.c

@@ -1,6 +1,7 @@
 #include "inputmanager.h"
 
 #include "convert.h"
+#include "hidpi.h"
 #include "lockutil.h"
 #include "log.h"
 
@@ -18,10 +19,19 @@ static void convert_to_renderer_coordinates(SDL_Renderer *renderer, int *x, int
 }
 
 static struct point get_mouse_point(struct screen *screen) {
-    int x;
-    int y;
-    SDL_GetMouseState(&x, &y);
-    convert_to_renderer_coordinates(screen->renderer, &x, &y);
+    int mx;
+    int my;
+    SDL_GetMouseState(&mx, &my);
+    convert_to_renderer_coordinates(screen->renderer, &mx, &my);
+
+    struct hidpi_scale hidpi_scale;
+    hidpi_get_scale(screen, &hidpi_scale);
+
+    // SDL sometimes uses "int", sometimes "Sint32"
+    Sint32 x = mx;
+    Sint32 y = my;
+    hidpi_unscale_coordinates(&hidpi_scale, &x, &y);
+
     SDL_assert_release(x >= 0 && x < 0x10000 && y >= 0 && y < 0x10000);
     return (struct point) {
         .x = (Uint16) x,
@@ -192,8 +202,12 @@ void input_manager_process_mouse_motion(struct input_manager *input_manager,
         // do not send motion events when no button is pressed
         return;
     }
+
+    struct hidpi_scale hidpi_scale;
+    hidpi_get_scale(input_manager->screen, &hidpi_scale);
+
     struct control_event control_event;
-    if (mouse_motion_from_sdl_to_android(event, input_manager->screen->frame_size, &control_event)) {
+    if (mouse_motion_from_sdl_to_android(event, input_manager->screen->frame_size, &hidpi_scale, &control_event)) {
         if (!controller_push_event(input_manager->controller, &control_event)) {
             LOGW("Cannot send mouse motion event");
         }
@@ -206,8 +220,12 @@ void input_manager_process_mouse_button(struct input_manager *input_manager,
         turn_screen_on(input_manager->controller);
         return;
     };
+
+    struct hidpi_scale hidpi_scale;
+    hidpi_get_scale(input_manager->screen, &hidpi_scale);
+
     struct control_event control_event;
-    if (mouse_button_from_sdl_to_android(event, input_manager->screen->frame_size, &control_event)) {
+    if (mouse_button_from_sdl_to_android(event, input_manager->screen->frame_size, &hidpi_scale, &control_event)) {
         if (!controller_push_event(input_manager->controller, &control_event)) {
             LOGW("Cannot send mouse button event");
         }

app/src/screen.c

@@ -141,7 +141,8 @@ SDL_bool screen_init_rendering(struct screen *screen, const char *device_name, s
 
     struct size window_size = get_initial_optimal_size(frame_size);
     screen->window = SDL_CreateWindow(device_name, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
-                                      window_size.width, window_size.height, SDL_WINDOW_HIDDEN | SDL_WINDOW_RESIZABLE);
+                                      window_size.width, window_size.height,
+                                      SDL_WINDOW_HIDDEN | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
     if (!screen->window) {
         LOGC("Could not create window: %s", SDL_GetError());
         return SDL_FALSE;