Add support for hints.

* sdl2/bindings.scm (SDL_HINT_DEFAULT, SDL_HINT_NORMAL, SDL_HINT_OVERRIDE)
(sdl-set-hint-with-priority, sdl-get-hint): New variables.
* sdl2/hints.scm: New file.
* doc/api.texi: Add Hints.

4 files changed, 181 insertions, 0 deletions

diff --git a/Makefile.am b/Makefile.am
index 287a19c..15007a6 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -46,6 +46,7 @@ SOURCES =					\
   sdl2/bindings.scm				\
   sdl2/blend-mode.scm				\
   sdl2/clipboard.scm				\
+  sdl2/hints.scm				\
   sdl2/rect.scm					\
   sdl2/surface.scm				\
   sdl2/render.scm				\
diff --git a/doc/api.texi b/doc/api.texi
index 3c4e645..288d0a6 100644
--- a/doc/api.texi
+++ b/doc/api.texi
@@ -10,6 +10,7 @@
 * Images::                      Loading and saving images.
 * Sound::                       Sound effects and music.
 * Fonts::                       Truetype and bitmap font rendering.
+* Hints::                       Getting and setting configuration hints.
 @end menu
 
 @node Basics
@@ -1648,3 +1649,26 @@ Render @var{text}, a UTF-8 encoded string, using @var{font} and @var{color}, the
 foreground color, and return a high-quality alpha-blended surface containing the
 results.
 @end deffn
+
+@node Hints
+@section Hints
+
+@example
+(use-modules (sdl2 hints))
+@end example
+
+@deffn {Procedure} get-hint hint
+Get the string value of @var{hint} or @code{#f} if if @var{hint} is unset.
+@end deffn
+
+@deffn {Procedure} set-hint! hint value [priority]
+Set @var{hint} to @var{value} at priority level @var{priority}.
+@var{priority} can be one of the symbols @code{default}, @code{normal} or
+@code{override} and defaults to @code{normal}.
+@var{value} will automatically be converted to a string if it is a boolean
+or a number.
+@end deffn
+
+Inside SDL2, the macro @code{SDL_HINT_SOME_HINT} corresponds to the
+environment variable @env{SDL_SOME_HINT}.  In Guile-SDL2, this hint would be
+represented by the symbol @code{some-symbol.}
diff --git a/sdl2/bindings.scm b/sdl2/bindings.scm
index a9fa17c..c46af8b 100644
--- a/sdl2/bindings.scm
+++ b/sdl2/bindings.scm
@@ -1301,3 +1301,17 @@ RETURN-TYPE and accept arguments of ARG-TYPES."
 
 (define-foreign sdl-has-clipboard-text
   int "SDL_HasClipboardText" '())
+
+;;;
+;;; Hints
+;;;
+
+(define-public SDL_HINT_DEFAULT 0)
+(define-public SDL_HINT_NORMAL 1)
+(define-public SDL_HINT_OVERRIDE 2)
+
+(define-foreign sdl-set-hint-with-priority
+  sdl-bool "SDL_SetHintWithPriority" (list '* '* int))
+
+(define-foreign sdl-get-hint
+  '* "SDL_GetHint" (list '*))
diff --git a/sdl2/hints.scm b/sdl2/hints.scm
new file mode 100644
index 0000000..9533e23
--- /dev/null
+++ b/sdl2/hints.scm
@@ -0,0 +1,142 @@
+;;; guile-sdl2 --- FFI bindings for SDL2
+;;; Copyright © 2021 Leo Prikler <leo.prikler@student.tugraz.at>
+;;;
+;;; This file is part of guile-sdl2.
+;;;
+;;; Guile-sdl2 is free software; you can redistribute it and/or modify
+;;; it under the terms of the GNU Lesser General Public License as
+;;; published by the Free Software Foundation; either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; Guile-sdl2 is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU Lesser General Public
+;;; License along with guile-sdl2.  If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+(define-module (sdl2 hints)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 optargs)
+  #:use-module (srfi srfi-9)
+  #:use-module (sdl2)
+  #:use-module ((sdl2 bindings) #:prefix ffi:)
+  #:use-module (system foreign)
+  #:export (get-hint set-hint!))
+
+(define (symbol->priority sym)
+  (match sym
+    ('default  ffi:SDL_HINT_DEFAULT)
+    ('normal   ffi:SDL_HINT_NORMAL)
+    ('override ffi:SDL_HINT_OVERRIDE)))
+
+(define (symbol->hint sym)
+  (match sym
+    ('accelerometer-as-joystick "SDL_ACCELEROMETER_AS_JOYSTICK")
+    ('allow-topmost "SDL_ALLOW_TOPMOST")
+    ('android-apk-expansion-main-file-version
+     "SDL_ANDROID_APK_EXPANSION_MAIN_FILE_VERSION")
+    ('android-apk-expansion-patch-file-version
+     "SDL_ANDROID_APK_EXPANSION_PATCH_FILE_VERSION")
+    ('android-separate-mouse-and-touch
+     "SDL_ANDROID_SEPARATE_MOUSE_AND_TOUCH")
+    ('apple-tv-ui-events "SDL_APPLE_TV_UI_EVENTS")
+    ('apple-tv-remote-allow-rotation
+     "SDL_APPLE_TV_REMOTE_ALLOW_ROTATION")
+    ('bmp-save-legacy-format "SDL_BMP_SAVE_LEGACY_FORMAT")
+    ('display-usable-bounds "SDL_DISPLAY_USABLE_BOUNDS")
+    ('emscripten-keyboard-element "SDL_EMSCRIPTEN_KEYBOARD_ELEMENT")
+    ('event-logging "SDL_EVENT_LOGGING")
+    ('framebuffer-acceleration "SDL_FRAMEBUFFER_ACCELERATION")
+    ('gamecontroller-ignore-devices "SDL_GAMECONTROLLER_IGNORE_DEVICES")
+    ('gamecontroller-ignore-devices-except
+     "SDL_GAMECONTROLLER_IGNORE_DEVICES_EXCEPT")
+    ('gamecontroller-use-button-labels "SDL_GAMECONTROLLER_USE_BUTTON_LABELS")
+    ('gamecontrollerconfig "SDL_GAMECONTROLLERCONFIG")
+    ('gamecontrollerconfig-file "SDL_GAMECONTROLLERCONFIG_FILE")
+    ('gamecontrollertype "SDL_GAMECONTROLLERTYPE")
+    ('grab-keyboard "SDL_GRAB_KEYBOARD")
+    ('idle-timer-disabled "SDL_IDLE_TIMER_DISABLED")
+    ('joystick-allow-background-events "SDL_JOYSTICK_ALLOW_BACKGROUND_EVENTS")
+    ('joystick-hidapi "SDL_JOYSTICK_HIDAPI")
+    ('joystick-hidapi-gamecube "SDL_JOYSTICK_HIDAPI_GAMECUBE")
+    ('joystick-hidapi-ps4 "SDL_JOYSTICK_HIDAPI_PS4")
+    ('joystick-hidapi-ps4-rumble "SDL_JOYSTICK_HIDAPI_PS4_RUMBLE")
+    ('joystick-hidapi-steam "SDL_JOYSTICK_HIDAPI_STEAM")
+    ('joystick-hidapi-steam-controllers
+     "SDL_JOYSTICK_HIDAPI_STEAM_CONTROLLERS")
+    ('joystick-hidapi-switch "SDL_JOYSTICK_HIDAPI_SWITCH")
+    ('joystick-hidapi-xbox "SDL_JOYSTICK_HIDAPI_XBOX")
+    ('mac-background-app "SDL_MAC_BACKGROUND_APP")
+    ('mac-ctrl-click-emulate-right-click
+     "SDL_MAC_CTRL_CLICK_EMULATE_RIGHT_CLICK")
+    ('mouse-double-click-radius "SDL_MOUSE_DOUBLE_CLICK_RADIUS")
+    ('mouse-focus-clickthrough "SDL_MOUSE_FOCUS_CLICKTHROUGH")
+    ('mouse-normal-speed-scale "SDL_MOUSE_NORMAL_SPEED_SCALE")
+    ('mouse-relative-mode-warp "SDL_MOUSE_RELATIVE_MODE_WARP")
+    ('mouse-relative-speed-scale "SDL_MOUSE_RELATIVE_SPEED_SCALE")
+    ('mouse-touch-events "SDL_MOUSE_TOUCH_EVENTS")
+    ('no-signal-handlers "SDL_NO_SIGNAL_HANDLERS")
+    ('orientations "SDL_ORIENTATIONS")
+    ('render-batching "SDL_RENDER_BATCHING")
+    ('render-direct3d11-debug "SDL_RENDER_DIRECT3D11_DEBUG")
+    ('render-direct3d-threadsafe "SDL_RENDER_DIRECT3D_THREADSAFE")
+    ('render-driver "SDL_RENDER_DRIVER")
+    ('render-logical-size-mode "SDL_RENDER_LOGICAL_SIZE_MODE")
+    ('render-opengl-shaders "SDL_RENDER_OPENGL_SHADERS")
+    ('render-scale-quality "SDL_RENDER_SCALE_QUALITY")
+    ('render-vsync "SDL_RENDER_VSYNC")
+    ('return-key-hides-ime "SDL_RETURN_KEY_HIDES_IME")
+    ('rpi-video-layer "SDL_RPI_VIDEO_LAYER")
+    ('qtwayland-content-orientation "SDL_QTWAYLAND_CONTENT_ORIENTATION")
+    ('qtwayland-window-flags "SDL_QTWAYLAND_WINDOW_FLAGS")
+    ('thread-stack-size "SDL_THREAD_STACK_SIZE")
+    ('timer-resolution "SDL_TIMER_RESOLUTION")
+    ('touch-mouse-events "SDL_TOUCH_MOUSE_EVENTS")
+    ('video-allow-screensaver "SDL_VIDEO_ALLOW_SCREENSAVER")
+    ('video-external-context "SDL_VIDEO_EXTERNAL_CONTEXT")
+    ('video-highdpi-disabled "SDL_VIDEO_HIGHDPI_DISABLED")
+    ('video-mac-fullscreen-spaces "SDL_VIDEO_MAC_FULLSCREEN_SPACES")
+    ('video-minimize-on-focus-loss "SDL_VIDEO_MINIMIZE_ON_FOCUS_LOSS")
+    ('video-window-share-pixel-format "SDL_VIDEO_WINDOW_SHARE_PIXEL_FORMAT")
+    ('video-win-d3dcompiler "SDL_VIDEO_WIN_D3DCOMPILER")
+    ('video-x11-force-egl "SDL_VIDEO_X11_FORCE_EGL")
+    ('video-x11-net-wm-ping "SDL_VIDEO_X11_NET_WM_PING")
+    ('video-x11-window-visualid "SDL_VIDEO_X11_WINDOW_VISUALID")
+    ('video-x11-xinerama "SDL_VIDEO_X11_XINERAMA")
+    ('video-x11-xrandr "SDL_VIDEO_X11_XRANDR")
+    ('video-x11-xvidmode "SDL_VIDEO_X11_XVIDMODE")
+    ('wave-fact-chunk "SDL_WAVE_FACT_CHUNK")
+    ('wave-riff-chunk-size "SDL_WAVE_RIFF_CHUNK_SIZE")
+    ('wave-truncation "SDL_WAVE_TRUNCATION")
+    ('windows-disable-thread-naming "SDL_WINDOWS_DISABLE_THREAD_NAMING")
+    ('windows-enable-message-loop "SDL_WINDOWS_ENABLE_MESSAGE_LOOP")
+    ('windows-intresource-icon "SDL_WINDOWS_INTRESOURCE_ICON")
+    ('windows-intresource-icon-small "SDL_WINDOWS_INTRESOURCE_ICON_SMALL")
+    ('windows-no-close-on-alt-f4 "SDL_WINDOWS_NO_CLOSE_ON_ALT_F4")
+    ('window-frame-usable-while-cursor-hidden
+     "SDL_WINDOW_FRAME_USABLE_WHILE_CURSOR_HIDDEN")
+    ('winrt-handle-back-button "SDL_WINRT_HANDLE_BACK_BUTTON")
+    ('winrt-privacy-policy-label "SDL_WINRT_PRIVACY_POLICY_LABEL")
+    ('winrt-privacy-policy-url "SDL_WINRT_PRIVACY_POLICY_URL")
+    ('xinput-enabled "SDL_XINPUT_ENABLED")
+    ('xinput-use-old-joystick-mapping "SDL_XINPUT_USE_OLD_JOYSTICK_MAPPING")))
+
+(define* (get-hint hint)
+  (let* ((hint* (string->pointer (symbol->hint hint)))
+         (value* (ffi:sdl-get-hint hint*)))
+    (and (not (null-pointer? value*))
+         (pointer->string value*))))
+
+(define* (set-hint! hint value #:optional (priority 'normal))
+  (let ((hint* (string->pointer (symbol->hint hint)))
+        (value* (string->pointer
+                 (match value
+                   (#t "1")
+                   (#f "0")
+                   ((? number? n) (number->string value))
+                   ((? string? s) s))))
+        (priority (symbol->priority priority)))
+    (= (ffi:sdl-set-hint-with-priority hint* value* priority) 1)))