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Added SDL_SetWindowOpacity() and SDL_GetWindowOpacity().

This is currently implemented for X11, Cocoa, Windows, and DirectFB.

This patch is based on work in Unreal Engine 4's fork of SDL,
compliments of Epic Games.
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icculus committed Jan 5, 2016
1 parent 5696e88 commit 3bdaf4c611182ee47089fb91597ba6f60f1c766e
@@ -845,6 +845,34 @@ extern DECLSPEC int SDLCALL SDL_SetWindowBrightness(SDL_Window * window, float b
*/
extern DECLSPEC float SDLCALL SDL_GetWindowBrightness(SDL_Window * window);

/**
* \brief Set the opacity for a window
*
* \param window The window which will be made transparent or opaque
* \param opacity Opacity (0.0f - transparent, 1.0f - opaque) This will be
* clamped internally between 0.0f and 1.0f.
*
* \return 0 on success, or -1 if setting the opacity isn't supported.
*
* \sa SDL_GetWindowOpacity()
*/
extern DECLSPEC int SDLCALL SDL_SetWindowOpacity(SDL_Window * window, float opacity);

/**
* \brief Get the opacity of a window.
*
* If transparency isn't supported on this platform, opacity will be reported
* as 1.0f without error.
*
* \param window The window in question.
* \param opacity Opacity (0.0f - transparent, 1.0f - opaque)
*
* \return 0 on success, or -1 on error (invalid window, etc).
*
* \sa SDL_SetWindowOpacity()
*/
extern DECLSPEC int SDLCALL SDL_GetWindowOpacity(SDL_Window * window, float * out_opacity);

/**
* \brief Set the gamma ramp for a window.
*
@@ -599,3 +599,5 @@
#define SDL_JoystickFromInstanceID SDL_JoystickFromInstanceID_REAL
#define SDL_GetDisplayUsableBounds SDL_GetDisplayUsableBounds_REAL
#define SDL_GetWindowBordersSize SDL_GetWindowBordersSize_REAL
#define SDL_SetWindowOpacity SDL_SetWindowOpacity_REAL
#define SDL_GetWindowOpacity SDL_GetWindowOpacity_REAL
@@ -633,3 +633,5 @@ SDL_DYNAPI_PROC(SDL_GameController*,SDL_GameControllerFromInstanceID,(SDL_Joysti
SDL_DYNAPI_PROC(SDL_Joystick*,SDL_JoystickFromInstanceID,(SDL_JoystickID a),(a),return)
SDL_DYNAPI_PROC(int,SDL_GetDisplayUsableBounds,(int a, SDL_Rect *b),(a,b),return)
SDL_DYNAPI_PROC(int,SDL_GetWindowBordersSize,(SDL_Window *a, int *b, int *c, int *d, int *e),(a,b,c,d,e),return)
SDL_DYNAPI_PROC(int,SDL_SetWindowOpacity,(SDL_Window *a, float b),(a,b),return)
SDL_DYNAPI_PROC(int,SDL_GetWindowOpacity,(SDL_Window *a, float *b),(a,b),return)
@@ -1368,6 +1368,24 @@ SDLTest_CommonEvent(SDLTest_CommonState * state, SDL_Event * event, int *done)
}
}
break;
case SDLK_o:
if (withControl) {
/* Ctrl-O (or Ctrl-Shift-O) changes window opacity. */
SDL_Window *window = SDL_GetWindowFromID(event->key.windowID);
if (window) {
float opacity;
if (SDL_GetWindowOpacity(window, &opacity) == 0) {
if (withShift) {
opacity += 0.20f;
} else {
opacity -= 0.20f;
}
SDL_SetWindowOpacity(window, opacity);
}
}
}
break;

case SDLK_c:
if (withControl) {
/* Ctrl-C copy awesome text! */
@@ -86,6 +86,8 @@ struct SDL_Window

SDL_DisplayMode fullscreen_mode;

float opacity;

float brightness;
Uint16 *gamma;
Uint16 *saved_gamma; /* (just offset into gamma) */
@@ -207,6 +209,7 @@ struct SDL_VideoDevice
void (*SetWindowMinimumSize) (_THIS, SDL_Window * window);
void (*SetWindowMaximumSize) (_THIS, SDL_Window * window);
int (*GetWindowBordersSize) (_THIS, SDL_Window * window, int *top, int *left, int *bottom, int *right);
int (*SetWindowOpacity) (_THIS, SDL_Window * window, float opacity);
void (*ShowWindow) (_THIS, SDL_Window * window);
void (*HideWindow) (_THIS, SDL_Window * window);
void (*RaiseWindow) (_THIS, SDL_Window * window);
@@ -1415,6 +1415,7 @@ SDL_CreateWindow(const char *title, int x, int y, int w, int h, Uint32 flags)
}
window->flags = ((flags & CREATE_FLAGS) | SDL_WINDOW_HIDDEN);
window->last_fullscreen_flags = window->flags;
window->opacity = 1.0f;
window->brightness = 1.0f;
window->next = _this->windows;
window->is_destroying = SDL_FALSE;
@@ -1475,6 +1476,7 @@ SDL_CreateWindowFrom(const void *data)
window->flags = SDL_WINDOW_FOREIGN;
window->last_fullscreen_flags = window->flags;
window->is_destroying = SDL_FALSE;
window->opacity = 1.0f;
window->brightness = 1.0f;
window->next = _this->windows;
if (_this->windows) {
@@ -2190,6 +2192,42 @@ SDL_GetWindowBrightness(SDL_Window * window)
return window->brightness;
}

int
SDL_SetWindowOpacity(SDL_Window * window, float opacity)
{
int retval;
CHECK_WINDOW_MAGIC(window, -1);

if (!_this->SetWindowOpacity) {
return SDL_Unsupported();
}

if (opacity < 0.0f) {
opacity = 0.0f;
} else if (opacity > 1.0f) {
opacity = 1.0f;
}

retval = _this->SetWindowOpacity(_this, window, opacity);
if (retval == 0) {
window->opacity = opacity;
}

return retval;
}

int
SDL_GetWindowOpacity(SDL_Window * window, float * out_opacity)
{
CHECK_WINDOW_MAGIC(window, -1);

if (out_opacity) {
*out_opacity = window->opacity;
}

return 0;
}

int
SDL_SetWindowGammaRamp(SDL_Window * window, const Uint16 * red,
const Uint16 * green,
@@ -87,6 +87,7 @@
device->SetWindowSize = Cocoa_SetWindowSize;
device->SetWindowMinimumSize = Cocoa_SetWindowMinimumSize;
device->SetWindowMaximumSize = Cocoa_SetWindowMaximumSize;
device->SetWindowOpacity = Cocoa_SetWindowOpacity;
device->ShowWindow = Cocoa_ShowWindow;
device->HideWindow = Cocoa_HideWindow;
device->RaiseWindow = Cocoa_RaiseWindow;
@@ -125,6 +125,7 @@ extern void Cocoa_SetWindowPosition(_THIS, SDL_Window * window);
extern void Cocoa_SetWindowSize(_THIS, SDL_Window * window);
extern void Cocoa_SetWindowMinimumSize(_THIS, SDL_Window * window);
extern void Cocoa_SetWindowMaximumSize(_THIS, SDL_Window * window);
extern int Cocoa_SetWindowOpacity(_THIS, SDL_Window * window, float opacity);
extern void Cocoa_ShowWindow(_THIS, SDL_Window * window);
extern void Cocoa_HideWindow(_THIS, SDL_Window * window);
extern void Cocoa_RaiseWindow(_THIS, SDL_Window * window);
@@ -1782,6 +1782,14 @@ take effect properly (e.g. setting the window size, etc.)
return 0; /* just succeed, the real work is done elsewhere. */
}

int
Cocoa_SetWindowOpacity(_THIS, SDL_Window * window, float opacity)
{
SDL_WindowData *data = (SDL_WindowData *) window->driverdata;
[data->nswindow setAlphaValue:opacity];
return 0;
}

#endif /* SDL_VIDEO_DRIVER_COCOA */

/* vi: set ts=4 sw=4 expandtab: */
@@ -121,6 +121,7 @@ DirectFB_CreateDevice(int devindex)
device->SetWindowIcon = DirectFB_SetWindowIcon;
device->SetWindowPosition = DirectFB_SetWindowPosition;
device->SetWindowSize = DirectFB_SetWindowSize;
device->SetWindowOpacity = DirectFB_SetWindowOpacity;
device->ShowWindow = DirectFB_ShowWindow;
device->HideWindow = DirectFB_HideWindow;
device->RaiseWindow = DirectFB_RaiseWindow;
@@ -529,4 +529,17 @@ DirectFB_AdjustWindowSurface(SDL_Window * window)
return;
}

int
DirectFB_SetWindowOpacity(_THIS, SDL_Window * window, float opacity)
{
const Uint8 alpha = (Uint8) ((unsigned int) (opacity * 255.0f));
SDL_DFB_WINDOWDATA(window);
SDL_DFB_CHECKERR(windata->dfbwin->SetOpacity(windata->dfbwin, alpha));
windata->opacity = alpha;
return 0;

error:
return -1;
}

#endif /* SDL_VIDEO_DRIVER_DIRECTFB */
@@ -75,6 +75,7 @@ extern SDL_bool DirectFB_GetWindowWMInfo(_THIS, SDL_Window * window,
struct SDL_SysWMinfo *info);

extern void DirectFB_AdjustWindowSurface(SDL_Window * window);
extern int DirectFB_SetWindowOpacity(_THIS, SDL_Window * window, float opacity);

#endif /* _SDL_directfb_window_h */

@@ -137,6 +137,7 @@ WIN_CreateDevice(int devindex)
device->SetWindowIcon = WIN_SetWindowIcon;
device->SetWindowPosition = WIN_SetWindowPosition;
device->SetWindowSize = WIN_SetWindowSize;
device->SetWindowOpacity = WIN_SetWindowOpacity;
device->ShowWindow = WIN_ShowWindow;
device->HideWindow = WIN_HideWindow;
device->RaiseWindow = WIN_RaiseWindow;
@@ -826,6 +826,39 @@ WIN_SetWindowHitTest(SDL_Window *window, SDL_bool enabled)
return 0; /* just succeed, the real work is done elsewhere. */
}

int
WIN_SetWindowOpacity(_THIS, SDL_Window * window, float opacity)
{
const SDL_WindowData *data = (SDL_WindowData *) window->driverdata;
const HWND hwnd = data->hwnd;
const LONG style = GetWindowLong(hwnd, GWL_EXSTYLE);

SDL_assert(style != 0);

if (opacity == 1.0f) {
/* want it fully opaque, just mark it unlayered if necessary. */
if (style & WS_EX_LAYERED) {
if (SetWindowLong(hwnd, GWL_EXSTYLE, style & ~WS_EX_LAYERED) == 0) {
return WIN_SetError("SetWindowLong()");
}
}
} else {
const BYTE alpha = (BYTE) ((int) (opacity * 255.0f));
/* want it transparent, mark it layered if necessary. */
if ((style & WS_EX_LAYERED) == 0) {
if (SetWindowLong(hwnd, GWL_EXSTYLE, style | WS_EX_LAYERED) == 0) {
return WIN_SetError("SetWindowLong()");
}
}

if (SetLayeredWindowAttributes(hwnd, 0, alpha, LWA_ALPHA) == 0) {
return WIN_SetError("SetLayeredWindowAttributes()");
}
}

return 0;
}

#endif /* SDL_VIDEO_DRIVER_WINDOWS */

/* vi: set ts=4 sw=4 expandtab: */
@@ -56,6 +56,7 @@ extern void WIN_SetWindowTitle(_THIS, SDL_Window * window);
extern void WIN_SetWindowIcon(_THIS, SDL_Window * window, SDL_Surface * icon);
extern void WIN_SetWindowPosition(_THIS, SDL_Window * window);
extern void WIN_SetWindowSize(_THIS, SDL_Window * window);
extern int WIN_SetWindowOpacity(_THIS, SDL_Window * window, float opacity);
extern void WIN_ShowWindow(_THIS, SDL_Window * window);
extern void WIN_HideWindow(_THIS, SDL_Window * window);
extern void WIN_RaiseWindow(_THIS, SDL_Window * window);
@@ -233,6 +233,7 @@ X11_CreateDevice(int devindex)
device->SetWindowMinimumSize = X11_SetWindowMinimumSize;
device->SetWindowMaximumSize = X11_SetWindowMaximumSize;
device->GetWindowBordersSize = X11_GetWindowBordersSize;
device->SetWindowOpacity = X11_SetWindowOpacity;
device->ShowWindow = X11_ShowWindow;
device->HideWindow = X11_HideWindow;
device->RaiseWindow = X11_RaiseWindow;
@@ -407,6 +408,7 @@ X11_VideoInit(_THIS)
GET_ATOM(_NET_WM_ICON_NAME);
GET_ATOM(_NET_WM_ICON);
GET_ATOM(_NET_WM_PING);
GET_ATOM(_NET_WM_WINDOW_OPACITY);
GET_ATOM(_NET_WM_USER_TIME);
GET_ATOM(_NET_ACTIVE_WINDOW);
GET_ATOM(UTF8_STRING);
@@ -104,6 +104,7 @@ typedef struct SDL_VideoData
Atom _NET_WM_ICON_NAME;
Atom _NET_WM_ICON;
Atom _NET_WM_PING;
Atom _NET_WM_WINDOW_OPACITY;
Atom _NET_WM_USER_TIME;
Atom _NET_ACTIVE_WINDOW;
Atom UTF8_STRING;
@@ -923,6 +923,25 @@ X11_GetWindowBordersSize(_THIS, SDL_Window * window, int *top, int *left, int *b
return result;
}

int
X11_SetWindowOpacity(_THIS, SDL_Window * window, float opacity)
{
SDL_WindowData *data = (SDL_WindowData *) window->driverdata;
Display *display = data->videodata->display;
Atom _NET_WM_WINDOW_OPACITY = data->videodata->_NET_WM_WINDOW_OPACITY;

if (opacity == 1.0f) {
X11_XDeleteProperty(display, data->xwindow, _NET_WM_WINDOW_OPACITY);
} else {
const Uint32 FullyOpaque = 0xFFFFFFFF;
const long alpha = (long) ((double)opacity * (double)FullyOpaque);
X11_XChangeProperty(display, data->xwindow, _NET_WM_WINDOW_OPACITY, XA_CARDINAL, 32,
PropModeReplace, (unsigned char *)&alpha, 1);
}

return 0;
}

void
X11_SetWindowBordered(_THIS, SDL_Window * window, SDL_bool bordered)
{
@@ -80,6 +80,7 @@ extern void X11_SetWindowPosition(_THIS, SDL_Window * window);
extern void X11_SetWindowMinimumSize(_THIS, SDL_Window * window);
extern void X11_SetWindowMaximumSize(_THIS, SDL_Window * window);
extern int X11_GetWindowBordersSize(_THIS, SDL_Window * window, int *top, int *left, int *bottom, int *right);
extern int X11_SetWindowOpacity(_THIS, SDL_Window * window, float opacity);
extern void X11_SetWindowSize(_THIS, SDL_Window * window);
extern void X11_ShowWindow(_THIS, SDL_Window * window);
extern void X11_HideWindow(_THIS, SDL_Window * window);

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