本文整理汇总了C++中SDL_VideoDevice::SetHWAlpha方法的典型用法代码示例。如果您正苦于以下问题：C++ SDL_VideoDevice::SetHWAlpha方法的具体用法？C++ SDL_VideoDevice::SetHWAlpha怎么用？C++ SDL_VideoDevice::SetHWAlpha使用的例子？那么, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类SDL_VideoDevice的用法示例。
在下文中一共展示了SDL_VideoDevice::SetHWAlpha方法的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C++代码示例。
示例1: SDL_SetAlpha
/* This function sets the alpha channel of a surface */
int SDL_SetAlpha (SDL_Surface *surface, Uint32 flag, Uint8 value)
{
Uint32 oldflags = surface->flags;
Uint32 oldalpha = surface->format->alpha;
/* Sanity check the flag as it gets passed in */
if ( flag & SDL_SRCALPHA ) {
if ( flag & (SDL_RLEACCEL|SDL_RLEACCELOK) ) {
flag = (SDL_SRCALPHA | SDL_RLEACCELOK);
} else {
flag = SDL_SRCALPHA;
}
} else {
flag = 0;
}
/* Optimize away operations that don't change anything */
if ( (flag == (surface->flags & (SDL_SRCALPHA|SDL_RLEACCELOK))) &&
(!flag || value == oldalpha) ) {
return(0);
}
if(!(flag & SDL_RLEACCELOK) && (surface->flags & SDL_RLEACCEL))
SDL_UnRLESurface(surface, 1);
if ( flag ) {
SDL_VideoDevice *video = current_video;
SDL_VideoDevice *this = current_video;
surface->flags |= SDL_SRCALPHA;
surface->format->alpha = value;
if ( (surface->flags & SDL_HWACCEL) == SDL_HWACCEL ) {
if ( (video->SetHWAlpha == NULL) ||
(video->SetHWAlpha(this, surface, value) < 0) ) {
surface->flags &= ~SDL_HWACCEL;
}
}
if ( flag & SDL_RLEACCELOK ) {
surface->flags |= SDL_RLEACCELOK;
} else {
surface->flags &= ~SDL_RLEACCELOK;
}
} else {
surface->flags &= ~SDL_SRCALPHA;
surface->format->alpha = SDL_ALPHA_OPAQUE;
}
/*
* The representation for software surfaces is independent of
* per-surface alpha, so no need to invalidate the blit mapping
* if just the alpha value was changed. (If either is 255, we still
* need to invalidate.)
*/
if((surface->flags & SDL_HWACCEL) == SDL_HWACCEL
|| oldflags != surface->flags
|| (((oldalpha + 1) ^ (value + 1)) & 0x100))
SDL_InvalidateMap(surface->map);
return(0);
}