SDL2 窗口在调整大小时变黑 [英] SDL2 Window turns black on resize
问题描述
我已经开始使用 SDL2 并且没有使用它的经验.我在 Mac 系统上工作.几乎一切都很好，但我有一个问题，当一个可调整大小的窗口被调整大小时，在拖动手柄时，窗口变黑，我只能在释放后重新绘制它.我已经检查过，在调整窗口大小时，没有产生任何事件，我无法干扰或检测到这一点，因为事件循环只是暂停.有什么可能的解决方案吗?
I have started to work with SDL2 and am not experienced with it. I am working on a Mac system. Almost everything has been good, but I have a problem that when a resizeable window is resized, while the handle is being dragged, the window turns black, and I can only repaint it after releasing. And I have checked that while the window is being resized, no event is being produced and I have no means to interfere or detect this, as the event loop is just paused. Is there any possible solutions?
这是代码(几乎是处理调整大小事件教程的副本):
Here is the code (Almost replica of a tutorial on handling resize event):
SDL_Event event;
SDL_Rect nativeSize;
SDL_Rect newWindowSize;
float scaleRatioW;//This is to change anything that might rely on something like mouse coords
float scaleRatioH; //(such as a button on screen) over to the new coordinate system scaling would create
SDL_Window * window; //Our beautiful window
SDL_Renderer * renderer; //The renderer for our window
SDL_Texture * backBuffer; //The back buffer that we will be rendering everything to before scaling up
SDL_Texture * ballImage; //A nice picture to demonstrate the scaling;
bool resize;
void InitValues(); //Initialize all the variables needed
void InitSDL(); //Initialize the window, renderer, backBuffer, and image;
bool HandleEvents(); //Handle the window changed size event
void Render(); //Switches the render target back to the window and renders the back buffer, then switches back.
void Resize(); //The important part for stretching. Changes the viewPort, changes the scale ratios
void InitValues()
{
nativeSize.x = 0;
nativeSize.y = 0;
nativeSize.w = 256;
nativeSize.h = 224; //A GameBoy size window width and height
scaleRatioW = 1.0f;
scaleRatioH = 1.0f;
newWindowSize.x = 0;
newWindowSize.y = 0;
newWindowSize.w = nativeSize.w;
newWindowSize.h = nativeSize.h;
window = NULL;
renderer = NULL;
backBuffer = NULL;
ballImage = NULL;
resize = false;
}
void InitSDL()
{
if(SDL_Init(SDL_INIT_EVERYTHING) < 0)
{
//cout << "Failed to initialize SDL" << endl;
printf("%d\r\n", __LINE__);
}
//Set the scaling quality to nearest-pixel
if(SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "0") < 0)
{
//cout << "Failed to set Render Scale Quality" << endl;
printf("%d\r\n", __LINE__);
}
//Window needs to be resizable
window = SDL_CreateWindow("Rescaling Windows!",
SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED,
256,
224,
SDL_WINDOW_RESIZABLE);
//You must use the SDL_RENDERER_TARGETTEXTURE flag in order to target the backbuffer
renderer = SDL_CreateRenderer(window,
-1,
SDL_RENDERER_ACCELERATED |
SDL_RENDERER_TARGETTEXTURE);
//Set to blue so it's noticeable if it doesn't do right.
SDL_SetRenderDrawColor(renderer, 0, 0, 200, 255);
//Similarly, you must use SDL_TEXTUREACCESS_TARGET when you create the texture
backBuffer = SDL_CreateTexture(renderer,
SDL_GetWindowPixelFormat(window),
SDL_TEXTUREACCESS_TARGET,
nativeSize.w,
nativeSize.h);
//IMPORTANT Set the back buffer as the target
SDL_SetRenderTarget(renderer, backBuffer);
//Load an image yay
SDL_Surface * image = SDL_LoadBMP("Ball.bmp");
ballImage = SDL_CreateTextureFromSurface(renderer, image);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 4);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 1);
SDL_FreeSurface(image);
}
bool HandleEvents()
{
while(SDL_PollEvent(&event) )
{
printf("%d\r\n", __LINE__);
if(event.type == SDL_QUIT)
{
printf("%d\r\n", __LINE__);
return true;
}
else if(event.type == SDL_WINDOWEVENT)
{
if(event.window.event == SDL_WINDOWEVENT_SIZE_CHANGED)
{
resize = true;
printf("%d\r\n", __LINE__);
}
}
return false;
}
return false;
}
void Render()
{
SDL_RenderCopy(renderer, ballImage, NULL, NULL); //Render the entire ballImage to the backBuffer at (0, 0)
printf("%d\r\n", __LINE__);
SDL_SetRenderTarget(renderer, NULL); //Set the target back to the window
if(resize)
{
Resize();
resize = false;
}
printf("%d\r\n", __LINE__);
SDL_RenderCopy(renderer, backBuffer, &nativeSize, &newWindowSize); //Render the backBuffer onto the screen at (0,0)
SDL_RenderPresent(renderer);
SDL_RenderClear(renderer); //Clear the window buffer
SDL_SetRenderTarget(renderer, backBuffer); //Set the target back to the back buffer
SDL_RenderClear(renderer); //Clear the back buffer
printf("%d\r\n", __LINE__);
}
void Resize()
{
int w, h;
printf("%d\r\n", __LINE__);
SDL_GetWindowSize(window, &w, &h);
scaleRatioW = w / nativeSize.w;
scaleRatioH = h / nativeSize.h; //The ratio from the native size to the new size
newWindowSize.w = w;
newWindowSize.h = h;
//In order to do a resize, you must destroy the back buffer. Try without it, it doesn't work
SDL_DestroyTexture(backBuffer);
backBuffer = SDL_CreateTexture(renderer,
SDL_GetWindowPixelFormat(window),
SDL_TEXTUREACCESS_TARGET, //Again, must be created using this
nativeSize.w,
nativeSize.h);
SDL_Rect viewPort;
SDL_RenderGetViewport(renderer, &viewPort);
if(viewPort.w != newWindowSize.w || viewPort.h != newWindowSize.h)
{
//VERY IMPORTANT - Change the viewport over to the new size. It doesn't do this for you.
SDL_RenderSetViewport(renderer, &newWindowSize);
}
}
int main(int argc, char * argv[])
{
InitValues();
InitSDL();
bool quit = false;
printf("%d\r\n", __LINE__);
while(!quit)
{
printf("%d\r\n", __LINE__);
quit = HandleEvents();
Render();
}
return 0;
}
推荐答案
好的，在与 SDL2 进行了一番斗争后，我让它与 macOS 10.12 一起工作.
Ok, after fighting a bit with SDL2, I got it working with macOS 10.12.
问题来了:
- 例如，当您使用
SDL_PollEvent(&event)轮询事件时，SDL2 会捕获调整大小事件并仅重新发送最后 3 个. - 在此期间(您按住鼠标左键单击调整大小区域并按住鼠标)
SDL_PollEvent正在阻塞.
- SDL2 catches resize events and resends only the last 3 when you poll events using
SDL_PollEvent(&event)for example. - During this time (you pressed left mouse click on resize area and hold the mouse) the
SDL_PollEventis blocking.
解决方法如下:
幸运的是，您可以使用 SDL_SetEventFilter 连接到事件处理程序.每次收到事件时都会触发.因此，对于所有发生的调整大小事件.
Luckily, you can hook into the event handler using SDL_SetEventFilter. This will fire every time a event is being received. So for all resize events as they occur.
所以你可以做的是注册你自己的事件过滤器回调，它基本上允许每个事件(通过返回1)，监听调整大小事件，并将它们发送到你的绘制循环.
So what you can do is to register your own event filter callback that basically allows every event (by returning 1), listens on resize events, and sends them to your draw loop.
示例:
//register this somewhere
int filterEvent(void *userdata, SDL_Event * event) {
if (event->type == SDL_WINDOWEVENT && event->window.event == SDL_WINDOWEVENT_RESIZED) {
//convert userdata pointer to yours and trigger your own draw function
//this is called very often now
//IMPORTANT: Might be called from a different thread, see SDL_SetEventFilter docs
((MyApplicationClass *)userdata)->myDrawFunction();
//return 0 if you don't want to handle this event twice
return 0;
}
//important to allow all events, or your SDL_PollEvent doesn't get any event
return 1;
}
///after SDL_Init
SDL_SetEventFilter(filterEvent, this) //this is instance of MyApplicationClass for example
重要提示:不要在 filterEvent 回调中调用 SDL_PollEvent，因为这会导致卡住事件的奇怪行为.(例如有时调整大小不会停止)
Important: Do not call SDL_PollEvent within your filterEvent callback, as this will result in weird behaviour of stuck events. (resize will not stop sometimes for example)
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