非常简单的程序,用于在屏幕上绘图(如在 Paint 中使用笔)
我正在使用 SDL 1.2。我正在处理的唯一事件是鼠标移动、鼠标左键单击和退出程序。我的问题是当我快速移动鼠标时 SDL_MOUSEMOTION 事件被“跳过”(当我说快速时,我的意思是快于 1 像素/秒)
为什么会发生这种情况?
屏幕截图:
http://postimg.org/image/gcb87v9zr/
http://postimg.org/image/i5e4w6v6f/
#include <SDL/SDL.h>
SDL_Event event;
SDL_Surface* screen;
bool clicked = false;
Uint32 whiteColor;
int W = 200; // screen width
int H = 200; // screen height
Uint32* screenPixels;
bool handleInput();
int main(int argc, char** argv)
{
SDL_Init(SDL_INIT_EVERYTHING);
screen = SDL_SetVideoMode(W,H,32,SDL_SWSURFACE);
whiteColor = SDL_MapRGB(screen->format,255,255,255);
screenPixels = (Uint32*) screen->pixels;
while(handleInput())
{
}
SDL_Quit();
return 0;
}
bool handleInput()
{
while(SDL_PollEvent(&event))
{
switch(event.type)
{
case SDL_QUIT:{
return false;
break;
}
case SDL_MOUSEBUTTONDOWN:{
clicked = true;
break;
}
case SDL_MOUSEBUTTONUP:{
clicked = false;
break;
}
case SDL_MOUSEMOTION:{
if(clicked)
{
int P_x = event.motion.x;
int P_y = event.motion.y;
screenPixels[P_y * W + P_x] = whiteColor;
SDL_Flip(screen);
}
break;
}
}
}
return true;
}