注：重复的例子没有列出
最快的图像平面块传送
将图像画到屏幕上有三种方式：1.创建一个图像平面并用SDL_BlitSurface传送到屏幕；2.在系统内存创建视频平面并调用SDL_UpdateRect；3.在显存创建视频平面并调用SDL_LockSurface。最好的方法是混合方式：
#include <stdio.h>
#include <stdlib.h>
#include "SDL.h"
#include "SDL_timer.h"
void ComplainAndExit(void)
{
fprintf(stderr, "Problem: %s\n", SDL_GetError());
exit(1);
}
int main(int argc, char *argv[])
{
SDL_PixelFormat fmt;
SDL_Surface *screen, *locked;
SDL_Surface *imagebmp, *image;
SDL_Rect
dstrect;
int
i;
Uint8
*buffer;
/*
Initialize SDL */
if (
SDL_Init(SDL_INIT_VIDEO) < 0 ) {
ComplainAndExit();
}
atexit(SDL_Quit);
/* Load a
BMP image into a surface */
imagebmp
= SDL_LoadBMP("image.bmp");
if (
imagebmp == NULL ) {
ComplainAndExit();
}
/* Set
the video mode (640x480 at native depth) */
screen =
SDL_SetVideoMode(640, 480, 0, SDL_HWSURFACE|SDL_FULLSCREEN);
if (
screen == NULL ) {
ComplainAndExit();
}
/* Set
the video colormap */
if (
imagebmp->format->palette != NULL ) {
SDL_SetColors(screen,
imagebmp->format->palette->colors, 0,
imagebmp->format->palette->ncolors);
}
/*
Convert the image to the video format (maps colors) */
image =
SDL_DisplayFormat(imagebmp);
SDL_FreeSurface(imagebmp);
if (
image == NULL ) {
ComplainAndExit();
}
/* Draw
bands of color on the raw surface */
if (
SDL_MUSTLOCK(screen) ) {
if ( SDL_LockSurface(screen) < 0 )
ComplainAndExit();
}
buffer=(Uint8 *)screen->pixels;
for (
i=0; ih; ++i ) {
memset(buffer,(i*255)/screen->h,
screen->w*screen->format->BytesPerPixel);
buffer
+= screen->pitch;
}
if (
SDL_MUSTLOCK(screen) ) {
SDL_UnlockSurface(screen);
}
/* Blit
the image to the center of the screen */
dstrect.x
= (screen->w-image->w)/2;
dstrect.y
= (screen->h-image->h)/2;
dstrect.w
= image->w;
dstrect.h
= image->h;
if (
SDL_BlitSurface(image, NULL, screen, &dstrect) < 0 ) {
SDL_FreeSurface(image);
ComplainAndExit();
}
SDL_FreeSurface(image);
/* Update
the screen */
SDL_UpdateRects(screen, 1, &dstrect);
SDL_Delay(5000);
/* Wait 5 seconds */
exit(0);
}
过滤和处理事件
#include <stdio.h>
#include <stdlib.h>
#include "SDL.h"
/* This function may run in a separate event thread */
int FilterEvents(const SDL_Event *event) {
static
int boycott = 1;
/* This
quit event signals the closing of the window */
if (
(event->type == SDL_QUIT) && boycott ) {
printf("Quit event filtered out -- try again.\n");
boycott = 0;
return(0);
}
if (
event->type == SDL_MOUSEMOTION ) {
printf("Mouse moved to (%d,%d)\n",
event->motion.x, event->motion.y);
return(0); /*
Drop it, we've handled it */
}
return(1);
}
int main(int argc, char *argv[])
{
SDL_Event
event;
/*
Initialize the SDL library (starts the event loop) */
if (
SDL_Init(SDL_INIT_VIDEO) < 0 ) {
fprintf(stderr,
"Couldn't initialize SDL: %s\n", SDL_GetError());
exit(1);
}
/* Clean
up on exit, exit on window close and interrupt */
atexit(SDL_Quit);
/* Ignore
key events */
SDL_EventState(SDL_KEYDOWN, SDL_IGNORE);
SDL_EventState(SDL_KEYUP, SDL_IGNORE);
/* Filter
quit and mouse motion events */
SDL_SetEventFilter(FilterEvents);
/* The
mouse isn't much use unless we have a display for reference */
if (
SDL_SetVideoMode(640, 480, 8, 0) == NULL ) {
fprintf(stderr, "Couldn't set 640x480x8 video mode: %s\n",
SDL_GetError());
exit(1);
}
/* Loop
waiting for ESC+Mouse_Button */
while (
SDL_WaitEvent(&event) >= 0 ) {
switch (event.type) {
case SDL_ACTIVEEVENT: {
if ( event.active.state & SDL_APPACTIVE ) {
if ( event.active.gain ) {
printf("App
activated\n");
} else {
printf("App iconified\n");
}
}
}
break;
case SDL_MOUSEBUTTONDOWN: {
Uint8 *keys;
keys = SDL_GetKeyState(NULL);
if ( keys[SDLK_ESCAPE] == SDL_PRESSED ) {
printf("Bye bye...\n");
exit(0);
}
printf("Mouse button pressed\n");
}
break;
case SDL_QUIT: {
printf("Quit requested, quitting.\n");
exit(0);
}
break;
}
}
/* This
should never happen */
printf("SDL_WaitEvent error: %s\n", SDL_GetError());
exit(1);
}
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