Mercurial > sdl-ios-xcode
view test/testalpha.c @ 615:7ec821f3cbd0
Date: Thu, 17 Apr 2003 23:27:34 -0400
From: Darrell Walisser
Subject: Yet another OS X cursor bug
The synopsis:
1. Call SDL_ShowCursor(0);
2. Call SDL_SetVideoMode();
3. Call SDL_GetEvent();
3. Call SDL_ShowCursor(1);
The result: Sometimes the cursor doesn't come back! Ack! Oddly enough,
it does come back when mousing over the dock or clicking in the menu
bar. But that's besides the point.
The reason why this is happening is a flaw in the handling of
activation/deactivation events. The short explanation is that the
HideCursor() and ShowCursor() calls must be balanced, but if the cursor
was initially hidden, HideCursor() was called again on the activate
event - so now the next ShowCursor() fails (as does the next, and the
next, for some reason).
So, here's the patch. All it does is keep track of the
HideCursor()/ShowCursor() calls so that they will always be balanced.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Sun, 20 Apr 2003 05:41:16 +0000 |
parents | 74212992fb08 |
children | 609543e2b3a1 |
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/* Simple program: Fill a colormap with gray and stripe it down the screen, Then move an alpha valued sprite around the screen. */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <math.h> #include "SDL.h" #define FRAME_TICKS (1000/30) /* 30 frames/second */ /* Create a "light" -- a yellowish surface with variable alpha */ SDL_Surface *CreateLight(SDL_Surface *screen, int radius) { Uint8 trans, alphamask; int range, addition; int xdist, ydist; Uint16 x, y; Uint16 skip; Uint32 pixel; SDL_Surface *light; #ifdef LIGHT_16BIT Uint16 *buf; /* Create a 16 (4/4/4/4) bpp square with a full 4-bit alpha channel */ /* Note: this isn't any faster than a 32 bit alpha surface */ alphamask = 0x0000000F; light = SDL_CreateRGBSurface(SDL_SWSURFACE, 2*radius, 2*radius, 16, 0x0000F000, 0x00000F00, 0x000000F0, alphamask); #else Uint32 *buf; /* Create a 32 (8/8/8/8) bpp square with a full 8-bit alpha channel */ alphamask = 0x000000FF; light = SDL_CreateRGBSurface(SDL_SWSURFACE, 2*radius, 2*radius, 32, 0xFF000000, 0x00FF0000, 0x0000FF00, alphamask); if ( light == NULL ) { fprintf(stderr, "Couldn't create light: %s\n", SDL_GetError()); return(NULL); } #endif /* Fill with a light yellow-orange color */ skip = light->pitch-(light->w*light->format->BytesPerPixel); #ifdef LIGHT_16BIT buf = (Uint16 *)light->pixels; #else buf = (Uint32 *)light->pixels; #endif /* Get a tranparent pixel value - we'll add alpha later */ pixel = SDL_MapRGBA(light->format, 0xFF, 0xDD, 0x88, 0); for ( y=0; y<light->h; ++y ) { for ( x=0; x<light->w; ++x ) { *buf++ = pixel; } buf += skip; /* Almost always 0, but just in case... */ } /* Calculate alpha values for the surface. */ #ifdef LIGHT_16BIT buf = (Uint16 *)light->pixels; #else buf = (Uint32 *)light->pixels; #endif for ( y=0; y<light->h; ++y ) { for ( x=0; x<light->w; ++x ) { /* Slow distance formula (from center of light) */ xdist = x-(light->w/2); ydist = y-(light->h/2); range = (int)sqrt(xdist*xdist+ydist*ydist); /* Scale distance to range of transparency (0-255) */ if ( range > radius ) { trans = alphamask; } else { /* Increasing transparency with distance */ trans = (Uint8)((range*alphamask)/radius); /* Lights are very transparent */ addition = (alphamask+1)/8; if ( (int)trans+addition > alphamask ) { trans = alphamask; } else { trans += addition; } } /* We set the alpha component as the right N bits */ *buf++ |= (255-trans); } buf += skip; /* Almost always 0, but just in case... */ } /* Enable RLE acceleration of this alpha surface */ SDL_SetAlpha(light, SDL_SRCALPHA|SDL_RLEACCEL, 0); /* We're done! */ return(light); } static Uint32 flashes = 0; static Uint32 flashtime = 0; void FlashLight(SDL_Surface *screen, SDL_Surface *light, int x, int y) { SDL_Rect position; Uint32 ticks1; Uint32 ticks2; /* Easy, center light */ position.x = x-(light->w/2); position.y = y-(light->h/2); position.w = light->w; position.h = light->h; ticks1 = SDL_GetTicks(); SDL_BlitSurface(light, NULL, screen, &position); ticks2 = SDL_GetTicks(); SDL_UpdateRects(screen, 1, &position); ++flashes; /* Update time spend doing alpha blitting */ flashtime += (ticks2-ticks1); } static int sprite_visible = 0; static SDL_Surface *sprite; static SDL_Surface *backing; static SDL_Rect position; static int x_vel, y_vel; static int alpha_vel; int LoadSprite(SDL_Surface *screen, char *file) { SDL_Surface *converted; /* Load the sprite image */ sprite = SDL_LoadBMP(file); if ( sprite == NULL ) { fprintf(stderr, "Couldn't load %s: %s", file, SDL_GetError()); return(-1); } /* Set transparent pixel as the pixel at (0,0) */ if ( sprite->format->palette ) { SDL_SetColorKey(sprite, SDL_SRCCOLORKEY, *(Uint8 *)sprite->pixels); } /* Convert sprite to video format */ converted = SDL_DisplayFormat(sprite); SDL_FreeSurface(sprite); if ( converted == NULL ) { fprintf(stderr, "Couldn't convert background: %s\n", SDL_GetError()); return(-1); } sprite = converted; /* Create the background */ backing = SDL_CreateRGBSurface(SDL_SWSURFACE, sprite->w, sprite->h, 8, 0, 0, 0, 0); if ( backing == NULL ) { fprintf(stderr, "Couldn't create background: %s\n", SDL_GetError()); SDL_FreeSurface(sprite); return(-1); } /* Convert background to video format */ converted = SDL_DisplayFormat(backing); SDL_FreeSurface(backing); if ( converted == NULL ) { fprintf(stderr, "Couldn't convert background: %s\n", SDL_GetError()); SDL_FreeSurface(sprite); return(-1); } backing = converted; /* Set the initial position of the sprite */ position.x = (screen->w-sprite->w)/2; position.y = (screen->h-sprite->h)/2; position.w = sprite->w; position.h = sprite->h; x_vel = 0; y_vel = 0; alpha_vel = 1; /* We're ready to roll. :) */ return(0); } void AttractSprite(Uint16 x, Uint16 y) { x_vel = ((int)x-position.x)/10; y_vel = ((int)y-position.y)/10; } void MoveSprite(SDL_Surface *screen, SDL_Surface *light) { SDL_Rect updates[2]; int alpha; /* Erase the sprite if it was visible */ if ( sprite_visible ) { updates[0] = position; SDL_BlitSurface(backing, NULL, screen, &updates[0]); } else { updates[0].x = 0; updates[0].y = 0; updates[0].w = 0; updates[0].h = 0; sprite_visible = 1; } /* Since the sprite is off the screen, we can do other drawing without being overwritten by the saved area behind the sprite. */ if ( light != NULL ) { int x, y; SDL_GetMouseState(&x, &y); FlashLight(screen, light, x, y); } /* Move the sprite, bounce at the wall */ position.x += x_vel; if ( (position.x < 0) || (position.x >= screen->w) ) { x_vel = -x_vel; position.x += x_vel; } position.y += y_vel; if ( (position.y < 0) || (position.y >= screen->h) ) { y_vel = -y_vel; position.y += y_vel; } /* Update transparency (fade in and out) */ alpha = sprite->format->alpha; if ( (alpha+alpha_vel) < 0 ) { alpha_vel = -alpha_vel; } else if ( (alpha+alpha_vel) > 255 ) { alpha_vel = -alpha_vel; } SDL_SetAlpha(sprite, SDL_SRCALPHA, (Uint8)(alpha+alpha_vel)); /* Save the area behind the sprite */ updates[1] = position; SDL_BlitSurface(screen, &updates[1], backing, NULL); /* Blit the sprite onto the screen */ updates[1] = position; SDL_BlitSurface(sprite, NULL, screen, &updates[1]); /* Make it so! */ SDL_UpdateRects(screen, 2, updates); } void WarpSprite(SDL_Surface *screen, int x, int y) { SDL_Rect updates[2]; /* Erase, move, Draw, update */ updates[0] = position; SDL_BlitSurface(backing, NULL, screen, &updates[0]); position.x = x-sprite->w/2; /* Center about X */ position.y = y-sprite->h/2; /* Center about Y */ updates[1] = position; SDL_BlitSurface(screen, &updates[1], backing, NULL); updates[1] = position; SDL_BlitSurface(sprite, NULL, screen, &updates[1]); SDL_UpdateRects(screen, 2, updates); } int main(int argc, char *argv[]) { const SDL_VideoInfo *info; SDL_Surface *screen; Uint8 video_bpp; Uint32 videoflags; Uint8 *buffer; int i, done; SDL_Event event; SDL_Surface *light; int mouse_pressed; Uint32 ticks, lastticks; /* Initialize SDL */ if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) { fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError()); exit(1); } atexit(SDL_Quit); /* Alpha blending doesn't work well at 8-bit color */ info = SDL_GetVideoInfo(); if ( info->vfmt->BitsPerPixel > 8 ) { video_bpp = info->vfmt->BitsPerPixel; } else { video_bpp = 16; } videoflags = SDL_SWSURFACE; while ( argc > 1 ) { --argc; if ( strcmp(argv[argc-1], "-bpp") == 0 ) { video_bpp = atoi(argv[argc]); --argc; } else if ( strcmp(argv[argc], "-hw") == 0 ) { videoflags |= SDL_HWSURFACE; } else if ( strcmp(argv[argc], "-warp") == 0 ) { videoflags |= SDL_HWPALETTE; } else if ( strcmp(argv[argc], "-fullscreen") == 0 ) { videoflags |= SDL_FULLSCREEN; } else { fprintf(stderr, "Usage: %s [-bpp N] [-warp] [-hw] [-fullscreen]\n", argv[0]); exit(1); } } /* Set 640x480 video mode */ if ( (screen=SDL_SetVideoMode(640,480,video_bpp,videoflags)) == NULL ) { fprintf(stderr, "Couldn't set 640x480x%d video mode: %s\n", video_bpp, SDL_GetError()); exit(2); } /* Set the surface pixels and refresh! */ if ( SDL_LockSurface(screen) < 0 ) { fprintf(stderr, "Couldn't lock the display surface: %s\n", SDL_GetError()); exit(2); } buffer=(Uint8 *)screen->pixels; for ( i=0; i<screen->h; ++i ) { memset(buffer,(i*255)/screen->h, screen->pitch); buffer += screen->pitch; } SDL_UnlockSurface(screen); SDL_UpdateRect(screen, 0, 0, 0, 0); /* Create the light */ light = CreateLight(screen, 82); if ( light == NULL ) { exit(1); } /* Load the sprite */ if ( LoadSprite(screen, "icon.bmp") < 0 ) { SDL_FreeSurface(light); exit(1); } /* Set a clipping rectangle to clip the outside edge of the screen */ { SDL_Rect clip; clip.x = 32; clip.y = 32; clip.w = screen->w-(2*32); clip.h = screen->h-(2*32); SDL_SetClipRect(screen, &clip); } /* Wait for a keystroke */ lastticks = SDL_GetTicks(); done = 0; mouse_pressed = 0; while ( !done ) { /* Update the frame -- move the sprite */ if ( mouse_pressed ) { MoveSprite(screen, light); mouse_pressed = 0; } else { MoveSprite(screen, NULL); } /* Slow down the loop to 30 frames/second */ ticks = SDL_GetTicks(); if ( (ticks-lastticks) < FRAME_TICKS ) { #ifdef CHECK_SLEEP_GRANULARITY fprintf(stderr, "Sleeping %d ticks\n", FRAME_TICKS-(ticks-lastticks)); #endif SDL_Delay(FRAME_TICKS-(ticks-lastticks)); #ifdef CHECK_SLEEP_GRANULARITY fprintf(stderr, "Slept %d ticks\n", (SDL_GetTicks()-ticks)); #endif } lastticks = ticks; /* Check for events */ while ( SDL_PollEvent(&event) ) { switch (event.type) { /* Attract sprite while mouse is held down */ case SDL_MOUSEMOTION: if (event.motion.state != 0) { AttractSprite(event.motion.x, event.motion.y); mouse_pressed = 1; } break; case SDL_MOUSEBUTTONDOWN: if ( event.button.button == 1 ) { AttractSprite(event.button.x, event.button.y); mouse_pressed = 1; } else { SDL_Rect area; area.x = event.button.x-16; area.y = event.button.y-16; area.w = 32; area.h = 32; SDL_FillRect(screen, &area, 0); SDL_UpdateRects(screen,1,&area); } break; case SDL_KEYDOWN: /* Any keypress quits the app... */ case SDL_QUIT: done = 1; break; default: break; } } } SDL_FreeSurface(light); SDL_FreeSurface(sprite); SDL_FreeSurface(backing); /* Print out some timing information */ if ( flashes > 0 ) { printf("%d alpha blits, ~%4.4f ms per blit\n", flashes, (float)flashtime/flashes); } return(0); }