notgne2/tuxpaint-pencil-sharpener
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XOR in a purpose-made funtion

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This commit is contained in:
Albert Cahalan 2005-01-09 03:54:39 +00:00
parent 6360e4fec9
commit 790cfbb837
1 changed files with 42 additions and 27 deletions
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69
src/tuxpaint.c
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@ -8985,7 +8985,6 @@ static SDL_Surface * thumbnail(SDL_Surface * src, int max_x, int max_y,
/* Get a pixel: */
static Uint32 getpixel(SDL_Surface * surface, int x, int y)
{
Uint8 * p;
@ -9034,7 +9033,6 @@ static Uint32 getpixel(SDL_Surface * surface, int x, int y)
/* Draw a single pixel into the surface: */
static void putpixel(SDL_Surface * surface, int x, int y, Uint32 pixel)
{
Uint8 * p;
@ -9042,7 +9040,6 @@ static void putpixel(SDL_Surface * surface, int x, int y, Uint32 pixel)
int BytesPerPixel = surface->format->BytesPerPixel;
/* Assuming the X/Y values are within the bounds of this surface... */
if (likely( likely((unsigned)x<(unsigned)surface->w) && likely((unsigned)y<(unsigned)surface->h) ))
{
// Set a pointer to the exact location in memory of the pixel
@ -9079,8 +9076,43 @@ static void putpixel(SDL_Surface * surface, int x, int y, Uint32 pixel)
}
/* Should really clip at the line level, but oh well... */
// XOR must show up on black, white, 0x7f grey, and 0x80 grey.
// XOR must be exactly 100% perfectly reversable.
static void xorpixel(int x, int y)
{
// if outside the canvas, return
if( (unsigned)x >= (unsigned)canvas->w || (unsigned)y >= (unsigned)canvas->h)
return;
// now switch to screen coordinates
x += r_canvas.x;
y += r_canvas.y;
Uint8 * p;
// Always 4, except 3 when loading a saved image.
int BytesPerPixel = screen->format->BytesPerPixel;
// Set a pointer to the exact location in memory of the pixel
p = (Uint8 *) (((Uint8 *)screen->pixels) + /* Start: beginning of RAM */
(y * screen->pitch) + /* Go down Y lines */
(x * BytesPerPixel)); /* Go in X pixels */
// XOR the (correctly-sized) piece of data in the screen's RAM
if (likely(BytesPerPixel == 4))
*(Uint32 *)p ^= 0x80808080u; // 32-bit display
else if (BytesPerPixel == 1)
*p ^= 0x80;
else if (BytesPerPixel == 2)
*(Uint16 *)p ^= 0xd6d6;
else if (BytesPerPixel == 3)
{
p[0] ^= 0x80;
p[1] ^= 0x80;
p[2] ^= 0x80;
}
}
/* Should really clip at the line level, but oh well... */
static void clipped_putpixel(SDL_Surface * dest, int x, int y, Uint32 c)
{
if (x >= 96 && x < (WINDOW_WIDTH - 96) &&
@ -9345,12 +9377,7 @@ static void line_xor(int x1, int y1, int x2, int y2)
{
num_drawn++;
if (num_drawn < 10 || dont_do_xor == 0)
{
// must show up on black, white, 0x7f grey, and 0x80 grey
// must be exactly 100% perfect reversable
clipped_putpixel(screen, x1 + 96, y,
0x80808080 ^ getpixel(screen, x1 + 96, y));
}
xorpixel(x1,y);
}
x1 = x1 + dx;
@ -9365,12 +9392,7 @@ static void line_xor(int x1, int y1, int x2, int y2)
num_drawn++;
if (num_drawn < 10 || dont_do_xor == 0)
{
// must show up on black, white, 0x7f grey, and 0x80 grey
// must be exactly 100% perfect reversable
clipped_putpixel(screen, x1 + 96, y,
0x80808080 ^ getpixel(screen, x1 + 96, y));
}
xorpixel(x1,y);
}
}
else
@ -9380,12 +9402,7 @@ static void line_xor(int x1, int y1, int x2, int y2)
num_drawn++;
if (num_drawn < 10 || dont_do_xor == 0)
{
// must show up on black, white, 0x7f grey, and 0x80 grey
// must be exactly 100% perfect reversable
clipped_putpixel(screen, x1 + 96, y,
0x80808080 ^ getpixel(screen, x1 + 96, y));
}
xorpixel(x1,y);
}
}
}
@ -13713,13 +13730,11 @@ static void stamp_xor(int x, int y)
{
if(!stamp_outline_data[xx + yy*stamp_outline_w])
continue;
sx = 96 + x + xx - stamp_outline_w/2;
sy = y + yy - stamp_outline_h/2;
sx = x + xx - stamp_outline_w/2;
sy = y + yy - stamp_outline_h/2;
if (stiple[sx%STIPLE_W + sy%STIPLE_H * STIPLE_W] != '8')
continue;
// must show up on black, white, 0x7f grey, and 0x80 grey
// must be exactly 100% perfect reversable
clipped_putpixel(screen, sx, sy, 0x80808080 ^ getpixel(screen, sx, sy));
xorpixel(sx, sy);
}
}
SDL_UnlockSurface(screen);