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Better fix to set the palette opaque, when there is also a colorkey

(see bug 3827)
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1bsyl committed Feb 24, 2020
1 parent e3b0713 commit e2b132ca747cbb23b1eb863b8458be7e573877d5
Showing with 45 additions and 91 deletions.
  1. +45 −91 src/video/SDL_surface.c
@@ -402,64 +402,6 @@ SDL_ConvertColorkeyToAlpha(SDL_Surface * surface, SDL_bool ignore_alpha)
SDL_SetSurfaceBlendMode(surface, SDL_BLENDMODE_BLEND);
}


static void
SDL_ConvertSetOpaque(SDL_Surface * surface)
{
int x, y;

if (!surface) {
return;
}

if (!surface->format->Amask) {
return;
}

SDL_LockSurface(surface);

switch (surface->format->BytesPerPixel) {
case 2:
{
Uint16 *row, *spot;
Uint16 mask = (Uint16) (surface->format->Amask);

row = (Uint16 *) surface->pixels;
for (y = surface->h; y--;) {
spot = row;
for (x = surface->w; x--;) {
*spot |= mask;
++spot;
}
row += surface->pitch / 2;
}
}
break;
case 3:
/* FIXME */
break;
case 4:
{
Uint32 *row, *spot;
Uint32 mask = surface->format->Amask;

row = (Uint32 *) surface->pixels;
for (y = surface->h; y--;) {
spot = row;
for (x = surface->w; x--;) {
*spot |= mask;
++spot;
}
row += surface->pitch / 4;
}
}
break;
}

SDL_UnlockSurface(surface);
}


int
SDL_SetSurfaceColorMod(SDL_Surface * surface, Uint8 r, Uint8 g, Uint8 b)
{
@@ -1023,6 +965,7 @@ SDL_ConvertSurface(SDL_Surface * surface, const SDL_PixelFormat * format,
SDL_bool palette_ck_transform = SDL_FALSE;
int palette_ck_value = 0;
SDL_bool palette_has_alpha = SDL_FALSE;
Uint8 *palette_saved_alpha = NULL;

if (!surface) {
SDL_InvalidParamError("surface");
@@ -1084,6 +1027,40 @@ SDL_ConvertSurface(SDL_Surface * surface, const SDL_PixelFormat * format,
bounds.w = surface->w;
bounds.h = surface->h;

/* Source surface has a palette with no real alpha (0 or OPAQUE).
* Destination format has alpha.
* -> set alpha channel to be opaque */
if (surface->format->palette && format->Amask) {
SDL_bool set_opaque = SDL_FALSE;
{
int i;
for (i = 0; i < surface->format->palette->ncolors; i++) {
Uint8 alpha_value = surface->format->palette->colors[i].a;

if (alpha_value != 0 && alpha_value != SDL_ALPHA_OPAQUE) {
/* Palette has at least one alpha value. Don't do anything */
set_opaque = SDL_FALSE;
palette_has_alpha = SDL_TRUE;
break;
}

if (alpha_value == 0) {
set_opaque = SDL_TRUE;
}
}
}

/* Set opaque and backup palette alpha values */
if (set_opaque) {
palette_saved_alpha = SDL_stack_alloc(Uint8, surface->format->palette->ncolors);
int i;
for (i = 0; i < surface->format->palette->ncolors; i++) {
palette_saved_alpha[i] = surface->format->palette->colors[i].a;
surface->format->palette->colors[i].a = SDL_ALPHA_OPAQUE;
}
}
}

/* Transform colorkey to alpha. for cases where source palette has duplicate values, and colorkey is one of them */
if (copy_flags & SDL_COPY_COLORKEY) {
if (surface->format->palette && !format->palette) {
@@ -1096,11 +1073,20 @@ SDL_ConvertSurface(SDL_Surface * surface, const SDL_PixelFormat * format,

ret = SDL_LowerBlit(surface, &bounds, convert, &bounds);

/* Restore value */
/* Restore colorkey alpha value */
if (palette_ck_transform) {
surface->format->palette->colors[surface->map->info.colorkey].a = palette_ck_value;
}

/* Restore palette alpha values */
if (palette_saved_alpha) {
int i;
for (i = 0; i < surface->format->palette->ncolors; i++) {
surface->format->palette->colors[i].a = palette_saved_alpha[i];
}
SDL_stack_free(palette_saved_alpha);
}

/* Clean up the original surface, and update converted surface */
convert->map->info.r = copy_color.r;
convert->map->info.g = copy_color.g;
@@ -1181,38 +1167,6 @@ SDL_ConvertSurface(SDL_Surface * surface, const SDL_PixelFormat * format,
}
SDL_SetClipRect(convert, &surface->clip_rect);

/* Source surface has a palette with alpha. Will need blend mode */
if (palette_has_alpha == SDL_FALSE && surface->format->palette) {
int i;
for (i = 0; i < surface->format->palette->ncolors; i++) {
Uint8 alpha_value = surface->format->palette->colors[i].a;
if (alpha_value != 0 && alpha_value != SDL_ALPHA_OPAQUE) {
palette_has_alpha = SDL_TRUE;
break;
}
}
}

/* Source surface has a palette with no alpha nor colorkey.
* Destination format has alpha.
* We may need to set the alpha channel to opaque. */
if (surface->format->palette && format->Amask && palette_has_alpha == SDL_FALSE) {
SDL_bool need_opaque = SDL_FALSE;
int i;
for (i = 0; i < surface->format->palette->ncolors; i++) {
Uint8 alpha_value = surface->format->palette->colors[i].a;
if (alpha_value == 0) {
need_opaque = SDL_TRUE;
break;
}
}

if (need_opaque) {
SDL_ConvertSetOpaque(convert);
}
}


/* Enable alpha blending by default if the new surface has an
* alpha channel or alpha modulation */
if ((surface->format->Amask && format->Amask) ||

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