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Add the blend method to wesmage.

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Also used the opportunity to better document the blend_surface function.
This commit is contained in:
Mark de Wever 2012-03-25 15:23:28 +00:00
parent 81636a48db
commit 6cdad25548
2 changed files with 56 additions and 1 deletions
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24
src/sdl_utils.hpp
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@ -287,7 +287,29 @@ surface blur_alpha_surface(const surface &surf, int depth = 1, bool optimize=tru
/** Cuts a rectangle from a surface. */
surface cut_surface(const surface &surf, SDL_Rect const &r);
surface blend_surface(const surface &surf, double amount, Uint32 color, bool optimize=true);
/**
* Blends a surface with a colour.
*
* Every pixel in the surface will be blended with the @p color given. The
* final colour of a pixel is amount * @p color + (1 - amount) * original.
*
* @param surf The surface to blend.
* @param amount The amount of the new colour is determined by
* @p color. Must be a number in the range
* [0, 1].
* @param color The colour to blend width, note its alpha
* channel is ignored.
* @param optimize Should the return surface be RLE optimized.
*
* @return The blended surface.
*/
surface blend_surface(
const surface &surf
, double amount
, Uint32 color
, bool optimize = true);
surface flip_surface(const surface &surf, bool optimize=true);
surface flop_surface(const surface &surf, bool optimize=true);
surface create_compatible_surface(const surface &surf, int width = -1, int height = -1);

33
src/wesmage/filter.cpp
View file

@ -153,6 +153,39 @@ REGISTER(brighten,
"colour channel is multiplied by this value. Value less than zero "
"are set to zero. The alpha channel is not modified.");
static void
blend(surface& surf, const std::string& parameters)
{
float amount;
unsigned colour;
const int count = sscanf(parameters.c_str(), "%f,%x", &amount, &colour);
if(count != 2) {
std::cerr << "Error: Arguments to blend »"
<< parameters
<< "« are not compatible.\n";
throw texit(EXIT_FAILURE);
}
surf = blend_surface(surf, amount, colour);
}
REGISTER(blend,
"|Blends an image with another colour."
"|amount"
"|float"
"|The amount every pixel needs to be blended with its original value. "
"The formula is:\n"
"result = amount * colour + (1 - amount) * original\n"
"The value needs to be in the range [0, 1]."
"|colour"
"|unsigned"
"|The colour to blend with. The value should be given as 32-bit "
"hexadecimal value. The first fields should look like AARRGGBB, "
"where AA is the alpha channel, RR is the red channel, GG is the "
"green channel and BB is the blue channel. (Note the alpha channel "
"is ignored.");
void
filter_apply(surface& surf, const std::string& filter)
{