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Fix RGBGFX to support -C/--color-curve in -r/--reverse mode (#2110)

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Clarifies error message when RGBGFX reverse mode has `-c` mismatching `-p`.
This commit is contained in:
Rangi
2026-09-18 17:35:22 -04:00
committed by GitHub
parent 0286d4119e
commit 89403ca23b
9 changed files with 75 additions and 39 deletions
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include/gfx/rgba.hpp
+9 -19
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@@ -20,23 +20,6 @@ struct Rgba {
explicit constexpr Rgba(uint32_t rgba = 0)
: red(rgba >> 24), green(rgba >> 16), blue(rgba >> 8), alpha(rgba) {}
// CGB colors are RGB555, so we use bit 15 to signify that the color is transparent instead
// Since the rest of the bits don't matter then, we return 0x8000 (1 << 15) exactly.
static constexpr uint16_t transparent = 0b1'00000'00000'00000;
static constexpr Rgba fromCGBColor(uint16_t color) {
constexpr auto _5to8 = [](uint8_t channel) -> uint8_t {
channel &= 0b11111; // For caller's convenience
return channel << 3 | channel >> 2;
};
return {
_5to8(color),
_5to8(color >> 5),
_5to8(color >> 10),
static_cast<uint8_t>(color & transparent ? 0x00 : 0xFF),
};
}
// Returns this RGBA as a 32-bit number that can be printed in hex (`#%08x`)
// to yield its CSS representation (`#rrggbbaa`).
uint32_t toCSS() const {
@@ -45,15 +28,22 @@ struct Rgba {
};
return shl(red, 24) | shl(green, 16) | shl(blue, 8) | shl(alpha, 0);
}
bool operator==(Rgba const &rhs) const { return toCSS() == rhs.toCSS(); }
// We allow some leeway to consider colors as transparent or opaque,
// but intermediate alpha values are still ambiguous.
static constexpr uint8_t transparency_threshold = 0x10;
bool isTransparent() const { return alpha < transparency_threshold; }
static constexpr uint8_t opacity_threshold = 0xF0;
bool isOpaque() const { return alpha >= opacity_threshold; }
bool isAmbiguous() const { return isTransparent() == isOpaque(); }
// Computes the equivalent CGB color, respects the color curve depending on options
// CGB colors are RGB555, so we use bit 15 to signify that the color is transparent instead
// Since the rest of the bits don't matter then, we return 0x8000 (1 << 15) exactly.
static constexpr uint16_t transparent = 0b1'00000'00000'00000;
// Computes the equivalent RGB888 color; respects the color curve depending on argument
static Rgba fromCGBColor(uint16_t color, bool useColorCurve);
// Computes the equivalent RGB555 color; respects the color curve depending on options
uint16_t cgbColor() const;
bool isGray() const { return red == green && green == blue; }