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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#include "mozilla/ArrayUtils.h" // for ArrayLength
#include "mozilla/mozalloc.h" // for operator delete, etc
#include "mozilla/MathAlgorithms.h"
#include "nsColor.h"
#include <sys/types.h> // for int32_t
#include "nsDebug.h" // for NS_ASSERTION, etc
#include "nsStaticNameTable.h"
#include "nsString.h" // for nsAutoCString, nsString, etc
#include "nscore.h" // for nsAString, etc
#include "prtypes.h" // for PR_BEGIN_MACRO, etc
using namespace mozilla;
static int ComponentValue(const char16_t* aColorSpec, int aLen, int color,
int dpc) {
int component = 0;
int index = (color * dpc);
if (2 < dpc) {
dpc = 2;
}
while (--dpc >= 0) {
char16_t ch = ((index < aLen) ? aColorSpec[index++] : '0');
if (('0' <= ch) && (ch <= '9')) {
component = (component * 16) + (ch - '0');
} else if ((('a' <= ch) && (ch <= 'f')) || (('A' <= ch) && (ch <= 'F'))) {
// "ch&7" handles lower and uppercase hex alphabetics
component = (component * 16) + (ch & 7) + 9;
} else { // not a hex digit, treat it like 0
component = (component * 16);
}
}
return component;
}
bool NS_HexToRGBA(const nsAString& aColorSpec, nsHexColorType aType,
nscolor* aResult) {
const char16_t* buffer = aColorSpec.BeginReading();
int nameLen = aColorSpec.Length();
bool hasAlpha = false;
if (nameLen != 3 && nameLen != 6) {
if ((nameLen != 4 && nameLen != 8) || aType == nsHexColorType::NoAlpha) {
// Improperly formatted color value
return false;
}
hasAlpha = true;
}
// Make sure the digits are legal
for (int i = 0; i < nameLen; i++) {
char16_t ch = buffer[i];
if (((ch >= '0') && (ch <= '9')) || ((ch >= 'a') && (ch <= 'f')) ||
((ch >= 'A') && (ch <= 'F'))) {
// Legal character
continue;
}
// Whoops. Illegal character.
return false;
}
// Convert the ascii to binary
int dpc = ((nameLen <= 4) ? 1 : 2);
// Translate components from hex to binary
int r = ComponentValue(buffer, nameLen, 0, dpc);
int g = ComponentValue(buffer, nameLen, 1, dpc);
int b = ComponentValue(buffer, nameLen, 2, dpc);
int a;
if (hasAlpha) {
a = ComponentValue(buffer, nameLen, 3, dpc);
} else {
a = (dpc == 1) ? 0xf : 0xff;
}
if (dpc == 1) {
// Scale single digit component to an 8 bit value. Replicate the
// single digit to compute the new value.
r = (r << 4) | r;
g = (g << 4) | g;
b = (b << 4) | b;
a = (a << 4) | a;
}
NS_ASSERTION((r >= 0) && (r <= 255), "bad r");
NS_ASSERTION((g >= 0) && (g <= 255), "bad g");
NS_ASSERTION((b >= 0) && (b <= 255), "bad b");
NS_ASSERTION((a >= 0) && (a <= 255), "bad a");
*aResult = NS_RGBA(r, g, b, a);
return true;
}
// This implements part of the algorithm for legacy behavior described in
bool NS_LooseHexToRGB(const nsString& aColorSpec, nscolor* aResult) {
if (aColorSpec.EqualsLiteral("transparent")) {
return false;
}
int nameLen = aColorSpec.Length();
const char16_t* colorSpec = aColorSpec.get();
if (nameLen > 128) {
nameLen = 128;
}
if ('#' == colorSpec[0]) {
++colorSpec;
--nameLen;
}
// digits per component
int dpc = (nameLen + 2) / 3;
int newdpc = dpc;
// Use only the rightmost 8 characters of each component.
if (newdpc > 8) {
nameLen -= newdpc - 8;
colorSpec += newdpc - 8;
newdpc = 8;
}
// And then keep trimming characters at the left until we'd trim one
// that would leave a nonzero value, but not past 2 characters per
// component.
while (newdpc > 2) {
bool haveNonzero = false;
for (int c = 0; c < 3; ++c) {
MOZ_ASSERT(c * dpc < nameLen,
"should not pass end of string while newdpc > 2");
char16_t ch = colorSpec[c * dpc];
if (('1' <= ch && ch <= '9') || ('A' <= ch && ch <= 'F') ||
('a' <= ch && ch <= 'f')) {
haveNonzero = true;
break;
}
}
if (haveNonzero) {
break;
}
--newdpc;
--nameLen;
++colorSpec;
}
// Translate components from hex to binary
int r = ComponentValue(colorSpec, nameLen, 0, dpc);
int g = ComponentValue(colorSpec, nameLen, 1, dpc);
int b = ComponentValue(colorSpec, nameLen, 2, dpc);
NS_ASSERTION((r >= 0) && (r <= 255), "bad r");
NS_ASSERTION((g >= 0) && (g <= 255), "bad g");
NS_ASSERTION((b >= 0) && (b <= 255), "bad b");
*aResult = NS_RGB(r, g, b);
return true;
}
// Fast approximate division by 255. It has the property that
// for all 0 <= n <= 255*255, FAST_DIVIDE_BY_255(n) == n/255.
// But it only uses two adds and two shifts instead of an
// integer division (which is expensive on many processors).
//
// equivalent to target=v/255
#define FAST_DIVIDE_BY_255(target, v) \
PR_BEGIN_MACRO \
unsigned tmp_ = v; \
target = ((tmp_ << 8) + tmp_ + 255) >> 16; \
PR_END_MACRO
// Macro to blend two colors
//
// equivalent to target = (bg*(255-fgalpha) + fg*fgalpha)/255
#define MOZ_BLEND(target, bg, fg, fgalpha) \
FAST_DIVIDE_BY_255(target, (bg) * (255 - fgalpha) + (fg) * (fgalpha))
nscolor NS_ComposeColors(nscolor aBG, nscolor aFG) {
// This function uses colors that are non premultiplied alpha.
int r, g, b, a;
int bgAlpha = NS_GET_A(aBG);
int fgAlpha = NS_GET_A(aFG);
// Compute the final alpha of the blended color
// a = fgAlpha + bgAlpha*(255 - fgAlpha)/255;
FAST_DIVIDE_BY_255(a, bgAlpha * (255 - fgAlpha));
a = fgAlpha + a;
int blendAlpha;
if (a == 0) {
// In this case the blended color is totally trasparent,
// we preserve the color information of the foreground color.
blendAlpha = 255;
} else {
blendAlpha = (fgAlpha * 255) / a;
}
MOZ_BLEND(r, NS_GET_R(aBG), NS_GET_R(aFG), blendAlpha);
MOZ_BLEND(g, NS_GET_G(aBG), NS_GET_G(aFG), blendAlpha);
MOZ_BLEND(b, NS_GET_B(aBG), NS_GET_B(aFG), blendAlpha);
return NS_RGBA(r, g, b, a);
}