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Unified Diff: app/gfx/color_utils.cc

Issue 215049: Reorder the color_utils functions in preparation for adding more:... (Closed) Base URL: svn://chrome-svn/chrome/trunk/src/
Patch Set: Created 11 years, 3 months ago
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Index: app/gfx/color_utils.cc
===================================================================
--- app/gfx/color_utils.cc (revision 26699)
+++ app/gfx/color_utils.cc (working copy)
@@ -1,4 +1,4 @@
-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
@@ -19,18 +19,23 @@
namespace color_utils {
+// Helper functions -----------------------------------------------------------
+
+namespace {
+
// These transformations are based on the equations in:
// http://en.wikipedia.org/wiki/Lab_color
-// http://en.wikipedia.org/wiki/SRGB_color_space#Specification_of_the_transformation
+// http://en.wikipedia.org/wiki/SRGB_color_space#
brettw 2009/09/22 16:40:51 I would have kept this link as-is, since now nobod
+// Specification_of_the_transformation
// See also:
// http://www.brucelindbloom.com/index.html?ColorCalculator.html
-static const double kCIEConversionAlpha = 0.055;
-static const double kCIEConversionGamma = 2.2;
-static const double kE = 0.008856;
-static const double kK = 903.3;
+const double kCIEConversionAlpha = 0.055;
+const double kCIEConversionGamma = 2.2;
+const double kE = 0.008856;
+const double kK = 903.3;
-static double CIEConvertNonLinear(uint8 color_component) {
+double CIEConvertNonLinear(uint8 color_component) {
double color_component_d = static_cast<double>(color_component) / 255.0;
if (color_component_d > 0.04045) {
double base = (color_component_d + kCIEConversionAlpha) /
@@ -41,46 +46,7 @@
}
}
-// Note: this works only for sRGB.
-void SkColorToCIEXYZ(SkColor c, CIE_XYZ* xyz) {
- uint8 r = SkColorGetR(c);
- uint8 g = SkColorGetG(c);
- uint8 b = SkColorGetB(c);
-
- xyz->X =
- 0.4124 * CIEConvertNonLinear(r) +
- 0.3576 * CIEConvertNonLinear(g) +
- 0.1805 * CIEConvertNonLinear(b);
- xyz->Y =
- 0.2126 * CIEConvertNonLinear(r) +
- 0.7152 * CIEConvertNonLinear(g) +
- 0.0722 * CIEConvertNonLinear(g);
- xyz->Z =
- 0.0193 * CIEConvertNonLinear(r) +
- 0.1192 * CIEConvertNonLinear(g) +
- 0.9505 * CIEConvertNonLinear(b);
-}
-
-static double LabConvertNonLinear(double value) {
- if (value > 0.008856) {
- double goat = pow(value, static_cast<double>(1) / 3);
- return goat;
- }
- return (kK * value + 16) / 116;
-}
-
-void CIEXYZToLabColor(const CIE_XYZ& xyz, LabColor* lab) {
- CIE_XYZ white_xyz;
- SkColorToCIEXYZ(SkColorSetRGB(255, 255, 255), &white_xyz);
- double fx = LabConvertNonLinear(xyz.X / white_xyz.X);
- double fy = LabConvertNonLinear(xyz.Y / white_xyz.Y);
- double fz = LabConvertNonLinear(xyz.Z / white_xyz.Z);
- lab->L = static_cast<int>(116 * fy) - 16;
- lab->a = static_cast<int>(500 * (fx - fy));
- lab->b = static_cast<int>(200 * (fy - fz));
-}
-
-static uint8 sRGBColorComponentFromLinearComponent(double component) {
+uint8 sRGBColorComponentFromLinearComponent(double component) {
double result;
if (component <= 0.0031308) {
result = 12.92 * component;
@@ -92,34 +58,32 @@
return std::min(static_cast<uint8>(255), static_cast<uint8>(result * 255));
}
-SkColor CIEXYZToSkColor(SkAlpha alpha, const CIE_XYZ& xyz) {
- double r_linear = 3.2410 * xyz.X - 1.5374 * xyz.Y - 0.4986 * xyz.Z;
- double g_linear = -0.9692 * xyz.X + 1.8760 * xyz.Y + 0.0416 * xyz.Z;
- double b_linear = 0.0556 * xyz.X - 0.2040 * xyz.Y + 1.0570 * xyz.Z;
- uint8 r = sRGBColorComponentFromLinearComponent(r_linear);
- uint8 g = sRGBColorComponentFromLinearComponent(g_linear);
- uint8 b = sRGBColorComponentFromLinearComponent(b_linear);
- return SkColorSetARGB(alpha, r, g, b);
+double LabConvertNonLinear(double value) {
+ if (value > 0.008856) {
+ double goat = pow(value, static_cast<double>(1) / 3);
+ return goat;
+ }
+ return (kK * value + 16) / 116;
}
-static double gen_yr(const LabColor& lab) {
+double gen_yr(const LabColor& lab) {
if (lab.L > (kE * kK))
return pow((lab.L + 16.0) / 116, 3.0);
return static_cast<double>(lab.L) / kK;
}
-static double fy(const LabColor& lab) {
+double fy(const LabColor& lab) {
double yr = gen_yr(lab);
if (yr > kE)
return (lab.L + 16.0) / 116;
return (kK * yr + 16.0) / 116;
}
-static double fx(const LabColor& lab) {
+double fx(const LabColor& lab) {
return (static_cast<double>(lab.a) / 500) + fy(lab);
}
-static double gen_xr(const LabColor& lab) {
+double gen_xr(const LabColor& lab) {
double x = fx(lab);
double x_cubed = pow(x, 3.0);
if (x_cubed > kE)
@@ -127,11 +91,11 @@
return (116.0 * x - 16.0) / kK;
}
-static double fz(const LabColor& lab) {
+double fz(const LabColor& lab) {
return fy(lab) - (static_cast<double>(lab.b) / 200);
}
-static double gen_zr(const LabColor& lab) {
+double gen_zr(const LabColor& lab) {
double z = fz(lab);
double z_cubed = pow(z, 3.0);
if (z_cubed > kE)
@@ -139,19 +103,76 @@
return (116.0 * z - 16.0) / kK;
}
-void LabColorToCIEXYZ(const LabColor& lab, CIE_XYZ* xyz) {
- CIE_XYZ result;
+int GetLumaForColor(SkColor* color) {
+ int r = SkColorGetR(*color);
+ int g = SkColorGetG(*color);
+ int b = SkColorGetB(*color);
- CIE_XYZ white_xyz;
- SkColorToCIEXYZ(SkColorSetRGB(255, 255, 255), &white_xyz);
+ int luma = static_cast<int>(0.3*r + 0.59*g + 0.11*b);
+ if (luma < 0)
+ luma = 0;
+ else if (luma > 255)
+ luma = 255;
- result.X = gen_xr(lab) * white_xyz.X;
- result.Y = gen_yr(lab) * white_xyz.Y;
- result.Z = gen_zr(lab) * white_xyz.Z;
+ return luma;
+}
- *xyz = result;
+// Next three functions' formulas from:
+// http://www.w3.org/TR/WCAG20/#relativeluminancedef
+// http://www.w3.org/TR/WCAG20/#contrast-ratiodef
+
+double ConvertSRGB(double eight_bit_component) {
+ const double component = eight_bit_component / 255.0;
+ return (component <= 0.03928) ?
+ (component / 12.92) : pow((component + 0.055) / 1.055, 2.4);
}
+double RelativeLuminance(SkColor color) {
+ return (0.2126 * ConvertSRGB(SkColorGetR(color))) +
+ (0.7152 * ConvertSRGB(SkColorGetG(color))) +
+ (0.0722 * ConvertSRGB(SkColorGetB(color)));
+}
+
+double ContrastRatio(SkColor color1, SkColor color2) {
+ const double l1 = RelativeLuminance(color1) + 0.05;
+ const double l2 = RelativeLuminance(color2) + 0.05;
+ return (l1 > l2) ? (l1 / l2) : (l2 / l1);
+}
+
+} // namespace
+
+// ----------------------------------------------------------------------------
+
+// Note: this works only for sRGB.
+void SkColorToCIEXYZ(SkColor c, CIE_XYZ* xyz) {
+ uint8 r = SkColorGetR(c);
+ uint8 g = SkColorGetG(c);
+ uint8 b = SkColorGetB(c);
+
+ xyz->X =
brettw 2009/09/22 16:40:51 Can you indent the wrapped lines 2 more spaces whi
+ 0.4124 * CIEConvertNonLinear(r) +
+ 0.3576 * CIEConvertNonLinear(g) +
+ 0.1805 * CIEConvertNonLinear(b);
+ xyz->Y =
+ 0.2126 * CIEConvertNonLinear(r) +
+ 0.7152 * CIEConvertNonLinear(g) +
+ 0.0722 * CIEConvertNonLinear(g);
+ xyz->Z =
+ 0.0193 * CIEConvertNonLinear(r) +
+ 0.1192 * CIEConvertNonLinear(g) +
+ 0.9505 * CIEConvertNonLinear(b);
+}
+
+SkColor CIEXYZToSkColor(SkAlpha alpha, const CIE_XYZ& xyz) {
+ double r_linear = 3.2410 * xyz.X - 1.5374 * xyz.Y - 0.4986 * xyz.Z;
+ double g_linear = -0.9692 * xyz.X + 1.8760 * xyz.Y + 0.0416 * xyz.Z;
+ double b_linear = 0.0556 * xyz.X - 0.2040 * xyz.Y + 1.0570 * xyz.Z;
+ uint8 r = sRGBColorComponentFromLinearComponent(r_linear);
+ uint8 g = sRGBColorComponentFromLinearComponent(g_linear);
+ uint8 b = sRGBColorComponentFromLinearComponent(b_linear);
+ return SkColorSetARGB(alpha, r, g, b);
+}
+
void SkColorToLabColor(SkColor c, LabColor* lab) {
CIE_XYZ xyz;
SkColorToCIEXYZ(c, &xyz);
@@ -164,14 +185,37 @@
return CIEXYZToSkColor(alpha, xyz);
}
-static const int kCloseToBoundary = 64;
-static const int kAverageBoundary = 15;
+void CIEXYZToLabColor(const CIE_XYZ& xyz, LabColor* lab) {
+ CIE_XYZ white_xyz;
+ SkColorToCIEXYZ(SkColorSetRGB(255, 255, 255), &white_xyz);
+ double fx = LabConvertNonLinear(xyz.X / white_xyz.X);
+ double fy = LabConvertNonLinear(xyz.Y / white_xyz.Y);
+ double fz = LabConvertNonLinear(xyz.Z / white_xyz.Z);
+ lab->L = static_cast<int>(116 * fy) - 16;
+ lab->a = static_cast<int>(500 * (fx - fy));
+ lab->b = static_cast<int>(200 * (fy - fz));
+}
+void LabColorToCIEXYZ(const LabColor& lab, CIE_XYZ* xyz) {
+ CIE_XYZ result;
+
+ CIE_XYZ white_xyz;
+ SkColorToCIEXYZ(SkColorSetRGB(255, 255, 255), &white_xyz);
+
+ result.X = gen_xr(lab) * white_xyz.X;
+ result.Y = gen_yr(lab) * white_xyz.Y;
+ result.Z = gen_zr(lab) * white_xyz.Z;
+
+ *xyz = result;
+}
+
bool IsColorCloseToTransparent(SkAlpha alpha) {
+ const int kCloseToBoundary = 64;
return alpha < kCloseToBoundary;
}
bool IsColorCloseToGrey(int r, int g, int b) {
+ const int kAverageBoundary = 15;
int average = (r + g + b) / 3;
return (abs(r - average) < kAverageBoundary) &&
(abs(g - average) < kAverageBoundary) &&
@@ -221,20 +265,6 @@
return result;
}
-inline int GetLumaForColor(SkColor* color) {
- int r = SkColorGetR(*color);
- int g = SkColorGetG(*color);
- int b = SkColorGetB(*color);
-
- int luma = static_cast<int>(0.3*r + 0.59*g + 0.11*b);
- if (luma < 0)
- luma = 0;
- else if (luma > 255)
- luma = 255;
-
- return luma;
-}
-
void BuildLumaHistogram(SkBitmap* bitmap, int histogram[256]) {
SkAutoLockPixels bitmap_lock(*bitmap);
// Assume ARGB_8888 format.
@@ -265,27 +295,6 @@
(SkColorGetB(background) * (0xFF - alpha))) / 0xFF);
}
-// Next three functions' formulas from:
-// http://www.w3.org/TR/WCAG20/#relativeluminancedef
-// http://www.w3.org/TR/WCAG20/#contrast-ratiodef
-static double ConvertSRGB(double eight_bit_component) {
- const double component = eight_bit_component / 255.0;
- return (component <= 0.03928) ?
- (component / 12.92) : pow((component + 0.055) / 1.055, 2.4);
-}
-
-static double RelativeLuminance(SkColor color) {
- return (0.2126 * ConvertSRGB(SkColorGetR(color))) +
- (0.7152 * ConvertSRGB(SkColorGetG(color))) +
- (0.0722 * ConvertSRGB(SkColorGetB(color)));
-}
-
-static double ContrastRatio(SkColor color1, SkColor color2) {
- const double l1 = RelativeLuminance(color1) + 0.05;
- const double l2 = RelativeLuminance(color2) + 0.05;
- return (l1 > l2) ? (l1 / l2) : (l2 / l1);
-}
-
SkColor PickMoreReadableColor(SkColor foreground1,
SkColor foreground2,
SkColor background) {
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