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Allow selection of ink density

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git-svn-id: file:///srv/svn/repos/haiku/trunk/current@6583 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Michael Pfeiffer
2004-02-14 00:00:18 +00:00
parent e2d8351ac4
commit 329e4f9a7b
2 changed files with 17 additions and 11 deletions
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headers/private/print/libprint/Halftone.h
+2 -2
View File
@@ -55,7 +55,7 @@ public:
kHighValueMeansBlack, kHighValueMeansBlack,
kLowValueMeansBlack, kLowValueMeansBlack,
}; };
Halftone(color_space cs, double gamma = 1.4, DitherType dither_type = kTypeFloydSteinberg); Halftone(color_space cs, double gamma = 1.4, double min = 0.0, DitherType dither_type = kTypeFloydSteinberg);
~Halftone(); ~Halftone();
void setPlanes(Planes planes); void setPlanes(Planes planes);
void setBlackValue(BlackValue blackValue); void setBlackValue(BlackValue blackValue);
@@ -70,7 +70,7 @@ protected:
void setGrayFunction(PFN_gray gray); void setGrayFunction(PFN_gray gray);
void setGrayFunction(GrayFunction grayFunction); void setGrayFunction(GrayFunction grayFunction);
void createGammaTable(double gamma); void createGammaTable(double gamma, double min);
void initElements(int x, int y, uchar *elements); void initElements(int x, int y, uchar *elements);
uint getDensity(ColorRGB32 c) const; uint getDensity(ColorRGB32 c) const;
uchar convertUsingBlackValue(uchar byte) const; uchar convertUsingBlackValue(uchar byte) const;
src/add-ons/print/drivers/shared/libprint/Halftone.cpp
+15 -9
View File
@@ -43,7 +43,7 @@ static uint channel_blue(ColorRGB32 c)
return c.little.blue; return c.little.blue;
} }
Halftone::Halftone(color_space cs, double gamma, DitherType dither_type) Halftone::Halftone(color_space cs, double gamma, double min, DitherType dither_type)
{ {
fPixelDepth = color_space2pixel_depth(cs); fPixelDepth = color_space2pixel_depth(cs);
fGray = gray; fGray = gray;
@@ -52,7 +52,7 @@ Halftone::Halftone(color_space cs, double gamma, DitherType dither_type)
initFloydSteinberg(); initFloydSteinberg();
createGammaTable(gamma); createGammaTable(gamma, min);
if (dither_type == kTypeFloydSteinberg) { if (dither_type == kTypeFloydSteinberg) {
fDither = &Halftone::ditherFloydSteinberg; fDither = &Halftone::ditherFloydSteinberg;
@@ -105,12 +105,14 @@ void Halftone::setBlackValue(BlackValue blackValue)
fBlackValue = blackValue; fBlackValue = blackValue;
} }
void Halftone::createGammaTable(double gamma) void Halftone::createGammaTable(double gamma, double min)
{ {
// gamma = 1.0f / gamma;
uint *g = fGammaTable; uint *g = fGammaTable;
const double kScalingFactor = 255.0 - min;
for (int i = 0; i < kGammaTableSize; i++) { for (int i = 0; i < kGammaTableSize; i++) {
*g++ = (uint)(pow((double)i / 255.0, gamma) * 256.0); const double kGammaCorrectedValue = pow((double)i / 255.0, gamma);
const double kTranslatedValue = min + kGammaCorrectedValue * kScalingFactor;
*g++ = (uint)(kTranslatedValue);
} }
} }
@@ -295,7 +297,8 @@ int Halftone::ditherFloydSteinberg(uchar *dst, const uchar* a_src, int x, int y,
} }
int* error_table = &fErrorTables[fCurrentPlane][1]; int* error_table = &fErrorTables[fCurrentPlane][1];
int current_error = 0, error; int current_error = error_table[0], error;
error_table[0] = 0;
const ColorRGB32 *src = (const ColorRGB32 *)a_src; const ColorRGB32 *src = (const ColorRGB32 *)a_src;
uchar cur = 0; // cleared bit means white, set bit means black uchar cur = 0; // cleared bit means white, set bit means black
for (int x = 0; x < width; x ++, src ++) { for (int x = 0; x < width; x ++, src ++) {
@@ -309,10 +312,13 @@ int Halftone::ditherFloydSteinberg(uchar *dst, const uchar* a_src, int x, int y,
error = density - 255; error = density - 255;
} }
// distribute error // distribute error using this pattern:
// 0 X 7 (current_error)
// (left) 3 5 1 (right)
// (middle)
int* right = &error_table[x+1]; int* right = &error_table[x+1];
current_error = *right + 7 * error; current_error = (*right) + 7 * error;
*right = error; *right = 1 * error;
int* middle = right - 1; int* middle = right - 1;
*middle += 5 * error; *middle += 5 * error;