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allow the gamma to be changed at runtime

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git-svn-id: http://skia.googlecode.com/svn/trunk@338 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
reed@android.com 2009-08-26 18:09:58 +00:00
parent ff3e92d2f8
commit 2a4d1ff189
1 changed files with 28 additions and 12 deletions
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40
src/ports/SkFontHost_gamma.cpp
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@ -4,7 +4,7 @@
// define this to use pre-compiled tables for gamma. This is slightly faster,
// and doesn't create any RW global memory, but means we cannot change the
// gamma at runtime.
#define USE_PREDEFINED_GAMMA_TABLES
//#define USE_PREDEFINED_GAMMA_TABLES
#ifndef USE_PREDEFINED_GAMMA_TABLES
// define this if you want to spew out the "C" code for the tables, given
@ -14,21 +14,22 @@
///////////////////////////////////////////////////////////////////////////////
#include "SkGraphics.h"
// declared here, so we can link against it elsewhere
void skia_set_text_gamma(float blackGamma, float whiteGamma);
#ifdef USE_PREDEFINED_GAMMA_TABLES
#include "sk_predefined_gamma.h"
void skia_set_text_gamma(float blackGamma, float whiteGamma) {}
#else // use writable globals for gamma tables
static bool gGammaIsBuilt;
static uint8_t gBlackGamma[256], gWhiteGamma[256];
#define SK_BLACK_GAMMA (1.4f)
#define SK_WHITE_GAMMA (1/1.4f)
static void build_power_table(uint8_t table[], float ee)
{
// printf("------ build_power_table %g\n", ee);
SkDebugf("------ build_power_table %g\n", ee);
for (int i = 0; i < 256; i++)
{
float x = i / 255.f;
@ -41,6 +42,21 @@ static void build_power_table(uint8_t table[], float ee)
}
}
static bool gGammaIsBuilt;
static uint8_t gBlackGamma[256], gWhiteGamma[256];
static float gBlackGammaCoeff = 1.4f;
static float gWhiteGammaCoeff = 1/1.4f;
void skia_set_text_gamma(float blackGamma, float whiteGamma) {
gBlackGammaCoeff = blackGamma;
gWhiteGammaCoeff = whiteGamma;
gGammaIsBuilt = false;
SkGraphics::SetFontCacheUsed(0);
build_power_table(gBlackGamma, gBlackGammaCoeff);
build_power_table(gWhiteGamma, gWhiteGammaCoeff);
}
#ifdef DUMP_GAMMA_TABLES
#include "SkString.h"
@ -72,13 +88,13 @@ void SkFontHost::GetGammaTables(const uint8_t* tables[2])
#ifndef USE_PREDEFINED_GAMMA_TABLES
if (!gGammaIsBuilt)
{
build_power_table(gBlackGamma, SK_BLACK_GAMMA);
build_power_table(gWhiteGamma, SK_WHITE_GAMMA);
build_power_table(gBlackGamma, gBlackGammaCoeff);
build_power_table(gWhiteGamma, gWhiteGammaCoeff);
gGammaIsBuilt = true;
#ifdef DUMP_GAMMA_TABLES
dump_a_table("gBlackGamma", gBlackGamma, SK_BLACK_GAMMA);
dump_a_table("gWhiteGamma", gWhiteGamma, SK_WHITE_GAMMA);
dump_a_table("gBlackGamma", gBlackGamma, gBlackGammaCoeff);
dump_a_table("gWhiteGamma", gWhiteGamma, gWhiteGammaCoeff);
#endif
}
#endif