gm/gamma.cpp - platform/external/skia - Gitiles

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #include "gm.h"
 #include "sk_tool_utils.h"

 #include "Resources.h"
 #include "SkBlendModePriv.h"
 #include "SkGradientShader.h"
 #include "SkPM4fPriv.h"

 DEF_SIMPLE_GM(gamma, canvas, 850, 200) {
     SkPaint p;
     const SkScalar sz = 50.0f;
     const int szInt = SkScalarTruncToInt(sz);
     const SkScalar tx = sz + 15.0f;
     const SkRect r = SkRect::MakeXYWH(0, 0, sz, sz);
     SkShader::TileMode rpt = SkShader::kRepeat_TileMode;
     auto srgbColorSpace = SkColorSpace::MakeSRGB();

     SkBitmap ditherBmp;
     ditherBmp.allocN32Pixels(2, 2);
     SkPMColor* pixels = reinterpret_cast<SkPMColor*>(ditherBmp.getPixels());
     pixels[0] = pixels[3] = SkPackARGB32(0xFF, 0xFF, 0xFF, 0xFF);
     pixels[1] = pixels[2] = SkPackARGB32(0xFF, 0, 0, 0);

     SkBitmap linearGreyBmp;
     SkImageInfo linearGreyInfo = SkImageInfo::MakeN32(szInt, szInt, kOpaque_SkAlphaType, nullptr);
     linearGreyBmp.allocPixels(linearGreyInfo);
     linearGreyBmp.eraseARGB(0xFF, 0x7F, 0x7F, 0x7F);

     SkBitmap srgbGreyBmp;
     SkImageInfo srgbGreyInfo = SkImageInfo::MakeN32(szInt, szInt, kOpaque_SkAlphaType,
                                                     srgbColorSpace);
     srgbGreyBmp.allocPixels(srgbGreyInfo);
     // 0xBC = 255 * linear_to_srgb(0.5f)
     srgbGreyBmp.eraseARGB(0xFF, 0xBC, 0xBC, 0xBC);

     SkBitmap mipmapBmp;
     SkImageInfo mipmapInfo = SkImageInfo::Make(2, 2, kN32_SkColorType, kOpaque_SkAlphaType,
                                                srgbColorSpace);
     mipmapBmp.allocPixels(mipmapInfo);
     SkPMColor* mipmapPixels = reinterpret_cast<SkPMColor*>(mipmapBmp.getPixels());
     unsigned s25 = 0x89;    // 255 * linear_to_srgb(0.25f)
     unsigned s75 = 0xE1;    // 255 * linear_to_srgb(0.75f)
     mipmapPixels[0] = mipmapPixels[3] = SkPackARGB32(0xFF, s25, s25, s25);
     mipmapPixels[1] = mipmapPixels[2] = SkPackARGB32(0xFF, s75, s75, s75);

     SkPaint textPaint;
     textPaint.setAntiAlias(true);
     textPaint.setColor(SK_ColorWHITE);
     sk_tool_utils::set_portable_typeface(&textPaint);

     // Helpers:
     auto advance = [&]() {
         canvas->translate(tx, 0);
         p.reset();
     };

     auto nextRect = [&](const char* label, const char* label2) {
         canvas->drawRect(r, p);
         canvas->drawText(label, strlen(label), 0, sz + textPaint.getFontSpacing(), textPaint);
         if (label2) {
             canvas->drawText(label2, strlen(label2), 0, sz + 2 * textPaint.getFontSpacing(),
                              textPaint);
         }
         advance();
     };

     auto nextBitmap = [&](const SkBitmap& bmp, const char* label) {
         canvas->drawBitmap(bmp, 0, 0);
         canvas->drawText(label, strlen(label), 0, sz + textPaint.getFontSpacing(), textPaint);
         advance();
     };

     auto nextXferRect = [&](SkColor srcColor, SkBlendMode mode, SkColor dstColor) {
         p.setColor(dstColor);
         canvas->drawRect(r, p);
         p.setColor(srcColor);
         p.setBlendMode(mode);
         canvas->drawRect(r, p);

         SkString srcText = SkStringPrintf("%08X", srcColor);
         SkString dstText = SkStringPrintf("%08X", dstColor);
         canvas->drawText(srcText.c_str(), srcText.size(), 0, sz + textPaint.getFontSpacing(),
                          textPaint);
         const char* modeName = SkBlendMode_Name(mode);
         canvas->drawText(modeName, strlen(modeName), 0, sz + 2 * textPaint.getFontSpacing(),
                          textPaint);
         canvas->drawText(dstText.c_str(), dstText.size(), 0, sz + 3 * textPaint.getFontSpacing(),
                          textPaint);
         advance();
     };

     // Necessary for certain Xfermode tests to work (ie some of them output white @ 50% alpha):
     canvas->clear(SK_ColorBLACK);

     // *Everything* should be perceptually 50% grey. Only the first rectangle
     // is guaranteed to draw that way, though.
     canvas->save();

     // Black/white dither, pixel perfect. This is ground truth.
     p.setShader(SkShader::MakeBitmapShader(ditherBmp, rpt, rpt));
     p.setFilterQuality(SkFilterQuality::kNone_SkFilterQuality);
     nextRect("Dither", "Reference");

     // Black/white dither, sampled at half-texel offset. Tests bilerp.
     // NOTE: We need to apply a non-identity scale and/or rotation to trick
     // the raster pipeline into *not* snapping to nearest.
     SkMatrix offsetMatrix = SkMatrix::Concat(
         SkMatrix::MakeScale(-1.0f), SkMatrix::MakeTrans(0.5f, 0.0f));
     p.setShader(SkShader::MakeBitmapShader(ditherBmp, rpt, rpt, &offsetMatrix));
     p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
     nextRect("Dither", "Bilerp");

     // Black/white dither, scaled down by 2x. Tests minification.
     SkMatrix scaleMatrix = SkMatrix::MakeScale(0.5f);
     p.setShader(SkShader::MakeBitmapShader(ditherBmp, rpt, rpt, &scaleMatrix));
     p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
     nextRect("Dither", "Scale");

     // 25%/75% dither, scaled down by 2x. Tests ALL aspects of minification. Specifically, are
     // sRGB sources decoded to linear before computing mipmaps?
     p.setShader(SkShader::MakeBitmapShader(mipmapBmp, rpt, rpt, &scaleMatrix));
     p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
     nextRect("MipMaps", 0);

     // 50% grey via paint color. Paint color (SkColor) is specified to be sRGB!
     p.setColor(0xffbcbcbc);
     nextRect("Color", 0);

     {
         // Black -> White gradient, scaled to sample just the middle.
         // Tests gradient interpolation.
         SkPoint points[2] = {
             SkPoint::Make(0 - (sz * 10), 0),
             SkPoint::Make(sz + (sz * 10), 0)
         };
         SkColor colors[2] = { SK_ColorBLACK, SK_ColorWHITE };
         p.setShader(SkGradientShader::MakeLinear(points, colors, nullptr, 2,
                                                  SkShader::kClamp_TileMode));
         nextRect("Gradient", "Interpolation");
     }

     {
         // Shallow gradient around 50% (perceptual) gray. Endpoints are SkColor, so sRGB.
         // Tests gamma-correction of gradient stops before interpolation in two-stop case
         SkPoint points[2] = {
             SkPoint::Make(0, 0),
             SkPoint::Make(sz, 0)
         };
         SkColor colors[2] = { 0xffbbbbbb, 0xffbdbdbd };
         p.setShader(SkGradientShader::MakeLinear(points, colors, nullptr, 2,
                                                  SkShader::kClamp_TileMode));
         nextRect("Gradient", "Endpoints");
     }

     {
         // Shallow 3-stop gradient around 50% (perceptual) gray. Endpoints are SkColor, so sRGB.
         // Tests gamma-correction of gradient stops before interpolation in three-stop case
         SkPoint points[2] = {
             SkPoint::Make(0, 0),
             SkPoint::Make(sz, 0)
         };
         SkColor colors[3] = { 0xffbbbbbb, 0xffbdbdbd, 0xffbbbbbb };
         p.setShader(SkGradientShader::MakeLinear(points, colors, nullptr, 3,
                                                  SkShader::kClamp_TileMode));
         nextRect("Gradient", "3-Stop");
     }

     {
         // Shallow N-stop gradient around 50% (perceptual) gray. Endpoints are SkColor, so sRGB.
         // Tests gamma-correction of gradient stops before interpolation in texture implementation
         SkPoint points[2] = {
             SkPoint::Make(0, 0),
             SkPoint::Make(sz, 0)
         };
         SkColor colors[5] = { 0xffbbbbbb, 0xffbdbdbd, 0xffbbbbbb, 0xffbdbdbd, 0xffbbbbbb };
         p.setShader(SkGradientShader::MakeLinear(points, colors, nullptr, 5,
                                                  SkShader::kClamp_TileMode));
         nextRect("Gradient", "Texture");
     }

     // 50% grey from linear bitmap, with drawBitmap
     nextBitmap(linearGreyBmp, "Lnr BMP");

     // 50% grey from sRGB bitmap, with drawBitmap
     nextBitmap(srgbGreyBmp, "sRGB BMP");

     // Bitmap wrapped in a shader (linear):
     p.setShader(SkShader::MakeBitmapShader(linearGreyBmp, rpt, rpt));
     p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
     nextRect("Lnr BMP", "Shader");

     // Bitmap wrapped in a shader (sRGB):
     p.setShader(SkShader::MakeBitmapShader(srgbGreyBmp, rpt, rpt));
     p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
     nextRect("sRGB BMP", "Shader");

     // Carriage return.
     canvas->restore();
     canvas->translate(0, 2 * sz);

     // Xfermode tests, all done off-screen so certain modes work...

     canvas->saveLayer(nullptr, nullptr);

     nextXferRect(0x7fffffff, SkBlendMode::kSrcOver, SK_ColorBLACK);
     nextXferRect(0x7f000000, SkBlendMode::kSrcOver, SK_ColorWHITE);

     nextXferRect(SK_ColorBLACK, SkBlendMode::kDstOver, 0x7fffffff);
     nextXferRect(SK_ColorWHITE, SkBlendMode::kSrcIn, 0x7fff00ff);
     nextXferRect(0x7fff00ff, SkBlendMode::kDstIn, SK_ColorWHITE);

     // 0x89 = 255 * linear_to_srgb(0.25)
     nextXferRect(0xff898989, SkBlendMode::kPlus, 0xff898989);

     // 0xDB = 255 * linear_to_srgb(sqrt(0.5))
     nextXferRect(0xffdbdbdb, SkBlendMode::kModulate, 0xffdbdbdb);

     canvas->restore();
 }
	/*
	* Copyright 2015 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include "gm.h"
	#include "sk_tool_utils.h"

	#include "Resources.h"
	#include "SkBlendModePriv.h"
	#include "SkGradientShader.h"
	#include "SkPM4fPriv.h"

	DEF_SIMPLE_GM(gamma, canvas, 850, 200) {
	SkPaint p;
	const SkScalar sz = 50.0f;
	const int szInt = SkScalarTruncToInt(sz);
	const SkScalar tx = sz + 15.0f;
	const SkRect r = SkRect::MakeXYWH(0, 0, sz, sz);
	SkShader::TileMode rpt = SkShader::kRepeat_TileMode;
	auto srgbColorSpace = SkColorSpace::MakeSRGB();

	SkBitmap ditherBmp;
	ditherBmp.allocN32Pixels(2, 2);
	SkPMColor* pixels = reinterpret_cast<SkPMColor*>(ditherBmp.getPixels());
	pixels[0] = pixels[3] = SkPackARGB32(0xFF, 0xFF, 0xFF, 0xFF);
	pixels[1] = pixels[2] = SkPackARGB32(0xFF, 0, 0, 0);

	SkBitmap linearGreyBmp;
	SkImageInfo linearGreyInfo = SkImageInfo::MakeN32(szInt, szInt, kOpaque_SkAlphaType, nullptr);
	linearGreyBmp.allocPixels(linearGreyInfo);
	linearGreyBmp.eraseARGB(0xFF, 0x7F, 0x7F, 0x7F);

	SkBitmap srgbGreyBmp;
	SkImageInfo srgbGreyInfo = SkImageInfo::MakeN32(szInt, szInt, kOpaque_SkAlphaType,
	srgbColorSpace);
	srgbGreyBmp.allocPixels(srgbGreyInfo);
	// 0xBC = 255 * linear_to_srgb(0.5f)
	srgbGreyBmp.eraseARGB(0xFF, 0xBC, 0xBC, 0xBC);

	SkBitmap mipmapBmp;
	SkImageInfo mipmapInfo = SkImageInfo::Make(2, 2, kN32_SkColorType, kOpaque_SkAlphaType,
	srgbColorSpace);
	mipmapBmp.allocPixels(mipmapInfo);
	SkPMColor* mipmapPixels = reinterpret_cast<SkPMColor*>(mipmapBmp.getPixels());
	unsigned s25 = 0x89; // 255 * linear_to_srgb(0.25f)
	unsigned s75 = 0xE1; // 255 * linear_to_srgb(0.75f)
	mipmapPixels[0] = mipmapPixels[3] = SkPackARGB32(0xFF, s25, s25, s25);
	mipmapPixels[1] = mipmapPixels[2] = SkPackARGB32(0xFF, s75, s75, s75);

	SkPaint textPaint;
	textPaint.setAntiAlias(true);
	textPaint.setColor(SK_ColorWHITE);
	sk_tool_utils::set_portable_typeface(&textPaint);

	// Helpers:
	auto advance = [&]() {
	canvas->translate(tx, 0);
	p.reset();
	};

	auto nextRect = [&](const char* label, const char* label2) {
	canvas->drawRect(r, p);
	canvas->drawText(label, strlen(label), 0, sz + textPaint.getFontSpacing(), textPaint);
	if (label2) {
	canvas->drawText(label2, strlen(label2), 0, sz + 2 * textPaint.getFontSpacing(),
	textPaint);
	}
	advance();
	};

	auto nextBitmap = [&](const SkBitmap& bmp, const char* label) {
	canvas->drawBitmap(bmp, 0, 0);
	canvas->drawText(label, strlen(label), 0, sz + textPaint.getFontSpacing(), textPaint);
	advance();
	};

	auto nextXferRect = [&](SkColor srcColor, SkBlendMode mode, SkColor dstColor) {
	p.setColor(dstColor);
	canvas->drawRect(r, p);
	p.setColor(srcColor);
	p.setBlendMode(mode);
	canvas->drawRect(r, p);

	SkString srcText = SkStringPrintf("%08X", srcColor);
	SkString dstText = SkStringPrintf("%08X", dstColor);
	canvas->drawText(srcText.c_str(), srcText.size(), 0, sz + textPaint.getFontSpacing(),
	textPaint);
	const char* modeName = SkBlendMode_Name(mode);
	canvas->drawText(modeName, strlen(modeName), 0, sz + 2 * textPaint.getFontSpacing(),
	textPaint);
	canvas->drawText(dstText.c_str(), dstText.size(), 0, sz + 3 * textPaint.getFontSpacing(),
	textPaint);
	advance();
	};

	// Necessary for certain Xfermode tests to work (ie some of them output white @ 50% alpha):
	canvas->clear(SK_ColorBLACK);

	// Everything should be perceptually 50% grey. Only the first rectangle
	// is guaranteed to draw that way, though.
	canvas->save();

	// Black/white dither, pixel perfect. This is ground truth.
	p.setShader(SkShader::MakeBitmapShader(ditherBmp, rpt, rpt));
	p.setFilterQuality(SkFilterQuality::kNone_SkFilterQuality);
	nextRect("Dither", "Reference");

	// Black/white dither, sampled at half-texel offset. Tests bilerp.
	// NOTE: We need to apply a non-identity scale and/or rotation to trick
	// the raster pipeline into not snapping to nearest.
	SkMatrix offsetMatrix = SkMatrix::Concat(
	SkMatrix::MakeScale(-1.0f), SkMatrix::MakeTrans(0.5f, 0.0f));
	p.setShader(SkShader::MakeBitmapShader(ditherBmp, rpt, rpt, &offsetMatrix));
	p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
	nextRect("Dither", "Bilerp");

	// Black/white dither, scaled down by 2x. Tests minification.
	SkMatrix scaleMatrix = SkMatrix::MakeScale(0.5f);
	p.setShader(SkShader::MakeBitmapShader(ditherBmp, rpt, rpt, &scaleMatrix));
	p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
	nextRect("Dither", "Scale");

	// 25%/75% dither, scaled down by 2x. Tests ALL aspects of minification. Specifically, are
	// sRGB sources decoded to linear before computing mipmaps?
	p.setShader(SkShader::MakeBitmapShader(mipmapBmp, rpt, rpt, &scaleMatrix));
	p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
	nextRect("MipMaps", 0);

	// 50% grey via paint color. Paint color (SkColor) is specified to be sRGB!
	p.setColor(0xffbcbcbc);
	nextRect("Color", 0);

	{
	// Black -> White gradient, scaled to sample just the middle.
	// Tests gradient interpolation.
	SkPoint points[2] = {
	SkPoint::Make(0 - (sz * 10), 0),
	SkPoint::Make(sz + (sz * 10), 0)
	};
	SkColor colors[2] = { SK_ColorBLACK, SK_ColorWHITE };
	p.setShader(SkGradientShader::MakeLinear(points, colors, nullptr, 2,
	SkShader::kClamp_TileMode));
	nextRect("Gradient", "Interpolation");
	}

	{
	// Shallow gradient around 50% (perceptual) gray. Endpoints are SkColor, so sRGB.
	// Tests gamma-correction of gradient stops before interpolation in two-stop case
	SkPoint points[2] = {
	SkPoint::Make(0, 0),
	SkPoint::Make(sz, 0)
	};
	SkColor colors[2] = { 0xffbbbbbb, 0xffbdbdbd };
	p.setShader(SkGradientShader::MakeLinear(points, colors, nullptr, 2,
	SkShader::kClamp_TileMode));
	nextRect("Gradient", "Endpoints");
	}

	{
	// Shallow 3-stop gradient around 50% (perceptual) gray. Endpoints are SkColor, so sRGB.
	// Tests gamma-correction of gradient stops before interpolation in three-stop case
	SkPoint points[2] = {
	SkPoint::Make(0, 0),
	SkPoint::Make(sz, 0)
	};
	SkColor colors[3] = { 0xffbbbbbb, 0xffbdbdbd, 0xffbbbbbb };
	p.setShader(SkGradientShader::MakeLinear(points, colors, nullptr, 3,
	SkShader::kClamp_TileMode));
	nextRect("Gradient", "3-Stop");
	}

	{
	// Shallow N-stop gradient around 50% (perceptual) gray. Endpoints are SkColor, so sRGB.
	// Tests gamma-correction of gradient stops before interpolation in texture implementation
	SkPoint points[2] = {
	SkPoint::Make(0, 0),
	SkPoint::Make(sz, 0)
	};
	SkColor colors[5] = { 0xffbbbbbb, 0xffbdbdbd, 0xffbbbbbb, 0xffbdbdbd, 0xffbbbbbb };
	p.setShader(SkGradientShader::MakeLinear(points, colors, nullptr, 5,
	SkShader::kClamp_TileMode));
	nextRect("Gradient", "Texture");
	}

	// 50% grey from linear bitmap, with drawBitmap
	nextBitmap(linearGreyBmp, "Lnr BMP");

	// 50% grey from sRGB bitmap, with drawBitmap
	nextBitmap(srgbGreyBmp, "sRGB BMP");

	// Bitmap wrapped in a shader (linear):
	p.setShader(SkShader::MakeBitmapShader(linearGreyBmp, rpt, rpt));
	p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
	nextRect("Lnr BMP", "Shader");

	// Bitmap wrapped in a shader (sRGB):
	p.setShader(SkShader::MakeBitmapShader(srgbGreyBmp, rpt, rpt));
	p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
	nextRect("sRGB BMP", "Shader");

	// Carriage return.
	canvas->restore();
	canvas->translate(0, 2 * sz);

	// Xfermode tests, all done off-screen so certain modes work...

	canvas->saveLayer(nullptr, nullptr);

	nextXferRect(0x7fffffff, SkBlendMode::kSrcOver, SK_ColorBLACK);
	nextXferRect(0x7f000000, SkBlendMode::kSrcOver, SK_ColorWHITE);

	nextXferRect(SK_ColorBLACK, SkBlendMode::kDstOver, 0x7fffffff);
	nextXferRect(SK_ColorWHITE, SkBlendMode::kSrcIn, 0x7fff00ff);
	nextXferRect(0x7fff00ff, SkBlendMode::kDstIn, SK_ColorWHITE);

	// 0x89 = 255 * linear_to_srgb(0.25)
	nextXferRect(0xff898989, SkBlendMode::kPlus, 0xff898989);

	// 0xDB = 255 * linear_to_srgb(sqrt(0.5))
	nextXferRect(0xffdbdbdb, SkBlendMode::kModulate, 0xffdbdbdb);

	canvas->restore();
	}