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aosp12/external/skqp/gm/gamma.cpp

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/*
* 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"
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);
SkFont font(sk_tool_utils::create_portable_typeface());
SkPaint textPaint;
textPaint.setAntiAlias(true);
textPaint.setColor(SK_ColorWHITE);
// Helpers:
auto advance = [&]() {
canvas->translate(tx, 0);
p.reset();
};
auto drawString = [&](const char str[], SkScalar x, SkScalar y) {
canvas->drawSimpleText(str, strlen(str), kUTF8_SkTextEncoding, x, y, font, textPaint);
};
auto nextRect = [&](const char* label, const char* label2) {
canvas->drawRect(r, p);
drawString(label, 0, sz + font.getSpacing());
if (label2) {
drawString(label2, 0, sz + 2 * font.getSpacing());
}
advance();
};
auto nextBitmap = [&](const SkBitmap& bmp, const char* label) {
canvas->drawBitmap(bmp, 0, 0);
drawString(label, 0, sz + font.getSpacing());
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);
drawString(srcText.c_str(), 0, sz + font.getSpacing());
const char* modeName = SkBlendMode_Name(mode);
drawString(modeName, 0, sz + 2 * font.getSpacing());
drawString(dstText.c_str(), 0, sz + 3 * font.getSpacing());
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", nullptr);
// 50% grey via paint color. Paint color (SkColor) is specified to be sRGB!
p.setColor(0xffbcbcbc);
nextRect("Color", nullptr);
{
// 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();
}
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