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Unified Diff: gm/gamma.cpp

Issue 1740213003: New GM that exercises gamma-correctness in various parts of the pipeline. (Closed) Base URL: https://skia.googlesource.com/skia.git@master
Patch Set: Fixed to use saveLayer so that the output images are opaque. Created 4 years, 10 months ago
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Index: gm/gamma.cpp
diff --git a/gm/gamma.cpp b/gm/gamma.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..003061baebff4e66760e36c46b97f2676d626df5
--- /dev/null
+++ b/gm/gamma.cpp
@@ -0,0 +1,171 @@
+/*
+ * 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 "Resources.h"
+#include "SkGradientShader.h"
+
+DEF_SIMPLE_GM(gamma, canvas, 500, 200) {
+ SkPaint p;
+ const SkScalar sz = 50.0f;
+ const int szInt = SkScalarTruncToInt(sz);
+ const SkScalar tx = sz + 5.0f;
+ const SkRect r = SkRect::MakeXYWH(0, 0, sz, sz);
+ SkShader::TileMode rpt = SkShader::kRepeat_TileMode;
+
+ 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,
+ kLinear_SkColorProfileType);
+ linearGreyBmp.allocPixels(linearGreyInfo);
+ linearGreyBmp.eraseARGB(0xFF, 0x7F, 0x7F, 0x7F);
+
+ SkBitmap srgbGreyBmp;
+ SkImageInfo srgbGreyInfo = SkImageInfo::MakeN32(szInt, szInt, kOpaque_SkAlphaType,
+ kSRGB_SkColorProfileType);
+ srgbGreyBmp.allocPixels(srgbGreyInfo);
+ srgbGreyBmp.eraseARGB(0xFF, 0xBC, 0xBC, 0xBC);
+
+ SkPaint textPaint;
+ textPaint.setColor(SK_ColorWHITE);
+
+ // 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, SkXfermode::Mode mode, SkColor dstColor) {
+ p.setColor(dstColor);
+ canvas->drawRect(r, p);
+ p.setColor(srcColor);
+ p.setXfermodeMode(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 = SkXfermode::ModeName(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::CreateBitmapShader(
+ ditherBmp, rpt, rpt))->unref();
+ 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::CreateBitmapShader(
+ ditherBmp, rpt, rpt, &offsetMatrix))->unref();
+ 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::CreateBitmapShader(
+ ditherBmp, rpt, rpt, &scaleMatrix))->unref();
+ p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
+ nextRect("Dither", "Scale");
+
+ // 50% grey via paint color.
+ p.setColor(0xff7f7f7f);
+ 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::CreateLinear(
+ points, colors, nullptr, 2, SkShader::kClamp_TileMode))->unref();
+ nextRect("Gradient", 0);
+
+ // 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::CreateBitmapShader(linearGreyBmp, rpt, rpt))->unref();
+ p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
+ nextRect("Lnr BMP", "Shader");
+
+ // Bitmap wrapped in a shader (sRGB):
+ p.setShader(SkShader::CreateBitmapShader(srgbGreyBmp, rpt, rpt))->unref();
+ p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
+ nextRect("sRGB BMP", "Shader");
+
+ // Carriage return.
+ canvas->restore();
+ canvas->translate(0, 2 * sz);
+
+ const U8CPU sqrtHalf = 0xB4;
+ const SkColor sqrtHalfAlpha = SkColorSetARGB(sqrtHalf, 0, 0, 0);
+ const SkColor sqrtHalfWhite = SkColorSetARGB(0xFF, sqrtHalf, sqrtHalf, sqrtHalf);
+
+ // Xfermode tests, all done off-screen so certain modes work...
+
+ canvas->saveLayer(nullptr, nullptr);
+
+ nextXferRect(0x7fffffff, SkXfermode::kSrcOver_Mode, SK_ColorBLACK);
+ nextXferRect(0x7f000000, SkXfermode::kSrcOver_Mode, SK_ColorWHITE);
+
+ nextXferRect(SK_ColorBLACK, SkXfermode::kDstOver_Mode, 0x7fffffff);
+ nextXferRect(SK_ColorWHITE, SkXfermode::kSrcIn_Mode, 0x7fff00ff);
+ nextXferRect(0x7fff00ff, SkXfermode::kDstIn_Mode, SK_ColorWHITE);
+ nextXferRect(sqrtHalfWhite, SkXfermode::kSrcIn_Mode, sqrtHalfAlpha);
+ nextXferRect(sqrtHalfAlpha, SkXfermode::kDstIn_Mode, sqrtHalfWhite);
+
+ nextXferRect(0xff3f3f3f, SkXfermode::kPlus_Mode, 0xff3f3f3f);
+ nextXferRect(sqrtHalfWhite, SkXfermode::kModulate_Mode, sqrtHalfWhite);
+
+ canvas->restore();
+
+ canvas->restore();
+}
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