Improve the gamma GM significantly

gm/gamma.cpp

 /*
  * 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"
 #include "SkPM4fPriv.h"
 
-DEF_SIMPLE_GM(gamma, canvas, 560, 200) {
+DEF_SIMPLE_GM(gamma, canvas, 650, 200) {
     SkPaint p;
     const SkScalar sz = 50.0f;
     const int szInt = SkScalarTruncToInt(sz);
-    const SkScalar tx = sz + 5.0f;
+    const SkScalar tx = sz + 15.0f;
     const SkRect r = SkRect::MakeXYWH(0, 0, sz, sz);
     SkShader::TileMode rpt = SkShader::kRepeat_TileMode;
     auto srgbColorSpace = SkColorSpace::NewNamed(SkColorSpace::kSRGB_Named);
 
     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);
 
@@ skipping 13 matching lines @@
     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);
@@ skipping 55 matching lines @@
     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.
-    p.setColor(0xff7f7f7f);
+    // 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,
@@ skipping 13 matching lines @@
 
     // 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);
 
-    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);
+    // 0x89 = 255 * linear_to_srgb(0.25)
+    nextXferRect(0xff898989, SkXfermode::kPlus_Mode, 0xff898989);
+
+    // 0xDB = 255 * linear_to_srgb(sqrt(0.5))
+    nextXferRect(0xffdbdbdb, SkXfermode::kModulate_Mode, 0xffdbdbdb);
 
     canvas->restore();
 }