extend compose-colorfilter to 4f

gm/color4f.cpp

 /*
  * Copyright 2011 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 "SkCanvas.h"
 #include "SkColorPriv.h"
@@ skipping 14 matching lines @@
 static SkColorFilter* make_cf_null() {
     return nullptr;
 }
 
 static SkColorFilter* make_cf0() {
     SkColorMatrix cm;
     cm.setSaturation(0.75f);
     return SkColorMatrixFilter::Create(cm);
 }
 
+static SkColorFilter* make_cf1() {
+    SkColorMatrix cm;
+    cm.setSaturation(0.75f);
+    SkAutoTUnref<SkColorFilter> a(SkColorMatrixFilter::Create(cm));
+    // CreateComposedFilter will try to concat these two matrices, resulting in a single
+    // filter (which is good for speed). For this test, we want to force a real compose of
+    // these two, so our inner filter has a scale-up, which disables the optimization of
+    // combining the two matrices.
+    cm.setScale(1.1f, 0.9f, 1);
+    SkAutoTUnref<SkColorFilter> b(SkColorMatrixFilter::Create(cm));
+    return SkColorFilter::CreateComposeFilter(a, b);
+}
+
 static void draw_into_canvas(SkCanvas* canvas) {
     const SkRect r = SkRect::MakeWH(100, 100);
     SkShader* (*shaders[])() { make_opaque_color, make_alpha_color };
-    SkColorFilter* (*filters[])() { make_cf_null, make_cf0 };
+    SkColorFilter* (*filters[])() { make_cf_null, make_cf0, make_cf1 };
     
     SkPaint paint;
     for (auto shProc : shaders) {
         paint.setShader(shProc())->unref();
         for (auto cfProc : filters) {
             SkSafeUnref(paint.setColorFilter(cfProc()));
             canvas->drawRect(r, paint);
             canvas->translate(120, 0);
         }
     }
 }
 
-DEF_SIMPLE_GM(color4f, canvas, 510, 250) {
+DEF_SIMPLE_GM(color4f, canvas, 620, 260) {
     canvas->translate(20, 20);
 
     SkPaint bg;
     // need the target to be opaque, so we can draw it to the screen
     // even if it holds sRGB values.
     bg.setColor(0xFFFFFFFF);
 
     SkColorProfileType const profiles[] { kLinear_SkColorProfileType, kSRGB_SkColorProfileType };
     for (auto profile : profiles) {
-        const SkImageInfo info = SkImageInfo::Make(500, 100, kN32_SkColorType, kPremul_SkAlphaType,
+        const SkImageInfo info = SkImageInfo::Make(600, 100, kN32_SkColorType, kPremul_SkAlphaType,
                                                    profile);
         SkAutoTUnref<SkSurface> surface(SkSurface::NewRaster(info));
         surface->getCanvas()->drawPaint(bg);
         draw_into_canvas(surface->getCanvas());
         surface->draw(canvas, 0, 0, nullptr);
         canvas->translate(0, 120);
     }
 }