extend compose-colorfilter to 4f

gm/color4f.cpp

Index: gm/color4f.cpp
diff --git a/gm/color4f.cpp b/gm/color4f.cpp
index 98ce0824cca6c6231b9c6619d0b91de15d045357..e912654bc911fd1a95f40741b41e0b38bd129c4d 100644
--- a/gm/color4f.cpp
+++ b/gm/color4f.cpp
@@ -32,10 +32,23 @@ static SkColorFilter* make_cf0() {
     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) {
@@ -48,7 +61,7 @@ static void draw_into_canvas(SkCanvas* canvas) {
     }
 }
 
-DEF_SIMPLE_GM(color4f, canvas, 510, 250) {
+DEF_SIMPLE_GM(color4f, canvas, 620, 260) {
     canvas->translate(20, 20);
 
     SkPaint bg;
@@ -58,7 +71,7 @@ DEF_SIMPLE_GM(color4f, canvas, 510, 250) {
 
     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);