Revert of Return color shader instead of 2-color gradient when color count is 1 (patchset #3 id:40001 of https://codereview.chromium.org/2259823005/ )

Reason for revert:
breaks 2-pt-conical, which can sometimes not draw anything

Original issue's description:
> Return color shader instead of 2-color gradient when color count is 1
>
> BUG=skia:
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2259823005
>
> Committed: https://skia.googlesource.com/skia/+/da082a5767d7edfd3abe74fc683392422565a606

TBR=fmenozzi@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review-Url: https://codereview.chromium.org/2257993002

1 files changed, 17 insertions, 12 deletions

diff --git a/src/effects/gradients/SkGradientShader.cpp b/src/effects/gradients/SkGradientShader.cpp
index 3b761a51ca..6ffe56b9d4 100644
--- a/src/effects/gradients/SkGradientShader.cpp
+++ b/src/effects/gradients/SkGradientShader.cpp
@@ -742,6 +742,18 @@ static bool valid_grad(const SkColor colors[], const SkScalar pos[], int count,
     return nullptr != colors && count >= 1 && tileMode < (unsigned)SkShader::kTileModeCount;
 }
 
+// assumes colors is SkColor* and pos is SkScalar*
+#define EXPAND_1_COLOR(count)               \
+    SkColor tmp[2];                         \
+    do {                                    \
+        if (1 == count) {                   \
+            tmp[0] = tmp[1] = colors[0];    \
+            colors = tmp;                   \
+            pos = nullptr;                     \
+            count = 2;                      \
+        }                                   \
+    } while (0)
+
 static void desc_init(SkGradientShaderBase::Descriptor* desc,
                       const SkColor colors[], const SkScalar pos[], int colorCount,
                       SkShader::TileMode mode, uint32_t flags, const SkMatrix* localMatrix) {
@@ -767,9 +779,7 @@ sk_sp<SkShader> SkGradientShader::MakeLinear(const SkPoint pts[2],
     if (!valid_grad(colors, pos, colorCount, mode)) {
         return nullptr;
     }
-    if (1 == colorCount) {
-        return SkShader::MakeColorShader(colors[0]);
-    }
+    EXPAND_1_COLOR(colorCount);
 
     SkGradientShaderBase::Descriptor desc;
     desc_init(&desc, colors, pos, colorCount, mode, flags, localMatrix);
@@ -788,9 +798,7 @@ sk_sp<SkShader> SkGradientShader::MakeRadial(const SkPoint& center, SkScalar rad
     if (!valid_grad(colors, pos, colorCount, mode)) {
         return nullptr;
     }
-    if (1 == colorCount) {
-        return SkShader::MakeColorShader(colors[0]);
-    }
+    EXPAND_1_COLOR(colorCount);
 
     SkGradientShaderBase::Descriptor desc;
     desc_init(&desc, colors, pos, colorCount, mode, flags, localMatrix);
@@ -818,9 +826,8 @@ sk_sp<SkShader> SkGradientShader::MakeTwoPointConical(const SkPoint& start,
             return SkShader::MakeEmptyShader();
         }
     }
-    if (1 == colorCount) {
-        return SkShader::MakeColorShader(colors[0]);
-    }
+
+    EXPAND_1_COLOR(colorCount);
 
     bool flipGradient = startRadius > endRadius;
 
@@ -860,9 +867,7 @@ sk_sp<SkShader> SkGradientShader::MakeSweep(SkScalar cx, SkScalar cy,
     if (!valid_grad(colors, pos, colorCount, SkShader::kClamp_TileMode)) {
         return nullptr;
     }
-    if (1 == colorCount) {
-        return SkShader::MakeColorShader(colors[0]);
-    }
+    EXPAND_1_COLOR(colorCount);
 
     SkGradientShaderBase::Descriptor desc;
     desc_init(&desc, colors, pos, colorCount, SkShader::kClamp_TileMode, flags, localMatrix);