From 4eb8c397f938044780661467ec70d0b2f99dc6ce Mon Sep 17 00:00:00 2001
From: drewcassidy <drewcassidy@me.com>
Date: Tue, 2 Mar 2021 18:27:35 -0800
Subject: [PATCH] Ground work for 3Color-black blocks

---
 src/BC1/BC1Encoder.cpp |  1 +
 src/BlockView.h        | 18 +++++++++++++-----
 src/Vector4Int.h       |  2 +-
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/BC1/BC1Encoder.cpp b/src/BC1/BC1Encoder.cpp
index 875924a..b45bbb6 100644
--- a/src/BC1/BC1Encoder.cpp
+++ b/src/BC1/BC1Encoder.cpp
@@ -667,6 +667,7 @@ void BC1Encoder::RefineBlockLS(Color4x4 &pixels, EncodeResults &block, BlockMetr
         }
     }
 }
+
 template <ColorMode M>
 void BC1Encoder::RefineBlockCF(Color4x4 &pixels, EncodeResults &block, BlockMetrics &metrics, ErrorMode error_mode, unsigned orderings) const {
     const int color_count = (unsigned)M & 0x0F;
diff --git a/src/BlockView.h b/src/BlockView.h
index feffc86..19236c3 100644
--- a/src/BlockView.h
+++ b/src/BlockView.h
@@ -131,7 +131,7 @@ template <size_t M, size_t N> class ColorBlockView : public BlockView<Color, M,
         return true;
     }
 
-    BlockMetrics GetMetrics(unsigned black_threshold = 4) {
+    BlockMetrics GetMetrics(bool ignore_black = false) {
         BlockMetrics metrics;
         metrics.min = Color(UINT8_MAX, UINT8_MAX, UINT8_MAX);
         metrics.max = Color(0, 0, 0);
@@ -139,18 +139,26 @@ template <size_t M, size_t N> class ColorBlockView : public BlockView<Color, M,
         metrics.is_greyscale = true;
         metrics.sums = {0, 0, 0};
 
+        unsigned total = 0;
+
         for (unsigned i = 0; i < M * N; i++) {
-            auto val = Base::Get(i);
+            Color val = Base::Get(i);
+            bool is_black = val.IsBlack();
+
+            metrics.has_black |= is_black;
+
+            if (ignore_black && is_black) { continue; }
+
+            metrics.is_greyscale &= val.IsGrayscale();
             for (unsigned c = 0; c < 3; c++) {
                 metrics.min[c] = std::min(metrics.min[c], val[c]);
                 metrics.max[c] = std::max(metrics.max[c], val[c]);
                 metrics.sums[c] += val[c];
             }
-            metrics.is_greyscale &= ((val.r == val.g) && (val.r == val.b));
-            metrics.has_black |= (val.r | val.g | val.b < black_threshold);
+            total++;
         }
 
-        for (unsigned c = 0; c < 3; c++) { metrics.avg[c] = (uint8_t)((unsigned)metrics.sums[c] / (M * N)); }
+        if (total > 0) metrics.avg = (metrics.sum + Vector4Int(total / 2)) / total;  // half-total added for better rounding
 
         return metrics;
     }
diff --git a/src/Vector4Int.h b/src/Vector4Int.h
index 186bebe..809652d 100644
--- a/src/Vector4Int.h
+++ b/src/Vector4Int.h
@@ -29,7 +29,7 @@ namespace rgbcx {
 
 class Vector4Int {
    public:
-    Vector4Int(int x = 0, int y = 0, int z = 0, int w = 0) {
+    Vector4Int(int x, int y, int z = 0, int w = 0) {
         _c[0] = x;
         _c[1] = y;
         _c[2] = z;