grab from latest android
git-svn-id: http://skia.googlecode.com/svn/trunk@27 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/core/SkColor.cpp b/src/core/SkColor.cpp
new file mode 100644
index 0000000..4256179
--- /dev/null
+++ b/src/core/SkColor.cpp
@@ -0,0 +1,138 @@
+/* libs/graphics/sgl/SkColor.cpp
+**
+** Copyright 2006, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+** http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+
+#include "SkColor.h"
+#include "SkColorPriv.h"
+
+SkPMColor SkPreMultiplyARGB(U8CPU a, U8CPU r, U8CPU g, U8CPU b) {
+ if (a != 255) {
+#if 0
+ unsigned scale = SkAlpha255To256(a);
+ r = SkAlphaMul(r, scale);
+ g = SkAlphaMul(g, scale);
+ b = SkAlphaMul(b, scale);
+#else
+ r = SkMulDiv255Round(r, a);
+ g = SkMulDiv255Round(g, a);
+ b = SkMulDiv255Round(b, a);
+#endif
+ }
+ return SkPackARGB32(a, r, g, b);
+}
+
+SkPMColor SkPreMultiplyColor(SkColor c) {
+ unsigned a = SkColorGetA(c);
+ unsigned r = SkColorGetR(c);
+ unsigned g = SkColorGetG(c);
+ unsigned b = SkColorGetB(c);
+
+ return SkPreMultiplyARGB(a, r, g, b);
+}
+
+//////////////////////////////////////////////////////////////////////////////////////////////
+
+static inline SkScalar ByteToScalar(U8CPU x) {
+ SkASSERT(x <= 255);
+ return SkIntToScalar(x) / 255;
+}
+
+static inline SkScalar ByteDivToScalar(int numer, U8CPU denom) {
+ // cast to keep the answer signed
+ return SkIntToScalar(numer) / (int)denom;
+}
+
+void SkRGBToHSV(U8CPU r, U8CPU g, U8CPU b, SkScalar hsv[3]) {
+ SkASSERT(hsv);
+
+ unsigned min = SkMin32(r, SkMin32(g, b));
+ unsigned max = SkMax32(r, SkMax32(g, b));
+ unsigned delta = max - min;
+
+ SkScalar v = ByteToScalar(max);
+ SkASSERT(v >= 0 && v <= SK_Scalar1);
+
+ if (0 == delta) { // we're a shade of gray
+ hsv[0] = 0;
+ hsv[1] = 0;
+ hsv[2] = v;
+ return;
+ }
+
+ SkScalar s = ByteDivToScalar(delta, max);
+ SkASSERT(s >= 0 && s <= SK_Scalar1);
+
+ SkScalar h;
+ if (r == max) {
+ h = ByteDivToScalar(g - b, delta);
+ } else if (g == max) {
+ h = SkIntToScalar(2) + ByteDivToScalar(b - r, delta);
+ } else { // b == max
+ h = SkIntToScalar(4) + ByteDivToScalar(r - g, delta);
+ }
+
+ h *= 60;
+ if (h < 0) {
+ h += SkIntToScalar(360);
+ }
+ SkASSERT(h >= 0 && h < SkIntToScalar(360));
+
+ hsv[0] = h;
+ hsv[1] = s;
+ hsv[2] = v;
+}
+
+static inline U8CPU UnitScalarToByte(SkScalar x) {
+ if (x < 0) {
+ return 0;
+ }
+ if (x >= SK_Scalar1) {
+ return 255;
+ }
+ return SkScalarToFixed(x) >> 8;
+}
+
+SkColor SkHSVToColor(U8CPU a, const SkScalar hsv[3]) {
+ SkASSERT(hsv);
+
+ U8CPU s = UnitScalarToByte(hsv[1]);
+ U8CPU v = UnitScalarToByte(hsv[2]);
+
+ if (0 == s) { // shade of gray
+ return SkColorSetARGB(a, v, v, v);
+ }
+ SkFixed hx = (hsv[0] < 0 || hsv[0] >= SkIntToScalar(360)) ? 0 : SkScalarToFixed(hsv[0]/60);
+ SkFixed f = hx & 0xFFFF;
+
+ unsigned v_scale = SkAlpha255To256(v);
+ unsigned p = SkAlphaMul(255 - s, v_scale);
+ unsigned q = SkAlphaMul(255 - (s * f >> 16), v_scale);
+ unsigned t = SkAlphaMul(255 - (s * (SK_Fixed1 - f) >> 16), v_scale);
+
+ unsigned r, g, b;
+
+ SkASSERT((unsigned)(hx >> 16) < 6);
+ switch (hx >> 16) {
+ case 0: r = v; g = t; b = p; break;
+ case 1: r = q; g = v; b = p; break;
+ case 2: r = p; g = v; b = t; break;
+ case 3: r = p; g = q; b = v; break;
+ case 4: r = t; g = p; b = v; break;
+ default: r = v; g = p; b = q; break;
+ }
+ return SkColorSetARGB(a, r, g, b);
+}
+