grab from latest android
git-svn-id: http://skia.googlecode.com/svn/trunk@27 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/experimental/SkSetPoly3To3_A.cpp b/experimental/SkSetPoly3To3_A.cpp
new file mode 100644
index 0000000..cc953f5
--- /dev/null
+++ b/experimental/SkSetPoly3To3_A.cpp
@@ -0,0 +1,90 @@
+#include "SkMatrix.h"
+
+#ifdef SK_SCALAR_IS_FIXED
+ typedef int64_t SkDScalar;
+
+ static SkScalar SkDScalar_toScalar(SkDScalar value) {
+ SkDScalar result = (value + (1 << 15)) >> 16;
+ int top = result >> 31;
+ SkASSERT(top == 0 || top == -1);
+ return (SkScalar)result;
+ }
+ static SkScalar div(SkDScalar numer, SkDScalar denom) {
+ denom >>= 16;
+ return numer / denom;
+ }
+#else
+ typedef double SkDScalar;
+
+ static SkScalar SkDScalar_toScalar(SkDScalar value) {
+ return static_cast<float>(value);
+ }
+ static SkScalar div(SkDScalar numer, SkDScalar denom) {
+ return static_cast<float>(numer / denom);
+ }
+#endif
+
+static SkDScalar SkDScalar_setMul(SkScalar a, SkScalar b) {
+ return (SkDScalar)a * b;
+}
+
+static void computeOuterProduct(SkScalar op[4],
+ const SkPoint pts0[3], const SkPoint& ave0,
+ const SkPoint pts1[3], const SkPoint& ave1) {
+ bzero(op, 4 * sizeof(op[0]));
+ for (int i = 0; i < 3; i++) {
+ SkScalar x0 = pts0[i].fX - ave0.fX;
+ SkScalar y0 = pts0[i].fY - ave0.fY;
+ SkScalar x1 = pts1[i].fX - ave1.fX;
+ SkScalar y1 = pts1[i].fY - ave1.fY;
+ op[0] += SkScalarMul(x0, x1);
+ op[1] += SkScalarMul(x0, y1);
+ op[2] += SkScalarMul(y0, x1);
+ op[3] += SkScalarMul(y0, y1);
+ }
+}
+
+static SkDScalar ddot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) {
+ return SkDScalar_setMul(ax, bx) + SkDScalar_setMul(ay, by);
+}
+
+static SkScalar dot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) {
+ return SkDScalar_toScalar(ddot(ax, ay, bx, by));
+}
+
+bool SkSetPoly3To3(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]) {
+ const SkPoint& srcAve = src[0];
+ const SkPoint& dstAve = dst[0];
+
+ SkScalar srcOP[4], dstOP[4];
+
+ computeOuterProduct(srcOP, src, srcAve, src, srcAve);
+ computeOuterProduct(dstOP, src, srcAve, dst, dstAve);
+
+ SkDScalar det = SkDScalar_setMul(srcOP[0], srcOP[3]) -
+ SkDScalar_setMul(srcOP[1], srcOP[2]);
+
+ SkDScalar M[4];
+
+ const SkScalar srcOP0 = srcOP[3];
+ const SkScalar srcOP1 = -srcOP[1];
+ const SkScalar srcOP2 = -srcOP[2];
+ const SkScalar srcOP3 = srcOP[0];
+
+ M[0] = ddot(srcOP0, srcOP1, dstOP[0], dstOP[2]);
+ M[1] = ddot(srcOP2, srcOP3, dstOP[0], dstOP[2]);
+ M[2] = ddot(srcOP0, srcOP1, dstOP[1], dstOP[3]);
+ M[3] = ddot(srcOP2, srcOP3, dstOP[1], dstOP[3]);
+
+ matrix->reset();
+ matrix->setScaleX(div(M[0], det));
+ matrix->setSkewX( div(M[1], det));
+ matrix->setSkewY (div(M[2], det));
+ matrix->setScaleY(div(M[3], det));
+ matrix->setTranslateX(dstAve.fX - dot(srcAve.fX, srcAve.fY,
+ matrix->getScaleX(), matrix->getSkewX()));
+ matrix->setTranslateY(dstAve.fY - dot(srcAve.fX, srcAve.fY,
+ matrix->getSkewY(), matrix->getScaleY()));
+ return true;
+}
+