reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 1 | #include "SkMatrix.h" |
| 2 | |
| 3 | #ifdef SK_SCALAR_IS_FIXED |
| 4 | typedef int64_t SkDScalar; |
| 5 | |
| 6 | static SkScalar SkDScalar_toScalar(SkDScalar value) { |
| 7 | SkDScalar result = (value + (1 << 15)) >> 16; |
| 8 | int top = result >> 31; |
| 9 | SkASSERT(top == 0 || top == -1); |
| 10 | return (SkScalar)result; |
| 11 | } |
| 12 | static SkScalar div(SkDScalar numer, SkDScalar denom) { |
| 13 | denom >>= 16; |
| 14 | return numer / denom; |
| 15 | } |
| 16 | #else |
| 17 | typedef double SkDScalar; |
| 18 | |
| 19 | static SkScalar SkDScalar_toScalar(SkDScalar value) { |
| 20 | return static_cast<float>(value); |
| 21 | } |
| 22 | static SkScalar div(SkDScalar numer, SkDScalar denom) { |
| 23 | return static_cast<float>(numer / denom); |
| 24 | } |
| 25 | #endif |
| 26 | |
| 27 | static SkDScalar SkDScalar_setMul(SkScalar a, SkScalar b) { |
| 28 | return (SkDScalar)a * b; |
| 29 | } |
| 30 | |
| 31 | static void computeOuterProduct(SkScalar op[4], |
| 32 | const SkPoint pts0[3], const SkPoint& ave0, |
| 33 | const SkPoint pts1[3], const SkPoint& ave1) { |
reed@android.com | 4516f47 | 2009-06-29 16:25:36 +0000 | [diff] [blame] | 34 | sk_bzero(op, 4 * sizeof(op[0])); |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 35 | for (int i = 0; i < 3; i++) { |
| 36 | SkScalar x0 = pts0[i].fX - ave0.fX; |
| 37 | SkScalar y0 = pts0[i].fY - ave0.fY; |
| 38 | SkScalar x1 = pts1[i].fX - ave1.fX; |
| 39 | SkScalar y1 = pts1[i].fY - ave1.fY; |
| 40 | op[0] += SkScalarMul(x0, x1); |
| 41 | op[1] += SkScalarMul(x0, y1); |
| 42 | op[2] += SkScalarMul(y0, x1); |
| 43 | op[3] += SkScalarMul(y0, y1); |
| 44 | } |
| 45 | } |
| 46 | |
| 47 | static SkDScalar ddot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) { |
| 48 | return SkDScalar_setMul(ax, bx) + SkDScalar_setMul(ay, by); |
| 49 | } |
| 50 | |
| 51 | static SkScalar dot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) { |
| 52 | return SkDScalar_toScalar(ddot(ax, ay, bx, by)); |
| 53 | } |
| 54 | |
| 55 | bool SkSetPoly3To3(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]) { |
| 56 | const SkPoint& srcAve = src[0]; |
| 57 | const SkPoint& dstAve = dst[0]; |
| 58 | |
| 59 | SkScalar srcOP[4], dstOP[4]; |
| 60 | |
| 61 | computeOuterProduct(srcOP, src, srcAve, src, srcAve); |
| 62 | computeOuterProduct(dstOP, src, srcAve, dst, dstAve); |
| 63 | |
| 64 | SkDScalar det = SkDScalar_setMul(srcOP[0], srcOP[3]) - |
| 65 | SkDScalar_setMul(srcOP[1], srcOP[2]); |
| 66 | |
| 67 | SkDScalar M[4]; |
| 68 | |
| 69 | const SkScalar srcOP0 = srcOP[3]; |
| 70 | const SkScalar srcOP1 = -srcOP[1]; |
| 71 | const SkScalar srcOP2 = -srcOP[2]; |
| 72 | const SkScalar srcOP3 = srcOP[0]; |
| 73 | |
| 74 | M[0] = ddot(srcOP0, srcOP1, dstOP[0], dstOP[2]); |
| 75 | M[1] = ddot(srcOP2, srcOP3, dstOP[0], dstOP[2]); |
| 76 | M[2] = ddot(srcOP0, srcOP1, dstOP[1], dstOP[3]); |
| 77 | M[3] = ddot(srcOP2, srcOP3, dstOP[1], dstOP[3]); |
| 78 | |
| 79 | matrix->reset(); |
| 80 | matrix->setScaleX(div(M[0], det)); |
| 81 | matrix->setSkewX( div(M[1], det)); |
| 82 | matrix->setSkewY (div(M[2], det)); |
| 83 | matrix->setScaleY(div(M[3], det)); |
| 84 | matrix->setTranslateX(dstAve.fX - dot(srcAve.fX, srcAve.fY, |
| 85 | matrix->getScaleX(), matrix->getSkewX())); |
| 86 | matrix->setTranslateY(dstAve.fY - dot(srcAve.fX, srcAve.fY, |
| 87 | matrix->getSkewY(), matrix->getScaleY())); |
| 88 | return true; |
| 89 | } |
| 90 | |