SkPatch abstraction

src/core/SkPatch.cpp

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkPatch.h"
+ 
+#include "SkGeometry.h"
+#include "SkGr.h"
+
+
+////////////////////////////////////////////////////////////////////////////////
+
+SkFwDCubicEvaluator::SkFwDCubicEvaluator(SkPoint a, SkPoint b, SkPoint c, SkPoint d){ 
+    fPoints[0] = a;
+    fPoints[1] = b;
+    fPoints[2] = c;
+    fPoints[3] = d;
+
+    SkScalar cx[4], cy[4];
+    SkGetCubicCoeff(fPoints, cx, cy);
+    fCoefs[0].set(cx[0], cy[0]);
+    fCoefs[1].set(cx[1], cy[1]);
+    fCoefs[2].set(cx[2], cy[2]);
+    fCoefs[3].set(cx[3], cy[3]);
+
+    this->reset(1);
+}
+
+void SkFwDCubicEvaluator::reset(int res){
+    fRes = res;
+    SkScalar h  = 1.f/res;
+    fCurrent    = 0;
+    fMax        = res + 1;
+    fFwDiff[0]  = fCoefs[3];
+    SkScalar h2 = h*h;
+    SkScalar h3 = h2*h;
+
+    fFwDiff[3].set(6.f*fCoefs[0].x()*h3, 6.f*fCoefs[0].y()*h3); //6ah^3
+    fFwDiff[2].set(fFwDiff[3].x() + 2.f*fCoefs[1].x()*h2, //6ah^3 + 2bh^2
+                   fFwDiff[3].y() + 2.f*fCoefs[1].y()*h2);
+    fFwDiff[1].set(fCoefs[0].x()*h3 + fCoefs[1].x()*h2 + fCoefs[2].x()*h, //ah^3 + bh^2 + ch
+                   fCoefs[0].y()*h3 + fCoefs[1].y()*h2 + fCoefs[2].y()*h);
+}
+
+const SkPoint* SkFwDCubicEvaluator::getPoints() { 
+    return fPoints; 
+}
+
+const SkPoint* SkFwDCubicEvaluator::getCoefs() { 
+    return fCoefs; 
+}
+
+int SkFwDCubicEvaluator::getResolution() {
+    return fRes;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+SkPatch::SkPatch(SkPoint points[12], SkColor (*colors)[4], int res)
+        : fCtrlPoints(points)
+    , fBottom(points[0], points[1], points[2], points[3])
+        , fTop(points[4], points[5], points[6], points[7])
+        , fLeft(points[0], points[8], points[9], points[4])
+        , fRight(points[3], points[10], points[11], points[7])
+    , fResX(res)
+    , fResY(res)
+    , fVertCount(0)
+    , fIndexCount(0)
+    , fPoints(NULL)
+    , fTexCoords(NULL)
+    , fColors(NULL)
+    , fIndices(NULL)
+    , fIsSet(false) {
+                fCornerColors[0] = SkPreMultiplyColor((*colors)[0]);
+                fCornerColors[1] = SkPreMultiplyColor((*colors)[1]);
+                fCornerColors[2] = SkPreMultiplyColor((*colors)[2]);
+                fCornerColors[3] = SkPreMultiplyColor((*colors)[3]);
+}
+
+void SkPatch::clean() {
+    SkDELETE_ARRAY (fPoints);
+    SkDELETE_ARRAY (fTexCoords);
+    SkDELETE_ARRAY (fColors);
+    SkDELETE_ARRAY (fIndices);
+    fVertCount = 0;
+    fIndexCount = 0;
+    fPoints = NULL;
+    fTexCoords = NULL;
+    fColors = NULL;
+    fIndices = NULL;
+    fIsSet = false;
+}
+
+SkPatch::~SkPatch() {
+    this->clean();
+}
+
+uint8_t bilinear(SkScalar tx, SkScalar ty, SkScalar c00, SkScalar c10, SkScalar c01, SkScalar c11) {
+    SkScalar a = c00 * (1.f - tx) + c10 * tx;
+    SkScalar b = c01 * (1.f - tx) + c11 * tx;
+    return uint8_t(a * (1.f - ty) + b * ty);
+}
+
+void SkPatch::setData() {
+
+    if (fIsSet) {
+        return;
+    }
+
+    fIsSet = true;
+    fVertCount = (fResX + 1) * (fResY + 1);
+    fIndexCount = fResX * fResY * 6;
+
+    fPoints = SkNEW_ARRAY(SkPoint, fVertCount);
+    fColors = SkNEW_ARRAY(uint32_t, fVertCount);
+    fTexCoords = SkNEW_ARRAY(SkPoint, fVertCount);
+    fIndices = SkNEW_ARRAY(uint16_t, fIndexCount);
+
+    fBottom.reset(fResX);
+    fTop.reset(fResX);
+
+    SkScalar u = 0.0f;
+    int stride = fResY+1;
+    for (int x = 0; x <= fResX; x++) {
+        SkPoint bottom = fBottom++, top = fTop++;
+        fLeft.reset(fResY);
+        fRight.reset(fResY);
+        SkScalar v = 0.f;
+        for (int y = 0; y <= fResY; y++) {
+            int dataIndex = x*(fResX + 1) + y;
+
+            SkPoint left = fLeft++, right = fRight++;
+
+            SkPoint s0 = SkPoint::Make((1.0f - v)*bottom.x() + v*top.x(), 
+                                       (1.0f - v)*bottom.y() + v*top.y());
+            SkPoint s1 = SkPoint::Make((1.0f - u)*left.x() + u*right.x(),
+                                       (1.0f - u)*left.y() + u*right.y());
+            SkPoint s2 = SkPoint::Make(
+                          (1.0f - v)*((1.0f - u)*fBottom.getPoints()[0].x() 
+                            + u*fBottom.getPoints()[3].x())
+                            + v*((1.0f - u)*fTop.getPoints()[0].x() + u*fTop.getPoints()[3].x()),
+                          (1.0f - v)*((1.0f - u)*fBottom.getPoints()[0].y() 
+                            + u*fBottom.getPoints()[3].y())
+                            + v*((1.0f - u)*fTop.getPoints()[0].y() + u*fTop.getPoints()[3].y()));
+            fPoints[dataIndex] = s0 + s1 - s2;
+
+            uint8_t a = bilinear(u, v, 
+                            SkScalar(SkColorGetA(fCornerColors[0])), 
+                            SkScalar(SkColorGetA(fCornerColors[1])), 
+                            SkScalar(SkColorGetA(fCornerColors[2])), 
+                            SkScalar(SkColorGetA(fCornerColors[3])));
+            uint8_t r = bilinear(u, v, 
+                            SkScalar(SkColorGetR(fCornerColors[0])), 
+                            SkScalar(SkColorGetR(fCornerColors[1])), 
+                            SkScalar(SkColorGetR(fCornerColors[2])), 
+                            SkScalar(SkColorGetR(fCornerColors[3])));
+            uint8_t g = bilinear(u, v, 
+                            SkScalar(SkColorGetG(fCornerColors[0])), 
+                            SkScalar(SkColorGetG(fCornerColors[1])), 
+                            SkScalar(SkColorGetG(fCornerColors[2])), 
+                            SkScalar(SkColorGetG(fCornerColors[3])));
+            uint8_t b = bilinear(u, v, 
+                            SkScalar(SkColorGetB(fCornerColors[0])), 
+                            SkScalar(SkColorGetB(fCornerColors[1])), 
+                            SkScalar(SkColorGetB(fCornerColors[2])), 
+                            SkScalar(SkColorGetB(fCornerColors[3])));
+            fColors[dataIndex] = SkPackARGB32(a,r,g,b);
+            
+
+            fTexCoords[dataIndex] = SkPoint::Make(u, v);
+
+            if(x < fResX && y < fResY) {
+                int i = 6*(x*fResY + y);
+                fIndices[i] = x*stride+y;
+                fIndices[i+1] = x*stride+1+y;
+                fIndices[i+2] = (x+1)*stride+1+y;
+                fIndices[i+3] = fIndices[i];
+                fIndices[i+4] = fIndices[i+2];
+                fIndices[i+5] = (x+1)*stride+y;
+            }
+            v+=1.f/fResY;
+        }
+        u+=1.f/fResX;
+    }
+}