clone of https://codereview.chromium.org/15316014/ with teaks

src/core/SkBitmapProcBicubic.cpp

Index: src/core/SkBitmapProcBicubic.cpp
diff --git a/src/core/SkBitmapProcBicubic.cpp b/src/core/SkBitmapProcBicubic.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..3c157ae9236b0b688c676287c53c0d7a95877d77
--- /dev/null
+++ b/src/core/SkBitmapProcBicubic.cpp
@@ -0,0 +1,115 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkBitmapProcBicubic.h"
+#include "SkBitmap.h"
+#include "SkColor.h"
+#include "SkColorPriv.h"
+#include "SkUnPreMultiply.h"
+#include "SkRTConf.h"
+#include "SkShader.h"
+
+#define DS(x) SkDoubleToScalar(x)
+
+inline SkPMColor cubicBlend(const SkScalar c[16], SkScalar t, SkPMColor c0, SkPMColor c1, SkPMColor c2, SkPMColor c3) {
+    SkScalar t2 = t * t, t3 = t2 * t;
+    SkScalar cc[4];
+    cc[0] = c[0]  + SkScalarMul(c[1], t) + SkScalarMul(c[2], t2) + SkScalarMul(c[3], t3);
+    cc[1] = c[4]  + SkScalarMul(c[5], t) + SkScalarMul(c[6], t2) + SkScalarMul(c[7], t3);
+    cc[2] = c[8]  + SkScalarMul(c[9], t) + SkScalarMul(c[10], t2) + SkScalarMul(c[11], t3);
+    cc[3] = c[12] + SkScalarMul(c[13], t) + SkScalarMul(c[14], t2) + SkScalarMul(c[15], t3);
+    SkScalar a = SkScalarClampMax(SkScalarMul(cc[0], SkGetPackedA32(c0)) + SkScalarMul(cc[1], SkGetPackedA32(c1)) + SkScalarMul(cc[2], SkGetPackedA32(c2)) + SkScalarMul(cc[3], SkGetPackedA32(c3)), 255);
+    SkScalar r = SkScalarMul(cc[0], SkGetPackedR32(c0)) + SkScalarMul(cc[1], SkGetPackedR32(c1)) + SkScalarMul(cc[2], SkGetPackedR32(c2)) + SkScalarMul(cc[3], SkGetPackedR32(c3));
+    SkScalar g = SkScalarMul(cc[0], SkGetPackedG32(c0)) + SkScalarMul(cc[1], SkGetPackedG32(c1)) + SkScalarMul(cc[2], SkGetPackedG32(c2)) + SkScalarMul(cc[3], SkGetPackedG32(c3));
+    SkScalar b = SkScalarMul(cc[0], SkGetPackedB32(c0)) + SkScalarMul(cc[1], SkGetPackedB32(c1)) + SkScalarMul(cc[2], SkGetPackedB32(c2)) + SkScalarMul(cc[3], SkGetPackedB32(c3));
+    return SkPackARGB32(SkScalarRoundToInt(a),
+                        SkScalarRoundToInt(SkScalarClampMax(r, a)),
+                        SkScalarRoundToInt(SkScalarClampMax(g, a)),
+                        SkScalarRoundToInt(SkScalarClampMax(b, a)));
+}
+
+static void bicubicFilter(const SkBitmapProcState& s, int x, int y,
+                          SkPMColor colors[], int count) {
+
+    static const SkScalar coefficients[16] = {
+        DS( 1.0 / 18.0), DS(-9.0 / 18.0), DS( 15.0 / 18.0), DS( -7.0 / 18.0),
+        DS(16.0 / 18.0), DS( 0.0 / 18.0), DS(-36.0 / 18.0), DS( 21.0 / 18.0),
+        DS( 1.0 / 18.0), DS( 9.0 / 18.0), DS( 27.0 / 18.0), DS(-21.0 / 18.0),
+        DS( 0.0 / 18.0), DS( 0.0 / 18.0), DS( -6.0 / 18.0), DS(  7.0 / 18.0),
+    };
+
+    SkPMColor *dptr = &(colors[0]);
+    while (count-- > 0) {
+        SkPoint srcPt;
+        s.fInvProc(*s.fInvMatrix, SkIntToScalar(x),
+                    SkIntToScalar(y), &srcPt);
+        srcPt.fX -= SK_ScalarHalf;
+        srcPt.fY -= SK_ScalarHalf;
+        SkScalar fractx = srcPt.fX - SkScalarFloorToScalar(srcPt.fX);
+        SkScalar fracty = srcPt.fY - SkScalarFloorToScalar(srcPt.fY);
+        int sx = SkScalarFloorToInt(srcPt.fX);
+        int sy = SkScalarFloorToInt(srcPt.fY);
+        int x0 = SkClampMax(sx - 1, s.fBitmap->width() - 1);
+        int x1 = SkClampMax(sx    , s.fBitmap->width() - 1);
+        int x2 = SkClampMax(sx + 1, s.fBitmap->width() - 1);
+        int x3 = SkClampMax(sx + 2, s.fBitmap->width() - 1);
+        int y0 = SkClampMax(sy - 1, s.fBitmap->height() - 1);
+        int y1 = SkClampMax(sy    , s.fBitmap->height() - 1);
+        int y2 = SkClampMax(sy + 1, s.fBitmap->height() - 1);
+        int y3 = SkClampMax(sy + 2, s.fBitmap->height() - 1);
+        SkPMColor s00 = *s.fBitmap->getAddr32(x0, y0);
+        SkPMColor s10 = *s.fBitmap->getAddr32(x1, y0);
+        SkPMColor s20 = *s.fBitmap->getAddr32(x2, y0);
+        SkPMColor s30 = *s.fBitmap->getAddr32(x3, y0);
+        SkPMColor s0 = cubicBlend(coefficients, fractx, s00, s10, s20, s30);
+        SkPMColor s01 = *s.fBitmap->getAddr32(x0, y1);
+        SkPMColor s11 = *s.fBitmap->getAddr32(x1, y1);
+        SkPMColor s21 = *s.fBitmap->getAddr32(x2, y1);
+        SkPMColor s31 = *s.fBitmap->getAddr32(x3, y1);
+        SkPMColor s1 = cubicBlend(coefficients, fractx, s01, s11, s21, s31);
+        SkPMColor s02 = *s.fBitmap->getAddr32(x0, y2);
+        SkPMColor s12 = *s.fBitmap->getAddr32(x1, y2);
+        SkPMColor s22 = *s.fBitmap->getAddr32(x2, y2);
+        SkPMColor s32 = *s.fBitmap->getAddr32(x3, y2);
+        SkPMColor s2 = cubicBlend(coefficients, fractx, s02, s12, s22, s32);
+        SkPMColor s03 = *s.fBitmap->getAddr32(x0, y3);
+        SkPMColor s13 = *s.fBitmap->getAddr32(x1, y3);
+        SkPMColor s23 = *s.fBitmap->getAddr32(x2, y3);
+        SkPMColor s33 = *s.fBitmap->getAddr32(x3, y3);
+        SkPMColor s3 = cubicBlend(coefficients, fractx, s03, s13, s23, s33);
+        *dptr++ = cubicBlend(coefficients, fracty, s0, s1, s2, s3);
+        x++;
+    }
+}
+
+SkBitmapProcState::ShaderProc32
+SkBitmapProcState::chooseBicubicFilterProc(const SkPaint& paint) {
+    // we need to be requested
+    uint32_t mask = SkPaint::kFilterBitmap_Flag
+                  | SkPaint::kBicubicFilterBitmap_Flag
+                  ;
+    if ((paint.getFlags() & mask) != mask) {
+        return NULL;
+    }
+
+    // TODO: consider supporting other configs (e.g. 565, A8)
+    if (fBitmap->config() != SkBitmap::kARGB_8888_Config) {
+        return NULL;
+    }
+    
+    // TODO: consider supporting repeat and mirror
+    if (SkShader::kClamp_TileMode != fTileModeX || SkShader::kClamp_TileMode != fTileModeY) {
+        return NULL;
+    }
+
+    // TODO: support blending inside our procs
+    if (0xFF != paint.getAlpha()) {
+        return NULL;
+    }
+
+    return bicubicFilter;
+}