--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/java.desktop/share/native/libawt/java2d/loops/AlphaMacros.c Fri Sep 19 09:41:05 2014 -0700
@@ -0,0 +1,185 @@
+/*
+ * Copyright (c) 2000, 2002, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "AlphaMacros.h"
+
+/*
+ * The following equation is used to blend each pixel in a compositing
+ * operation between two images (a and b). If we have Ca (Component of a)
+ * and Cb (Component of b) representing the alpha and color components
+ * of a given pair of corresponding pixels in the two source images,
+ * then Porter & Duff have defined blending factors Fa (Factor for a)
+ * and Fb (Factor for b) to represent the contribution of the pixel
+ * from the corresponding image to the pixel in the result.
+ *
+ * Cresult = Fa * Ca + Fb * Cb
+ *
+ * The blending factors Fa and Fb are computed from the alpha value of
+ * the pixel from the "other" source image. Thus, Fa is computed from
+ * the alpha of Cb and vice versa on a per-pixel basis.
+ *
+ * A given factor (Fa or Fb) is computed from the other alpha using
+ * one of the following blending factor equations depending on the
+ * blending rule and depending on whether we are computing Fa or Fb:
+ *
+ * Fblend = 0
+ * Fblend = ONE
+ * Fblend = alpha
+ * Fblend = (ONE - alpha)
+ *
+ * The value ONE in these equations represents the same numeric value
+ * as is used to represent "full coverage" in the alpha component. For
+ * example it is the value 0xff for 8-bit alpha channels and the value
+ * 0xffff for 16-bit alpha channels.
+ *
+ * Each Porter-Duff blending rule thus defines a pair of the above Fblend
+ * equations to define Fa and Fb independently and thus to control
+ * the contributions of the two source pixels to the destination pixel.
+ *
+ * Rather than use conditional tests per pixel in the inner loop,
+ * we note that the following 3 logical and mathematical operations
+ * can be applied to any alpha value to produce the result of one
+ * of the 4 Fblend equations:
+ *
+ * Fcomp = ((alpha AND Fk1) XOR Fk2) PLUS Fk3
+ *
+ * Through appropriate choices for the 3 Fk values we can cause
+ * the result of this Fcomp equation to always match one of the
+ * defined Fblend equations. More importantly, the Fcomp equation
+ * involves no conditional tests which can stall pipelined processor
+ * execution and typically compiles very tightly into 3 machine
+ * instructions.
+ *
+ * For each of the 4 Fblend equations the desired Fk values are
+ * as follows:
+ *
+ * Fblend Fk1 Fk2 Fk3
+ * ------ --- --- ---
+ * 0 0 0 0
+ * ONE 0 0 ONE
+ * alpha ONE 0 0
+ * ONE-alpha ONE -1 ONE+1
+ *
+ * This gives us the following derivations for Fcomp. Note that
+ * the derivation of the last equation is less obvious so it is
+ * broken down into steps and uses the well-known equality for
+ * two's-complement arithmetic "((n XOR -1) PLUS 1) == -n":
+ *
+ * ((alpha AND 0 ) XOR 0) PLUS 0 == 0
+ *
+ * ((alpha AND 0 ) XOR 0) PLUS ONE == ONE
+ *
+ * ((alpha AND ONE) XOR 0) PLUS 0 == alpha
+ *
+ * ((alpha AND ONE) XOR -1) PLUS ONE+1 ==
+ * ((alpha XOR -1) PLUS 1) PLUS ONE ==
+ * (-alpha) PLUS ONE == ONE - alpha
+ *
+ * We have assigned each Porter-Duff rule an implicit index for
+ * simplicity of referring to the rule in parameter lists. For
+ * a given blending operation which uses a specific rule, we simply
+ * use the index of that rule to index into a table and load values
+ * from that table which help us construct the 2 sets of 3 Fk values
+ * needed for applying that blending rule (one set for Fa and the
+ * other set for Fb). Since these Fk values depend only on the
+ * rule we can set them up at the start of the outer loop and only
+ * need to do the 3 operations in the Fcomp equation twice per
+ * pixel (once for Fa and again for Fb).
+ * -------------------------------------------------------------
+ */
+
+/*
+ * The following definitions represent terms in the Fblend
+ * equations described above. One "term name" is chosen from
+ * each of the following 3 pairs of names to define the table
+ * values for the Fa or the Fb of a given Porter-Duff rule.
+ *
+ * AROP_ZERO the first operand is the constant zero
+ * AROP_ONE the first operand is the constant one
+ *
+ * AROP_PLUS the two operands are added together
+ * AROP_MINUS the second operand is subtracted from the first
+ *
+ * AROP_NAUGHT there is no second operand
+ * AROP_ALPHA the indicated alpha is used for the second operand
+ *
+ * These names expand to numeric values which can be conveniently
+ * combined to produce the 3 Fk values needed for the Fcomp equation.
+ *
+ * Note that the numeric values used here are most convenient for
+ * generating the 3 specific Fk values needed for manipulating images
+ * with 8-bits of alpha precision. But Fk values for manipulating
+ * images with other alpha precisions (such as 16-bits) can also be
+ * derived from these same values using a small amount of bit
+ * shifting and replication.
+ */
+#define AROP_ZERO 0x00
+#define AROP_ONE 0xff
+#define AROP_PLUS 0
+#define AROP_MINUS -1
+#define AROP_NAUGHT 0x00
+#define AROP_ALPHA 0xff
+
+/*
+ * This macro constructs a single Fcomp equation table entry from the
+ * term names for the 3 terms in the corresponding Fblend equation.
+ */
+#define MAKE_AROPS(add, xor, and) { AROP_ ## add, AROP_ ## and, AROP_ ## xor }
+
+/*
+ * These macros define the Fcomp equation table entries for each
+ * of the 4 Fblend equations described above.
+ *
+ * AROPS_ZERO Fblend = 0
+ * AROPS_ONE Fblend = 1
+ * AROPS_ALPHA Fblend = alpha
+ * AROPS_INVALPHA Fblend = (1 - alpha)
+ */
+#define AROPS_ZERO MAKE_AROPS( ZERO, PLUS, NAUGHT )
+#define AROPS_ONE MAKE_AROPS( ONE, PLUS, NAUGHT )
+#define AROPS_ALPHA MAKE_AROPS( ZERO, PLUS, ALPHA )
+#define AROPS_INVALPHA MAKE_AROPS( ONE, MINUS, ALPHA )
+
+/*
+ * This table maps a given Porter-Duff blending rule index to a
+ * pair of Fcomp equation table entries, one for computing the
+ * 3 Fk values needed for Fa and another for computing the 3
+ * Fk values needed for Fb.
+ */
+AlphaFunc AlphaRules[] = {
+ { {0, 0, 0}, {0, 0, 0} }, /* 0 - Nothing */
+ { AROPS_ZERO, AROPS_ZERO }, /* 1 - RULE_Clear */
+ { AROPS_ONE, AROPS_ZERO }, /* 2 - RULE_Src */
+ { AROPS_ONE, AROPS_INVALPHA }, /* 3 - RULE_SrcOver */
+ { AROPS_INVALPHA, AROPS_ONE }, /* 4 - RULE_DstOver */
+ { AROPS_ALPHA, AROPS_ZERO }, /* 5 - RULE_SrcIn */
+ { AROPS_ZERO, AROPS_ALPHA }, /* 6 - RULE_DstIn */
+ { AROPS_INVALPHA, AROPS_ZERO }, /* 7 - RULE_SrcOut */
+ { AROPS_ZERO, AROPS_INVALPHA }, /* 8 - RULE_DstOut */
+ { AROPS_ZERO, AROPS_ONE }, /* 9 - RULE_Dst */
+ { AROPS_ALPHA, AROPS_INVALPHA }, /*10 - RULE_SrcAtop */
+ { AROPS_INVALPHA, AROPS_ALPHA }, /*11 - RULE_DstAtop */
+ { AROPS_INVALPHA, AROPS_INVALPHA }, /*12 - RULE_Xor */
+};