libs/graphics/sgl/SkFilterProc.h

/* libs/graphics/sgl/SkFilterProc.h
**
** Copyright 2006, Google Inc.
**
** Licensed under the Apache License, Version 2.0 (the "License"); 
** you may not use this file except in compliance with the License. 
** You may obtain a copy of the License at 
**
**     http://www.apache.org/licenses/LICENSE-2.0 
**
** Unless required by applicable law or agreed to in writing, software 
** distributed under the License is distributed on an "AS IS" BASIS, 
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
** See the License for the specific language governing permissions and 
** limitations under the License.
*/

#ifndef SkFilter_DEFINED
#define SkFilter_DEFINED

#include "SkMath.h"

typedef unsigned (*SkFilterProc)(unsigned x00, unsigned x01, unsigned x10, unsigned x11);

const SkFilterProc* SkGetBilinearFilterProcTable();

inline SkFilterProc SkGetBilinearFilterProc(const SkFilterProc* table, SkFixed x, SkFixed y)
{
    SkASSERT(table);

    // convert to dot 2
    x = (unsigned)(x << 16) >> 30;
    y = (unsigned)(y << 16) >> 30;
    return table[(y << 2) | x];
}

/** Special version of SkFilterProc. This takes the address of 4 ints, and combines them a byte at a
    time. AABBCCDD.
*/
typedef uint32_t (*SkFilterPtrProc)(const uint32_t*, const uint32_t*, const uint32_t*, const uint32_t*);

const SkFilterPtrProc* SkGetBilinearFilterPtrProcTable();
inline SkFilterPtrProc SkGetBilinearFilterPtrProc(const SkFilterPtrProc* table, SkFixed x, SkFixed y)
{
    SkASSERT(table);

    // convert to dot 2
    x = (unsigned)(x << 16) >> 30;
    y = (unsigned)(y << 16) >> 30;
    return table[(y << 2) | x];
}

/** Given a Y value, return a subset of the proc table for that value.
    Pass this to SkGetBilinearFilterPtrXProc with the corresponding X value to get the
    correct proc.
*/
inline const SkFilterPtrProc* SkGetBilinearFilterPtrProcYTable(const SkFilterPtrProc* table, SkFixed y)
{
    SkASSERT(table);

    y = (unsigned)(y << 16) >> 30;
    return table + (y << 2);
}

/** Given a subtable returned by SkGetBilinearFilterPtrProcYTable(), return the proc for the
    specified X value.
*/
inline SkFilterPtrProc SkGetBilinearFilterPtrXProc(const SkFilterPtrProc* table, SkFixed x)
{
    SkASSERT(table);

    // convert to dot 2
    x = (unsigned)(x << 16) >> 30;
    return table[x];
}

#endif