102 lines
3.0 KiB
C
102 lines
3.0 KiB
C
/* FreeRDP: A Remote Desktop Protocol Client
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* Alpha blending routines.
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* vi:ts=4 sw=4:
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*
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* (c) Copyright 2012 Hewlett-Packard Development Company, L.P.
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License. You may obtain
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* a copy of the License at http://www.apache.org/licenses/LICENSE-2.0.
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
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* or implied. See the License for the specific language governing
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* permissions and limitations under the License.
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*
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* Note: this code assumes the second operand is fully opaque,
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* e.g.
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* newval = alpha1*val1 + (1-alpha1)*val2
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* rather than
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* newval = alpha1*val1 + (1-alpha1)*alpha2*val2
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* The IPP gives other options.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <freerdp/types.h>
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#include <freerdp/primitives.h>
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#include "prim_internal.h"
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#define ALPHA(_k_) (((_k_) & 0xFF000000U) >> 24)
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#define RED(_k_) (((_k_) & 0x00FF0000U) >> 16)
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#define GRN(_k_) (((_k_) & 0x0000FF00U) >> 8)
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#define BLU(_k_) (((_k_) & 0x000000FFU))
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/* ------------------------------------------------------------------------- */
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static pstatus_t general_alphaComp_argb(
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const BYTE* pSrc1, UINT32 src1Step,
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const BYTE* pSrc2, UINT32 src2Step,
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BYTE* pDst, UINT32 dstStep,
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UINT32 width, UINT32 height)
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{
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UINT32 y;
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for (y = 0; y < height; y++)
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{
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const UINT32* sptr1 = (const UINT32*) (pSrc1 + y * src1Step);
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const UINT32* sptr2 = (const UINT32*) (pSrc2 + y * src2Step);
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UINT32* dptr = (UINT32*) (pDst + y * dstStep);
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UINT32 x;
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for (x = 0; x < width; x++)
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{
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const UINT32 src1 = *sptr1++;
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const UINT32 src2 = *sptr2++;
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UINT32 alpha = ALPHA(src1) + 1;
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if (alpha == 256)
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{
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/* If alpha is 255+1, just copy src1. */
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*dptr++ = src1;
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}
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else if (alpha <= 1)
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{
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/* If alpha is 0+1, just copy src2. */
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*dptr++ = src2;
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}
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else
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{
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/* A perfectly accurate blend would do (a*src + (255-a)*dst)/255
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* rather than adding one to alpha and dividing by 256, but this
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* is much faster and only differs by one 16% of the time.
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* I'm not sure who first designed the double-ops trick
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* (Red Blue and Alpha Green).
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*/
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UINT32 rb, ag;
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UINT32 s2rb = src2 & 0x00FF00FFU;
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UINT32 s2ag = (src2 >> 8) & 0x00FF00FFU;
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UINT32 s1rb = src1 & 0x00FF00FFU;
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UINT32 s1ag = (src1 >> 8) & 0x00FF00FFU;
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UINT32 drb = s1rb - s2rb;
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UINT32 dag = s1ag - s2ag;
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drb *= alpha;
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dag *= alpha;
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rb = ((drb >> 8) + s2rb) & 0x00FF00FFU;
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ag = (((dag >> 8) + s2ag) << 8) & 0xFF00FF00U;
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*dptr++ = rb | ag;
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}
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}
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}
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return PRIMITIVES_SUCCESS;
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}
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/* ------------------------------------------------------------------------- */
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void primitives_init_alphaComp(primitives_t* prims)
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{
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prims->alphaComp_argb = general_alphaComp_argb;
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}
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