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/*************************************************************************** |
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* Copyright (c) 2024 Microsoft Corporation |
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* |
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* This program and the accompanying materials are made available under the |
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* terms of the MIT License which is available at |
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* https://opensource.org/licenses/MIT. |
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* |
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* SPDX-License-Identifier: MIT |
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**************************************************************************/ |
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/**************************************************************************/ |
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/**************************************************************************/ |
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/** */ |
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/** GUIX Component */ |
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/** */ |
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/** Display Management (Display) */ |
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/** */ |
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/**************************************************************************/ |
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#define GX_SOURCE_CODE |
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#include "gx_api.h" |
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#include "gx_display.h" |
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#define ALPHAVAL(_c) (GX_UBYTE)((_c) >> 24) |
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#define REDVAL(_c) (GX_UBYTE)((_c) >> 16) |
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#define GREENVAL(_c) (GX_UBYTE)((_c) >> 8) |
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#define BLUEVAL(_c) (GX_UBYTE)(_c) |
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#define ASSEMBLECOLOR(_a, _r, _g, _b) \ |
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(((_a) << 24) | \ |
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((_r) << 16) | \ |
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((_g) << 8) | \ |
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(_b)) |
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/**************************************************************************/ |
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/* */ |
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/* FUNCTION RELEASE */ |
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/* */ |
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/* _gx_display_driver_32argb_pixel_blend PORTABLE C */ |
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/* 6.1.3 */ |
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/* AUTHOR */ |
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/* */ |
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/* Kenneth Maxwell, Microsoft Corporation */ |
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/* */ |
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/* DESCRIPTION */ |
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/* */ |
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/* Pixel blend function for 32argb color format. */ |
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/* */ |
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/* INPUT */ |
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/* */ |
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/* context Drawing context */ |
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/* x X coordinate */ |
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/* y Y coordinate */ |
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/* color Color of line to write */ |
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/* alpha blending value 0 to 255 */ |
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/* */ |
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/* OUTPUT */ |
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/* */ |
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/* None */ |
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/* */ |
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/* CALLS */ |
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/* */ |
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/* None */ |
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/* */ |
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/* CALLED BY */ |
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/* */ |
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/* GUIX Internal Code */ |
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/* */ |
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/* RELEASE HISTORY */ |
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/* */ |
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/* DATE NAME DESCRIPTION */ |
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/* */ |
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/* 05-19-2020 Kenneth Maxwell Initial Version 6.0 */ |
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/* 09-30-2020 Kenneth Maxwell Modified comment(s), */ |
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/* resulting in version 6.1 */ |
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/* 12-31-2020 Kenneth Maxwell Modified comment(s), */ |
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/* fix pixel blend logic, */ |
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/* resulting in version 6.1.3 */ |
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/* */ |
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/**************************************************************************/ |
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90447488 |
VOID _gx_display_driver_32argb_pixel_blend(GX_DRAW_CONTEXT *context, INT x, INT y, GX_COLOR fcolor, GX_UBYTE alpha) |
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{ |
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GX_UBYTE falpha, fred, fgreen, fblue; |
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GX_UBYTE balpha, bred, bgreen, bblue; |
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GX_UBYTE oalpha; |
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ULONG bcolor; |
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ULONG *put; |
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INT combined_alpha; |
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falpha = ALPHAVAL(fcolor); |
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falpha = (GX_UBYTE)((falpha * alpha) / 255); |
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/* Is the pixel non-transparent? */ |
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✓✓ |
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if (falpha > 0) |
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{ |
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/* calculate address of pixel */ |
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80844484 |
put = (ULONG *)context -> gx_draw_context_memory; |
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80844484 |
put += context -> gx_draw_context_pitch * y; |
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80844484 |
put += x; |
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/* No need to blend if alpha value is 255. */ |
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✓✓ |
80844484 |
if (falpha == 255) |
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{ |
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32858080 |
*put = (ULONG)fcolor; |
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32858080 |
return; |
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} |
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/* split foreground into alpha, red, green, and blue components */ |
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47986404 |
fred = REDVAL(fcolor); |
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47986404 |
fgreen = GREENVAL(fcolor); |
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47986404 |
fblue = BLUEVAL(fcolor); |
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/* read background color */ |
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47986404 |
bcolor = *put; |
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/* split background color into red, green, and blue components */ |
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47986404 |
balpha = ALPHAVAL(bcolor); |
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47986404 |
bred = REDVAL(bcolor); |
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47986404 |
bgreen = GREENVAL(bcolor); |
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47986404 |
bblue = BLUEVAL(bcolor); |
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/* background alpha is inverse of foreground alpha */ |
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47986404 |
combined_alpha = (falpha * balpha) / 0xff; |
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/* blend foreground and background, each color channel */ |
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47986404 |
oalpha = (GX_UBYTE)(falpha + balpha - combined_alpha); |
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fred = (GX_UBYTE)((fred * falpha + bred * balpha - bred * combined_alpha) / oalpha); |
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fgreen = (GX_UBYTE)((fgreen * falpha + bgreen * balpha - bgreen * combined_alpha) / oalpha); |
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fblue = (GX_UBYTE)((fblue * falpha + bblue * balpha - bblue * combined_alpha) / oalpha); |
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/* re-assemble into 16-bit color and write it out */ |
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47986404 |
*put = (ULONG)ASSEMBLECOLOR(oalpha, fred, fgreen, fblue); |
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} |
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} |
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