git.sesse.net Git - mlt/blob - src/modules/vmfx/filter_mono.c

   1 /*
   2  * filter_mono.c -- Arbitrary alpha channel shaping
   3  * Copyright (C) 2005 Visual Media Fx Inc.
   4  * Author: Charles Yates <charles.yates@pandora.be>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  19  */
  20
  21 #include "filter_mono.h"
  22 #include <string.h>
  23 #include <framework/mlt_factory.h>
  24 #include <framework/mlt_frame.h>
  25 #include <framework/mlt_producer.h>
  26 #include <framework/mlt_geometry.h>
  27
  28 /** Get the images and apply the luminance of the mask to the alpha of the frame.
  29 */
  30
  31 static int filter_get_image( mlt_frame this, uint8_t **image, mlt_image_format *format, int *width, int *height, int writable )
  32 {
  33         int use_alpha = mlt_deque_pop_back_int( MLT_FRAME_IMAGE_STACK( this ) );
  34         int midpoint = mlt_deque_pop_back_int( MLT_FRAME_IMAGE_STACK( this ) );
  35
  36         // Render the frame
  37         if ( mlt_frame_get_image( this, image, format, width, height, writable ) == 0 )
  38         {
  39                 uint8_t *p = *image;
  40                 int size = *width * *height;
  41
  42                 if ( !use_alpha )
  43                 {
  44                         while( size -- )
  45                         {
  46                                 if ( *p >= midpoint )
  47                                         *p ++ = 16;
  48                                 else
  49                                         *p ++ = 235;
  50                                 *p ++ = 128;
  51                         }
  52                 }
  53                 else
  54                 {
  55                         uint8_t *alpha = mlt_frame_get_alpha_mask( this );
  56                         while( size -- )
  57                         {
  58                                 if ( *alpha ++ < midpoint )
  59                                         *p ++ = 16;
  60                                 else
  61                                         *p ++ = 235;
  62                                 *p ++ = 128;
  63                         }
  64                 }
  65         }
  66
  67         return 0;
  68 }
  69
  70 /** Filter processing.
  71 */
  72
  73 static mlt_frame filter_process( mlt_filter this, mlt_frame frame )
  74 {
  75         int midpoint = mlt_properties_get_int( MLT_FILTER_PROPERTIES( this ), "midpoint" );
  76         int use_alpha = mlt_properties_get_int( MLT_FILTER_PROPERTIES( this ), "use_alpha" );
  77         mlt_deque_push_back_int( MLT_FRAME_IMAGE_STACK( frame ), midpoint );
  78         mlt_deque_push_back_int( MLT_FRAME_IMAGE_STACK( frame ), use_alpha );
  79         mlt_frame_push_get_image( frame, filter_get_image );
  80         return frame;
  81 }
  82
  83 /** Constructor for the filter.
  84 */
  85
  86 mlt_filter filter_mono_init( char *arg )
  87 {
  88         mlt_filter this = mlt_filter_new( );
  89         if ( this != NULL )
  90         {
  91                 mlt_properties_set_int( MLT_FILTER_PROPERTIES( this ), "midpoint", 128 );
  92                 mlt_properties_set_int( MLT_FILTER_PROPERTIES( this ), "use_alpha", 0 );
  93                 this->process = filter_process;
  94         }
  95         return this;
  96 }
  97