mm_cb.c

在linux下多媒体开发实例linux下多媒体开发

/*
 * This file contains the callback routines for MusicMachine
 */

#include <assert.h>

#include "forms.h"
#include "mm.h"
#include "soundit.h"
#include "mm_util.h"

/* array containing notes for all channels */
int notes[NUM_CHANNELS][NUM_PAGES*NUM_CHANNELS];

/* current position in notes array for each channel */
int pos[NUM_CHANNELS];

/* flags indicating if a channel is stopped */
int stopped[NUM_CHANNELS];

/* main window file menu */
void file_menu_cbk(FL_OBJECT *ob, long data)
{
  const char *filename;

  switch (fl_get_menu(ob)) {
  case 1: /* load */
    filename = fl_show_fselector("Load from file:", "", "", "");
    if (filename != 0)
      load_sample_file(filename);
    break;
  case 2: /* save */
    filename = fl_show_fselector("Save to file:", "", "", "");
    if (filename != 0) {
      save_sample_file(filename);
      fl_invalidate_fselector_cache();
    }
    break;
  case 3: /* new */
    if (fl_show_question("Clear the current patterns?", 0, 0)) {
      clear_samples();
      update_bitmaps();
    }
    break;
  case 4: /* about */
    fl_show_form(about_window, FL_PLACE_CENTER, FL_FULLBORDER, "About");
    break;
  case 5: /* quit */
    if (fl_show_question("Do you want to quit?", 0, 0)) {
      Snd_restore();
      exit(0);
    }
    break;
  default:
    assert(0); /* should never happen */
  }
}

/* main window edit menu */
void edit_menu_cbk(FL_OBJECT *ob, long data)
{
  /* only menu item is "options" */
  fl_show_form(sample_window, FL_PLACE_CENTER, FL_FULLBORDER, "Options");
}

/* play button */
void play_button_cbk(FL_OBJECT *ob, long data)
{
  int i;

  /* reset position to the start for all channels */
  for (i = 0 ; i < NUM_CHANNELS ; i++) {
    pos[i] = 0;
    stopped[i] = 0;
  }

  /* start timer object by giving it a very small non-zero value */
  fl_set_timer(timer, 0.001);
}

/* tempo slider */
void tempo_slider_cbk(FL_OBJECT *ob, long data)
{
  /* nothing to do */
}

/* used by callbacks for rhythm buttons for all channels */
void channel_callback(FL_OBJECT *ob, long data, int channel)
{
  /* get current value */
  int i = (int) data + SAMPLES_PER_PAGE * (int) fl_get_counter_value(page);

  /* see which mouse button was pushed */
  switch (fl_get_button_numb(ob)) {
  case 1:
    /* increment value */
    notes[channel][i]++;
    break;
  case 2:
    /* note value becomes a rest */
    notes[channel][i] = REST;
    break;
  case 3:
    /* decrement value */
    notes[channel][i]--;
    break;
  default:
    assert(0); /* should never happen */
  }

  /* wrap around when first or last value reached */
  if (notes[channel][i] == STOP-1)
    notes[channel][i] = 16;
  if (notes[channel][i] > NUM_SAMPLES)
    notes[channel][i] = STOP;

  update_bitmap(ob, notes[channel][i]);
}

/* rhythm buttons for channel 0 */
void channel_0_cbk(FL_OBJECT *ob, long data)
{
  channel_callback(ob, data, 0);
}

/* rhythm buttons for channel 1 */
void channel_1_cbk(FL_OBJECT *ob, long data)
{
  channel_callback(ob, data, 1);
}

/* rhythm buttons for channel 2 */
void channel_2_cbk(FL_OBJECT *ob, long data)
{
  channel_callback(ob, data, 2);
}

/* rhythm buttons for channel 3 */
void channel_3_cbk(FL_OBJECT *ob, long data)
{
  channel_callback(ob, data, 3);
}

/* rhythm buttons for channel 4 */
void channel_4_cbk(FL_OBJECT *ob, long data)
{
  channel_callback(ob, data, 4);
}

/* rhythm buttons for channel 5 */
void channel_5_cbk(FL_OBJECT *ob, long data)
{
  channel_callback(ob, data, 5);
}

/* rhythm buttons for channel 6 */
void channel_6_cbk(FL_OBJECT *ob, long data)
{
  channel_callback(ob, data, 6);
}

/* rhythm buttons for channel 7 */
void channel_7_cbk(FL_OBJECT *ob, long data)
{
  channel_callback(ob, data, 7);
}

/* page button */
void page_button_cbk(FL_OBJECT *ob, long data)
{
  /* the button itself updates the page number, we just need to update
     the display */
  update_bitmaps();
}

/* stop button */
void stop_button_cbk(FL_OBJECT *ob, long data)
{
  /* stop timer by giving it a zero value */
  fl_set_timer(timer, 0);
}

/* callback for timer */
void timer_cbk(FL_OBJECT *ob, long data)
{
  int ch;

  for (ch = 0 ; ch < NUM_CHANNELS ; ch++)
    /* play sound for this channel if it is a note and channel has not
       been stopped */
    if (notes[ch][pos[ch]] > 0 &&
	notes[ch][pos[ch]] <= NUM_SAMPLES &&
	!stopped[ch])
      Snd_effect(notes[ch][pos[ch]] - 1, ch);

  /* advance to next position */
  for (ch = 0 ; ch < NUM_CHANNELS ; ch++) {
    pos[ch]++;

    /* wrap around at end */
    if (pos[ch] >= NUM_PAGES*SAMPLES_PER_PAGE)
      pos[ch] = 0;

    /* check for loop back to start */
    if (notes[ch][pos[ch]] == LOOP)
      pos[ch] = 0;

    /* check for stop */
    if (notes[ch][pos[ch]] == STOP)
      stopped[ch] = 1;
  }

  /* set timer for next time, tempo is in beats per minute */
  fl_set_timer(ob, 60.0 / fl_get_slider_value(tempo));
}

/* sample file entry */
void sample_file_cbk(FL_OBJECT *ob, long data)
{
  char file[256];
  char msg[256];

  /* make sure file exists */
  strcpy(file, fl_get_input(sample_dir));
  strcat(file, "/");
  strcat(file, fl_get_input(ob));

  if (!file_exists(file)) {
    sprintf(msg, "Sample file \"%s\" does not exist.", file);
    fl_show_alert("Warning:",
		  msg,
		  "Enter a valid sample file name and try again.",
		  0);
  }
}

/* apply button */
void samples_apply_cbk(FL_OBJECT *ob, long data)
{
  /* reload new set of samples and parameters */
  init_samples();
}

/* options dismiss button */
void samples_dismiss_cbk(FL_OBJECT *ob, long data)
{
  /* make window go away */
  fl_hide_form(sample_window);
}

/* audio device entry field */
void audio_device_cbk(FL_OBJECT *ob, long data)
{
  char msg[256];
  const char *file = fl_get_input(ob);

  if (!file_exists(file)) {
    sprintf(msg, "Sample device \"%s\" does not exist.", file);
    fl_show_alert("Warning:",
		  msg,
		  "Enter a valid sample device file name and try again.",
		  0);
  }
}

/* sampling rate entry field */
void sampling_rate_cbk(FL_OBJECT *ob, long data)
{
  /* do a simple range check */
  int rate = atoi(fl_get_input(sampling_rate));
  if (rate < 4000 || rate > 45000)
    fl_show_alert("Warning:",
		  "Invalid sample rate.",
		  "Enter a decimal number between 4000 and 45000",
		  0);
}

/* buttons next to each sample file */
void test_sample_cbk(FL_OBJECT *ob, long data)
{
  /* play the sample passed to callback */
  Snd_effect(data, data % NUM_CHANNELS);
}

/* callback for sample directory entry field */
void sample_dir_cbk(FL_OBJECT *ob, long data)
{
  const char *file = fl_get_input(ob);
  char msg[256];

  if (!file_exists(file)) {
    sprintf(msg, "Sample directory \"%s\" does not exist.", file);
    fl_show_alert("Warning:",
		  msg,
		  "Enter a valid directory name and try again.",
		  0);
  }
}

/* about dismiss button */
void about_dismiss_cbk(FL_OBJECT *obj, long data)
{
  /* make window go away */
  fl_hide_form(about_window);
}