src/apps/patchbay/MidiEventMeter.cpp

   1 /* MidiEventMeter.cpp
   2  * ------------------
   3  * Implements the MidiEventMeter class.
   4  *
   5  * Copyright 2013, Haiku, Inc. All rights reserved.
   6  * Distributed under the terms of the MIT License.
   7  *
   8  * Revisions by Pete Goodeve
   9  *
  10  * Copyright 1999, Be Incorporated.   All Rights Reserved.
  11  * This file may be used under the terms of the Be Sample Code License.
  12  */
  13
  14 #include "MidiEventMeter.h"
  15
  16 #include <stdio.h>
  17 #include <MidiRoster.h>
  18 #include <MidiProducer.h>
  19 #include <MidiConsumer.h>
  20 #include <View.h>
  21
  22 #include "CountEventConsumer.h"
  23
  24 static const BRect METER_BOUNDS(0, 0, 7, 31);
  25
  26 // If we get this number of events per pulse or greater, we will
  27 // max out the event meter.
  28 // Value was determined empirically based on my banging on a MIDI
  29 // keyboard controller with a pulse of 200ms.
  30 static const int32 METER_SCALE = 10;
  31
  32
  33 MidiEventMeter::MidiEventMeter(int32 producerID)
  34         :
  35         fCounter(NULL),
  36         fMeterLevel(0)
  37 {
  38         BMidiRoster* roster = BMidiRoster::MidiRoster();
  39         if (roster != NULL) {
  40                 BMidiProducer* producer = roster->FindProducer(producerID);
  41                 if (producer != NULL) {
  42                         BString name;
  43                         name << producer->Name() << " Event Meter";
  44                         fCounter = new CountEventConsumer(name.String());
  45                         producer->Connect(fCounter);
  46                         producer->Release();
  47                 }
  48         }
  49 }
  50
  51
  52 MidiEventMeter::~MidiEventMeter()
  53 {
  54         if (fCounter != NULL)
  55                 fCounter->Release();
  56 }
  57
  58
  59 void
  60 MidiEventMeter::Pulse(BView* view)
  61 {
  62         int32 newLevel = fMeterLevel;
  63         if (fCounter != NULL) {
  64                 newLevel = CalcMeterLevel(fCounter->CountEvents());
  65                 fCounter->Reset();
  66         }
  67         if (newLevel != fMeterLevel) {
  68                 fMeterLevel = newLevel;
  69                 view->Invalidate(BRect(METER_BOUNDS).InsetBySelf(1, 1));
  70         }
  71 }
  72
  73
  74 BRect
  75 MidiEventMeter::Bounds() const
  76 {
  77         return METER_BOUNDS;
  78 }
  79
  80
  81 void
  82 MidiEventMeter::Draw(BView* view)
  83 {
  84         const rgb_color METER_BLACK = { 0, 0, 0, 255 };
  85         const rgb_color METER_GREY = { 180, 180, 180, 255 };
  86         const rgb_color METER_GREEN = { 0, 255, 0, 255 };
  87
  88         view->PushState();
  89
  90         // draw the frame
  91         BPoint lt = METER_BOUNDS.LeftTop();
  92         BPoint rb = METER_BOUNDS.RightBottom();
  93         view->BeginLineArray(4);
  94         view->AddLine(BPoint(lt.x, lt.y), BPoint(rb.x - 1, lt.y), METER_BLACK);
  95         view->AddLine(BPoint(rb.x, lt.y), BPoint(rb.x, rb.y - 1), METER_BLACK);
  96         view->AddLine(BPoint(rb.x, rb.y), BPoint(lt.x + 1, rb.y), METER_BLACK);
  97         view->AddLine(BPoint(lt.x, rb.y), BPoint(lt.x, lt.y + 1), METER_BLACK);
  98         view->EndLineArray();
  99
 100         // draw the cells
 101         BRect cell = METER_BOUNDS;
 102         cell.InsetBy(1, 1);
 103         cell.bottom = cell.top + (cell.Height() + 1) / 5;
 104         cell.bottom--;
 105
 106         const float kTintArray[] =
 107                 {B_DARKEN_4_TINT,
 108                  B_DARKEN_3_TINT,
 109                  B_DARKEN_2_TINT,
 110                  B_DARKEN_1_TINT,
 111                  B_NO_TINT};
 112
 113         for (int32 i = 4; i >= 0; i--) {
 114                 rgb_color color;
 115                 if (fMeterLevel > i) {
 116                         color = tint_color(METER_GREEN, kTintArray[i]);
 117                 } else {
 118                         color = METER_GREY;
 119                 }
 120                 view->SetHighColor(color);
 121                 view->FillRect(cell);
 122                 cell.OffsetBy(0, cell.Height() + 1);
 123         }
 124
 125         view->PopState();
 126 }
 127
 128
 129 int32
 130 MidiEventMeter::CalcMeterLevel(int32 eventCount) const
 131 {
 132         // we use an approximately logarithmic scale for determing the actual
 133         // drawn meter level, so that low-density event streams show up well.
 134         if (eventCount == 0)
 135                 return 0;
 136         else if (eventCount < (int32)(0.5 * METER_SCALE))
 137                 return 1;
 138         else if (eventCount < (int32)(0.75 * METER_SCALE))
 139                 return 2;
 140         else if (eventCount < (int32)(0.9 * METER_SCALE))
 141                 return 3;
 142         else if (eventCount < METER_SCALE)
 143                 return 4;
 144         return 5;
 145 }