Android Open Source - note-trainer Music Staff View

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From Project

Back to project page note-trainer.

License

The source code is released under:

Apache License

Java Source Code

package org.programmerplanet.notetrainer.android;
// w w w . j a v  a2 s.  co  m
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.util.AttributeSet;
import android.view.View;

/**
 * @author <a href="jfifield@programmerplanet.org">Joseph Fifield</a>
 * 
 * Copyright (c) 2011 Joseph Fifield
 */
public class MusicStaffView extends View {

  private static final int STAFF_SPACE_HEIGHT = 16;
  private static final int STAFF_LINE_COUNT = 5;
  private static final int STAFF_SPACE_COUNT = STAFF_LINE_COUNT - 1;
  private static final int STAFF_HEIGHT = STAFF_SPACE_HEIGHT * STAFF_SPACE_COUNT;
  private static final int STAFF_LEFT_RIGHT_MARGIN = 5;

  private static final int CLEF_TOP_OFFSET = -26;
  private static final int CLEF_LEFT_MARGIN = 5;

  private static final int LEDGER_LINE_PADDING = 10;

  private int staffTop;
  private int staffBottom;
  private Bitmap trebleClef;
  private Bitmap wholeNote;
  private Note note = Note.MIDDLE_C;

  public MusicStaffView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    initialize();
  }

  public MusicStaffView(Context context, AttributeSet attrs) {
    super(context, attrs);
    initialize();
  }

  public MusicStaffView(Context context) {
    super(context);
    initialize();
  }

  private void initialize() {
    trebleClef = BitmapFactory.decodeResource(getContext().getResources(), R.drawable.treble_clef);
    wholeNote = BitmapFactory.decodeResource(getContext().getResources(), R.drawable.whole_note);
  }

  public void setNote(Note note) {
    this.note = note;
    this.invalidate();
  }

  public Note getNote() {
    return note;
  }

  protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
    staffTop = (h / 2) - (STAFF_HEIGHT / 2);
    staffBottom = staffTop + STAFF_HEIGHT;
  }

  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    int width = measureWidth(widthMeasureSpec);
    int height = measureHeight(heightMeasureSpec);
    setMeasuredDimension(width, height);
  }

  private int measureWidth(int measureSpec) {
    int preferred = (CLEF_LEFT_MARGIN * 2) + (STAFF_LEFT_RIGHT_MARGIN * 2) + trebleClef.getWidth() * 2;
    int measurement = getMeasurement(measureSpec, preferred);
    return measurement;
  }

  private int measureHeight(int measureSpec) {
    int preferred = STAFF_HEIGHT * 2;
    int measurement = getMeasurement(measureSpec, preferred);
    return measurement;
  }

  private int getMeasurement(int measureSpec, int preferred) {
    int specSize = MeasureSpec.getSize(measureSpec);
    int measurement = preferred;
    switch (MeasureSpec.getMode(measureSpec)) {
      case MeasureSpec.EXACTLY:
        measurement = specSize;
        break;
      case MeasureSpec.AT_MOST:
        measurement = Math.min(preferred, specSize);
        break;
    }
    return measurement;
  }

  protected void onDraw(Canvas canvas) {
    drawBackground(canvas);
    drawStaff(canvas);
    drawClef(canvas);
    drawNote(canvas);
  }

  private void drawBackground(Canvas canvas) {
    canvas.drawColor(Color.WHITE);
  }

  private void drawStaff(Canvas canvas) {
    int width = getWidth();
    Paint paint = getStaffLinePaint();
    for (int i = 0; i < STAFF_LINE_COUNT; i++) {
      int y = (i * STAFF_SPACE_HEIGHT) + staffTop;
      canvas.drawLine(STAFF_LEFT_RIGHT_MARGIN, y, width - STAFF_LEFT_RIGHT_MARGIN, y, paint);
    }
  }

  private void drawClef(Canvas canvas) {
    int left = CLEF_LEFT_MARGIN + STAFF_LEFT_RIGHT_MARGIN;
    int top = staffTop + CLEF_TOP_OFFSET;
    canvas.drawBitmap(trebleClef, left, top, null);
  }

  private void drawNote(Canvas canvas) {
    int left = ((getWidth() + trebleClef.getWidth()) / 2) - (wholeNote.getWidth() / 2);

    int middleC = staffBottom + STAFF_SPACE_HEIGHT;

    int noteOffset = Note.MIDDLE_C.getName() - note.getName();

    int noteCenterY = middleC + ((STAFF_SPACE_HEIGHT / 2) * noteOffset);
    noteCenterY = noteCenterY - ((STAFF_SPACE_HEIGHT / 2) * Note.NOTE_COUNT * note.getOctave());

    canvas.drawBitmap(wholeNote, left, noteCenterY - (STAFF_SPACE_HEIGHT / 2), null);

    Paint paint = getStaffLinePaint();

    if (noteCenterY < staffTop) {
      int ledgerLineY = staffTop;
      while ((ledgerLineY -= STAFF_SPACE_HEIGHT) >= noteCenterY) {
        canvas.drawLine(left - LEDGER_LINE_PADDING, ledgerLineY, left + wholeNote.getWidth() + LEDGER_LINE_PADDING, ledgerLineY, paint);
      }
    } else if (noteCenterY > staffBottom) {
      int ledgerLineY = staffBottom;
      while ((ledgerLineY += STAFF_SPACE_HEIGHT) <= noteCenterY) {
        canvas.drawLine(left - LEDGER_LINE_PADDING, ledgerLineY, left + wholeNote.getWidth() + LEDGER_LINE_PADDING, ledgerLineY, paint);
      }
    }
  }

  private Paint getStaffLinePaint() {
    Paint paint = new Paint();
    paint.setColor(Color.BLACK);
    paint.setStyle(Style.STROKE);
    paint.setStrokeWidth(2);
    return paint;
  }

}

Java Source Code List

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