自定义View--day1

public class MyVolumnView extends View {
    int count_dark = 7;
    final int MAX_COUNT = 15;
    Paint paint;
    Bitmap dark;
    Bitmap light;
    final int SPAN = 5;

    public MyVolumnView(Context context, AttributeSet attrs) {
        super(context, attrs);
        paint = new Paint();
        dark = BitmapFactory.decodeResource(getResources(),
                R.drawable.sound_line1);
        light = BitmapFactory.decodeResource(getResources(),
                R.drawable.sound_line);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        // 画的黑条目
        for (int i = 0; i < count_dark; i++) {
            canvas.drawBitmap(dark,
                    new Rect(0, 0, dark.getWidth(), dark.getHeight()),
                    new Rect(0, i * (dark.getHeight() + SPAN), dark.getWidth(),
                            i * (dark.getHeight() + SPAN) + dark.getHeight()),
                    paint);
        }

        // 画亮条目
        for (int j = count_dark; j < MAX_COUNT; j++) {
            canvas.drawBitmap(light,
                    new Rect(0, 0, dark.getWidth(), dark.getHeight()),
                    new Rect(0, j * (dark.getHeight() + SPAN), dark.getWidth(),
                            j * (dark.getHeight() + SPAN) + dark.getHeight()),
                    paint);
        }
        super.onDraw(canvas);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        //决定控件的宽高
        int realWidth = getRealSize(widthMeasureSpec, true);
        int realHeight = getRealSize(heightMeasureSpec, false);
        this.setMeasuredDimension(realWidth, realHeight);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        //触摸事件
        int action = event.getAction();
        float x = 0, y = 0;
        switch (action) {
        case MotionEvent.ACTION_DOWN:
            x = event.getX();
            y = event.getY();
            break;
        case MotionEvent.ACTION_MOVE:
            x = event.getX();
            y = event.getY();
            break;
        case MotionEvent.ACTION_UP:
            x = event.getX();
            y = event.getY();
            break;
        default:
            break;
        }
        if (x > dark.getWidth()) {
            return true;
        }
        float percent = y
                / (MAX_COUNT * dark.getHeight() + (MAX_COUNT - 1) * SPAN);
        if (percent > 1) {
            return true;
        }
        count_dark = (int) (percent * 15);
        this.invalidate();
        // Log.i("INFO", "count of dark is:"+count_dark);
        return true;
    }

    private int getRealSize(int length, boolean isWidth) {
        int realSize = 0;
        int specMode = MeasureSpec.getMode(length);
        int size = MeasureSpec.getSize(length);
        int padding = isWidth ? this.getPaddingLeft() + this.getPaddingRight()
                : this.getPaddingTop() + this.getPaddingBottom();
        if (specMode == MeasureSpec.EXACTLY) {
            realSize = size;
        } else {
            realSize = isWidth ? dark.getWidth() + padding : MAX_COUNT
                    * (dark.getHeight() + padding) + (MAX_COUNT - 1) * SPAN;
            if (specMode == MeasureSpec.UNSPECIFIED) {
                realSize = Math.min(realSize, size);
            }
        }
        Log.i("INFO", "realSize:" + realSize);
        return realSize;
    }
}