如何在Android中使用画布绘制ECG波形

Question

我尝试使用画布方法绘制波形。不幸的是，我得到当前位置到结束位置，但我需要全面展示视野。

MainActivity

public class LineView extends ActionBarActivity { 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_line_view); 

} 

XML

<LinearLayout android:orientation="vertical" 
    android:layout_height="350dp" 
    android:layout_width="fill_parent"> 

<com.akasmedical.android.linedrawing.DemoView 
    android:layout_height="match_parent" 
    android:layout_width="wrap_content"/> 

`

我的看法是这里

public class DemoView extends View { 
private final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG); 
private final Paint paint1 = new Paint(Paint.ANTI_ALIAS_FLAG); 
int x = 35, j = 35; 
int i = 0; 
//ECG Wave form 
int[] a = {20, 50, 40, 65, 56, 43, 22, 23, 55, 77, 76, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25}; 

public DemoView(Context context) { 
    super(context); 
    init(); 
} 

public DemoView(Context context, AttributeSet attrs) { 
    super(context, attrs); 
    init(); 
} 

public DemoView(Context context, AttributeSet attrs, int defStyleAttr) { 
    super(context, attrs, defStyleAttr); 
    init(); 

} 

public void init() { 
    paint.setColor(Color.WHITE); 
    paint1.setColor(Color.RED); 
} 

@Override 
protected synchronized void onDraw(Canvas canvas) { 
    super.onDraw(canvas); 

    try { 
     Thread.sleep(50); 
    } catch (InterruptedException e) { 
     e.printStackTrace(); 
    } 

    if (i != 0) { 
     //draw wave form here 
     canvas.drawLine(x, (getHeight()/4) - a[i], x + 1, (getHeight()/4) - a[i - 1], paint1); 
     System.out.println(x); 
    } 
    i++; 
    if (i == 22) { 
     i = 0; 
    } 
    //Repaint wave form 
    if (x > getWidth() - 25) { 
     canvas.drawRect(j, 0, j + 20, getHeight(), paint); 
     j += 4; 
     if (j > getWidth() - 25) 
      j = 35; 
    } else { 
     x += 4; 
    } 
    invalidate(); 
}} 

预计产量喜欢这里

我不仅需要当前到结束的位置。我希望以前的位置也吸引了观看活动。

Answer 1

您必须将您的数据点映射到像素并在这些像素之间画线。

您应该在onDraw（）中绘制所有点，而不只是一个。这样的事情：

@Override 
protected synchronized void onDraw(Canvas canvas) { 
    super.onDraw(canvas); 
    int ecg_max = 250; 
    int pixelx=0; 
    int pixely=0; 
    int pixelx_prev=0; 
    int pixely_prev=0; 

    for (int i=0;i<a.length;i++){ 
     //map point number to X 
     pixelx = getWidth()*(i/a.length); 
     //map point value to Y (notice that the axis is inverted) 
     pixely = getHeight() - getHeight()*(a[i]/ecg_max); 
     canvas.drawLine(pixelx, pixely, pixelx_prev, pixely_prev, paint); 
     pixelx_prev = pixelx; 
     pixely_prev = pixely; 
    } 

}