2

我编写了以下代码，但输出什么也没显示。没有任何异常抛出，也没有使用此代码绘制线条。请帮助我哪里错了？？？

主班

    @Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    View custom_view = (View) findViewById(R.id.custom_view);

    Paint p = new Paint();
    p.setColor(Color.BLACK);
    p.setStyle(Paint.Style.STROKE);
    p.setStrokeWidth((float)5);
    Canvas canvas = new Canvas();
    canvas.drawColor(Color.BLUE);

    canvas.drawLine((float)0, (float)0, (float)100, (float)100, p);
    custom_view.draw(canvas);

}

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#00000010" >

<View
    android:id="@+id/custom_view"
    android:background="#cccccc"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true" /></RelativeLayout>
4

2 回答 2

1

我认为问题在于您需要为您的View

尝试类似：

public class CustomView extends View{

private Paint p;

public CustomView(Context context, AttributeSet attrs) {
    super(context, attrs); 

    init();        
}

public CustomView(Context context){
    super(context);     

    init();
}

private void init() {       

    p = new Paint();
    p.setColor(Color.WHITE);
    p.setStyle(Paint.Style.STROKE);
    p.setStrokeWidth(5);
    p.setAntiAlias(true);
}

@Override
protected void onDraw(Canvas canvas) {

    super.onDraw(canvas);

    canvas.drawLine(0, 0, 100, 100, p);
}
}

在你的活动课上：

RelativeLayout mLayout;
CustomView mView;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);      

    mLayout = (RelativeLayout)findViewById(R.id.rootLayout);
    mView = new CustomView(this);
    mLayout.addView(mView);
}

并将一个 Id 放到rootLayout.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout     
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/rootLayout"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<View
    android:id="@+id/custom_view"
    android:background="#000000"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"    
/>
</RelativeLayout>

希望有帮助。

于 2012-08-03T01:14:43.843 回答
0

布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="horizontal" >

    <RelativeLayout
        android:id="@+id/camera_preview"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >

        <com.example.drawingapp.CameraView
            android:id="@+id/cameraView1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_alignParentTop="true" />

    </RelativeLayout>

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="20dp"
        android:layout_marginTop="152dp"
        android:contentDescription="@string/app_name"
        android:src="@drawable/ic_launcher" />

    <Button
        android:id="@+id/button_capture"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:text="@string/capture" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="152dp"
        android:text="@string/app_name" />

</RelativeLayout>

自定义视图类

public class CameraView extends View {

    private Paint p;
    int width = 0;
    int height = 0;
    int pass = 0;
    int xpos = 0;
    int ypos = 0;

    public CameraView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
        p = new Paint();
        p.setColor(Color.WHITE);
        p.setStyle(Paint.Style.STROKE);
        p.setStrokeWidth(1);
        p.setAntiAlias(true);
    }

    public CameraView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        p = new Paint();
        p.setColor(Color.WHITE);
        p.setStyle(Paint.Style.STROKE);
        p.setStrokeWidth(1);
        p.setAntiAlias(true);
    }

    public CameraView(Context context, AttributeSet attrs) {
        super(context, attrs);
        p = new Paint();
        p.setColor(Color.WHITE);
        p.setStyle(Paint.Style.STROKE);
        p.setStrokeWidth(1);
        p.setAntiAlias(true);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        super.onDraw(canvas);
        width = getWidth();
        height = getHeight();
        xpos = width / 5;
        ypos = height / 5;
        for (int i = 0; i < 5; i++) {

            p.setColor(Color.argb(100, 255, 255, 255));
            canvas.drawLine(xpos + (xpos * i), 0, xpos + (xpos * i),
                    height, p);
            // canvas.drawLine(startX, startY, stopX, stopY, paint)

        }
        p.setStyle(Style.STROKE);
        for (int i = 0; i < 5; i++) {
            p.setColor(Color.argb(100, 255, 255, 255));
            canvas.drawLine(0, (ypos * pass) + 5, width, (ypos * pass) + 5,
                    p);
            pass++;

        }
    }
    public void hide(){
        Visibility visibility = new Visibility();
        visibility.

    }

}

活动课

public class MainActivity extends Activity {


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);


}
于 2012-08-03T12:49:18.013 回答