android 使用 XML 布局中的 View 来绘制 Canvas

Question

所以基本上我想使用 xml 布局，但我还想要一个可以执行图形的 Canvas 。我所做的是在我的 xml 布局中创建一个 View ，如下所示。然后在我的应用程序中，我让 View 绘制了 Canvas ，但它不起作用。我不确定我解决这个问题的方法是完全错误的还是什么。因此，请看一下我的代码，然后告诉我您是否看到了快速修复或是否有更好的方法。提前致谢，我真的很感激。

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

<Button
    android:id="@+id/bTest"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Button" />



<View
    android:id="@+id/vMain"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

</LinearLayout>

这是xml布局

package sm.view.test;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Align;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.Button;

public class ViewActivity extends Activity implements OnTouchListener {
/** Called when the activity is first created. */

View v;
Button b;
boolean isRun =true;
SurfaceHolder ourHolder;
Thread ourThread;
Canvas canvas;
boolean isTure = true;
TheSurface ourSurfaceView;


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    b= (Button) findViewById(R.id.bTest);
    v = (View) findViewById(R.id.vMain);

    canvas = new Canvas();
    ourSurfaceView = new TheSurface(this);
    ourSurfaceView.setOnTouchListener(this);
    v.draw(canvas);
   // v.setBackgroundColor(Color.BLUE);
}
protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();
    ourSurfaceView.pause();
}

@Override
protected void onResume() {
    // TODO Auto-generated method stub
    super.onResume();
    ourSurfaceView.resume();
}






public boolean onTouch(View arg0, MotionEvent arg1) {
    // TODO Auto-generated method stub
    return false;
}
public class TheSurface extends SurfaceView implements Runnable{

    public TheSurface(Context context) {
        super(context);
        ourHolder= getHolder();

    }
    public void resume(){
        isRun= true;
        ourThread = new Thread(this);
        ourThread.start();  
    }
    public void pause(){
        isRun = false;
        while(true){
            try {
                ourThread.join();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            break;
        }
        ourThread= null;
    }

    public void run() {
        // TODO Auto-generated method stub

        Paint textPaint = new Paint();
        textPaint.setColor(Color.WHITE);
        while(isTure){
        if(!ourHolder.getSurface().isValid())
            continue;
        //v.draw(canvas);

         canvas = ourHolder.lockCanvas();
        canvas.drawLine(0, 0, canvas.getWidth(), canvas.getHeight(), textPaint);
        ourHolder.unlockCanvasAndPost(canvas);
        v.draw(canvas);
        }
    }

}

Answer 1

从这里开始(这也需要您输入命名空间部分“yourProjectNamespace”):

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

    <Button android:id="@+id/bTest"
        android:layout_width="wrap_content"     
        android:layout_height="wrap_content"
        android:text="Button" />    

    <sm.view.test.TheSurface android:id="@+id/vMain"
        android:layout_width="wrap_content"     
        android:layout_height="wrap_content" />  

</LinearLayout> 

在您的 TheSurface 中

实现可覆盖的例程:

public TheSurface(Context C){
    super(C);

    // Other setup code you want here
}

public TheSurface(Context C, AttributeSet attribs){
    super(C, attribs);

    // Other setup code you want here
}

public TheSurface(Context C, AttributeSet attribs, int defStyle){
    super(C, attribs, defStyle);

    // Other setup code you want here
}

protected void onDraw(Canvas canvas){
    super.onDraw(canvas);

    Paint textPaint = new Paint();
    textPaint.setColor(Color.WHITE);

    canvas.drawLine(0, 0, canvas.getWidth(), canvas.getHeight(), textPaint);

    // Other drawing functions here!!!
}

这应该可以完成您的绘图!!!

同样在我的例子中，你不必将它实现为 SurfaceView，你可以将它实现为 View，它不需要实现 runnable!!!