Question

我的任务是在用户单击按钮时在第二个活动上绘制形状。所以我尝试了下面的代码，但是没有用。

我已经介绍了很多教程，但是它们都是在另一个View中完成的。我不了解该视图。

MainActivity.java

public class MainActivity extends AppCompatActivity implements 
View.OnClickListener {
    Button draw;
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        draw = findViewById(R.id.drawButton);
        draw.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        shape = dropdown.getSelectedItem().toString();
        Bundle b = new Bundle();
        b.putString("shape",shape);
        Intent i = new Intent(getApplicationContext(),shapes.class);
        i.putExtras(b);
        startActivity(i);
    }
}

Shapes.java

public class shapes extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_shapes);
        Canvas canvas = new Canvas();
        Rect rec = new Rect();
        rec.top=100;
        rec.left=100;
        rec.bottom = rec.top + 100;
        rec.right = rec.left+ 100;
        Paint p = new Paint();
        p.setColor(Color.GREEN);
        canvas.drawRect(rec,p);

    }
}

Answer 1

单击按钮时，您正在调用意图，它将创建一个新的活动。您可以在活动主布局中添加一个简单的图像视图，然后可以如下设置画布图形。

   ImageView imageView=(ImageView) findViewById(R.id.image);
    Bitmap bitmap = Bitmap.createBitmap(100, 100, 
    Bitmap.Config.ARGB_8888);    
    Canvas canvas = new Canvas(bitmap);
    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setColor(Color.BLACK);
    Rect rec = new Rect();
    rec.top=0;
    rec.left=0;
    rec.bottom = rec.top + 100;
    rec.right = rec.left+ 100;
    canvas.drawRect(rec,paint);
    imageView.setImageBitmap(bitmap);

在不使用自定义视图的情况下在Android Studio中使用画布绘制形状

1 个答案: