通过将画布视为一个视图来绘制矩形

Question

是否有一种简单的方法在画布上绘制矩形并将其显示在像TextView这样的活动中？

我极力把我的矩形像这样：

Paint paint = new Paint(); 
paint.setStyle(Paint.Style.FILL); 
paint.setColor(Color.MAGENTA); 
Bitmap b = Bitmap.createBitmap(100, 100, Bitmap.Config.ARGB_8888); 
Canvas c = new Canvas(b); 

Rect locationrect = new Rect(10, 10, 200, 100); 
c.drawRect(locationrect, paint); 

View locationpic = (View)findViewById(R.id.locationview); 
locationpic.draw(c); 

在我的xml：

<View 
    android:id="@+id/locationview" 
    android:layout_width="520dp" 
    android:layout_height="489dp" 
    android:layout_marginLeft="40dp" 
    android:layout_marginTop="220dp" /> 

这显然是不工作（它不会崩溃，但不显示矩形）..任何帮助，将不胜感激！ 谢谢！

Answer 1

创建一个Java文件并写入：

package com.samplecanvas;

import java.util.ArrayList; 

import android.app.Activity; import android.content.Context; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Path; import android.graphics.Rect; import android.graphics.RectF; 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.view.ViewGroup.LayoutParams; import android.view.Window; import android.view.WindowManager; import android.widget.FrameLayout;

import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.view.View;

 public class SampleCanvasActivity extends View { 
     vPaint paint = new Paint(); 

      public SampleCanvasActivity(Context context) { 
       super(context); 
      } 

@Override 
public void onDraw(Canvas canvas) { 
    paint.setColor(Color.BLACK); 
    paint.setStrokeWidth(3); 
    canvas.drawRect(130, 130, 180, 180, paint); 
    paint.setStrokeWidth(0); 
    paint.setColor(Color.CYAN); 
    canvas.drawRect(133, 160, 177, 177, paint); 
    paint.setColor(Color.YELLOW); 
    canvas.drawRect(133, 133, 177, 160, paint); 

} 

}

使用此文件中的XML乌尔

筛选。

<com.samplecanvas.SampleCanvasActivity 
android:id="@+id/widthView" 
android:layout_width="wrap_content" 
android:layout_height="wrap_content" 
android:layout_marginLeft="30dp" 
android:layout_marginTop="150dp" 
/>