在图像视图中看不到android三角形形状背景

Question

我想在应用程序中为图像视图给出一个三角形背景。imageview的宽度为40dp和高度23dp，但它不显示背景。我将宽度和高度更改为imageview匹配parent.Then背景是可见的。 下面是创建三角形的可绘图。

trgl_shp.xml：

<?xml version="1.0" encoding="utf-8"?> 
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" > 
    <item> 
     <rotate 
      android:fromDegrees="-45" 
      android:pivotX="220%" 
      android:pivotY="70%" 
      android:toDegrees="45" > 
      <shape android:shape="rectangle" 
       > 
       <stroke 
        android:width="0dp" 
        android:color="#00000000" 
        /> 

       <solid android:color="#00ACED" /> 
      </shape> 
     </rotate> 
    </item> 
</layer-list> 

pick_drop.xml：

<ImageView 
      android:layout_width="40dp" 
      android:layout_height="23dp" 
      android:id="@+id/triangle1" 
      android:background="@drawable/trgl_shp" 
      android:layout_marginLeft="35dp" 
      android:layout_below="@+id/pick"></ImageView> 
     <ImageView 
      android:layout_width="40dp" 
      android:layout_height="23dp" 
      android:id="@+id/triangle" 
      android:background="@drawable/trgl_shp" 
      android:layout_marginLeft="35dp" 
      android:layout_below="@+id/drop" 
      android:layout_alignLeft="@+id/drop" 
      android:layout_alignStart="@+id/drop" 
      android:layout_marginStart="28dp"></ImageView> 

绘制形状：

Answer 1

创建一个三角形形状的ImageView .....

使用这个Java文件.......

package com.customshape; 

import android.widget.ImageView; 
import android.content.Context; 
import android.graphics.Bitmap; 
import android.graphics.Bitmap.Config; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.graphics.Path; 
import android.graphics.Point; 
import android.graphics.PorterDuff.Mode; 
import android.graphics.PorterDuffXfermode; 
import android.graphics.Rect; 
import android.graphics.drawable.BitmapDrawable; 
import android.graphics.drawable.Drawable; 
import android.util.AttributeSet; 





public class TriangleImageView extends ImageView { 

    public TriangleImageView(Context ctx, AttributeSet attrs) { 
     super(ctx, attrs); 
    } 

    @Override 
    protected void onDraw(Canvas canvas) { 

     Drawable drawable = getDrawable(); 

     if (drawable == null) { 
      return; 
     } 

     if (getWidth() == 0 || getHeight() == 0) { 
      return; 
     } 
     Bitmap b = ((BitmapDrawable) drawable).getBitmap(); 
     Bitmap bitmap = b.copy(Bitmap.Config.ARGB_8888, true); 

     int w = getWidth(), h = getHeight(); 

     Bitmap roundBitmap = getRoundedCroppedBitmap(bitmap, w); 
     canvas.drawBitmap(roundBitmap, 0, 0, null); 

    } 

    public static Bitmap getRoundedCroppedBitmap(Bitmap bitmap, int radius) { 
     Bitmap finalBitmap; 
     if (bitmap.getWidth() != radius || bitmap.getHeight() != radius) 
      finalBitmap = Bitmap.createScaledBitmap(bitmap, radius, radius, 
        false); 
     else 
      finalBitmap = bitmap; 
     Bitmap output = Bitmap.createBitmap(finalBitmap.getWidth(), 
       finalBitmap.getHeight(), Config.ARGB_8888); 
     Canvas canvas = new Canvas(output); 

     Paint paint = new Paint(); 
     final Rect rect = new Rect(0, 0, finalBitmap.getWidth(), 
       finalBitmap.getHeight()); 

     Point point1_draw = new Point(75, 0); 
     Point point2_draw = new Point(0, 180); 
     Point point3_draw = new Point(180, 180); 

     Path path = new Path(); 
     path.moveTo(point1_draw.x, point1_draw.y); 
     path.lineTo(point2_draw.x, point2_draw.y); 
     path.lineTo(point3_draw.x, point3_draw.y); 
     path.lineTo(point1_draw.x, point1_draw.y); 
     path.close(); 
     canvas.drawARGB(0, 0, 0, 0); 
     paint.setColor(Color.parseColor("#BAB399")); 
     canvas.drawPath(path, paint); 
     paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN)); 
     canvas.drawBitmap(finalBitmap, rect, rect, paint); 

     return output; 
    } 


} 

，并在XML文件中的变化.....

<com.customshape.TriangleImageView 
    android:id="@+id/imageView_triangle" 
    android:layout_width="100dp" 
    android:layout_height="100dp" 
    android:layout_marginTop="15dp" 
    android:src="@drawable/ic_launcher" 
/>