Android三角形形状背景在ImageView中不可见

Question

I want to give a triangle background for the imageview in the application.The width is 40dp and height 23dp for the imageview.But it doesnot show the background.I changed the width and height of imageview to match parent.Then the background was visible. Below is the drawable for creating triangular shape.

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>

drawable shape:

Answer 1

to create a triangle shape Imageview .....

use this java file.......

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;
    }


}

and change in xml file.....

<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" 
/>