Transparent bitmap is black

Question

I have two overlapping imageviews. I want one to stay unchanged while the other one is completely transparent. I am drawing with canvas to the transparent one, but I can not get a transparent bitmap. How can I rectify this?

When I set its color closer to the transparent color (by diminishing alpha channel) using bitmap.eraseColor(color), it becomes closer and closer to black. When I set it to bm.eraseColor(Color.Transparent) it appears completely black. The imageview that contains the bitmap has a transparent background, so I can show it from the outside of the black bitmap (which is supposed to transparent).

bm.add(decodeSampledBitmapFromResource(
    getIntent().getExtras().getString("filePath"),
    iv.getHeight(), iv.getWidth()).copy(
        Bitmap.Config.ARGB_8888, true));

    scaleBitmap();

    originalImage.setImageBitmap(bm.get(N).copy(
        Bitmap.Config.ARGB_8888, false));

    bm.get(N).eraseColor(Color.TRANSPARENT);
    iv.setImageBitmap(bm.get(N));

Here is the related part of the layout code:

<RelativeLayout
    android:id="@+id/myImages"
    android:layout_width="fill_parent"
    android:layout_height="0dp"
    android:layout_weight="6"
     >

    <ImageView
        android:id="@+id/originalImage"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:paddingLeft="0dp"
        android:paddingRight="0dp"
        android:scaleType="centerInside"
        android:visibility="visible" />

    <com.abacus.colorsketch.MyImageView
        android:id="@+id/workingImage"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="@android:color/transparent"
        android:paddingLeft="0dp"
        android:paddingRight="0dp"
        android:scaleType="centerInside" />
</RelativeLayout>

Yuhta Yuhta · Accepted Answer · 2013-08-15T22:44:53

3

votes

You need to call setHasAlpha before eraseColor.

Transparent bitmap is black

1 Answers