Android extends imageView gradient transparent vertical linear from input bitmap

Asked Jul 10 '17 at 10:20

Active Jul 10 '17 at 12:03

Viewed 919 times

i need to extends custom ImageView with linear gradient tranparent. like below image.my input is bitmap data from fresco. botton 0% opacity and top 100%. can you help me how to?

public class MyImageView extends ImageView (or View) {
    ....
}

and

myImageView.doIt(myBitmapImageWithoutGradient);

thanks.

UPDATE:

public class GradientImageAlpha extends View {

    private Bitmap bitmap;
    private Paint paint;

    public GradientImageAlpha(Context context) {
        super(context);
        init();
    }

    public GradientImageAlpha(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public GradientImageAlpha(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        paint = new Paint();
    }

    public void inputBitmap(Bitmap bitmap) {
        this.bitmap = bitmap;

        Shader shaderA = new LinearGradient(0, 0, bitmap.getWidth(), 0, 0xffffffff, 0x00ffffff, Shader.TileMode.CLAMP);
        Shader shaderB = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        paint.setShader(new ComposeShader(shaderA, shaderB, PorterDuff.Mode.SRC_IN));

        invalidate();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawRect(0, 0, bitmap.getWidth(), bitmap.getHeight(), paint);
    }
}

edited Jul 10 '17 at 12:03

asked Jul 10 '17 at 10:20

Farzad

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you can this trick for transparent view [link](https://stackoverflow.com/a/14345943/4797289) – Rasoul Miri Jul 10 '17 at 10:29
@RasoulMiri this solution need to solid color match with background color :| – Farzad Jul 10 '17 at 10:36
1

https://stackoverflow.com/a/40395350/2252830 – pskink Jul 10 '17 at 10:44
no problem really – pskink Jul 10 '17 at 11:03
@pskink [stackoverflow.com/a/40395350/2252830](https://stackoverflow.com/a/40395350/2252830) this fix, but i need scaleType center Crop. what is solution? should reszie bitmap to screen? – Farzad Jul 10 '17 at 11:19
no, make a custom `BitmapDrawable` class – pskink Jul 10 '17 at 11:26
@pskink can you help me. i;m noob – Farzad Jul 10 '17 at 11:33
create a class that extends `BitmapDrawable` – pskink Jul 10 '17 at 11:34
@pskink instead extends `View` ? – Farzad Jul 10 '17 at 11:37
yes, instead extends `View` – pskink Jul 10 '17 at 11:49
@pskink `BitmapDrawable` have not `onDraw` method and `Default constructor in android.graphics.drawable.BitmapDrawable is deprecated`. can you write for me. thanks. i;m noob – Farzad Jul 10 '17 at 11:58
read https://developer.android.com/reference/android/graphics/drawable/Drawable.html and use the constructor that is not deprecated: did you see how many constructors you can use when extending `BitmapDrawable`(there are 3 non deprecated ones) ? – pskink Jul 10 '17 at 12:00
@pskink please see update my question – Farzad Jul 10 '17 at 12:04
and? this is a copy of my custom `View` it does not use any `scaleType` - it draws the image in its exact size with no scaling – pskink Jul 10 '17 at 12:07
@pskink after call my image is zoom on display. i want scaletype centercrop `imageview` method – Farzad Jul 10 '17 at 12:09
so make a custom `BitmapDrawable` then – pskink Jul 10 '17 at 12:11
@pskink `so make a custom BitmapDrawable then`. how ? :( – Farzad Jul 10 '17 at 12:11
`class MyBitmapDrawable extends BitmapDrawable {...` – pskink Jul 10 '17 at 12:13
@pskink ok, after make it, how to add to xml view? – Farzad Jul 10 '17 at 12:14
you cant add custom `Drawable` to xml - you have ti use `ImageView` api to set this `Drawable` as the content of the `ImageView` - see `ImageView` documentation – pskink Jul 10 '17 at 12:17
@pskink ok undrestand. `((ImageView) findViewById(R.id.imgeview)).setImageDrawable(new CustomDrawable(...))` ? – Farzad Jul 10 '17 at 12:19
yes, exactly... – pskink Jul 10 '17 at 12:24
what's the solution for this question? Can you please post the correct code? – KayD Dec 08 '19 at 20:22

Android extends imageView gradient transparent vertical linear from input bitmap

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