Android: Zoom in-out ImageView with buttons (without MotionEvent)

Question

I need to be able to Zoom an ImageView in/out with two buttons: one for zoom in, another for zoom out. I have successfully implemented zoom in/out with MotionEvent, but have no idea how to implement with buttons. Maybe I could create fake MotionEvents or something similar?

Answer 1

Add these 2 method in TouchImageView Class

public void zoomIn() { //bind on zoomIn Button
    oldScale = saveScale;

    if(saveScale<=maxScale)
    {
        saveScale += .5;
        matrix.setScale(saveScale, saveScale);
        setImageMatrix(matrix);
        invalidate();

        // Center the image
        // Center the image
        if(bmHeight>bmWidth)
        {
        redundantXSpace = width - (saveScale * bmWidth);
        redundantXSpace /= 2;
        }
        else 
        {
            redundantYSpace = height - (saveScale * bmHeight) ;
            redundantYSpace /= 2;
        }

        matrix.postTranslate(redundantXSpace , redundantYSpace );
        setImageMatrix(matrix);
        invalidate();
    }
}

public void zoomOut() { 


 //Bind on zoom Out Button

    if(saveScale>=minScale)
    {
        saveScale -= .5;
        matrix.setScale(saveScale, saveScale);
        setImageMatrix(matrix);
        invalidate();

        // Center the image
        if(bmHeight>bmWidth)
        {
        redundantXSpace = width - (saveScale * bmWidth);
        redundantXSpace /= 2;
        }
        else 
        {
            redundantYSpace = height - (saveScale * bmHeight) ;
            redundantYSpace /= 2;
        }
        matrix.postTranslate(redundantXSpace , redundantYSpace );
        setImageMatrix(matrix);
        invalidate();
    }
}

for on Button click protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);

setContentView(R.layout.LAYOUT_NAME);

Button zoonIn = (Button)findViewById(R.id.ZOOM_IN_BUTTON_ID);
Button zoonOut = (Button)findViewById(R.id.ZOOM_OUT_BUTTON_ID);

final TouchImageView touch = (TouchImageView)findViewById(R.id.YOUR_TOUCH_IMAGE_VIEW_)ID);

Bitmap bImage = BitmapFactory.decodeResource(this.getResources(), R.drawable.DRAWABLE_ID);

touch.setImageBitmap(bImage);

touch.setMaxZoom(4f); //change the max level of zoom, default is 3f


zoonIn.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        touch.zoomIn();
    }
});


zoonOut.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        touch.zoomOut();
    }
});

}