android - ImageView Pinch-zoom Scale Limits and pan bounds

Question

I wanted to create a gallery with images. The images within the gallery should be zoomable and pannable. I could able to pinch-zoom an image but could not able to set zoom limits and prevent the image from being panned off the screen. I used the following code to zoom an image:

First approach : I used TouchImageView to supply images to the gallery, this allows me to pinch-zoom but I can't scroll the gallery, i.e. I can't differentiate between 'single tab event' and 'tab to scroll event'.

Second approach : Used ImageView to supply images to gallery, and if user clicks on any of the gallery items display the selected image in TouchImageView, where the user can Pinch-Zoom an image. But this also prevents me from scrolling the gallery view. And also how to set zoom limits and pan bounds on the selected image?

Answer 1

This fixed the zoom-limit problem for me. After the image is zoomed in/out to the limit, it just stops going further. It's also smooth and there are no lags. 0.7 and 2.0 are the minimum and maximum zoom levels.

....
} else if (mode == ZOOM) {
    float[] f = new float[9];

    float newDist = spacing(event);
    if (newDist > 10f) {
            matrix.set(savedMatrix);
            float tScale = newDist / dist;
            matrix.postScale(tScale, tScale, mid.x, mid.y);
    }

    matrix.getValues(f);
    float scaleX = f[Matrix.MSCALE_X];
    float scaleY = f[Matrix.MSCALE_Y];

    if(scaleX <= 0.7f) {
            matrix.postScale((0.7f)/scaleX, (0.7f)/scaleY, mid.x, mid.y);
    } else if(scaleX >= 2.5f) {
            matrix.postScale((2.5f)/scaleX, (2.5f)/scaleY, mid.x, mid.y);
    }
}
....