Image out of bounds after transformation on view

Question

I'm having a problem with displaying my image.

I have an Image I want to display full screen. So I have this Imageview with match_parent and 20dp padding.

It looks good but when I apply rotation on it, it seems that the bounds of the view doesn't change and the image can get clipped out of the screen ! Totally don't want that to happen! How do I rescale the image so that the image also fits in the ImageView when its 90 degrees rotated.

This is my XML WITH rotation in it.

EDIT:

How to fix the bounds of the Image so the Text is aligned just above the image?

Answer 1

The rotation is not taken into account when measuring the view and calculating the scale ratio. A possible solution is to do it yourself :

public class RotatedImageView extends ImageView {

    ...
    constructors
    ...


    private double mRotatedWidth;
    private double mRotatedHeight;

    private boolean update() {
        Drawable d = getDrawable();

        if (d == null) {
            return false;
        }

        int drawableWidth = d.getIntrinsicWidth();
        int drawableHeight = d.getIntrinsicHeight();

        if (drawableWidth <= 0 || drawableHeight <= 0) {
            return false;
        }

        double rotationRad = getRotation() / 180 * Math.PI;

        // calculate intrinsic rotated size
        // see diagram

        mRotatedWidth = (Math.abs(Math.sin(rotationRad)) * drawableHeight
                + Math.abs(Math.cos(rotationRad)) * drawableWidth);
        mRotatedHeight = (Math.abs(Math.cos(rotationRad)) * drawableHeight
                + Math.abs(Math.sin(rotationRad)) * drawableWidth);

        return true;
    }


    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        if (update()) {
            double ratio = mRotatedWidth / mRotatedHeight;

            int wMax = Math.min(getDefaultSize(Integer.MAX_VALUE, widthMeasureSpec), getMaxWidth());
            int hMax = Math.min(getDefaultSize(Integer.MAX_VALUE, heightMeasureSpec), getMaxHeight());

            int w = (int) Math.min(wMax, hMax * ratio);
            int h = (int) Math.min(hMax, wMax / ratio);

            setMeasuredDimension(w, h);
        } else {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }

    }

    private final float[] values = new float[9];

    protected void onDraw(Canvas canvas) {

        if (update()) {
            int availableWidth = getMeasuredWidth();
            int availableHeight = getMeasuredHeight();

            float scale = (float) Math.min(availableWidth / mRotatedWidth, availableHeight / mRotatedHeight);

            getImageMatrix().getValues(values);

            setScaleX(scale / values[Matrix.MSCALE_X]);
            setScaleY(scale / values[Matrix.MSCALE_Y]);
        }

        super.onDraw(canvas);
    }

    @Override
    public void setRotation(float rotation) {
        super.setRotation(rotation);
        requestLayout();
    }
}

adjustViewBounds must be true :

<com.mypackage.RotatedImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_margin="20dp"
    android:adjustViewBounds="true"
    android:rotation="90"
    android:maxWidth="100dp"
    android:maxHeight="100dp"
    android:scaleType="fitCenter"
    android:src="@drawable/test" />

A nice explanation of the calculation, courtesy of Cheticamp :

UPDATE: Now trying to adjust the bounds. There is no difference between wrap_content and match_parent (both grow as much as possible, based on the image aspect). You should instead use maxWidth and / or maxHeight, or put it in a LinearLayout with a 0 size and a weight.

It is also not animatable, adjusting bounds while animating requires a layout pass for each frame, which is very inefficient. See the other answer for a version usable with View.animate()