AspectRatioImageView.java

/*
 * Copyright (C) 2015 Dominik Schürmann <dominik@dominikschuermann.de>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.sufficientlysecure.keychain.ui.widget;

import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.widget.ImageView;

import org.sufficientlysecure.keychain.R;

/**
 * Maintains an aspect ratio based on either width or height. Disabled by default.
 *
 * from https://gist.github.com/JakeWharton/2856179
 */
public class AspectRatioImageView extends ImageView {
    // NOTE: These must be kept in sync with the AspectRatioImageView attributes in attrs.xml.
    public static final int MEASUREMENT_WIDTH = 0;
    public static final int MEASUREMENT_HEIGHT = 1;

    private static final float DEFAULT_ASPECT_RATIO = 1f;
    private static final boolean DEFAULT_ASPECT_RATIO_ENABLED = false;
    private static final int DEFAULT_DOMINANT_MEASUREMENT = MEASUREMENT_WIDTH;

    private float aspectRatio;
    private boolean aspectRatioEnabled;
    private int dominantMeasurement;

    public AspectRatioImageView(Context context) {
        this(context, null);
    }

    public AspectRatioImageView(Context context, AttributeSet attrs) {
        super(context, attrs);

        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.AspectRatioImageView);
        aspectRatio = a.getFloat(R.styleable.AspectRatioImageView_aspectRatio, DEFAULT_ASPECT_RATIO);
        aspectRatioEnabled = a.getBoolean(R.styleable.AspectRatioImageView_aspectRatioEnabled,
                DEFAULT_ASPECT_RATIO_ENABLED);
        dominantMeasurement = a.getInt(R.styleable.AspectRatioImageView_dominantMeasurement,
                DEFAULT_DOMINANT_MEASUREMENT);
        a.recycle();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (!aspectRatioEnabled) return;

        int newWidth;
        int newHeight;
        switch (dominantMeasurement) {
            case MEASUREMENT_WIDTH:
                newWidth = getMeasuredWidth();
                newHeight = (int) (newWidth * aspectRatio);
                break;

            case MEASUREMENT_HEIGHT:
                newHeight = getMeasuredHeight();
                newWidth = (int) (newHeight * aspectRatio);
                break;

            default:
                throw new IllegalStateException("Unknown measurement with ID " + dominantMeasurement);
        }

        setMeasuredDimension(newWidth, newHeight);
    }

    /**
     * Get the aspect ratio for this image view.
     */
    public float getAspectRatio() {
        return aspectRatio;
    }

    /**
     * Set the aspect ratio for this image view. This will update the view instantly.
     */
    public void setAspectRatio(float aspectRatio) {
        this.aspectRatio = aspectRatio;
        if (aspectRatioEnabled) {
            requestLayout();
        }
    }

    /**
     * Get whether or not forcing the aspect ratio is enabled.
     */
    public boolean getAspectRatioEnabled() {
        return aspectRatioEnabled;
    }

    /**
     * set whether or not forcing the aspect ratio is enabled. This will re-layout the view.
     */
    public void setAspectRatioEnabled(boolean aspectRatioEnabled) {
        this.aspectRatioEnabled = aspectRatioEnabled;
        requestLayout();
    }

    /**
     * Get the dominant measurement for the aspect ratio.
     */
    public int getDominantMeasurement() {
        return dominantMeasurement;
    }

    /**
     * Set the dominant measurement for the aspect ratio.
     *
     * @see #MEASUREMENT_WIDTH
     * @see #MEASUREMENT_HEIGHT
     */
    public void setDominantMeasurement(int dominantMeasurement) {
        if (dominantMeasurement != MEASUREMENT_HEIGHT && dominantMeasurement != MEASUREMENT_WIDTH) {
            throw new IllegalArgumentException("Invalid measurement type.");
        }
        this.dominantMeasurement = dominantMeasurement;
        requestLayout();
    }
}