Abit/app/src/main/java/im/delight/android/identicons/Identicon.java

package im.delight.android.identicons;

/**
 * Copyright 2014 www.delight.im <info@delight.im>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.security.MessageDigest;
import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Build;
import android.util.AttributeSet;
import android.view.View;

abstract public class Identicon extends View {

    private static final String HASH_ALGORITHM = "SHA-256";
    private final int mRowCount;
    private final int mColumnCount;
    private final Paint mPaint;
    private volatile int mCellWidth;
    private volatile int mCellHeight;
    private volatile byte[] mHash;
    private volatile int[][] mColors;
    private volatile boolean mReady;

    public Identicon(Context context) {
        super(context);

        mRowCount = getRowCount();
        mColumnCount = getColumnCount();
        mPaint = new Paint();

        init();
    }

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

        mRowCount = getRowCount();
        mColumnCount = getColumnCount();
        mPaint = new Paint();

        init();
    }

    public Identicon(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

        mRowCount = getRowCount();
        mColumnCount = getColumnCount();
        mPaint = new Paint();

        init();
    }

    @SuppressLint("NewApi")
    protected void init() {
        mPaint.setStyle(Paint.Style.FILL);
        mPaint.setAntiAlias(true);
        mPaint.setDither(true);

        setWillNotDraw(false);
        if (Build.VERSION.SDK_INT >= 11) {
            setLayerType(View.LAYER_TYPE_SOFTWARE, null);
        }
    }

    public void show(String input) {
        // if the input was null
        if (input == null) {
            // we can't create a hash value and have nothing to show (draw to the view)
            mHash = null;
        }
        // if the input was a proper string (non-null)
        else {
            // generate a hash from the string to get unique but deterministic byte values
            try {
                final MessageDigest digest = java.security.MessageDigest.getInstance(HASH_ALGORITHM);
                digest.update(input == null ? new byte[0] : input.getBytes());
                mHash = digest.digest();
            }
            catch (Exception e) {
                mHash = null;
            }
        }

        // set up the cell colors according to the input that was provided via show(...)
        setupColors();

        // this view may now be drawn (and thus must be re-drawn)
        mReady = true;
        invalidate();
    }

    public void show(int input) {
        show(String.valueOf(input));
    }

    public void show(long input) {
        show(String.valueOf(input));
    }

    public void show(float input) {
        show(String.valueOf(input));
    }

    public void show(double input) {
        show(String.valueOf(input));
    }

    public void show(byte input) {
        show(String.valueOf(input));
    }

    public void show(char input) {
        show(String.valueOf(input));
    }

    public void show(boolean input) {
        show(String.valueOf(input));
    }

    public void show(Object input) {
        if (input == null) {
            mHash = null;
        }
        else {
            show(String.valueOf(input));
        }
    }

    protected void setupColors() {
        mColors = new int[mRowCount][mColumnCount];
        int colorVisible = getIconColor();

        for (int r = 0; r < mRowCount; r++) {
            for (int c = 0; c < mColumnCount; c++) {
                if (isCellVisible(r, c)) {
                    mColors[r][c] = colorVisible;
                }
                else {
                    mColors[r][c] = Color.TRANSPARENT;
                }
            }
        }
    }

    protected byte getByte(int index) {
        if (mHash == null) {
            return -128;
        }
        else {
            return mHash[index % mHash.length];
        }
    }

    abstract protected int getRowCount();

    abstract protected int getColumnCount();

    abstract protected boolean isCellVisible(int row, int column);

    abstract protected int getIconColor();

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);

        mCellWidth = w / mColumnCount;
        mCellHeight = h / mRowCount;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int size = Math.min(getMeasuredWidth(), getMeasuredHeight());
        setMeasuredDimension(size, size);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (mReady) {
            int x, y;
            for (int r = 0; r < mRowCount; r++) {
                for (int c = 0; c < mColumnCount; c++) {
                    x = mCellWidth * c;
                    y = mCellHeight * r;

                    mPaint.setColor(mColors[r][c]);

                    canvas.drawRect(x, y + mCellHeight, x + mCellWidth, y, mPaint);
                }
            }
        }
    }

}