Returns a Bitmap representing the thumbnail of the specified Bitmap. - Android Graphics

Android examples for Graphics:Bitmap Thumbnail

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  4. Bitmap Thumbnail

Description

Returns a Bitmap representing the thumbnail of the specified Bitmap.

Demo Code

/**//from   w  ww.  j av  a2s  . com
 * Copyright 2014 Zhenguo Jin
 *
 * 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.
 */
//package com.java2s;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;

import android.graphics.Canvas;

import android.graphics.Paint;
import android.graphics.PaintFlagsDrawFilter;

import android.graphics.Rect;

public class Main {
    /**
     * Returns a Bitmap representing the thumbnail of the specified Bitmap. The
     * size of the thumbnail is defined by the dimension
     * android.R.dimen.launcher_application_icon_size.
     * <p/>
     * This method is not thread-safe and should be invoked on the UI thread
     * only.
     *
     * @param bitmap  The bitmap to get a thumbnail of.
     * @param context The application's context.
     * @return A thumbnail for the specified bitmap or the bitmap itself if the
     * thumbnail could not be created.
     */
    public static Bitmap createThumbnailBitmap(Bitmap bitmap,
            Context context) {
        int sIconWidth = -1;
        int sIconHeight = -1;
        final Resources resources = context.getResources();
        sIconWidth = sIconHeight = (int) resources
                .getDimension(android.R.dimen.app_icon_size);

        final Paint sPaint = new Paint();
        final Rect sBounds = new Rect();
        final Rect sOldBounds = new Rect();
        Canvas sCanvas = new Canvas();

        int width = sIconWidth;
        int height = sIconHeight;

        sCanvas.setDrawFilter(new PaintFlagsDrawFilter(Paint.DITHER_FLAG,
                Paint.FILTER_BITMAP_FLAG));

        final int bitmapWidth = bitmap.getWidth();
        final int bitmapHeight = bitmap.getHeight();

        if (width > 0 && height > 0) {
            if (width < bitmapWidth || height < bitmapHeight) {
                final float ratio = (float) bitmapWidth / bitmapHeight;

                if (bitmapWidth > bitmapHeight) {
                    height = (int) (width / ratio);
                } else if (bitmapHeight > bitmapWidth) {
                    width = (int) (height * ratio);
                }

                final Config c = (width == sIconWidth && height == sIconHeight) ? bitmap
                        .getConfig() : Config.ARGB_8888;
                final Bitmap thumb = Bitmap.createBitmap(sIconWidth,
                        sIconHeight, c);
                final Canvas canvas = sCanvas;
                final Paint paint = sPaint;
                canvas.setBitmap(thumb);
                paint.setDither(false);
                paint.setFilterBitmap(true);
                sBounds.set((sIconWidth - width) / 2,
                        (sIconHeight - height) / 2, width, height);
                sOldBounds.set(0, 0, bitmapWidth, bitmapHeight);
                canvas.drawBitmap(bitmap, sOldBounds, sBounds, paint);
                return thumb;
            } else if (bitmapWidth < width || bitmapHeight < height) {
                final Config c = Config.ARGB_8888;
                final Bitmap thumb = Bitmap.createBitmap(sIconWidth,
                        sIconHeight, c);
                final Canvas canvas = sCanvas;
                final Paint paint = sPaint;
                canvas.setBitmap(thumb);
                paint.setDither(false);
                paint.setFilterBitmap(true);
                canvas.drawBitmap(bitmap, (sIconWidth - bitmapWidth) / 2,
                        (sIconHeight - bitmapHeight) / 2, paint);
                return thumb;
            }
        }

        return bitmap;
    }
}

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