content: /*******************************************************************************
   * Copyright 2013 Sergey Tarasevich
   *
   * 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.nostra13.universalimageloader.utils;
  
  import android.graphics.BitmapFactory;
  import android.opengl.GLES10;
  import com.nostra13.universalimageloader.core.assist.ImageSize;
  import com.nostra13.universalimageloader.core.assist.ViewScaleType;
  import com.nostra13.universalimageloader.core.imageaware.ImageAware;
  
  import javax.microedition.khronos.opengles.GL10;
  
  /**
   * Provides calculations with image sizes, scales
   *
   * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
   * @since 1.8.3
   */
  public final class ImageSizeUtils {
  
  	private static final int DEFAULT_MAX_BITMAP_DIMENSION = 2048;
  
  	private static ImageSize maxBitmapSize;
  
  	static {
  		int[] maxTextureSize = new int[1];
  		GLES10.glGetIntegerv(GL10.GL_MAX_TEXTURE_SIZE, maxTextureSize, 0);
  		int maxBitmapDimension = Math.max(maxTextureSize[0], DEFAULT_MAX_BITMAP_DIMENSION);
  		maxBitmapSize = new ImageSize(maxBitmapDimension, maxBitmapDimension);
  	}
  
  	private ImageSizeUtils() {
  	}
  
  	/**
  	 * Defines target size for image aware view. Size is defined by target
  	 * {@link com.nostra13.universalimageloader.core.imageaware.ImageAware view} parameters, configuration
  	 * parameters or device display dimensions.<br />
  	 */
  	public static ImageSize defineTargetSizeForView(ImageAware imageAware, ImageSize maxImageSize) {
  		int width = imageAware.getWidth();
  		if (width <= 0) width = maxImageSize.getWidth();
  
  		int height = imageAware.getHeight();
  		if (height <= 0) height = maxImageSize.getHeight();
  
  		return new ImageSize(width, height);
  	}
  
  	/**
  	 * Computes sample size for downscaling image size (<b>srcSize</b>) to view size (<b>targetSize</b>). This sample
  	 * size is used during
  	 * {@linkplain BitmapFactory#decodeStream(java.io.InputStream, android.graphics.Rect, android.graphics.BitmapFactory.Options)
  	 * decoding image} to bitmap.<br />
  	 * <br />
  	 * <b>Examples:</b><br />
  	 * <p/>
  	 * <pre>
  	 * srcSize(100x100), targetSize(10x10), powerOf2Scale = true -> sampleSize = 8
  	 * srcSize(100x100), targetSize(10x10), powerOf2Scale = false -> sampleSize = 10
  	 *
  	 * srcSize(100x100), targetSize(20x40), viewScaleType = FIT_INSIDE -> sampleSize = 5
  	 * srcSize(100x100), targetSize(20x40), viewScaleType = CROP       -> sampleSize = 2
  	 * </pre>
  	 * <p/>
  	 * <br />
  	 * The sample size is the number of pixels in either dimension that correspond to a single pixel in the decoded
  	 * bitmap. For example, inSampleSize == 4 returns an image that is 1/4 the width/height of the original, and 1/16
  	 * the number of pixels. Any value <= 1 is treated the same as 1.
  	 *
  	 * @param srcSize       Original (image) size
  	 * @param targetSize    Target (view) size
  	 * @param viewScaleType {@linkplain ViewScaleType Scale type} for placing image in view
  	 * @param powerOf2Scale <i>true</i> - if sample size be a power of 2 (1, 2, 4, 8, ...)
  	 * @return Computed sample size
  	 */
  	public static int computeImageSampleSize(ImageSize srcSize, ImageSize targetSize, ViewScaleType viewScaleType,
  			boolean powerOf2Scale) {
  		final int srcWidth = srcSize.getWidth();
  		final int srcHeight = srcSize.getHeight();
  		final int targetWidth = targetSize.getWidth();
  		final int targetHeight = targetSize.getHeight();
  
  		int scale = 1;
  
  		switch (viewScaleType) {
  			case FIT_INSIDE:
  				if (powerOf2Scale) {
  					final int halfWidth = srcWidth / 2;
  					final int halfHeight = srcHeight / 2;
  					while ((halfWidth / scale) > targetWidth || (halfHeight / scale) > targetHeight) { // ||
  						scale *= 2;
  					}
  				} else {
  					scale = Math.max(srcWidth / targetWidth, srcHeight / targetHeight); // max
  				}
  				break;
  			case CROP:
  				if (powerOf2Scale) {
  					final int halfWidth = srcWidth / 2;
  					final int halfHeight = srcHeight / 2;
  					while ((halfWidth / scale) > targetWidth && (halfHeight / scale) > targetHeight) { // &&
  						scale *= 2;
  					}
  				} else {
  					scale = Math.min(srcWidth / targetWidth, srcHeight / targetHeight); // min
  				}
  				break;
  		}
  
  		if (scale < 1) {
  			scale = 1;
  		}
  		scale = considerMaxTextureSize(srcWidth, srcHeight, scale, powerOf2Scale);
  
  		return scale;
  	}
  
  	private static int considerMaxTextureSize(int srcWidth, int srcHeight, int scale, boolean powerOf2) {
  		final int maxWidth = maxBitmapSize.getWidth();
  		final int maxHeight = maxBitmapSize.getHeight();
  		while ((srcWidth / scale) > maxWidth || (srcHeight / scale) > maxHeight) {
  			if (powerOf2) {
  				scale *= 2;
  			} else {
  				scale++;
  			}
  		}
  		return scale;
  	}
  
  	/**
  	 * Computes minimal sample size for downscaling image so result image size won't exceed max acceptable OpenGL
  	 * texture size.<br />
  	 * We can't create Bitmap in memory with size exceed max texture size (usually this is 2048x2048) so this method
  	 * calculate minimal sample size which should be applied to image to fit into these limits.
  	 *
  	 * @param srcSize Original image size
  	 * @return Minimal sample size
  	 */
  	public static int computeMinImageSampleSize(ImageSize srcSize) {
  		final int srcWidth = srcSize.getWidth();
  		final int srcHeight = srcSize.getHeight();
  		final int targetWidth = maxBitmapSize.getWidth();
  		final int targetHeight = maxBitmapSize.getHeight();
  
  		final int widthScale = (int) Math.ceil((float) srcWidth / targetWidth);
  		final int heightScale = (int) Math.ceil((float) srcHeight / targetHeight);
  
  		return Math.max(widthScale, heightScale); // max
  	}
  
  	/**
  	 * Computes scale of target size (<b>targetSize</b>) to source size (<b>srcSize</b>).<br />
  	 * <br />
  	 * <b>Examples:</b><br />
  	 * <p/>
  	 * <pre>
  	 * srcSize(40x40), targetSize(10x10) -> scale = 0.25
  	 *
  	 * srcSize(10x10), targetSize(20x20), stretch = false -> scale = 1
  	 * srcSize(10x10), targetSize(20x20), stretch = true  -> scale = 2
  	 *
  	 * srcSize(100x100), targetSize(20x40), viewScaleType = FIT_INSIDE -> scale = 0.2
  	 * srcSize(100x100), targetSize(20x40), viewScaleType = CROP       -> scale = 0.4
  	 * </pre>
  	 *
  	 * @param srcSize       Source (image) size
  	 * @param targetSize    Target (view) size
  	 * @param viewScaleType {@linkplain ViewScaleType Scale type} for placing image in view
  	 * @param stretch       Whether source size should be stretched if target size is larger than source size. If <b>false</b>
  	 *                      then result scale value can't be greater than 1.
  	 * @return Computed scale
  	 */
  	public static float computeImageScale(ImageSize srcSize, ImageSize targetSize, ViewScaleType viewScaleType,
  			boolean stretch) {
  		final int srcWidth = srcSize.getWidth();
  		final int srcHeight = srcSize.getHeight();
  		final int targetWidth = targetSize.getWidth();
  		final int targetHeight = targetSize.getHeight();
  
  		final float widthScale = (float) srcWidth / targetWidth;
  		final float heightScale = (float) srcHeight / targetHeight;
  
  		final int destWidth;
  		final int destHeight;
  		if ((viewScaleType == ViewScaleType.FIT_INSIDE && widthScale >= heightScale) || (viewScaleType == ViewScaleType.CROP && widthScale < heightScale)) {
  			destWidth = targetWidth;
  			destHeight = (int) (srcHeight / widthScale);
  		} else {
  			destWidth = (int) (srcWidth / heightScale);
  			destHeight = targetHeight;
  		}
  
  		float scale = 1;
  		if ((!stretch && destWidth < srcWidth && destHeight < srcHeight) || (stretch && destWidth != srcWidth && destHeight != srcHeight)) {
  			scale = (float) destWidth / srcWidth;
  		}
  
  		return scale;
  	}
  }
  