com.nostra13.universalimageloader.utils

类 ImageSizeUtils

java.lang.Object

com.nostra13.universalimageloader.utils.ImageSizeUtils

public final class ImageSizeUtils
extends Object

Provides calculations with image sizes, scales

从以下版本开始:

1.8.3

方法概要

限定符和类型	方法和说明
static int	computeImageSampleSize(ImageSize srcSize, ImageSize targetSize, ViewScaleType viewScaleType, boolean powerOf2Scale) Computes sample size for downscaling image size (srcSize) to view size (targetSize).
static float	computeImageScale(ImageSize srcSize, ImageSize targetSize, ViewScaleType viewScaleType, boolean stretch) Computes scale of target size (targetSize) to source size (srcSize).
static int	computeMinImageSampleSize(ImageSize srcSize) Computes minimal sample size for downscaling image so result image size won't exceed max acceptable OpenGL texture size.
static ImageSize	defineTargetSizeForView(ImageAware imageAware, ImageSize maxImageSize) Defines target size for image aware view.

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

方法详细资料

defineTargetSizeForView

public static ImageSize defineTargetSizeForView(ImageAware imageAware,
                                                ImageSize maxImageSize)

Defines target size for image aware view. Size is defined by target view parameters, configuration parameters or device display dimensions.

computeImageSampleSize

public static int computeImageSampleSize(ImageSize srcSize,
                                         ImageSize targetSize,
                                         ViewScaleType viewScaleType,
                                         boolean powerOf2Scale)

Computes sample size for downscaling image size (srcSize) to view size (targetSize). This sample size is used during decoding image to bitmap.

Examples:

 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
 

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.

参数:

srcSize - Original (image) size

targetSize - Target (view) size

viewScaleType - Scale type for placing image in view

powerOf2Scale - true - if sample size be a power of 2 (1, 2, 4, 8, ...)

返回:

Computed sample size

computeMinImageSampleSize

public static int computeMinImageSampleSize(ImageSize srcSize)

Computes minimal sample size for downscaling image so result image size won't exceed max acceptable OpenGL texture size.
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.

参数:

srcSize - Original image size

返回:

Minimal sample size

computeImageScale

public static float computeImageScale(ImageSize srcSize,
                                      ImageSize targetSize,
                                      ViewScaleType viewScaleType,
                                      boolean stretch)

Computes scale of target size (targetSize) to source size (srcSize).

Examples:

 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
 

参数:

srcSize - Source (image) size

targetSize - Target (view) size

viewScaleType - Scale type for placing image in view

stretch - Whether source size should be stretched if target size is larger than source size. If false then result scale value can't be greater than 1.

返回:

Computed scale