/*
* Copyright (C) 2024 Huawei Device Co., Ltd.
* 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 { BaseDownsampling } from './BaseDownsampling';
import { getScale, highestOneBit, round, SampleSizeRounding } from './DownsampleUtils';
export class FitCenter implements BaseDownsampling {
getName() {
return 'FitCenter'
}
getScaleFactor(sourceWidth: number, sourceHeight: number, requestedWidth: number, requestedHeight: number,
downsampType: DownsampleStrategy
): number {
//重新计算宽高比;
let outSize: Size = {
width: round(getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType) * sourceWidth),
height:round(getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType) * sourceHeight)
}
let scaleFactor = downsampType === DownsampleStrategy.FIT_CENTER_QUALITY?
Math.max(1, highestOneBit(Math.max(sourceWidth / outSize.width, sourceHeight / outSize.height))) :
Math.max(1, highestOneBit(Math.min(sourceWidth / outSize.width, sourceHeight / outSize.height)))//将整型的缩放因子转换为2的次幂采样大小
if (downsampType === DownsampleStrategy.FIT_CENTER_MEMORY
&& (scaleFactor < (1 / getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType)))) {
scaleFactor = scaleFactor << 1;
}
return scaleFactor
}
}
/*宽高进行等比缩放宽高里面最小的比例先放进去
然后再更据原图的缩放比去适配另一边*/
export class AtLeast implements BaseDownsampling {
getName() {
return 'AtLeast'
}
getScaleFactor(sourceWidth: number, sourceHeight: number, requestedWidth: number, requestedHeight: number): number {
const widthPercentage = requestedWidth / sourceWidth;
const heightPercentage = requestedHeight / sourceHeight;
//返回宽度和高度比例中最大的值
let outSize: Size = {
width: round(Math.max(widthPercentage, heightPercentage) * sourceWidth),
height:round(Math.max(widthPercentage, heightPercentage) * sourceHeight)
}
let scaleFactor = Math.max(1, highestOneBit(Math.max(sourceWidth / outSize.width, sourceHeight / outSize.height)))
return scaleFactor
}
}
/*请求尺寸大于实际尺寸不进行放大,按照原图展示*/
export class AtMost implements BaseDownsampling {
getName() {
return 'AtMost'
}
getScaleFactor(sourceWidth: number, sourceHeight: number, requestedWidth: number, requestedHeight: number): number {
const maxIntegerFactor = Math.ceil(Math.max(sourceHeight / requestedHeight, sourceWidth / requestedWidth));
let lesserOrEqualSampleSize = Math.max(1, highestOneBit(maxIntegerFactor));
let greaterOrEqualSampleSize = lesserOrEqualSampleSize
if (lesserOrEqualSampleSize < maxIntegerFactor) {
greaterOrEqualSampleSize = lesserOrEqualSampleSize <<= 1;
}
greaterOrEqualSampleSize = lesserOrEqualSampleSize << (lesserOrEqualSampleSize < maxIntegerFactor ? 1 : 0)
let outSize: Size = {
width: round((1 / greaterOrEqualSampleSize) * sourceWidth),
height:round((1 / greaterOrEqualSampleSize) * sourceHeight)
}
let scaleFactor = Math.max(1, highestOneBit(Math.min(sourceWidth / outSize.width, sourceHeight / outSize.height)))
if ((scaleFactor < greaterOrEqualSampleSize)) {
scaleFactor = scaleFactor << 1;
}
return scaleFactor
}
}
/*宽高进行等比缩放宽高里面最大的比例先放进去
然后再更据原图的缩放比去适配另一边*/
export class CenterInside implements BaseDownsampling {
getName() {
return 'CenterInside'
}
getScaleFactor(sourceWidth: number, sourceHeight: number, requestedWidth: number, requestedHeight: number,
downsampType: DownsampleStrategy
): number {
let outSize: Size = {
width: round(Math.min(1, getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType)) * sourceWidth),
height:round(Math.min(1, getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType)) * sourceHeight)
}
//将整型的缩放因子转换为2的次幂采样大小
let scaleFactor = this.getSampleSizeType(sourceWidth, sourceHeight, requestedWidth, requestedHeight,
downsampType) == SampleSizeRounding.QUALITY ?
Math.max(1, highestOneBit(Math.max(sourceWidth / outSize.width, sourceHeight / outSize.height))) :
Math.max(1, highestOneBit(Math.min(sourceWidth / outSize.width, sourceHeight / outSize.height)))
if (this.getSampleSizeType(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType)
== SampleSizeRounding.MEMORY && (scaleFactor < (1 / Math.min(1, getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType))))) {
scaleFactor = scaleFactor << 1;
}
return scaleFactor
}
getSampleSizeType(sourceWidth: number, sourceHeight: number, requestedWidth: number, requestedHeight: number,
downsampType: DownsampleStrategy
): SampleSizeRounding {
//如果缩放因子为 1，表示没有缩放，优先选择质量
if (Math.min(1, getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType)) === 1) {
return SampleSizeRounding.QUALITY
}
//否则，使用 FIL_CENTER 的 SampleSizeRounding 值
return downsampType === DownsampleStrategy.CENTER_INSIDE_MEMORY?SampleSizeRounding.MEMORY:SampleSizeRounding.QUALITY
}
}
// 默认值，图片分辨率超过上限7680 * 4320，宽高等比降为7680 * 4320
export class DefaultDownSampling implements BaseDownsampling {
getName(): string {
return 'DefaultDownSampling'
}
getScaleFactor(sourceWidth: number, sourceHeight: number, requestWidth: number, requestHeight: number, downsampType?: DownsampleStrategy | undefined): number {
let resolution_max_8k = 7680 * 4320
let resolution_source = sourceWidth * sourceHeight
if ( resolution_source <= resolution_max_8k ) {
return 1
} else {
return resolution_source / resolution_max_8k
}
}
}
export enum DownsampleStrategy {
//请求尺寸大于实际尺寸不进行放大
AT_MOST,
//两边自适应内存优先
FIT_CENTER_MEMORY,
//两边自适应质量优先
FIT_CENTER_QUALITY,
//按照宽高比的最大比进行适配内存优先
CENTER_INSIDE_MEMORY,
//按照宽高比的最大比进行适配质量优先
CENTER_INSIDE_QUALITY,
//宽高进行等比缩放宽高里面最小的比例先放进去，然后再根据原图的缩放比去适配
AT_LEAST,
//不进行降采样
NONE,
// 默认值，图片分辨率超过上限7680 * 4320，宽高等比降为7680 * 4320
DEFAULT
}
