#鸿蒙通关秘籍#如何在HarmonyOS中提取和分析图片的主要颜色？

提取和分析图片的主要颜色涉及到从图片中提取像素信息并确定那些最常出现的颜色。步骤如下：

1. 将图片解码为PixelMap对象来处理像素信息：

   let pixelMap: image.PixelMap = await image2PixelMap(item.icon);
   
   export async function image2PixelMap(icon: string): Promise<image.PixelMap> {
     let rawFileDescriptor: resourceManager.RawFileDescriptor = resourceMgs.getRawFdSync(icon);
     let imageSource: image.ImageSource = image.createImageSource(rawFileDescriptor);
     let pixelMap: image.PixelMap = await imageSource.createPixelMap({
       editable: false,
       desiredPixelFormat: image.PixelMapFormat.BGRA_8888,
       desiredSize: { width: 40, height: 40 }
     });
     return pixelMap;
   }
   

2. 提取像素到一个数字数组并用Map统计每个像素值出现的次数：

   let allPixels: number[] = await traverseAllPixel(pixelMap);
   
   export async function traverseAllPixel(pixelMap: image.PixelMap): Promise<number[]> {
     const pixelArrayBuffer: ArrayBuffer = new ArrayBuffer(40 * 40 * 4);
     await pixelMap.readPixelsToBuffer(pixelArrayBuffer);
     const allPixels: number[] = [];
     const unit8Pixels: Uint8Array = new Uint8Array(pixelArrayBuffer);
     for (let i = 0; i < unit8Pixels.length; i += 4) {
       const rgb: ColorRgb = {
         red: unit8Pixels[i+2],
         green: unit8Pixels[i+1],
         blue: unit8Pixels[i],
         alpha:unit8Pixels[i+3]
       }
       if (rgb.red === 0 && rgb.green === 0 && rgb.blue === 0 && rgb.alpha === 0) {
         continue;
       }
       allPixels.push(ColorUtils.rgbToNumber(rgb));
     }
     return allPixels;
   }
   

3. 寻找最大出现次数的颜色：

   export function findMaxPixel(allPixels: number[]): number {
     let map: Map<number, number> = new Map();
     allPixels.forEach((pixel: number) => {
       if (map.has(pixel)) {
         map.set(pixel, map.get(pixel)! + 1);
       } else {
         map.set(pixel, 1);
       }
     })
     let maxPixel: number = 0;
     let maxTimes: number = 0;
     map.forEach((value: number, key: number) => {
       if (value >= maxTimes) {
         maxTimes = value;
         maxPixel = key;
       }
     })
     return maxPixel;
   }