缩短非GPU加速下图片马赛克处理近3倍时间

Signed-off-by: Bo Lan <mai925093@gmail.com>

library/src/main/ets/components/imageknife/utils/PixelUtils.ets

@@ -34,43 +34,14 @@ export namespace pixelUtils {
       func?.asyncTransform("GrayscaleTransformation The image size does not exist.", null)
       return;
     }
+
     let targetWidth: number = size.width;
     let targetHeight: number = size.height;
 
-    let pixEntry: Array<PixelEntry> = new Array()
-    let inPixels: Array<Array<number>> = CalculatePixelUtils.createInt2DArray(targetHeight, targetWidth);
-
     let bufferData = new ArrayBuffer(bitmap.getPixelBytesNumber());
     await bitmap.readPixelsToBuffer(bufferData);
     let dataArray = new Uint8Array(bufferData);
 
-    let ph:number = 0;
-    let pw:number = 0;
-
-
-    for (let index = 0; index < dataArray.length; index += 4) {
-      const r = dataArray[index];
-      const g = dataArray[index+1];
-      const b = dataArray[index+2];
-      const f = dataArray[index+3];
-
-      let entry = new PixelEntry();
-      entry.a = 0;
-      entry.b = b;
-      entry.g = g;
-      entry.r = r;
-      entry.f = f;
-      entry.pixel = ColorUtils.rgb(entry.r, entry.g, entry.b);
-      pixEntry.push(entry);
-      inPixels[ph][pw] = ColorUtils.rgb(entry.r, entry.g, entry.b);
-      if (pw == targetWidth - 1) {
-        pw = 0;
-        ph++;
-      } else {
-        pw++;
-      }
-    }
-
     let realPixel_W = pixel > targetWidth ? targetWidth : pixel;
     let realPixel_H = pixel > targetHeight ? targetHeight : pixel;
 
@@ -78,54 +49,54 @@ export namespace pixelUtils {
     let x_index = Math.floor(targetWidth / realPixel_W);
     // 纵排的正方形个数
     let y_index = Math.floor(targetHeight / realPixel_H);
+    let inPixels: Array<Array<number>> = CalculatePixelUtils.createInt2DArray(y_index, x_index)
 
+    // 每个马赛克块左上角的像素在图片一维数组中对应的索引位置
+    let startIndex = 0
+    // 像素步进数
+    const PIXEL_STEP = 4
+    // 图片马赛克化之后，一行马赛克所包含的像素数
+    const mosaicRowPixels = targetWidth * pixel * PIXEL_STEP
     for (let ch = 0; ch < y_index; ch++) {
       for (let cw = 0; cw < x_index; cw++) {
-
+        startIndex = mosaicRowPixels * ch + cw * pixel * PIXEL_STEP
-        let max_x = (cw + 1) * realPixel_W > targetWidth ? targetWidth : (cw + 1) * realPixel_W;
+        const r = dataArray[startIndex]
-        let max_y = (ch + 1) * realPixel_H > targetHeight ? targetHeight : (ch + 1) * realPixel_H;
+        const g = dataArray[startIndex+1];
-
+        const b = dataArray[startIndex+2];
-
+        const f = dataArray[startIndex+3];
-        let min_x = cw * realPixel_W;
+        let entry = new PixelEntry();
-        let min_y = ch * realPixel_H;
+        entry.a = 0;
-
+        entry.b = b;
-        // 取左上角的像素值
+        entry.g = g;
-        let center_p = inPixels[min_y+1][min_x+1];
+        entry.r = r;
-        // 设置该正方形里的像素统一
+        entry.f = f;
-        for (let zh = min_y; zh < max_y; zh++) {
+        inPixels[ch][cw] = ColorUtils.rgb(entry.r, entry.g, entry.b);
-          for (let zw = min_x; zw < max_x; zw++) {
-            inPixels[zh][zw] = center_p;
       }
     }
-      }
-    }
-
 
     let bufferNewData = new ArrayBuffer(bitmap.getPixelBytesNumber());
     let dataNewArray = new Uint8Array(bufferNewData);
-    let index = 0;
-    let mh = 0;
-    let nw = 0;
 
-    for (let i = 0; i < dataNewArray.length; i += 4) {
+    for (let i = 0; i < dataNewArray.length; i += PIXEL_STEP) {
-      let pixel_1 = inPixels[mh][nw];
+      // 像素在二维数组中纵轴方向上的索引
+      let y = Math.floor(i / targetHeight / PIXEL_STEP)
+      // 像素在二维数组中横轴方向上的索引
+      let x = Math.floor((i - (y * targetHeight * PIXEL_STEP)) / PIXEL_STEP)
 
-      if (nw == targetWidth - 1) {
+      // 对应马赛克块二维数组的位置
-        nw = 0;
+      y = Math.floor(y / pixel)
-        mh++;
+      x = Math.floor(x / pixel)
-      } else {
-        nw++;
-      }
 
-      let p_r = ColorUtils.red(pixel_1);
+      // 未被马赛克覆盖的部分，用最近的色块颜色覆盖
-      let p_g = ColorUtils.green(pixel_1);
+      y = y >= y_index ? y_index - 1 : y
-      let p_b = ColorUtils.blue(pixel_1);
+      x = x >= x_index ? x_index - 1 : x
 
-      dataNewArray[i] = p_r;
+      const color = inPixels[y][x]
-      dataNewArray[i+1] = p_g;
+
-      dataNewArray[i+2] = p_b;
+      dataNewArray[i] = ColorUtils.red(color);
-      dataNewArray[i+3] = pixEntry[index].f;
+      dataNewArray[i+1] = ColorUtils.green(color);
-      index++;
+      dataNewArray[i+2] = ColorUtils.blue(color);
+      dataNewArray[i+3] = ColorUtils.alpha(color)
     }
     await bitmap.writeBufferToPixels(bufferNewData);
     if (func) {