fix: targetbuffer check and scaling fix

Author: Ouwen

src/imageLoader/createImage.js

@@ -55,18 +55,7 @@ function convertToIntPixelData(floatPixelData) {
  * @param imageFrame
  */
 function setPixelDataType(imageFrame, preScale) {
-  const isScaled = preScale?.scaled;
-  const scalingParmeters = preScale?.scalingParameters;
-  let isNegative = false;
-  if (isScaled && scalingParmeters) {
-    const rescaleSlope = scalingParmeters?.rescaleSlope || 1;
-    const rescaleIntercept = scalingParmeters?.rescaleIntercep || 0;
-    const suvbw = scalingParmeters?.suvbw || 1;
-    isNegative =
-      suvbw *
-        (imageFrame.smallestPixelValue * rescaleSlope + rescaleIntercept) <
-      0;
-  }
+  const isNegative = preScale?.isNegative;
 
   if (imageFrame.bitsAllocated === 32) {
     imageFrame.pixelData = new Float32Array(imageFrame.pixelData);
@@ -174,7 +163,7 @@ function createImage(imageId, pixelData, transferSyntax, options = {}) {
       // We can't have done it within the thread incase it was a SharedArrayBuffer.
       let alreadyTyped = false;
 
-      if (options.targetBuffer) {
+      if (options.targetBuffer && options.targetBuffer.type) {
         let offset, length;
         // If we have a target buffer, write to that instead. This helps reduce memory duplication.
 

src/shared/decodeImageFrame.js

@@ -181,7 +181,7 @@ function postProcessDecodedPixels(imageFrame, options, start, decodeConfig) {
 
   imageFrame.pixelDataLength = imageFrame.pixelData.length;
 
-  if (options.targetBuffer) {
+  if (options.targetBuffer && options.targetBuffer.type) {
     let offset, length;
     // If we have a target buffer, write to that instead. This helps reduce memory duplication.
 
@@ -256,18 +256,19 @@ function postProcessDecodedPixels(imageFrame, options, start, decodeConfig) {
       typeof rescaleSlope === 'number' &&
       typeof rescaleIntercept === 'number'
     ) {
-      if (scaleArray(pixelDataArray, scalingParameters)) {
-        imageFrame.preScale = {
-          ...options.preScale,
-          scaled: true,
-        };
-      }
+      scaleArray(
+        imageFrame,
+        options.preScale,
+        pixelDataArray,
+        scalingParameters
+      );
     }
   }
 
   // Handle cases where the targetBuffer is not backed by a SharedArrayBuffer
   if (
     options.targetBuffer &&
+    options.targetBuffer.type &&
     (!options.targetBuffer.arrayBuffer ||
       options.targetBuffer.arrayBuffer instanceof ArrayBuffer)
   ) {

src/shared/scaling/scaleArray.js

@@ -1,20 +1,45 @@
-export default function scaleArray(array, scalingParameters) {
+export default function scaleArray(
+  imageFrame,
+  preScaleOptions,
+  array,
+  scalingParameters
+) {
   const arrayLength = array.length;
-  const { rescaleSlope, rescaleIntercept, suvbw } = scalingParameters;
+  const rescaleSlope = scalingParameters?.rescaleSlope || 1;
+  const rescaleIntercept = scalingParameters?.rescaleIntercept || 0;
+  const suvbw = scalingParameters?.suvbw || 1;
+
+  let isNegative = false;
 
   if (scalingParameters.modality === 'PT') {
     if (typeof suvbw !== 'number') {
       return;
     }
 
     for (let i = 0; i < arrayLength; i++) {
-      array[i] = suvbw * (array[i] * rescaleSlope + rescaleIntercept);
+      const value = suvbw * (array[i] * rescaleSlope + rescaleIntercept);
+
+      array[i] = value;
+      if (value < 0 && !isNegative) {
+        isNegative = true;
+      }
     }
   } else {
     for (let i = 0; i < arrayLength; i++) {
-      array[i] = array[i] * rescaleSlope + rescaleIntercept;
+      const value = array[i] * rescaleSlope + rescaleIntercept;
+
+      array[i] = value;
+      if (value < 0 && !isNegative) {
+        isNegative = true;
+      }
     }
   }
 
+  imageFrame.preScale = {
+    ...preScaleOptions,
+    scaled: true,
+    isNegative,
+  };
+
   return true;
 }