Add support for bit depth with raw input and output (#2762)

* Determine input raw pixel depth from the given typed array
* Allow pixel depth to be set on raw output

src/common.cc

@@ -92,6 +92,9 @@ namespace sharp {
     }
     // Raw pixel input
     if (HasAttr(input, "rawChannels")) {
+      descriptor->rawDepth = static_cast<VipsBandFormat>(
+        vips_enum_from_nick(nullptr, VIPS_TYPE_BAND_FORMAT,
+        AttrAsStr(input, "rawDepth").data()));
       descriptor->rawChannels = AttrAsUint32(input, "rawChannels");
       descriptor->rawWidth = AttrAsUint32(input, "rawWidth");
       descriptor->rawHeight = AttrAsUint32(input, "rawHeight");
@@ -297,7 +300,7 @@ namespace sharp {
       if (descriptor->rawChannels > 0) {
         // Raw, uncompressed pixel data
         image = VImage::new_from_memory(descriptor->buffer, descriptor->bufferLength,
-          descriptor->rawWidth, descriptor->rawHeight, descriptor->rawChannels, VIPS_FORMAT_UCHAR);
+          descriptor->rawWidth, descriptor->rawHeight, descriptor->rawChannels, descriptor->rawDepth);
         if (descriptor->rawChannels < 3) {
           image.get_image()->Type = VIPS_INTERPRETATION_B_W;
         } else {

src/common.h

@@ -54,6 +54,7 @@ namespace sharp {
     size_t bufferLength;
     bool isBuffer;
     double density;
+    VipsBandFormat rawDepth;
     int rawChannels;
     int rawWidth;
     int rawHeight;
@@ -78,6 +79,7 @@ namespace sharp {
       bufferLength(0),
       isBuffer(FALSE),
       density(72.0),
+      rawDepth(VIPS_FORMAT_UCHAR),
       rawChannels(0),
       rawWidth(0),
       rawHeight(0),

src/pipeline.cc

@@ -889,9 +889,9 @@ class PipelineWorker : public Napi::AsyncWorker {
             image = image[0];
             baton->channels = 1;
           }
-          if (image.format() != VIPS_FORMAT_UCHAR) {
-            // Cast pixels to uint8 (unsigned char)
-            image = image.cast(VIPS_FORMAT_UCHAR);
+          if (image.format() != baton->rawDepth) {
+            // Cast pixels to requested format
+            image = image.cast(baton->rawDepth);
           }
           // Get raw image data
           baton->bufferOut = static_cast<char*>(image.write_to_memory(&baton->bufferOutLength));
@@ -1131,6 +1131,9 @@ class PipelineWorker : public Napi::AsyncWorker {
       info.Set("width", static_cast<uint32_t>(width));
       info.Set("height", static_cast<uint32_t>(height));
       info.Set("channels", static_cast<uint32_t>(baton->channels));
+      if (baton->formatOut == "raw") {
+        info.Set("depth", vips_enum_nick(VIPS_TYPE_BAND_FORMAT, baton->rawDepth));
+      }
       info.Set("premultiplied", baton->premultiplied);
       if (baton->hasCropOffset) {
         info.Set("cropOffsetLeft", static_cast<int32_t>(baton->cropOffsetLeft));
@@ -1457,6 +1460,11 @@ Napi::Value pipeline(const Napi::CallbackInfo& info) {
   baton->heifSpeed = sharp::AttrAsUint32(options, "heifSpeed");
   baton->heifChromaSubsampling = sharp::AttrAsStr(options, "heifChromaSubsampling");
 
+  // Raw output
+  baton->rawDepth = static_cast<VipsBandFormat>(
+    vips_enum_from_nick(nullptr, VIPS_TYPE_BAND_FORMAT,
+    sharp::AttrAsStr(options, "rawDepth").data()));
+
   // Animated output
   if (sharp::HasAttr(options, "pageHeight")) {
     baton->pageHeight = sharp::AttrAsUint32(options, "pageHeight");

src/pipeline.h

@@ -169,6 +169,7 @@ struct PipelineBaton {
   int heifSpeed;
   std::string heifChromaSubsampling;
   bool heifLossless;
+  VipsBandFormat rawDepth;
   std::string err;
   bool withMetadata;
   int withMetadataOrientation;
@@ -298,6 +299,7 @@ struct PipelineBaton {
     heifSpeed(5),
     heifChromaSubsampling("4:4:4"),
     heifLossless(false),
+    rawDepth(VIPS_FORMAT_UCHAR),
     withMetadata(false),
     withMetadataOrientation(-1),
     withMetadataDensity(0.0),