Add support for embedded single channel previews, fixes #4419

rtengine/image16.cc

@@ -78,7 +78,7 @@ void Image16::getScanline (int row, unsigned char* buffer, int bps)
  * void Image16::setScanline (int row, unsigned char* buffer, int bps, int minValue[3], int maxValue[3]);
  * has not been implemented yet, because as of now, this method is called for IIOSF_FLOAT sample format only
  */
-void Image16::setScanline (int row, unsigned char* buffer, int bps, float *minValue, float *maxValue)
+void Image16::setScanline (int row, unsigned char* buffer, int bps, unsigned int numSamples, float *minValue, float *maxValue)
 {
 
     if (data == nullptr) {
@@ -92,12 +92,17 @@ void Image16::setScanline (int row, unsigned char* buffer, int bps, float *minVa
         case (IIOSF_UNSIGNED_CHAR): {
             int ix = 0;
 
-            for (int i = 0; i < width; ++i) {
+            if(numSamples == 1) {
-                r(row, i) = static_cast<unsigned short>(buffer[ix++]) * 257;
+                for (int i = 0; i < width; ++i) {
-                g(row, i) = static_cast<unsigned short>(buffer[ix++]) * 257;
+                    r(row, i) = g(row, i) = b(row, i) = static_cast<unsigned short>(buffer[ix++]) * 257;
-                b(row, i) = static_cast<unsigned short>(buffer[ix++]) * 257;
+                }
+            } else {
+                for (int i = 0; i < width; ++i) {
+                    r(row, i) = static_cast<unsigned short>(buffer[ix++]) * 257;
+                    g(row, i) = static_cast<unsigned short>(buffer[ix++]) * 257;
+                    b(row, i) = static_cast<unsigned short>(buffer[ix++]) * 257;
+                }
             }
-
             break;
         }
 

rtengine/image16.h

@@ -56,7 +56,7 @@ public:
         return 8 * sizeof(unsigned short);
     }
     virtual void         getScanline (int row, unsigned char* buffer, int bps);
-    virtual void         setScanline (int row, unsigned char* buffer, int bps, float *minValue = nullptr, float *maxValue = nullptr);
+    virtual void         setScanline (int row, unsigned char* buffer, int bps, unsigned int numSamples, float *minValue = nullptr, float *maxValue = nullptr);
 
     // functions inherited from IImage16:
     virtual MyMutex&     getMutex ()

rtengine/image8.cc

@@ -55,7 +55,7 @@ void Image8::getScanline (int row, unsigned char* buffer, int bps)
     }
 }
 
-void Image8::setScanline (int row, unsigned char* buffer, int bps, float *minValue, float *maxValue)
+void Image8::setScanline (int row, unsigned char* buffer, int bps, unsigned int numSamples, float *minValue, float *maxValue)
 {
 
     if (data == nullptr) {
@@ -67,7 +67,13 @@ void Image8::setScanline (int row, unsigned char* buffer, int bps, float *minVal
 
     switch (sampleFormat) {
     case (IIOSF_UNSIGNED_CHAR):
-        memcpy (data + row * width * 3u, buffer, width * 3);
+        if(numSamples == 1) {
+            for(size_t i = 0; i < static_cast<size_t>(width); ++i) {
+                data[row * width * 3 + 3 * i] = data[row * width * 3 + 3 * i + 1] = data[row * width * 3 + 3 * i + 2] = buffer[i];
+            }
+        } else {
+            memcpy (data + row * width * 3u, buffer, width * 3);
+        }
         break;
 
     case (IIOSF_UNSIGNED_SHORT): {

rtengine/image8.h

@@ -51,7 +51,7 @@ public:
         return 8 * sizeof(unsigned char);
     }
     virtual void         getScanline (int row, unsigned char* buffer, int bps);
-    virtual void         setScanline (int row, unsigned char* buffer, int bps, float *minValue = nullptr, float *maxValue = nullptr);
+    virtual void         setScanline (int row, unsigned char* buffer, int bps, unsigned int numSamples, float *minValue = nullptr, float *maxValue = nullptr);
 
     // functions inherited from IImage*:
     virtual MyMutex&     getMutex ()

rtengine/imagefloat.cc

@@ -44,7 +44,7 @@ Imagefloat::~Imagefloat ()
 }
 
 // Call this method to handle floating points input values of different size
-void Imagefloat::setScanline (int row, unsigned char* buffer, int bps, float *minValue, float *maxValue)
+void Imagefloat::setScanline (int row, unsigned char* buffer, int bps, unsigned int numSamples, float *minValue, float *maxValue)
 {
 
     if (data == nullptr) {

rtengine/imagefloat.h

@@ -60,7 +60,7 @@ public:
         return 8 * sizeof(float);
     }
     virtual void         getScanline (int row, unsigned char* buffer, int bps);
-    virtual void         setScanline (int row, unsigned char* buffer, int bps, float *minValue = nullptr, float *maxValue = nullptr);
+    virtual void         setScanline (int row, unsigned char* buffer, int bps, unsigned int numSamples, float *minValue = nullptr, float *maxValue = nullptr);
 
     // functions inherited from IImagefloat:
     virtual MyMutex&     getMutex ()

rtengine/imageio.cc

@@ -523,7 +523,7 @@ int ImageIO::loadJPEGFromMemory (const char* buffer, int bufsize)
             return IMIO_READERROR;
         }
 
-        setScanline (cinfo.output_scanline - 1, row, 8);
+        setScanline (cinfo.output_scanline - 1, row, 8, cinfo.num_components);
 
         if (pl && !(cinfo.output_scanline % 100)) {
             pl->setProgress ((double)(cinfo.output_scanline) / cinfo.output_height);
@@ -860,7 +860,7 @@ int ImageIO::loadTIFF (Glib::ustring fname)
             }
         }
 
-        setScanline (row, linebuffer, bitspersample, nullptr, nullptr);
+        setScanline (row, linebuffer, bitspersample);
 
         if (pl && !(row % 100)) {
             pl->setProgress ((double)(row + 1) / height);

rtengine/imageio.h

@@ -113,7 +113,7 @@ public:
 
     virtual int     getBPS      () = 0;
     virtual void    getScanline (int row, unsigned char* buffer, int bps) {}
-    virtual void    setScanline (int row, unsigned char* buffer, int bps, float minValue[3] = nullptr, float  maxValue[3] = nullptr) {}
+    virtual void    setScanline (int row, unsigned char* buffer, int bps, unsigned int numSamples = 3, float minValue[3] = nullptr, float  maxValue[3] = nullptr) {}
 
     virtual bool    readImage   (Glib::ustring &fname, FILE *fh)
     {