Merge branch 'stbiw-fix-jpeg-flipping' of https://github.com/DanielGibson/stb into working

stb_image_write.h

@@ -1470,14 +1470,16 @@ static int stbi_write_jpg_core(stbi__write_context *s, int width, int height, in
             float YDU[64], UDU[64], VDU[64];
             for(row = y, pos = 0; row < y+8; ++row) {
                for(col = x; col < x+8; ++col, ++pos) {
-                  int p = (stbi__flip_vertically_on_write ? height-1-row : row)*width*comp + col*comp;
                   float r, g, b;
-                  if(row >= height) {
-                     p -= width*comp*(row+1 - height);
-                  }
-                  if(col >= width) {
-                     p -= comp*(col+1 - width);
+                  int p;
+                  if(row < height) {
+                     p = (stbi__flip_vertically_on_write ? (height-1-row) : row)*width*comp;
+                  } else {
+                     // row >= height => use last input row (=> first if flipping)
+                     p = stbi__flip_vertically_on_write ? 0 : ((height-1)*width*comp);
                   }
+                  // if col >= width => use pixel from last input column
+                  p += ((col < width) ? col : (width-1))*comp;
 
                   r = imageData[p+0];
                   g = imageData[p+ofsG];