public string DataFromImage(System.Drawing.Image image, bool useMaxWidth = true)
{
int maxWidth = useMaxWidth ? _main.CalcMaxWidth() : int.MaxValue;
if (maxWidth <= 0)
{
maxWidth = 1;
}
if (maxWidth > image.Width)
{
maxWidth = image.Width;
}
// The quantizer runs super slow with big images so start at a small reasonable size
int newWidth = 640; // starting point
if (newWidth > maxWidth)
{
newWidth = maxWidth;
}
string data = "";
// keep scaling down until we go below the threshold
data = ScaleToWidth(image, newWidth);
if (data.Length < threshold && newWidth < maxWidth)
{
// already below threshold at our starting point? try starting at 1600 px then
newWidth = 1600;
if (newWidth > maxWidth)
{
newWidth = maxWidth;
}
data = ScaleToWidth(image, newWidth);
}
if (data.Length < threshold && newWidth < maxWidth)
{
// still below threshold at our starting point? start with the real size of the image i suppose, up to the hardlimit
const int hardLimit = 3840;
newWidth = image.Width;
if (newWidth > hardLimit)
{
newWidth = hardLimit;
}
if (newWidth > maxWidth)
{
newWidth = maxWidth;
}
data = ScaleToWidth(image, newWidth);
}
while (data.Length >= threshold)
{
int nextWidth = newWidth;
// scale down
double diffRatio = Math.Sqrt(threshold / (double)data.Length);
nextWidth = (int)(nextWidth * diffRatio);
// align to 8 px
nextWidth = (nextWidth / 8) * 8;
if (nextWidth == newWidth)
{
nextWidth -= 8;
}
if (nextWidth <= 0)
{
throw new Exception("Something very troubling is going on resizing this image you gave me.");
}
newWidth = nextWidth;
data = ScaleToWidth(image, newWidth);
}
// now we are below the threshold! this time let's just move up until we go over.
while (newWidth < maxWidth)
{
newWidth += 16;
string newData = ScaleToWidth(image, newWidth);
if (newData.Length < threshold)
{
data = newData;
}
else
{
break;
}
}
return(data);
}
