Code version for read PNG and GIF images
void ddImageReader( const string & name, UInt32 *width, UInt32 *height)
{
// OPEN THE FILE
unsigned char header[25];
ifstream file;
file.open(name.c_str(), ios::binary | ios::in);
// MAKE SURE FILE IS GOOD
bool isGood = file.good();
if(file.good())
{
// READ THE FILE HEADER
file.seekg(0, ios::beg);
file.read((char*)header, 25);
file.close();
if(memcmp(header,"\211PNG\r\n\032\n",8)==0)
{
// PNG FILE
*width = ((int(header[16])<<8 | int(header[17]))<<8 |
int(header[18]))<<8 | int(header[19]);
*height = ((int(header[20])<<8 | int(header[21]))<<8 |
int(header[22]))<<8 | int(header[23]);
}
else if((memcmp(header,"GIF8", 4)==0) && ((header[4]=='9') ||
(header[4]=='7') ) && (header[5]=='a')
)
{
// GIF FILE
*width = int(header[7])<<8 | int(header[6]);
*height = int(header[9])<<8 | int(header[8]);
}
else
{
// UNKNOWN FILE
*width = 0;
*height = 0;
}
return;
}
XASSERT(false);
}
-----Original Message-----
From: Daniel Derr [mailto:[email protected]]
Sent: Thu 12/18/2008 12:11 AM
To: [email protected]
Subject: RE: [Wt-interest] Is there a way to know the image width and height?
I wrote this today from file format specs. Maybe this will help. I don't think
there is any legal issues with gif and such, however it is hard to say. I plan
on improving it a bit, but this is a good start. Seems to work for me.
#include <iostream>
#include <fstream>
using namespace std;
DDImageReader::DDImageReader(string name, DDImage * image)
{
// OPEN THE FILE
ifstream file;
file.open(name.c_str(), ios::binary | ios::in);
// MAKE SURE FILE IS GOOD
if(file.good())
{
unsigned char header[10];
unsigned char value[4];
// IDENTIFY THE TYPE
file.seekg(0, ios::beg);
file.read((char*)header, 10);
image->setName(name);
if(memcmp(header,"\211PNG\r\n\032\n",8)==0)
{
// SET NAME AND TYPE
image->setType(DDIMAGE_PNG);
// SEEK TO DIMENSION BITS
file.seekg(16, ios::beg);
// WIDTH AND HEIGHT
file.read((char*)value, 4);
image->setWidth (int(value[0])<<24 | int(value[1])<<16 |
int(value[2])<<8 | int(value[3]));
file.read((char*)value, 4);
image->setHeight(int(value[0])<<24 | int(value[1])<<16 |
int(value[2])<<8 | int(value[3]));
}
else if((memcmp(header,"GIF89a", 6)==0) ||
(memcmp(header,"GIF87a", 6)==0) )
{
// SET NAME AND TYPE
image->setType(DDIMAGE_GIF);
// WIDTH AND HEIGHT
image->setWidth (int(header[7])<<8 | int(header[6]));
image->setHeight(int(header[9])<<8 | int(header[8]));
}
else
{
image->setType(DDIMAGE_UNKNOWN);
image->setWidth (0);
image->setHeight(0);
}
}
// CLOSE THE FILE
file.close();
}
-----Original Message-----
From: Daniel Derr [mailto:[email protected]]
Sent: Wed 12/17/2008 12:15 AM
To: [email protected]
Subject: RE: [Wt-interest] Is there a way to know the image width and height?
I also having issue with needed to know the size of an image on the server
side. So it would be desirable to read the image size from the file without
having to load the entire image into memory. I will keep you posted if I find
out any new information.
Daniel
-----Original Message-----
From: Koen Deforche [mailto:[email protected]]
Sent: Tue 12/9/2008 8:24 AM
To: [email protected]
Subject: Re: [Wt-interest] Is there a way to know the image width and height?
Hey David,
2008/12/8 David Eriksson <[email protected]>:
> Hi,
>
> Maybe you can use Boost GIL:
> http://www.boost.org/doc/libs/1_37_0/libs/gil/doc/index.html
Thanks for that link. I didn't know about Gil. I wonder if (and hope
that) boost will ever adopt a rasterizer and font rendering library
(such as Cairo or Anti Grain) to complement Gil.
That would be nice to use as bitmap backend to WPaintDevice (next to
the <canvas>, SVG and VML vector graphics backends).
Regards,
koen
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