How to Create a Bitmap Programmatically? - winapi

Question

I'd like to create programmatically a random X height and Y width bitmap file.
The content, for me, is irrelevant. It could be all white, empty. What is important is the dimension.
How to do it using Windows API?

Answer 1

You wish to create a Bitmap File using the windows API? There is no specific helper for this. a BMP file however is very simple:
Write out a BITMAPFILEHEADER struct.
Write out a BITMAPINFO struct.
Write out an array of bytes, enough to hold the format and dimensions described in the BITMAPINFO struct.
The MSDN has an Article with sample code demonstrating how.

Answer 2

I suppose you have Microsoft .NET 2.0 Framework installed. (1.1 is also usable).
Using Notepad, create test.cs file with this code:
namespace test
{
class Program
{
static void Main(string[] args)
{
if (args.Length == 3)
new System.Drawing.Bitmap(System.Convert.ToInt32(args[0]), System.Convert.ToInt32(args[1]))
.Save(args[2] + ".bmp", System.Drawing.Imaging.ImageFormat.Bmp);
else
System.Console.WriteLine("Usage: test.exe 100 200 filename");
}
}
}
Then create test.cmd file with this code:
#echo off
%windir%\Microsoft.NET\Framework\v2.0.50727\csc.exe /t:exe test.cs
Execute test.cmd
Execute text.exe

Answer 3

In .Net you can just new up a Bitmap object:
Image myImage = new Bitmap(width, height);

Answer 4

GDI+ includes commands to load/save BMP images in C++. This sample code shows how to load and save images: Converting a BMP Image to a PNG Image. The Bitmap class also has a ctor that takes a width, a height and a pixel format to create empty images.

Answer 5

If you really insist on making an image with windows API,you should use Gdi32.dll
In C# just call
Import dll file into your assembly, so you can use external methods in
DllImport["Gdi32.dll"]
HBITMAP CreateCompatibleBitmap(
HDC hdc,
int nWidth,
int nHeight
);
Then call Bitmap class from this Bitmap like
Bitmap bmp = Bitmap.FromHbitmap( nameOfBitmap );
bmp.Save("C:\NewImage.jpg");
There is an example in msdn page here