Re: How to access all the pixels of a bitmap with C#?
- From: "Ma Xiaoguang" <maxiaoguang10000@xxxxxxxx>
- Date: Fri, 1 Apr 2005 09:55:10 +0800
Hi Olaf,
Thank you very much!
Best regards.
Xiaoguang
"Olaf Baeyens" <olaf.baeyens@xxxxxxxxxx> wrote in message
news:424bc005$0$1417$ba620e4c@xxxxxxxxxxxxxxxxx
> > How to access all the pixels of a bitmap with C#? I am working with
> > Delphi before. In Delphi, you can use TBitmap.Scanline property to
access
> > all the pixels of a bitmap object. How to do this with C#? Any hints?
> Thank
> > you very much.
> >
> Something like this:
>
>
>
> /// <summary>
> /// Create a gray gradient bar to represent the colors palette.
> /// </summary>
> private void MakeGrayColorPaletteBitmap() {
> try {
> int iWidth=this.Width;
> if (iWidth<=0) iWidth=256;
> int iHeight=this.Height;
> if (iHeight<=0) iHeight=1;
> Palette=new Bitmap(iWidth,iHeight, PixelFormat.Format8bppIndexed);
> // Lock a rectangular portion of the bitmap for writing so we can
> fill this with a gradient value.
> BitmapData bitmapData=null;
> Rectangle rect = new Rectangle(0, 0, iWidth, iHeight);
> try {
> bitmapData =
>
Palette.LockBits(rect,ImageLockMode.WriteOnly,PixelFormat.Format8bppIndexed)
> ;
> // Write to the temporary buffer that is provided by LockBits.
> // Copy the pixels from the source image in this loop.
> // Because you want an index, convert RGB to the appropriate
> // palette index here.
> IntPtr pixels = bitmapData.Scan0;
> unsafe {
> // Get the pointer to the image bits.
> // This is the unsafe operation.
> byte * pBits;
> if (bitmapData.Stride > 0) {
> pBits = (byte *)pixels.ToPointer();
> } else {
> // If the Stide is negative, Scan0 points to the last
> // scanline in the buffer. To normalize the loop,
obtain
> // a pointer to the front of the buffer that is
located
> // (Height-1) scanlines previous.
> pBits = (byte *)pixels.ToPointer() +
> bitmapData.Stride*(Height-1);
> }
> uint stride = (uint)Math.Abs(bitmapData.Stride);
> float fStep=(float)(256.0/Width);
> for ( uint row = 0; row < Height; ++row ) {
> for ( uint col = 0; col < Width; ++col ) {
> byte * p8bppPixel = pBits + row*stride + col;
> *p8bppPixel=(byte)(fStep*col);
> }
> }
> }
> } finally {
> // To commit the changes, unlock the portion of the bitmap.
> Palette.UnlockBits(bitmapData);
> }
> } catch {
> }
> }
>
> --
> http://www.skyscan.be
>
>
.
- References:
- How to access all the pixels of a bitmap with C#?
- From: Ma Xiaoguang
- Re: How to access all the pixels of a bitmap with C#?
- From: Olaf Baeyens
- How to access all the pixels of a bitmap with C#?
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