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POC# Bitmap using unsafe code
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  1. POC# Bitmap using unsafe code
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    copied!<p>I'm using the following code to make image masks in C#:</p> <pre><code>for(int x = 0; x &lt; width; x++) { for(int y = 0; y &lt; height; y++) { bmp.SetPixel(x,y,Color.White); } } for(int x = left; x &lt; width; x++) { for(int y = top; y &lt; height; y++) { bmp.SetPixel(x,y,Color.Transparent); } } </code></pre> <p>But it's WAY too slow... What is the unsafe equivalent to this? Will it be allot faster? </p> <p>In the end I do a bmp.Save() in PNG format.</p> <p><strong>UPDATE:</strong></p> <p>After reading through <a href="http://www.bobpowell.net/lockingbits.htm" rel="noreferrer">http://www.bobpowell.net/lockingbits.htm</a> as suggested by MusiGenesis, I made it work using the following code (for anyone who needs it):</p> <pre><code>Bitmap bmp = new Bitmap(1000,1000,PixelFormat.Format32bppArgb); BitmapData bmd = bmp.LockBits(new Rectangle(0, 0, bmp.Width,bmp.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite, bmp.PixelFormat); int PixelSize=4; unsafe { for(int y=0; y&lt;bmd.Height; y++) { byte* row=(byte *)bmd.Scan0+(y*bmd.Stride); for(int x=0; x&lt;bmd.Width; x++) { row[x*PixelSize] = 0; //Blue 0-255 row[x*PixelSize + 1] = 255; //Green 0-255 row[x*PixelSize + 2] = 0; //Red 0-255 row[x*PixelSize + 3] = 50; //Alpha 0-255 } } } bmp.UnlockBits(bmd); bmp.Save("test.png",ImageFormat.Png); </code></pre> <p>Alpha channel: 0 being fully transparent, 255 being no transparency on that pixel.</p> <p>I'm sure you can easily modify the loop for painting a rectangle :)</p>
 

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