Aspect Ratio

I need to resize an image(shrink) and maintain the aspect ratio. I have a constant new width 500px and of course I know how big it is to start with.

This is what I have. It works about 90% of the time. In fact it migrated 1000+ images. Total mb for images to start was 150mb after it is 36mb, and all the images look very good.

Code:

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int nHeight = ((int)( 100 * (int)System.Math.Round(((decimal)500)/((decimal)bmp.Width)) * bmp.Height) / 100);

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I know it's bad to do all that on one line. So far it blows up on images that are 1024x768 with a new height = 0. I don't know what the problem is other than the values being calculated when it craps out are like 0.4567 and the it just goes bad. It took me a week to find this way that almost works all the time... somebody please help.

Code:

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                public static System.Drawing.Bitmap WebOptimize(System.Drawing.Bitmap bmp)
                {
                        if(bmp.Width > 500)
                        {        //((int)( 100 * (int)System.Math.Round(((decimal)500)/((decimal)bmp.Width)) * bmp.Height) / 100);
                                double iWidth = 0;                        //500 / bmp.Width;
                                double iRatioPercent = 0;        //100 * iWidth
                                double iHeight = 0;                        //iRatioPercent * bmp.Height
                                int nHeight = 0;                        //iHeight / 100
                                                                       
                                iWidth = 500 / bmp.Width;
                                //if(iWidth <= 0){iWidth = 1;}

                                iRatioPercent = 100 * iWidth;
                                //if(iRatioPercent <= 0){iRatioPercent = 1;}

                                iHeight = iRatioPercent * bmp.Height;
                                //if(iHeight < 0){iHeight = System.Math.Round(iHeight);}

                                iHeight = iHeight / 100;

                                nHeight =(int)System.Math.Round(iHeight);

                               
                                if(nHeight > 0)
                                {
                                        System.Drawing.Bitmap nBmp = new System.Drawing.Bitmap(500, nHeight);
                                        System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(nBmp);
                               
                                        g.DrawImage(bmp, new System.Drawing.Rectangle(0, 0, 500, nHeight), 0, 0, bmp.Width, bmp.Height, System.Drawing.GraphicsUnit.Pixel);
                                        return nBmp;
                                }
                        }
                        return bmp;
                }

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this is C# code btw

Is this C++?


I am not sure but I guess that since you are using int in the calculations you are getting numbers that are under 0.5, and those are rounded to 0. If you try to use double, then cast that to int after the calculation, then you might get a better answer. But not sure. Havn't looked that closely on your code

And BTW you should really try to devide that line, so it is easier too see...I have used a minute too look at it....and for me it looks like you are mulitpluing and dividing the same number on 100....try to split it up, it is easier to see what goes wrong that way that way...

Quote:

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Posted by NoteMe
Is this C++?

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Quote:

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Posted by Magiaus
this is C# code btw

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;)

Hehehe...ok...my first line of C# is comming up...this should work...I hope...:D:D:D:

Code:

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int newHieght = (int)((500.0 / (double)bmp.Width) * (double)bmp.Height);

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Edited...if there is nothing called doufle in C# then use float, or decimal..:D:D