Question

我有一个功能，它可以接收图像并调整大小以适应画布，同时保持其宽高比。此代码只是此答案的代码的少量修改版本：c# Image resizing to different size while preserving aspect ratio

对于此示例，我的画布高度为642，我的画布宽度为823。

当我运行以下功能时，行

graphic.DrawImage(image, posX, posY, newWidth, newHeight);

似乎对图像大小没有任何作用。进去：

Image.Height == 800, 
Image.Width == 1280.
newHeight = 514,
newWidth == 823

运行graphic.DrawImage

之后

Image.Height == 800, 
Image.Width == 1280.

如您所见，Image的高度和宽度不变。

有没有人看到会导致这种情况发生的明显错误？谢谢！

    private Bitmap resizeImage(Bitmap workingImage,
                         int canvasWidth, int canvasHeight)
    {
        Image image = (Bitmap)workingImage.Clone();

        System.Drawing.Image thumbnail =
            new Bitmap(canvasWidth, canvasHeight); 

        double ratioX = (double)canvasWidth / (double)workingImage.Width;
        double ratioY = (double)canvasHeight / (double)workingImage.Height;

        double ratio = ratioX < ratioY ? ratioX : ratioY;

        int newHeight = Convert.ToInt32((double)workingImage.Height * ratio);
        int newWidth = Convert.ToInt32((double)workingImage.Width * ratio);

        int posX = Convert.ToInt32((canvasWidth - ((double)workingImage.Width * ratio)) / 2);
        int posY = Convert.ToInt32((canvasHeight - ((double)workingImage.Height * ratio)) / 2);

        using (Graphics graphic = Graphics.FromImage(thumbnail))
        {
            graphic.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            graphic.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            graphic.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
            graphic.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;

            graphic.Clear(SystemColors.Control); 
            graphic.DrawImage(image, posX, posY, newWidth, newHeight); //<--- HERE
        }

        System.Drawing.Imaging.ImageCodecInfo[] info =
                         System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders();
        System.Drawing.Imaging.EncoderParameters encoderParameters;
        encoderParameters = new System.Drawing.Imaging.EncoderParameters(1);
        encoderParameters.Param[0] = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality,
                         100L);

        return workingImage;
    }

Answer 1

图片大小在此处定义

Image image = (Bitmap)workingImage.Clone();

此

graphic.DrawImage(image, posX, posY, newWidth, newHeight);

仅使用指定的参数绘制图像，但这并不意味着图像大小会发生变化。换句话说，绘制图像根本不会改变它的大小，它只是拍摄图像并将其绘制在画布上。

Answer 2

Image Resizing functanality pupose请参阅以下链接

http://www.codeproject.com/Articles/30524/An-Easy-to-Use-Image-Resizing-and-Cropping-Control?msg=5203911#xx5203911xx

此链接内容可能会对您有所帮助

Graphics.DrawImage不会改变图像的大小

2 个答案: