[英]How to resize a cropped image?
目标:
我目前的目标是从pictureBox1
裁剪原始图像并将其显示在pictureBox2
中并将其大小(高度和宽度)增加0.8
。
当前代码:
//...
private Point LocationXY;
private Point LocationX1Y1;
private void button1_Click(object sender, EventArgs e)
{
if (Clipboard.ContainsImage())
{
pictureBox1.Image?.Dispose();
pictureBox1.Image = Clipboard.GetImage();
}
}
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
if(e.Button == MouseButtons.Left)
LocationXY = e.Location;
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
LocationX1Y1 = e.Location;
pictureBox1.Invalidate();
}
}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
if(e.Button == MouseButtons.Left)
{
LocationX1Y1 = e.Location;
pictureBox1.Invalidate();
pictureBox2.Invalidate();
}
}
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
if (MouseButtons == MouseButtons.Left)
e.Graphics.DrawRectangle(Pens.Red, GetRect());
}
private void pictureBox2_Paint(object sender, PaintEventArgs e)
{
var src = GetRect();
if (src == Rectangle.Empty) return;
var des = new Rectangle(0, 0, src.Width, src.Height);
e.Graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
e.Graphics.SmoothingMode = SmoothingMode.HighQuality;
e.Graphics.CompositingQuality = CompositingQuality.HighQuality;
e.Graphics.DrawImage(pictureBox1.Image,
des, src, GraphicsUnit.Pixel);
}
private Rectangle GetRect()
{
return new Rectangle(
Math.Min(LocationXY.X, LocationX1Y1.X),
Math.Min(LocationXY.Y, LocationX1Y1.Y),
Math.Abs(LocationXY.X - LocationX1Y1.X),
Math.Abs(LocationXY.Y - LocationX1Y1.Y)
);
}
//...
裁剪图像:
//...
private Bitmap GetCroppedImage()
{
var src = GetRect();
if (src == Rectangle.Empty) return null;
var des = new Rectangle(0, 0, src.Width, src.Height);
var b = new Bitmap(src.Width, src.Height);
using (var g = Graphics.FromImage(b))
{
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.SmoothingMode = SmoothingMode.HighQuality;
g.CompositingQuality = CompositingQuality.HighQuality;
g.DrawImage(pictureBox1.Image, des, src, GraphicsUnit.Pixel);
}
return b;
}
//...
当前代码 - 它有什么作用
目前,此代码能够在pictureBox2
中标记一个红色区域并在pictureBox1
中显示裁剪后的图像。
问题:
如何将裁剪后的图像高度和宽度增加/调整大小0.8
?
计算比例与源大小的比例,并使用它来计算图像的新大小。 因此, pictureBox2.Paint
事件代码:
private void pictureBox2_Paint(object sender, PaintEventArgs e)
{
var src = GetRect();
if (src == Rectangle.Empty || src.Width == 0 || src.Height == 0) return;
e.Graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
e.Graphics.SmoothingMode = SmoothingMode.HighQuality;
e.Graphics.CompositingQuality = CompositingQuality.HighQuality;
var widthScale = 0.8;
var heightScale = 0.8;
var widthRatio = (src.Width * widthScale + src.Width) / src.Width;
var heightRatio = (src.Height * heightScale + src.Height) / src.Height;
var newWidth = (int)(src.Width * widthRatio);
var newHeight = (int)(src.Height * heightRatio);
var des = new Rectangle(0, 0, newWidth, newHeight);
e.Graphics.DrawImage(pictureBox1.Image,
des, src, GraphicsUnit.Pixel);
}
要将其应用于GetCroppedImage()
function:
private Image GetCroppedImage(double scale = 0)
{
var src = GetRect();
if (src == Rectangle.Empty || src.Width == 0 || src.Height == 0) return null;
var widthRatio = (src.Width * scale + src.Width) / src.Width;
var heightRatio = (src.Height * scale + src.Height) / src.Height;
var newWidth = (int)(src.Width * widthRatio);
var newHeight = (int)(src.Height * heightRatio);
if (newWidth == 0 || newHeight == 0) return null;
var des = new Rectangle(0, 0, newWidth, newHeight);
var b = new Bitmap(newWidth, newHeight);
using (var g = Graphics.FromImage(b))
{
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.SmoothingMode = SmoothingMode.HighQuality;
g.CompositingQuality = CompositingQuality.HighQuality;
g.DrawImage(pictureBox1.Image, des, src, GraphicsUnit.Pixel);
}
return b;
}
此外,您可以使用Image.GetThumbnailImage从主图像中获取小尺寸。 如果您需要退回大件,不推荐。 阅读备注了解更多信息。
public static Bitmap ResizeImage(System.Drawing.Image image, int width, int height)
{
var destRect = new Rectangle(0, 0, width, height);
var destImage = new Bitmap(width, height);
destImage.SetResolution(image.HorizontalResolution, image.VerticalResolution);
using (var graphics = Graphics.FromImage(destImage))
{
graphics.CompositingMode = CompositingMode.SourceCopy;
graphics.CompositingQuality = CompositingQuality.HighQuality;
graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphics.SmoothingMode = SmoothingMode.HighQuality;
graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
using (var wrapMode = new ImageAttributes())
{
wrapMode.SetWrapMode(WrapMode.TileFlipXY);
graphics.DrawImage(image, destRect, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel, wrapMode);
}
}
return destImage;
}
用法:
ResizeImage(originalImg, (int)(originalImg.Width * 0.8), (int)(originalImg.Height * 0.8));
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