C# 如何在光标位置裁剪图像的一部分?
我按照下面的步骤来裁剪和圆整图像。然而,它不工作的方式,我想要的。我花了一些时间,但不知道在哪里修复代码以获得我想要的C# 如何在光标位置裁剪图像的一部分?,c#,image,winforms,graphics,bitmap,C#,Image,Winforms,Graphics,Bitmap,我按照下面的步骤来裁剪和圆整图像。然而,它不工作的方式,我想要的。我花了一些时间,但不知道在哪里修复代码以获得我想要的 public Image CropToCircle(Image srcImage, PointF center, float radius, Color backGround) { Image dstImage = new Bitmap((int)Math.Round(Math.Ceiling(radius*2)), (int)Math.Round(Math.Ceili
public Image CropToCircle(Image srcImage, PointF center, float radius, Color backGround)
{
Image dstImage = new Bitmap((int)Math.Round(Math.Ceiling(radius*2)), (int)Math.Round(Math.Ceiling(radius*2)), srcImage.PixelFormat);
using (Graphics g = Graphics.FromImage(dstImage))
{
RectangleF r = new RectangleF(center.X - radius, center.Y - radius, 2*radius, 2 * radius);
using (Brush br = new SolidBrush(backGround))
{
g.FillRectangle(br, 0, 0, dstImage.Width, dstImage.Height);
}
GraphicsPath path = new GraphicsPath();
path.AddEllipse(r);
g.SetClip(path);
g.DrawImage(srcImage, 0, 0);
return dstImage;
}
}
dstImage-应在给定光标位置显示主图像的裁剪图像
上述代码工作正常,但输出图像位置随X、Y坐标移动。我想要的是始终显示光标位置下主图像的100x100平方米图像。(就像镜头在图像上移动)
这就是我调用函数的方式
private void drawWindows(Point mousePoint)
{
Image RoundedImage = CropToCircle(StartImage, new PointF(mousePoint.X, mousePoint.Y), 75, Color.FromArgb(0, 101, 167));
PB.Image = RoundedImage;
}
我想在图像中心的给定位置下显示图像,如下所示:
但当我改变X,Y坐标时,当前裁剪的图像会向内移动。我希望圆形图像仍然在中心
我在哪里犯错?我觉得g.DrawImage(srcImage,0,0)很可能是罪魁祸首。有什么想法吗?当您使用一个控件作为图像的容器,并且图像被缩放以适应容器的边界(例如,将a设置为)以便可以在UI中以预定义的度量显示图像时,当您需要选择图像的一部分时,您需要计算缩放因子。换句话说,确定容器大小与图像实际大小之间的比率 最好使用较小的容器作为参考,这样就可以将相对度量值乘以比例,而不是除以比例:
private float GetImageScaledRatio(RectangleF canvas, SizeF imageSize)
{
return Math.Max(canvas.Width, canvas.Height) /
Math.Max(imageSize.Width, imageSize.Height);
}
如果希望镜头跟随鼠标指针的位置,则镜头在容器内的位置由指针坐标减去镜头大小的一半给出:
private PointF GetLensPosition(PointF centerPosition, RectangleF lens)
{
return new PointF(centerPosition.X - (lens.Width / 2),
centerPosition.Y - (lens.Height / 2));
}
要确定相对于位图实际大小的镜头(选择)尺寸的实际大小,必须在需要绘制或剪裁位图部分时缩放镜头尺寸:
private SizeF GetScaledLensSize(RectangleF canvas, SizeF imageSize, SizeF lensSize)
{
float scaleRatio = GetImageScaledRatio(canvas, imageSize);
return new SizeF(lensSize.Width * scaleRatio, lensSize.Width * scaleRatio);
}
此外,当显示由镜头表示的当前选择的预览时,选择需要缩放到用于预览镜头选择的容器的大小:
private RectangleF CanvasToImageRect(RectangleF canvas, SizeF imageSize, RectangleF rect)
{
float scaleRatio = GetImageScaledRatio(canvas, imageSize);
return new RectangleF(new PointF(rect.X / scaleRatio, rect.Y / scaleRatio),
new SizeF(rect.Width / scaleRatio, rect.Height / scaleRatio));
}
这些简单的方法允许计算与所考虑图像相关的选择的实际大小,以及用于预览的控件的大小
使用镜头选择绘制预览时,最好使用常用方法绘制图像部分:该方法也可用于在新位图中绘制选择,然后将其保存到光盘或以其他方式存储
在这里,pctLens
是用于预览的图片盒,矩形部分
是镜头测量,重新缩放为pctLens
大小(用于预览),当然源图像
是原始图像:
private void pctLens_Paint(object sender, PaintEventArgs e)
{
RectangleF section = CanvasToImageRect(pctOriginal.ClientRectangle, sourceImage.Size, imageLens);
DrawImageSelection(e.Graphics, pctLens.ClientRectangle, section, sourceImage);
}
private void DrawImageSelection(Graphics g, RectangleF canvas, RectangleF imageSection, Image image)
{
g.SmoothingMode = SmoothingMode.AntiAlias;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.DrawImage(image, canvas, imageSection, GraphicsUnit.Pixel);
switch (lensType)
{
case LensType.Circular:
using (var path = new GraphicsPath())
{
path.AddEllipse(canvas);
g.SetClip(path, CombineMode.Exclude);
using (var brush = new SolidBrush(Color.FromArgb(160, Color.Black)))
{
g.FillRectangle(brush, canvas);
g.ResetClip();
using (var pen = new Pen(brush, 1f))
g.DrawEllipse(pen, canvas);
}
}
break;
case LensType.Rectangular:
// NOP
break;
}
}
可视化结果(图像:1200x675
,图片框:300x175
,SizeMode:Zoom
)
完成源代码以再现动画中显示的内容:
位图源图像
是原始位图,必须将其设置为现有对象。矩形成像透镜
是用于定义相对透镜尺寸的形状。Size lensPixelSize
是相对于UI表示的imageLens
的大小(以像素为单位)。pctOriginal
是显示原始图像的图片框。pctLens
是绘制镜头部分预览的图片框
Bitmap sourceImage = null;
RectangleF imageLens = RectangleF.Empty;
Size lensPixelSize = new Size(100, 100);
LensType lensType = LensType.Circular;
bool lensUseRelativeSize = false;
bool drawLens = false;
private enum LensType
{
Circular,
Rectangular
}
private void pctOriginal_MouseMove(object sender, MouseEventArgs e)
{
imageLens.Location = GetLensPosition(e.Location, imageLens);
imageLens.Size = lensUseRelativeSize
? GetScaledLensSize(pctOriginal.ClientRectangle, sourceImage.Size, lensPixelSize)
: lensPixelSize;
pctOriginal.Invalidate();
pctLens.Invalidate();
}
private PointF GetLensPosition(PointF centerPosition, RectangleF rect)
{
return new PointF(centerPosition.X - (rect.Width / 2),
centerPosition.Y - (rect.Height / 2));
}
private SizeF GetScaledLensSize(RectangleF canvas, SizeF imageSize, SizeF lensSize)
{
float scaleRatio = GetImageScaledRatio(canvas, imageSize);
return new SizeF(lensSize.Width * scaleRatio, lensSize.Width * scaleRatio);
}
private float GetImageScaledRatio(RectangleF canvas, SizeF imageSize)
{
return Math.Max(canvas.Width, canvas.Height) /
Math.Max(imageSize.Width, imageSize.Height);
}
private RectangleF CanvasToImageRect(RectangleF canvas, SizeF imageSize, RectangleF rect)
{
float scaleRatio = GetImageScaledRatio(canvas, imageSize);
return new RectangleF(new PointF(rect.X / scaleRatio, rect.Y / scaleRatio),
new SizeF(rect.Width / scaleRatio, rect.Height / scaleRatio));
}
private void pctOriginal_Paint(object sender, PaintEventArgs e)
{
using (Pen pen = new Pen(Color.Red, 2.0f))
{
pen.DashStyle = DashStyle.Dash;
switch (lensType)
{
case LensType.Circular:
e.Graphics.DrawEllipse(pen, Rectangle.Round(imageLens));
break;
case LensType.Rectangular:
e.Graphics.DrawRectangle(pen, Rectangle.Round(imageLens));
break;
}
}
}
private void pctLens_Paint(object sender, PaintEventArgs e)
{
if (!drawLens) return;
RectangleF section = CanvasToImageRect(pctOriginal.ClientRectangle, sourceImage.Size, imageLens);
DrawImageSelection(e.Graphics, pctLens.ClientRectangle, section, sourceImage);
}
private void DrawImageSelection(Graphics g, RectangleF canvas, RectangleF imageSection, Image image)
{
g.SmoothingMode = SmoothingMode.AntiAlias;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.DrawImage(image, canvas, imageSection, GraphicsUnit.Pixel);
switch (lensType)
{
case LensType.Circular:
using (var path = new GraphicsPath())
{
path.AddEllipse(canvas);
g.SetClip(path, CombineMode.Exclude);
using (var brush = new SolidBrush(Color.FromArgb(160, Color.Black)))
{
g.FillRectangle(brush, canvas);
g.ResetClip();
using (var pen = new Pen(brush, 1f))
g.DrawEllipse(pen, canvas);
}
}
break;
case LensType.Rectangular:
// NOP
break;
}
}
private void chkSizeRelative_CheckedChanged(object sender, EventArgs e)
=> lensUseRelativeSize = chkSizeRelative.Checked;
private void radLensType_CheckedChanged(object sender, EventArgs e)
=> lensType = (LensType)(int.Parse((sender as Control).Tag.ToString()));
private void pctOriginal_MouseEnter(object sender, EventArgs e)
=> drawLens = true;
private void pctOriginal_MouseLeave(object sender, EventArgs e)
{
drawLens = false;
pctLens.Invalidate();
}
你从哪里得到鼠标坐标?是否有两个PictureBox控件,一个显示原始图像,一个显示结果?什么是SizeMode?什么是PB?图片盒?如果是:它有多大尺寸?如果不正常,则需要鼠标坐标。。