我按照链接来裁剪和舍入图像。然而它并没有按照我想要的方式工作。我花了一些时间但不明白在哪里修复代码才能得到我想要的东西。
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 - 应在给定的光标位置显示主图像的裁剪图像。
上面的代码工作正常,但输出图像位置随 X、Y 坐标移动。我想要的是始终在光标位置下显示主图像的 100x100 方形图像。 (就像镜头在图像上移动一样)
这就是我调用该函数的方式
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:
但是当我更改 X、Y 坐标时,当前裁剪的图像会移动到内部。我希望圆形图像仍然位于中心。
我哪里出错了?我觉得
g.DrawImage(srcImage, 0, 0)
可能是罪魁祸首。当您使用控件作为图像的容器并且图像被缩放以适合容器的边界时(例如,将 PictureBox.SizeMode 设置为 PictureBoxSizeMode.Zoom),以便可以使用预定义的方式在 UI 中显示图像度量,当需要选择图像的一部分时,需要计算比例因子。换句话说,确定容器的大小与图像实际大小之间的比率。
使用较小的容器作为参考可能会更好,因此您可以将相对尺寸乘以而不是除以比例:
private float GetImageScaledRatio(RectangleF canvas, SizeF imageSize)
{
return Math.Max(canvas.Width, canvas.Height) /
Math.Max(imageSize.Width, imageSize.Height);
}
容器内镜头的位置 - 如果您希望镜头跟随鼠标指针的位置 - 由指针坐标减去镜头尺寸的一半给出:
private PointF GetLensPosition(PointF centerPosition, RectangleF lens)
{
return new PointF(centerPosition.X - (lens.Width / 2),
centerPosition.Y - (lens.Height / 2));
}
为了确定镜头(选择)尺寸相对于位图实际尺寸的实际尺寸,当需要绘制或以其他方式剪切位图的一部分时,必须缩放镜头尺寸:
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,当显示镜头代表的当前选择的预览时,需要将选择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的图像相关的选区的实际大小以及用于预览的控件的大小。
使用镜头选区绘制预览时,最好使用常用方法来绘制图像部分:该方法也可用于在新位图中绘制选区,然后将其保存到光盘或以其他方式存储。
这里,
pctLens
是用于预览的PictureBox,RectangleF section
是重新调整为pctLens
尺寸的镜头尺寸(用于预览),当然sourceImage
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;
}
}
视觉效果(图片:
1200x675
,图片框:300x175
,SizeMode: Zoom
)
重现动画中显示内容的完整源代码:
Bitmap sourceImage
是原始Bitmap,必须将其设置为现有对象。RectangleF imageLens
是用于定义相对镜头尺寸的形状。Size lensPixelSize
是 imageLens
相对于 UI 表示的大小(以像素为单位)。pctOriginal
是显示原始图像的 PictureBox。pctLens
是绘制镜头部分preview 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();
}