在缩放模式图片框中平移矩形位置

Question

我正在确定图像中的矩形区域，并在PictureBox中将其显示给用户。
由于图像有时可能非常大，因此我使用的PictureBox的SizeMode设置为Zoom。

我正在使用以下代码转换矩形（X，Y）坐标：

public Point TranslateZoomMousePosition(Point coordinates)
{
    // test to make sure our image is not null
    if (pictureBox5.Image == null) return coordinates;
    // Make sure our control width and height are not 0 and our 
    // image width and height are not 0
    if (pictureBox5.Width == 0 || pictureBox5.Height == 0 || pictureBox5.Image.Width == 0 || pictureBox5.Image.Height == 0) return coordinates;
    // This is the one that gets a little tricky. Essentially, need to check 
    // the aspect ratio of the image to the aspect ratio of the control
    // to determine how it is being rendered
    float imageAspect = (float)pictureBox5.Image.Width / pictureBox5.Image.Height;
    float controlAspect = (float)pictureBox5.Width / pictureBox5.Height;
    float newX = coordinates.X;
    float newY = coordinates.Y;
    if (imageAspect > controlAspect)
    {
        // This means that we are limited by width, 
        // meaning the image fills up the entire control from left to right
        float ratioWidth = (float)pictureBox5.Image.Width / pictureBox5.Width;
        newX *= ratioWidth;
        float scale = (float)pictureBox5.Width / pictureBox5.Image.Width;
        float displayHeight = scale * pictureBox5.Image.Height;
        float diffHeight = pictureBox5.Height - displayHeight;
        diffHeight /= 2;
        newY -= diffHeight;
        newY /= scale;
    }
    else
    {
        // This means that we are limited by height, 
        // meaning the image fills up the entire control from top to bottom
        float ratioHeight = (float)pictureBox5.Image.Height / pictureBox5.Height;
        newY *= ratioHeight;
        float scale = (float)pictureBox5.Height / pictureBox5.Image.Height;
        float displayWidth = scale * pictureBox5.Image.Width;
        float diffWidth = pictureBox5.Width - displayWidth;
        diffWidth /= 2;
        newX -= diffWidth;
        newX /= scale;
    }
    return new Point((int)newX, (int)newY);
}

在确定的位置添加框架控件：

pictureBox5.Controls.Clear();
var c = new FrameControl();
c.Size = new Size(myrect.Width, myrect.Height);
c.Location=TranslateZoomMousePosition(newPoint(myrect.Location.X,myrect.Location.Y));
pictureBox5.Controls.Add(c);

但是确定的框架/矩形位置不正确。
我在做什么错了？

Answer 1

您可以通过以下方式将图片框上的选定矩形转换为图像上的矩形：

public RectangleF GetRectangeOnImage(PictureBox p, Rectangle selectionRect)
{
    var method = typeof(PictureBox).GetMethod("ImageRectangleFromSizeMode",
        System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
    var imageRect = (Rectangle)method.Invoke(p, new object[] { p.SizeMode });
    if (p.Image == null)
        return selectionRect;
    var cx = (float)p.Image.Width / (float)imageRect.Width;
    var cy = (float)p.Image.Height / (float)imageRect.Height;
    var r2 = Rectangle.Intersect(imageRect, selectionRect);
    r2.Offset(-imageRect.X, -imageRect.Y);
    return new RectangleF(r2.X * cx, r2.Y * cy, r2.Width * cx, r2.Height * cy);
}

注意：您可以找到ImageRectangleFromSizeMode方法source code here并将其用作编写此方法的一部分，作为您的应用程序代码的一部分。

示例-具有SizeMode = Zoom的PictureBox的裁剪图像

作为示例，以下代码将裁剪图片框1的给定矩形，并将结果设置为图片框2的图像：

var selectedRectangle = new Rectangle(7, 30, 50, 40);
var result = GetRectangeOnImage(pictureBox1, selectedRectangle);
using (var bm = new Bitmap((int)result.Width, (int)result.Height))
{
    using (var g = Graphics.FromImage(bm))
        g.DrawImage(pictureBox1.Image, 0, 0, result, GraphicsUnit.Pixel);
    pictureBox2.Image = (Image)bm.Clone();
}

这是输入图像：

这是结果：

Answer 2

请考虑将其添加到Reza Aghaei answer中。

---

一个专门的类，提供一些帮助工具来确定选择的比例因子，并将选择坐标转换为缩放的Bitmap坐标。
此版本仅适用于缩放的图像。

ZoomFactor类提供了以下方法：

PointF TranslateZoomPosition(PointF Coordinates, SizeF ContainerSize, SizeF ImageSize) ：
将容器内某个Point位置的PointF转换后的坐标返回到位图内该Point位置的缩放坐标。

RectangleF TranslateZoomSelection(RectangleF Selection, SizeF ContainerSize, SizeF ImageSize) ：
返回RectangleF，代表在Container中创建的选择，并转换为位图坐标。

RectangleF TranslateSelectionToZoomedSel(RectangleF SelectionRect, SizeF ContainerSize, SizeF ImageSize) ：
返回 RectangleF ，代表原始位图的预选区域，该区域已转换为容器内缩放后的选择图像。

PointF GetImageScaledOrigin(SizeF ContainerSize, SizeF ImageSize) ：
返回容器内缩放的图像原点坐标的PointF参考。

SizeF GetImageScaledSize(SizeF ContainerSize, SizeF ImageSize) ：
在容器内缩放时，返回图像的SizeF参考。

示例用法，显示如何使用在Container控件内创建的选择Rectangle裁剪位图。 TranslateZoomSelection方法返回与选择区域相对应的Bitmap部分：

ZoomFactor ZoomHelper = new ZoomFactor()
Bitmap originalBitmap;

RectangleF currentSelection = [Current Selection Rectangle];
RectangleF bitmapRect = ZoomHelper.TranslateZoomSelection(currentSelection, [Container].Size, originalBitmap.Size);
using (Bitmap croppedBitmap = new Bitmap((int)bitmapRect.Width, (int)bitmapRect.Height, originalBitmap.PixelFormat))
using (Graphics g = Graphics.FromImage(croppedBitmap))
{
    g.DrawImage(originalBitmap, new Rectangle(Point.Empty, Size.Round(bitmapRect.Size)), 
                bitmapRect, GraphicsUnit.Pixel);
    [Container].Image = (Bitmap)croppedBitmap.Clone();
}

上述行为的示例：

注意：在该示例中，“人像”中的图像预选择会反转Width和Height

ZoomFactor类：

public class ZoomFactor
{
    public ZoomFactor() { }

    public PointF TranslateZoomPosition(PointF Coordinates, SizeF ContainerSize, SizeF ImageSize)
    {
        PointF imageOrigin = TranslateCoordinatesOrigin(Coordinates, ContainerSize, ImageSize);
        float scaleFactor = GetScaleFactor(ContainerSize, ImageSize);
        return new PointF(imageOrigin.X / scaleFactor, imageOrigin.Y / scaleFactor);
    }

    public RectangleF TranslateZoomSelection(RectangleF SelectionRect, SizeF ContainerSize, SizeF ImageSize)
    {
        PointF selectionTrueOrigin = TranslateZoomPosition(SelectionRect.Location, ContainerSize, ImageSize);
        float scaleFactor = GetScaleFactor(ContainerSize, ImageSize);

        SizeF selectionTrueSize = new SizeF(SelectionRect.Width / scaleFactor, SelectionRect.Height / scaleFactor);
        return new RectangleF(selectionTrueOrigin, selectionTrueSize);
    }

    public RectangleF TranslateSelectionToZoomedSel(RectangleF SelectionRect, SizeF ContainerSize, SizeF ImageSize)
    {
        float scaleFactor = GetScaleFactor(ContainerSize, ImageSize);
        RectangleF zoomedSelectionRect = new
            RectangleF(SelectionRect.X * scaleFactor, SelectionRect.Y * scaleFactor,
                       SelectionRect.Width * scaleFactor, SelectionRect.Height * scaleFactor);

        PointF imageScaledOrigin = GetImageScaledOrigin(ContainerSize, ImageSize);
        zoomedSelectionRect.Location = new PointF(zoomedSelectionRect.Location.X + imageScaledOrigin.X,
                                                  zoomedSelectionRect.Location.Y + imageScaledOrigin.Y);
        return zoomedSelectionRect;
    }

    public PointF TranslateCoordinatesOrigin(PointF Coordinates, SizeF ContainerSize, SizeF ImageSize)
    {
        PointF imageOrigin = GetImageScaledOrigin(ContainerSize, ImageSize);
        return new PointF(Coordinates.X - imageOrigin.X, Coordinates.Y - imageOrigin.Y);
    }

    public PointF GetImageScaledOrigin(SizeF ContainerSize, SizeF ImageSize)
    {
        SizeF imageScaleSize = GetImageScaledSize(ContainerSize, ImageSize);
        return new PointF((ContainerSize.Width - imageScaleSize.Width) / 2,
                          (ContainerSize.Height - imageScaleSize.Height) / 2);
    }

    public SizeF GetImageScaledSize(SizeF ContainerSize, SizeF ImageSize)
    {
        float scaleFactor = GetScaleFactor(ContainerSize, ImageSize);
        return new SizeF(ImageSize.Width * scaleFactor, ImageSize.Height * scaleFactor);

    }
    internal float GetScaleFactor(SizeF Scaled, SizeF Original)
    {
        return (Original.Width > Original.Height) ? (Scaled.Width / Original.Width)
                                                  : (Scaled.Height / Original.Height);
    }
}