在缩放模式下平移图片框中的矩形位置

问题描述 投票：0回答：2

我正在确定图像中的矩形区域并将其在 PictureBox 中显示给用户。
由于图像有时可能非常大，因此我使用 PictureBox，并将其 

SizeMode
设置为 
Zoom
。

我使用以下代码来平移矩形（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);

但确定的框/矩形位置不正确。
我做错了什么？

更新： 我正在尝试使用类似的代码将图像上的矩形转换为 PictureBox 上的框架控件

public Rectangle GetRectangeOnPictureBox(PictureBox p, Rectangle selectionRect,Bitmap bit)
    {
        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;
        int cx = bit.Width / imageRect.Width;
        int cy = bit.Height / imageRect.Height;
        Rectangle trsRectangle = new Rectangle(selectionRect.X * cx, selectionRect.Y * cy, selectionRect.Width * cx, selectionRect.Height * cy);

        trsRectangle.Offset(imageRect.X, imageRect.Y);
        return trsRectangle;
    }

这会产生无效的结果。请建议

c# .net winforms picturebox system.drawing
2个回答
7
投票

您可以通过以下方式将图片框中选定的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：您可以在此处找到

ImageRectangleFromSizeMode
方法源代码并将其用作将此类方法编写为应用程序代码的一部分。

示例 - 裁剪具有 SizeMode = Zoom

的 PictureBox 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：

这就是结果：

5
投票

一个专门的类，提供一些辅助工具来确定选择的缩放因子并将选择坐标转换为缩放后的 

Bitmap
坐标。
此版本仅适用于缩放图像。

ZoomFactor
类提供了这些方法：

PointF TranslateZoomPosition(PointF Coordinates, SizeF ContainerSize, SizeF ImageSize)
：
将容器内的点位置的 
PointF
转换坐标返回到位图内的点位置（在容器中放大）。

RectangleF TranslateZoomSelection(RectangleF Selection, SizeF ContainerSize, SizeF ImageSize)
：
返回一个 
RectangleF
表示在容器内创建的选择，转换为位图坐标。

RectangleF TranslateSelectionToZoomedSel(RectangleF SelectionRect, SizeF ContainerSize, SizeF ImageSize)
：
返回一个 
RectangleF
，表示原始位图的预选区域，转换为容器内的缩放选择图像。

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

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

示例用法，展示如何使用在容器控件内创建的选择矩形来裁剪位图。 

TranslateZoomSelection
方法返回对应于选择区域的Bitmap部分：

ZoomFactor zoomHelper = new ZoomFactor()
Bitmap originalBitmap;

RectangleF currentSelection = [Current Selection Rectangle];
RectangleF bitmapRect = zoomHelper.TranslateZoomSelection(currentSelection, [Container].Size, originalBitmap.Size);

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

上述行为示例：

注意： 示例中，预选肖像中的图像会反转 

Width
和 
Height

ZoomFactor
班：

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);
    }
}
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