获取缩放图片上的鼠标位置

Question

我正在创建一个截图制作器/上传器，一切都很好，但现在我想集成一些东西，比如油漆。所以首先我要创建铅笔功能。但是开始出现我可以绘制的问题：D 但不是我的鼠标位置。他占据了我的光标以外的位置？

所以问题是： 锄头在放大的图片框上获取鼠标位置？

我的代码：

private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
    {
        if (draw && pencil)
        {
            Graphics panel = Graphics.FromImage(ScreenShot);

            Pen pen = new Pen(Color.Black, 14);

            pen.EndCap = LineCap.Round;
            pen.StartCap = LineCap.Round;

            panel.DrawLine(pen, pX, pY, e.X, e.Y);

            pictureBox1.CreateGraphics().DrawImage(ScreenShot, pictureBox1.Width, pictureBox1.Height);

            pictureBox1.Invalidate();
        }
        Point p = pictureBox1.PointToClient(Cursor.Position);

        pX = p.X;
        pY = p.Y;
    }

Answer 1

在缩放图像上使用鼠标时，报告的像素是缩放坐标。所以我们需要得到真实的像素..

在以某种方式设置之后..

float pbZoom = 3f;  // the factor by which the PictureBox is zoomed in or out

pictureBox.SizeMode = PictureBoxSizeMode.Zoom;
pictureBox.ClientSize = new Size((int)(pictureBox.Image.Width * pbZoom),
         (int)(pictureBox.Image.Height * pbZoom));

pictureBox.Paint     += pictureBox_Paint;
pictureBox.MouseDown += pictureBox_MouseDown;
pictureBox.MouseMove += pictureBox_MouseMove;
pictureBox.MouseUp   += pictureBox_MouseUp;

.. 您可以编写事件以在缩放的图像上绘制或绘制。

首先是一个辅助函数来取消对一个点的缩放：

PointF unZoomed(PointF pt) { return new PointF(pt.X / pbZoom, pt.Y / pbZoom );}

为简单起见，让我们在类级别保留一些内容：

PointF mDown    = PointF.Empty;   // mouse down point
PointF mCurrent = PointF.Empty;   // current mouse location

我们通过计算未缩放的e.Location来启动每个鼠标事件。

我们的测试会在表面上绘制一条直线移动的红线，直到您松开鼠标。然后那条线以绿色绘制到图像中。

MouseDown 只是存储起点，未缩放：

void pictureBox_MouseDown(object sender, MouseEventArgs e)
{
    mDown = unZoomed(e.Location);
}

在MouseMove中我们存储当前点并触发Paint事件：

void pictureBox_MouseMove(object sender, MouseEventArgs e)
{
    if (e.Button == System.Windows.Forms.MouseButtons.None) return;

    PointF e_ = unZoomed(e.Location);
    mCurrent = e_;
    pictureBox.Invalidate();
}

在MouseUp中我们画线到PictureBox的Image，改变它的像素；然后我们设置Image 并重置积分：

void pictureBox_MouseUp(object sender, MouseEventArgs e)
{
    Bitmap bmp = (Bitmap) pictureBox.Image;
    using (Graphics G = Graphics.FromImage(bmp))
    {
        G.SmoothingMode = SmoothingMode.HighQuality;
        G.DrawLine(Pens.Green, mDown, mCurrent);
     }
    mDown = PointF.Empty;
    mCurrent = PointF.Empty;
    pictureBox.Image = bmp;

}

我们使用Paint 事件在控制表面上绘图。要按比例绘制，我们使用Matrix..：

void pictureBox_Paint(object sender, PaintEventArgs e)
{
    Matrix scaleMatrix = new Matrix();
    scaleMatrix.Scale(pbZoom, pbZoom);
    e.Graphics.MultiplyTransform(scaleMatrix);
    e.Graphics.DrawLine(Pens.Red, mDown, mCurrent);
}

Answer 2

我也使用缩放图像。我只是使用此代码，它正在工作。因此，您可以在放大/缩小之前与位图（原始图像）进行比较。

private void pbInput_MouseMove(object sender, MouseEventArgs e) { 
    if (pbInput.Image == null) {
        mouseY.Text = "";
        mouseX.Text = "";
    }

    else {
        Bitmap b = new Bitmap(pbInput.Image);
        int x = b.Width * e.X / pbInput.Width;
        int y = b.Height * e.Y / pbInput.Height;

        mouseX.Text = x.ToString();
        mouseY.Text = y.ToString();
    }
}

Answer 3

this.Cursor = new Cursor(Cursor.Current.Handle);

            Size size1 = pictureBox1.Image.Size;
            Size size2 = pictureBox1.Size;


            float x1 = (float)size1.Width / ((float)size2.Width + 1);
            float y1 = (float)size1.Height / ((float)size2.Height + 1);

            float divisor = x1 >= y1 ? x1 : y1;

            divisor = divisor > 0 ? divisor : 1;

            Size imagesize = new Size((int)(size1.Width / divisor), (int)(size1.Height / divisor));
            int ex = imagesize.Width - size2.Width >= 0 ? imagesize.Width - size2.Width : size2.Width - imagesize.Width;
            int ey = imagesize.Height - size2.Height >= 0 ? imagesize.Height - size2.Height : size2.Height - imagesize.Height;



            float ftx = ((float)size1.Width / (float)imagesize.Width) * ((float)(Cursor.Position.X - this.Location.X - pictureBox1.Location.X - (ex / 2) - 8));
            float fty = ((float)size1.Height / (float)imagesize.Height) * ((float)(Cursor.Position.Y - this.Location.Y - pictureBox1.Location.Y - (ey / 2) - 31));

            Point LOP = new Point(Convert.ToInt32(ftx), Convert.ToInt32(fty)); //point of cursos on picturebox image pixel ...