为什么当我用鼠标拖动pictureBox中的图像时，它将图像恢复为原始大小？

Question

In my code im using the mouse wheel to resize the image in the pictureBox.

void pictureBox1_MouseWheel(object sender, MouseEventArgs e)
        {
            CalculateNewSizeFactor(e.Delta);
            if (pictureBox1.Image != null) pictureBox1.Image.Dispose();
            pictureBox1.Image = null;
            pictureBox1.Image = ResizeImage(new Size((int)(img.Width * factor), (int)(img.Height * factor)));
        }

        public Image ResizeImage(Size size)
        {
            return new Bitmap(img, size);
        }

        private void CalculateNewSizeFactor(int delta)
        {
            if (delta > 0 && factor < 2)
            {
                factor *= increment;
            }
            else if (delta < 0 && factor > 0.25)
            {
                factor /= increment;
            }
        }

Now i added a new checkbox so if its checked i can drag the image around inside the pictureBox:

private void checkBox1_CheckedChanged(object sender, EventArgs e)
        {
            if (checkBox1.Checked)
            {
                panning = true;
            }
        }

private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (checkBox1.Checked)
            {
                panning = true;
            }
            startingPoint = new Point(e.Location.X - movingPoint.X,
                                      e.Location.Y - movingPoint.Y);
        }

        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            panning = false;
        }

        private void pictureBox1_Paint(object sender, PaintEventArgs e)
        {
            if (panning)
            {
                e.Graphics.Clear(Color.White);
                e.Graphics.DrawImage(img, movingPoint);
            }
        }

There are some problems:

1. When i check the checkbox once i move the mouse inside the pictureBox1 area it capture and drag the image and i want it will do it only when i make left click on the mouse.

2. If first i use the mouse wheel and make the image size smaller or bigger and then try to drag it around once i click the image to drag it(mouse down) or when i leave it(mouse up) the image change its size back to its ogirinal size. I want it to be kept on the size i changed it with the mouse wheel when i drag it.

How can i solve this two problems ?

Answer 1

1. You set panning mode when you check your checkbox - just get rid of that handler - and that`s all. Because you set panning mode as well in your mouseDown handler - based on checkBox state.

2. When you paint you picture box you are drawing img, which is (probably) is your original image. So just save your resized image somewhere and repaint it.