Got a useful piece of here which I have implemented in following way to make a image preview form.
private void frmPreview_Load(object sender, EventArgs e)
{
try
{
pboxMain.Image = Image.FromFile(_imagePath);
pboxMain.Tag = Image.FromFile(_imagePath);
}
catch(Exception ex)
{
Log.Error(ex);
}
}
private void btFit_Click(object sender, EventArgs e)
{
if (btFit.Text == "Fit to Screen")
{
handleFitToWindow(true);
btFit.Text = "Actual Size";
}
else
{
handleFitToWindow(false);
btFit.Text = "Fit to Screen";
}
}
private void handleFitToWindow(bool doFit)
{
try
{
/* Don’t perform any operation if no image is loaded. */
if (this.pboxMain.Tag != null)
{
if (doFit) /* We’re fitting it to the window, and centering it. */
{
/* Create a temporary Image.
* Always work from the original image, stored in the Tag.
*/
Image tempImage = (Image)this.pboxMain.Tag;
/* Calculate the dimensions necessary for an image to fit. */
Size fitImageSize = this.getScaledImageDimensions(
tempImage.Width, tempImage.Height, this.pboxMain.Width, this.pboxMain.Height);
/* Create a new Bitmap from the original image with the new dimensions.
* The constructor for the Bitmap object automatically scales as necessary.
*/
Bitmap imgOutput = new Bitmap(tempImage, fitImageSize.Width, fitImageSize.Height);
/* Clear any existing image in the PictureBox. */
this.pboxMain.Image = null;
/* When fitting the image to the window, we want to keep it centered. */
this.pboxMain.SizeMode = PictureBoxSizeMode.CenterImage;
/* Finally, set the Image property to point to the new, resized image. */
this.pboxMain.Image = imgOutput;
}
else /* Restore the image to its original size */
{
/* Clear any existing image int he PictureBox. */
this.pboxMain.Image = null;
/* Set the resize more to Normal; this will place the image
* in the upper left-hand corner, clipping the image as required.
*/
this.pboxMain.SizeMode = PictureBoxSizeMode.Normal;
/* Finally, set the Image property to point to the original image. */
this.pboxMain.Image = (Image)this.pboxMain.Tag;
}
}
}
catch (System.Exception e)
{
Console.WriteLine(e);
}
}
private Size getScaledImageDimensions(
int currentImageWidth,
int currentImageHeight,
int desiredImageWidth,
int desiredImageHeight)
{
/* First, we must calculate a multiplier that will be used
* to get the dimensions of the new, scaled image.
*/
double scaleImageMultiplier = 0;
/* This multiplier is defined as the ratio of the
* Desired Dimension to the Current Dimension.
* Specifically which dimension is used depends on the larger
* dimension of the image, as this will be the constraining dimension
* when we fit to the window.
*/
/* Determine if Image is Portrait or Landscape. */
if (currentImageHeight > currentImageWidth) /* Image is Portrait */
{
/* Calculate the multiplier based on the heights. */
if (desiredImageHeight > desiredImageWidth)
{
scaleImageMultiplier = (double)desiredImageWidth / (double)currentImageWidth;
}
else
{
scaleImageMultiplier = (double)desiredImageHeight / (double)currentImageHeight;
}
}
else /* Image is Landscape */
{
/* Calculate the multiplier based on the widths. */
if (desiredImageHeight > desiredImageWidth)
{
scaleImageMultiplier = (double)desiredImageWidth / (double)currentImageWidth;
}
else
{
scaleImageMultiplier = (double)desiredImageHeight / (double)currentImageHeight;
}
}
/* Generate and return the new scaled dimensions.
* Essentially, we multiply each dimension of the original image
* by the multiplier calculated above to yield the dimensions
* of the scaled image. The scaled image can be larger or smaller
* than the original.
*/
return new Size(
(int)(currentImageWidth * scaleImageMultiplier),
(int)(currentImageHeight * scaleImageMultiplier));
}
}
