public void RotationZoomIsCalculated(int imageWidth, int imageHeight, float angle, float expected)
{
float result = ImageMaths.ZoomAfterRotation(imageWidth, imageHeight, angle);
result.Should().BeApproximately(expected, 0.01f, "because the zoom level after rotation should have been calculated");
result.Should().BePositive("because we're always zooming in so the zoom level should always be positive");
result.Should().BeGreaterOrEqualTo(1, "because the zoom should always increase the size and not reduce it");
}
/// <summary>
/// Rotates the inside of an image to the given angle at the given position.
/// </summary>
/// <param name="image">
/// The image to rotate
/// </param>
/// <param name="angleInDegrees">
/// The angle in degrees.
/// </param>
/// <param name="keepSize">
/// Whether to keep the image dimensions.
/// <para>
/// If set to true, the image is zoomed to fit the bounding area.
/// </para>
/// <para>
/// If set to false, the area is cropped to fit the rotated image.
/// </para>
/// </param>
/// <remarks>
/// Based on the Rotate effect
/// </remarks>
/// <returns>
/// The image rotated to the given angle at the given position.
/// </returns>
private Bitmap RotateImage(Image image, float angleInDegrees, bool keepSize)
{
Size newSize = new Size(image.Width, image.Height);
float zoom = ImageMaths.ZoomAfterRotation(image.Width, image.Height, angleInDegrees);
// if we don't keep the image dimensions, calculate the new ones
if (!keepSize)
{
newSize.Width = Math.Max(1, (int)Math.Floor(newSize.Width / zoom));
newSize.Height = Math.Max(1, (int)Math.Floor(newSize.Height / zoom));
}
// Center of the image
float rotateAtX = Math.Abs(image.Width / 2);
float rotateAtY = Math.Abs(image.Height / 2);
// Create a new empty bitmap to hold rotated image
Bitmap newImage = new Bitmap(newSize.Width, newSize.Height, PixelFormat.Format32bppPArgb);
newImage.SetResolution(image.HorizontalResolution, image.VerticalResolution);
// Make a graphics object from the empty bitmap
using (Graphics graphics = Graphics.FromImage(newImage))
{
// Reduce the jagged edge.
graphics.SmoothingMode = SmoothingMode.AntiAlias;
graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
graphics.CompositingQuality = CompositingQuality.HighQuality;
if (keepSize)
{
// Put the rotation point in the "center" of the image
graphics.TranslateTransform(rotateAtX, rotateAtY);
// Rotate the image
graphics.RotateTransform(angleInDegrees);
// Zooms the image to fit the area
graphics.ScaleTransform(zoom, zoom);
// Move the image back
graphics.TranslateTransform(-rotateAtX, -rotateAtY);
// Draw passed in image onto graphics object
graphics.DrawImage(image, new PointF(0, 0));
}
else
{
float previousX = rotateAtX;
float previousY = rotateAtY;
// Calculate the difference between the center of the original image
// and the center of the new image.
rotateAtX = Math.Abs(newImage.Width / 2);
rotateAtY = Math.Abs(newImage.Height / 2);
// Put the rotation point in the "center" of the image
graphics.TranslateTransform(rotateAtX, rotateAtY);
// Rotate the image
graphics.RotateTransform(angleInDegrees);
// Draw passed in image onto graphics object
graphics.DrawImage(image, new PointF(-previousX, -previousY));
}
}
image.Dispose();
return(newImage);
}
/// <summary>
/// Rotates the inside of an image to the given angle at the given position.
/// </summary>
/// <param name="image">
/// The image to rotate
/// </param>
/// <param name="angleInDegrees">
/// The angle in degrees.
/// </param>
/// <param name="keepSize">
/// Whether to keep the image dimensions.
/// <para>
/// If set to true, the image is zoomed to fit the bounding area.
/// </para>
/// <para>
/// If set to false, the area is cropped to fit the rotated image.
/// </para>
/// </param>
/// <remarks>
/// Based on the Rotate effect
/// </remarks>
/// <returns>
/// The image rotated to the given angle at the given position.
/// </returns>
private Bitmap RotateImage(Image image, float angleInDegrees, bool keepSize)
{
var newSize = new Size(image.Width, image.Height);
var zoom = ImageMaths.ZoomAfterRotation(image.Width, image.Height, angleInDegrees);
// if we don't keep the image dimensions, calculate the new ones
if (!keepSize)
{
newSize.Width = Math.Max(1, (int)Math.Floor(newSize.Width / zoom));
newSize.Height = Math.Max(1, (int)Math.Floor(newSize.Height / zoom));
}
// Center of the image
float rotateAtX = Math.Abs(image.Width / 2);
float rotateAtY = Math.Abs(image.Height / 2);
// Create a new empty bitmap to hold rotated image
var newImage = new Bitmap(newSize.Width, newSize.Height, PixelFormat.Format32bppPArgb);
newImage.SetResolution(image.HorizontalResolution, image.VerticalResolution);
// Make a graphics object from the empty bitmap
using (var graphics = Graphics.FromImage(newImage))
{
GraphicsHelper.SetGraphicsOptions(graphics);
if (keepSize)
{
// Put the rotation point in the "center" of the image
graphics.TranslateTransform(rotateAtX, rotateAtY);
// Rotate the image
graphics.RotateTransform(angleInDegrees);
// Zooms the image to fit the area
graphics.ScaleTransform(zoom, zoom);
// Move the image back
graphics.TranslateTransform(-rotateAtX, -rotateAtY);
// Draw passed in image onto graphics object
graphics.DrawImage(image, new PointF(0, 0));
}
else
{
var previousX = rotateAtX;
var previousY = rotateAtY;
// Calculate the difference between the center of the original image
// and the center of the new image.
rotateAtX = Math.Abs(newImage.Width / 2);
rotateAtY = Math.Abs(newImage.Height / 2);
// Put the rotation point in the "center" of the image
graphics.TranslateTransform(rotateAtX, rotateAtY);
// Rotate the image
graphics.RotateTransform(angleInDegrees);
// Draw passed in image onto graphics object
graphics.DrawImage(image, new PointF(-previousX, -previousY));
}
}
image.Dispose();
return(newImage);
}
