Andy De George
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title, ms.date, dev_langs, helpviewer_keywords, ms.assetid
| title | ms.date | dev_langs | helpviewer_keywords | ms.assetid | |||||
|---|---|---|---|---|---|---|---|---|---|
| How to: Rotate, Reflect, and Skew Images | 03/30/2017 |
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a3bf97eb-63ed-425a-ba07-dcc65efb567c |
How to: Rotate, Reflect, and Skew Images
You can rotate, reflect, and skew an image by specifying destination points for the upper-left, upper-right, and lower-left corners of the original image. The three destination points determine an affine transformation that maps the original rectangular image to a parallelogram.
Example
For example, suppose the original image is a rectangle with upper-left corner at (0, 0), upper-right corner at (100, 0), and lower-left corner at (0, 50). Now suppose you map those three points to destination points as follows.
| Original point | Destination point |
|---|---|
| Upper-left (0, 0) | (200, 20) |
| Upper-right (100, 0) | (110, 100) |
| Lower-left (0, 50) | (250, 30) |
The following illustration shows the original image and the image mapped to the parallelogram. The original image has been skewed, reflected, rotated, and translated. The x-axis along the top edge of the original image is mapped to the line that runs through (200, 20) and (110, 100). The y-axis along the left edge of the original image is mapped to the line that runs through (200, 20) and (250, 30).
The following illustration shows a similar transformation applied to a photographic image:
The following illustration shows a similar transformation applied to a metafile:
The following example produces the images shown in the first illustration.
[!code-csharpSystem.Drawing.WorkingWithImages#61] [!code-vbSystem.Drawing.WorkingWithImages#61]
Compiling the Code
The preceding example is designed for use with Windows Forms, and it requires xref:System.Windows.Forms.PaintEventArgs e, which is a parameter of the xref:System.Windows.Forms.Control.Paint event handler. Make sure to replace Stripes.bmp with the path to an image that is valid on your system.