Class ImageHelper

Provides utility methods for image manipulation, processing, and conversion operations.

Inheritance

System.Object

ImageHelper

Inherited Members

System.Object.ToString()

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.ReferenceEquals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

Namespace: Telerik.WinControls

Assembly: Telerik.WinControls.dll

Syntax

public static class ImageHelper

Remarks

Contains static methods for common image operations including alpha blending, masking, cropping, format conversion, and pixel-level manipulations. Supports various image formats and provides efficient bitmap manipulation methods using unsafe code for performance-critical operations.

Methods

ApplyAlpha(Bitmap, Single)

Applies a uniform alpha (transparency) value to all pixels in the specified bitmap.

Declaration

public static void ApplyAlpha(Bitmap bitmap, float fAlpha)

Parameters

System.Drawing.Bitmap bitmap The bitmap to modify. Must be in 32bpp ARGB format.

System.Single fAlpha The alpha value to apply, ranging from 0.0 (fully transparent) to 1.0 (fully opaque).

Remarks

Directly modifies the alpha channel of each pixel using unsafe code for optimal performance. The bitmap must be in 32bpp ARGB format. Commonly used for fade effects and transparency adjustments.

ApplyMask(Bitmap, Brush)

Applies a brush-based alpha mask to a bitmap, modifying the transparency of pixels based on the brush pattern.

Declaration

public static void ApplyMask(Bitmap bitmap, Brush brush)

Parameters

System.Drawing.Bitmap bitmap The bitmap to apply the mask to.

System.Drawing.Brush brush The brush defining the alpha mask pattern. The brush's color values determine the transparency.

Remarks

This method creates a temporary bitmap filled with the specified brush pattern, then uses the red channel values from this pattern as alpha values for the original bitmap. This allows for complex transparency effects based on gradients, patterns, or solid colors.

The masking process:

1. Creates a temporary bitmap the same size as the original
2. Fills the temporary bitmap with the brush pattern
3. Uses the red channel values as alpha channel values for each corresponding pixel

This is useful for creating fade effects, vignettes, and complex transparency patterns.

AreColorsSame(Color, Color)

Declaration

public static bool AreColorsSame(Color color1, Color color2)

Parameters

System.Drawing.Color color1

System.Drawing.Color color2

Returns

System.Boolean

BitmapInvertColors(Bitmap)

Declaration

public static Bitmap BitmapInvertColors(Bitmap original)

Parameters

System.Drawing.Bitmap original

Returns

System.Drawing.Bitmap

ChangeImagePixels(Image, Color)

Declaration

public static Image ChangeImagePixels(Image image, Color color)

Parameters

System.Drawing.Image image

System.Drawing.Color color

Returns

System.Drawing.Image

ConvertToDib(Image)

Converts the image to Device Independent Bitmap format of type BITFIELDS. This is (wrongly) accepted by many applications as containing transparency

Declaration

public static byte[] ConvertToDib(Image image)

Parameters

System.Drawing.Image image Image to convert to DIB

Returns

System.Byte[] The image converted to DIB, in bytes.

CopyImageToClipboard(Image)

Copies given image to the clipboard. Different applications understand different image formats, so this method applies the three most common image formats to the data object - Bitmap, PNG and DIB.

Declaration

public static void CopyImageToClipboard(Image image)

Parameters

System.Drawing.Image image The image to copy.

Crop(Bitmap, Rectangle)

Crops a rectangular region from a bitmap and returns it as a new bitmap with high-quality rendering.

Declaration

public static Bitmap Crop(Bitmap image, Rectangle cropRectangle)

Parameters

System.Drawing.Bitmap image The source bitmap to crop from.

System.Drawing.Rectangle cropRectangle The rectangular region to extract from the source image, in pixel coordinates.

Returns

System.Drawing.Bitmap A new System.Drawing.Bitmap containing the cropped region, with dimensions matching the crop rectangle.

Remarks

This method creates a new bitmap with the exact dimensions of the crop rectangle and draws the specified region from the source image using high-quality rendering settings:

• Anti-aliased smoothing for clean edges
• High-quality bicubic interpolation for smooth scaling
• High-quality pixel offset mode for precise positioning

The crop rectangle coordinates are relative to the source image. If the rectangle extends beyond the source image boundaries, the out-of-bounds areas will be filled with transparent pixels.

The caller is responsible for disposing of the returned bitmap when no longer needed.

GetBitmapRegionPath(Bitmap, Color)

Declaration

public static GraphicsPath GetBitmapRegionPath(Bitmap bmp, Color transparent)

Parameters

System.Drawing.Bitmap bmp

System.Drawing.Color transparent

Returns

System.Drawing.Drawing2D.GraphicsPath

GetBytesFromImage(Image)

Declaration

public static byte[] GetBytesFromImage(Image image)

Parameters

System.Drawing.Image image

Returns

System.Byte[]

GetClipboardImage()

Gets image from the clipboard and preserves pixel transparency. If there is no image data in the clipboard, returns null.

Declaration

public static Image GetClipboardImage()

Returns

System.Drawing.Image The image from clipboard.

GetClipboardImage(DataObject)

Retrieves an image from the given clipboard data object, in the order PNG, DIB, Bitmap, Image object.

Declaration

public static Bitmap GetClipboardImage(DataObject clipboardData)

Parameters

System.Windows.Forms.DataObject clipboardData The clipboard data.

Returns

System.Drawing.Bitmap The extracted image, or null if no supported image type was found.

GetImageData(Bitmap, out Int32)

Gets the raw bytes from an image.

Declaration

public static byte[] GetImageData(Bitmap sourceImage, out int stride)

Parameters

System.Drawing.Bitmap sourceImage The image to get the bytes from.

System.Int32 stride Stride of the retrieved image data.

Returns

System.Byte[] The raw bytes of the image

GetImageFromBytes(Byte[])

Declaration

public static Image GetImageFromBytes(byte[] bytes)

Parameters

System.Byte[] bytes

Returns

System.Drawing.Image

HslToRgb(Double, Double, Double, Double)

Declaration

public static Color HslToRgb(double h, double s, double l, double a)

Parameters

System.Double h

System.Double s

System.Double l

System.Double a

Returns

System.Drawing.Color

IsDarkColor(Color)

Declaration

public static bool IsDarkColor(Color color)

Parameters

System.Drawing.Color color

Returns

System.Boolean

PointInRegion(Region, Point)

Declaration

public static bool PointInRegion(Region region, Point client)

Parameters

System.Drawing.Region region

System.Drawing.Point client

Returns

System.Boolean

RegionFromBitmap(Bitmap, Color)

Declaration

public static Region RegionFromBitmap(Bitmap bmp, Color transparent)

Parameters

System.Drawing.Bitmap bmp

System.Drawing.Color transparent

Returns

System.Drawing.Region