LinearGradientBrush::RotateTransform method (gdiplusbrush.h)

The LinearGradientBrush::RotateTransform method updates this brush's current transformation matrix with the product of itself and a rotation matrix.

Syntax

Status RotateTransform(
  [in] REAL        angle,
  [in] MatrixOrder order
);

Parameters

[in] angle

Type: REAL

Real number that specifies the angle of rotation in degrees.

[in] order

Type: MatrixOrder

Optional. Element of the MatrixOrder enumeration that specifies the order of the multiplication. MatrixOrderPrepend specifies that the rotation matrix is on the left, and MatrixOrderAppend specifies that the rotation matrix is on the right. The default value is MatrixOrderPrepend.

Return value

Type: Status

If the method succeeds, it returns Ok, which is an element of the Status enumeration.

If the method fails, it returns one of the other elements of the Status enumeration.

Remarks

A single 3 ×3 matrix can store any sequence of affine transformations. If you have several 3 ×3 matrices, each of which represents an affine transformation, the product of those matrices is a single 3 ×3 matrix that represents the entire sequence of transformations. The transformation represented by that product is called a composite transformation. For example, suppose matrix T represents a translation, and matrix R represents a rotation. If matrix M is the product TR, then matrix M represents a composite transformation: first translate, then rotate.

The order of matrix multiplication is important. In general, the matrix product RT is not the same as the matrix product TR. In the example given in the previous paragraph, the composite transformation represented by RT (first rotate, then translate) is not the same as the composite transformation represented by TR (first translate, then rotate).

Examples

The following example creates a linear gradient brush and uses it to fill a rectangle. Next, the code modifies the brush's transformation matrix, applying a composite transformation, and then fills a rectangle with the transformed brush.

VOID Example_RotateTrans(HDC hdc)
{
   Graphics myGraphics(hdc);

   LinearGradientBrush linGrBrush(
      Rect(0, 0, 80, 40),
      Color(255, 255, 0, 0),  // red
      Color(255, 0, 0, 255),  // blue
      LinearGradientModeHorizontal);

   // Fill a large area with the linear gradient brush (no transformation).
   myGraphics.FillRectangle(&linGrBrush, 0, 0, 800, 150);

   // Apply a composite transformation: first scale, then rotate.
   linGrBrush.ScaleTransform(2, 1);                    // horizontal doubling
   linGrBrush.RotateTransform(20, MatrixOrderAppend);  // 20-degree rotation

   // Fill a large area with the transformed linear gradient brush.
   myGraphics.FillRectangle(&linGrBrush, 0, 200, 800, 150);  
}

Requirements

See also

Brushes and Filled Shapes

Filling Shapes with a Gradient Brush

LinearGradientBrush

LinearGradientBrush::MultiplyTransform

LinearGradientBrush::ScaleTransform

LinearGradientBrush::TranslateTransform

Matrix

Matrix Representation of Transformations

MatrixOrder

Rect

Transformations