LinearGradientBrush::ScaleTransform method (gdiplusbrush.h)

Article
10/13/2021

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

Syntax

Status ScaleTransform(
  [in] REAL        sx,
  [in] REAL        sy,
  [in] MatrixOrder order
);

Parameters

[in] sx

Type: REAL

Real number that specifies the amount to scale in the x direction.

[in] sy

Type: REAL

Real number that specifies the amount to scale in the y direction.

[in] order

Type: MatrixOrder

Optional. Element of the MatrixOrder enumeration that specifies the order of the multiplication. MatrixOrderPrepend specifies that the scaling matrix is on the left, and MatrixOrderAppend specifies that the scaling 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 S represents a scaling. If matrix M is the product TS, then matrix M represents a composite transformation: first translate, then scale.

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_ScaleTrans(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 translate, then scale.
   linGrBrush.TranslateTransform(60, 0);            // horizontal translation
   linGrBrush.ScaleTransform(2, MatrixOrderAppend); // horizontal doubling

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

Requirements

Requirement	Value
Minimum supported client	Windows XP, Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	gdiplusbrush.h (include Gdiplus.h)
Library	Gdiplus.lib
DLL	Gdiplus.dll

Share via