GdipVectorTransformMatrixPointsIfunction

Multiplies each vector in an array by a matrix. The translation elements of a matrix (third row) are ignored. Each vector is treated as a row matrix. The multiplication is performed with the row matrix on the left and a matrix on the right.

Syntax

FUNCTION GdipVectorTransformMatrixPointsI (BYVAL matrix AS GpMatrix PTR, BYVAL pts AS GpPoint PTR, BYVAL count AS INT_) AS GpStatus

Parameters

Description

Multiplies each vector in an array by a matrix. The translation elements of a matrix (third row) are ignored. Each vector is treated as a row matrix. The multiplication is performed with the row matrix on the left and a matrix on the right.

Example

' ======================================================================================== ' The following example creates a vector and a point. The tip of the vector and the point ' are at the same location: (100, 50). The code creates a Matrix object and initializes its ' elements so that it represents a clockwise rotation followed by a translation 100 units ' to the right. The code calls the GdipTransformMatrixPoints functioon of the matrix ' to transform the point and calls the GdipVectorTransformMatrixPoints function to transform ' the vector. The entire transformation (rotation followed by translation) is performed on ' the point, but only the rotation part of the transformation is performed on the vector. ' The elements of the matrix that represent translation are ignored by the ' GdipVectorTransformMatrixPoints function ' ======================================================================================== SUB Example_VectorTransformMatrixPoints (BYVAL hdc AS HDC)

DIM hStatus AS LONG

' // Create a graphics object from the device context DIM graphics AS GpGraphics PTR hStatus = GdipCreateFromHDC(hdc, @graphics)

' // Get the DPI scaling ratios DIM dpiX AS SINGLE hStatus = GdipGetDpiX(graphics, @dpiX) DIM rxRatio AS SINGLE = dpiX / 96 DIM dpiY AS SINGLE hStatus = GdipGetDpiY(graphics, @dpiY) Dim ryRatio AS SINGLE = dpiY / 96 hStatus = GdipScaleWorldTransform(graphics, rxRatio, ryRatio, MatrixOrderPrepend)

' // Create pen DIM pen AS GpPen PTR hStatus = GdipCreatePen1(ARGB_BLUE, 2 * rxRatio, UnitPixel, @pen) hStatus = GdipSetPenEndCap(pen, LineCapArrowAnchor)

' // Create a solid brush DIM brush AS GpSolidFill PTR hStatus = GdipCreateSolidFill(ARGB_BLUE, @brush)

' // A point and a vector, same representation but different behavior DIM pt AS GpPointF = (100, 50) DIM vector AS GpPointF = (100, 50)

' // Draw the original point and vector in blue hStatus = GdipFillEllipse(graphics, brush, pt.x - 5.0, pt.y - 5.0, 10.0, 10.0) hStatus = GdipDrawLine(graphics, pen, 0, 0, vector.x, vector.y)

' // Transform DIM matrix AS GpMatrix PTR hStatus = GdipCreateMatrix2(0.8, 0.6, -0.6, 0.8, 100.0, 0.0,@matrix) hStatus = GdipTransformMatrixPoints(matrix, @pt, 1) hStatus = GdipVectorTransformMatrixPoints(matrix, @vector, 1)

' // Draw the transformed point and vector in red. hStatus = GdipSetPenColor(pen, ARGB_RED) hStatus = GdipSetSolidFillColor(brush, ARGB_RED) hStatus = GdipFillEllipse(graphics, brush, pt.X - 5.0, pt.Y - 5.0, 10.0, 10.0) hStatus = GdipDrawLine(graphics, pen, 0, 0, vector.x, vector.y)

' // Cleanup IF pen THEN GdipDeletePen(pen) IF brush THEN GdipDeleteBrush(brush) IF matrix THEN GdipDeleteMatrix(matrix) IF graphics THEN GdipDeleteGraphics(graphics)

END SUB ' ========================================================================================

Reference

• Defined in AfxNova/AfxGdiPlus.bi:2213
• Documented in Graphics/GdiPlus Flat Api/GdiPlusMatrix.md
• Topic: GdiPlusMatrix