Coordinate System

void cdCanvasGetSize(cdCanvas* canvas, int *width, int *height, double *width_mm, double *height_mm); [in C]

canvas:GetSize() -> (width, height, mm_width, mm_height: number) [in Lua]

Returns the canvas size in pixels and in millimeters. You can provide only the desired values and NULL for the others.

int cdCanvasUpdateYAxis(cdCanvas* canvas, int *y); [in C]
double cdfCanvasUpdateYAxis(cdCanvas* canvas, double *y); [in C]

canvas:UpdateYAxis(yc: number) -> (yr: number) [in Lua]

Invert the given Y coordinate if the native Y axis orientation is different from the CD axis orientation. The CD axis orientation is always bottom-top. It also returns the changed value.

int cdCanvasInvertYAxis(cdCanvas* canvas, int y); [in C]
double cdfCanvasInvertYAxis(cdCanvas* canvas, double y); [in C]

canvas:InvertYAxis(yc: number) -> (yr: number) [in Lua]

Invert the given Y coordinate independent of the driver Y axis orientation. It returns the changed value.

void cdCanvasMM2Pixel(cdCanvas* canvas, double mm_dx, double mm_dy, int *dx, int *dy); [in C]
void cdfCanvasMM2Pixel(cdCanvas* canvas, double mm_dx, double mm_dy, double *dx, double *dy); [in C]

canvas:MM2Pixel(mm_dx, mm_dy: number) -> (dx, dy: number) [in Lua]
canvas:fMM2Pixel(mm_dx, mm_dy: number) -> (dx, dy: number) [in Lua]

Converts sizes in millimeters into pixels (canvas coordinates). You can provide only the desired values and NULL for the others.

void cdCanvasPixel2MM(cdCanvas* canvas, int dx, int dy, double *mm_dx, double *mm_dy); [in C]
void cdfCanvasPixel2MM(cdCanvas* canvas, double dx, double dy, double *mm_dx, double *mm_dy); [in C]

canvas:Pixel2MM(dx, dy: number) -> (mm_dx, mm_dy: number) [in Lua]
canvas:fPixel2MM(dx, dy: number) -> (mm_dx, mm_dy: number) [in Lua]

Converts sizes in pixels (canvas coordinates) into millimeters. You can provide only the desired values and NULL for the others. Use this function to obtain the horizontal and vertical resolution of the canvas by passing 1 as parameter in dx and dy. The resolution value is obtained using the formula res=1.0/mm.

void cdCanvasOrigin(cdCanvas* canvas, int x, int y); [in C]
void cdfCanvasOrigin(cdCanvas* canvas, double x, double y); [in C]

canvas:Origin(x, y: number) [in Lua]
canvas:fOrigin(x, y: number) [in Lua]

Allows translating the origin - for instance, to the center of the canvas. The function profits from the architecture of the library to simulate a translation of the origin, which in fact is never actually passed to the canvas in the respective driver. It is not related with WD nor Transformation Matrix. Default values: (0, 0)

void cdCanvasGetOrigin(cdCanvas* canvas, int *x, int *y); [in C]
void cdfCanvasGetOrigin(cdCanvas* canvas, double *x, double *y); [in C]

canvas:GetOrigin() -> (x, y: number) [in Lua]
canvas:fGetOrigin() -> (x, y: number) [in Lua]

Returns the origin.

Transformation Matrix

void cdCanvasTransform(cdCanvas* canvas, const double* matrix); [in C]

canvas:Transform(matrix: table) [in Lua]

Defines a transformation matrix with 6 elements. If the matrix is NULL (nil in Lua), the transformation is reset to the identity. Default value: NULL.

The matrix contains scale (sx,sy), rotation (angle) and translation (dx,dy) elements as follows:

|x'|   |sx*cos(angle)    -sin(angle)  dx|   |x|                     |0   2   4| 
|y'| = |   sin(angle)  sy*cos(angle)  dy| * |y|      with indices   |1   3   5|

In other words:

matrix[0] = sx*cos(angle)           // Horizontal Scale and Rotation component
matrix[1] =    sin(angle)           // Rotation component (can also contain an horizontal shear component)
matrix[2] =   -sin(angle)           // Rotation component (can also contain a vertical shear component)
matrix[3] = sy*cos(angle)           // Vertical Scale and Rotation component
matrix[4] = dx                      // Horizontal Translation component
matrix[5] = dy                      // Vertical Translation component

But notice that the indices are different of the cdCanvasVectorTextTransform.

Functions that retrieve images from the canvas are not affected by the transformation matrix, such as GetImage, GetImageRGB and ScrollArea.

Transformation matrix is independent of the World Coordinate and Origin functions. And those are affected if a transformation is set, just like other regular primitives.

The transformation matrix and world coordinates perform similar functions. World coordinates were developed before the transformation matrix support. The transformation matrix operates at a lower level than world coordinates, and, as such, might be faster, but might behave differently on different platforms. World coordinates behave consistently across platforms.

double* cdCanvasGetTransform(cdCanvas* canvas); [in C]

canvas:GetTransform() -> (matrix: table) [in Lua]

Returns the transformation matrix. If the identity is set, returns NULL.

void cdCanvasTransforMultiply(cdCanvas* canvas, const double* matrix); [in C]

canvas:TransformMultiply(matrix: table) [in Lua]

Left multiply the current transformation by the given transformation.

void cdCanvasTransformTranslate(cdCanvas* canvas, double dx, double dy); [in C]

canvas:TransformTranslate(dx, dy: number) [in Lua]

Applies a translation to the current transformation.

void cdCanvasTransformScale(cdCanvas* canvas, double sx, double sy); [in C]

canvas:TransformScale(sx, sy: number) [in Lua]

Applies a scale to the current transformation.

void cdCanvasTransformRotate(cdCanvas* canvas, double angle); [in C]

canvas:TransformRotate(angle: number) [in Lua]

Applies a rotation to the current transformation. Angle is in degrees, oriented counter-clockwise from the horizontal axis.

void cdCanvasTransformPoint(cdCanvas* canvas, int x, int y, int *tx, int *ty); [in C]
void cdfCanvasTransformPoint(cdCanvas* canvas, double x, double y, double *tx, double *ty); [in C]

canvas:TransformPoint(x, y: number) -> (tx, ty: number) [in Lua]
canvas:fTransformPoint(x, y: number) -> (tx, ty: number) [in Lua]

Applies a transformation to a given point.