Coordinate System

CD - Canvas Draw

Coordinate System

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

canvas:GetCanvasSize() -> (width, heigth, 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]

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

In some graph systems, the origin is at the upper left corner of the canvas, with the direction of the Y axis pointing down. In this case, the function converts the coordinate system of the CD library into the internal system of the active canvas' driver, and the other way round. If this is not the case, nothing happens. This is just "y = height-1 - y". 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. 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, the transformation is reset to the identity. Default value: NULL.

The matrix contains scale, rotation and translation 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|

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.

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

canvas:GetTransformation() -> (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.