Clipping

From 7b52cc13af4e85f1ca2deb6b6c77de9c95ea0dcf Mon Sep 17 00:00:00 2001 From: scuri Date: Fri, 17 Oct 2008 06:10:33 +0000 Subject: First commit - moving from LuaForge to SourceForge --- html/en/func/clipping.html | 62 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 html/en/func/clipping.html (limited to 'html/en/func/clipping.html') diff --git a/html/en/func/clipping.html b/html/en/func/clipping.html new file mode 100644 index 0000000..b30db55 --- /dev/null +++ b/html/en/func/clipping.html @@ -0,0 +1,62 @@ + + + + Clipping + + + + + +

Clipping

The clipping area is an area that limits the available drawing area inside the + canvas. Any primitive is drawn only inside the clipping area. It affects all + primitives.

You can set the clipping area by using the function cdClipArea, and + retrieve it using cdGetClipArea. The clipping area is a rectangle by + default, but it can has other shapes. In some drivers a polygon area can be + defined, and in display based drivers a complex region can be defined. The + complex region can be a combination of boxes, polygons, sectors, chords and + texts.

The cdClip function activates and deactivaes the clipping.

int cdCanvasClip(cdCanvas* canvas, int mode); [in C]
+
+canvas:Clip(mode: number) -> (old_mode: number) [in Lua]

Activates or deactivates clipping. Returns the previous status. Values: CD_CLIPAREA, + CD_CLIPPOLYGON, CD_CLIPREGION or CD_CLIPOFF. The value CD_QUERY + simply returns the current status. Default value: CD_CLIPOFF.

The value CD_CLIPAREA activates a rectangular area as the clipping + region. +

The value CD_CLIPPOLYGON activates a polygon as a clipping region, but + works only in some drivers (please refer to the notes of each driver). The + clipping polygon must be defined before activating the polygon clipping; if it + is not defined, the current clipping state remains unchanged. See the + documentation of cdBegin/cdVertex/cdEnd to create a + polygon.

The value CD_CLIPREGION activates a complex clipping region. See the + documentation of Regions.

void cdCanvasClipArea(cdCanvas* canvas, int xmin, int xmax, int ymin, int ymax); [in C]
+void cdfCanvasClipArea(cdCanvas* canvas, double xmin, double xmax, double ymin, double ymax); [in C]
+void wdCanvasClipArea(cdCanvas* canvas, double xmin, double xmax, double ymin, double ymax); (WC) [in C]
+
+canvas:ClipArea(xmin, xmax, ymin, ymax: number) [in Lua]
+canvas:wClipArea(xmin, xmax, ymin, ymax: number) (WC) [in Lua]

Defines a rectangle for clipping. Only the points in the interval xmin<= + x <= xmax and ymin <= y <= ymax will + be printed. Default region: (0, w-1, 0, h-1). +

int cdCanvasGetClipArea(cdCanvas* canvas, int *xmin, int *xmax, int *ymin, int *ymax); [in C]
+int cdfCanvasGetClipArea(cdCanvas* canvas, double *xmin, double *xmax, double *ymin, double *ymax); [in C]
+int wdCanvasGetClipArea(cdCanvas* canvas, double *xmin, double *xmax, double *ymin, double *ymax); (WC) [in C]
+
+canvas:GetClipArea() -> (xmin, xmax, ymin, ymax, status: number) [in Lua]
+canvas:wGetClipArea() -> (xmin, xmax, ymin, ymax, status: number) (WC) [in Lua]

Returns the rectangle and the clipping status. It is not necessary to provide + all return pointers, you can provide only the desired values and NULL + for the others.

Polygons

A polygon for clipping can be created using cdBegin(CD_CLIP)/cdVertex(x,y)/.../cdEnd().

See the documentation of cdBegin/cdVertex/cdEnd.

+ + -- cgit v1.2.3