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Canvas

This set of APIs allows you to modify what is displayed on the main canvas. You can exploit this to allow for more efficient graphical rendering techniques.

• Acquisition
• Enums
  • enum: DOME_DrawMode
• Struct
  • struct: DOME_Color
• Methods
  • method: draw
  • method: getWidth
  • method: getHeight
  • method: line
  • method: pget
  • method: pset
  • method: rect
  • method: rectfill
  • method: unsafePset

Acquisition

CANVAS_API_v0* canvas = (CANVAS_API_v0*)DOME_getAPI(API_CANVAS, CANVAS_API_VERSION);

Enums

enum: DOME_DrawMode

Some methods in this API allow you to enable or disable alpha-blending for performance gains.

enum DOME_DrawMode {
  DOME_DRAWMODE_BLEND
}

Struct

struct: DOME_Color

The DOME_Bitmap type contains the following fields:

Field	Type	Purpose
a	uint8_t	This is the color’s alpha channel, from 0 - 255.
r	uint8_t	This is the color’s red channel, from 0 - 255.
g	uint8_t	This is the color’s green channel, from 0 - 255.
b	uint8_t	This is the color’s blue channel, from 0 - 255.

This type is also a union. You can get all the fields simultaneously as a 32-bit integer, value, arranged in the layout 0xAABBGGRR.

Methods

method: draw

void draw(DOME_Context ctx, DOME_Bitmap* bitmap, int32_t x, int32_t y, DOME_DRAWMODE mode)

Draws the bitmap to the canvas at (x, y). If the mode is set, alpha-blending will be applied. This will ignore the canvas draw context (offset, clipping region, etc).

method: getWidth

uint32_t getWidth(DOME_Context ctx)

Returns the width of the canvas, in pixels.

method: getHeight

uint32_t getHeight(DOME_Context ctx)

Returns the height of the canvas, in pixels.

method: line

void line(DOME_Context ctx, int64_t x0, int64_t y0, int64_t x1, int64_t y1, DOME_Color color);

Draws a one pixel wide line between (x0, y0) and (x1, y1), in the chosen color.

method: pget

DOME_Color pget(DOME_Context ctx, uint32_t x, uint32_t y)

Returns the color of the pixel located at (x, y) in the canvas.

method: pset

void pset(DOME_Context ctx, uint32_t x, uint32_t y, DOME_Color color)

Sets the color of the pixel located at (x, y) in the canvas to color.

method: rect

void rect(DOME_Context ctx, int64_t x, int64_t y, int64_t width, int64_t height, DOME_Color color);

Draws a rectangle (edges only) with size (width, height), with it’s top-left corner at (x, y).

method: rectfill

void rectfill(DOME_Context ctx, int64_t x, int64_t y, int64_t width, int64_t height, DOME_Color color);

Draws a filled rectangle with size (width, height), with it’s top-left corner at (x, y).

method: unsafePset

void unsafePset(DOME_Context ctx, uint32_t x, uint32_t y, DOME_Color color)

Sets the color of the pixel located at (x, y) in the canvas to color. This function is provided for performance-sensitive applications. It does not do range checks. If you attempt to set a pixel outside the canvas, you risk crashing DOME.