Documentation
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Overview ¶
Package draw contains the RunWindow function which you call from runners to open a window. You pass it a callback which is called at 60 frames per second. The callback gives you a Window which you use to do input handling, rendering and audio output. See the documentation for Window for more details on what you can do.
Index ¶
Constants ¶
This section is empty.
Variables ¶
View Source
var ( Black = Color{0, 0, 0, 1} White = Color{1, 1, 1, 1} Gray = Color{0.5, 0.5, 0.5, 1} LightGray = Color{0.75, 0.75, 0.75, 1} DarkGray = Color{0.25, 0.25, 0.25, 1} Red = Color{1, 0, 0, 1} LightRed = Color{1, 0.5, 0.5, 1} DarkRed = Color{0.5, 0, 0, 1} Green = Color{0, 1, 0, 1} LightGreen = Color{0.5, 1, 0.5, 1} DarkGreen = Color{0, 0.5, 0, 1} Blue = Color{0, 0, 1, 1} LightBlue = Color{0.5, 0.5, 1, 1} DarkBlue = Color{0, 0, 0.5, 1} Purple = Color{1, 0, 1, 1} LightPurple = Color{1, 0.5, 1, 1} DarkPurple = Color{0.5, 0, 0.5, 1} Yellow = Color{1, 1, 0, 1} LightYellow = Color{1, 1, 0.5, 1} DarkYellow = Color{0.5, 0.5, 0, 1} Cyan = Color{0, 1, 1, 1} LightCyan = Color{0.5, 1, 1, 1} DarkCyan = Color{0, 0.5, 0.5, 1} Brown = Color{0.5, 0.2, 0, 1} LightBrown = Color{0.75, 0.3, 0, 1} )
These are predefined colors for intuitive use, no need to set color channels.
Functions ¶
Types ¶
type Color ¶
type Color struct{ R, G, B, A float32 }
Color consists of four channels ranging from 0 to 1 each. A specifies the opacity, 1 being fully opaque and 0 being fully transparent.
type Key ¶
type Key int
Key represents a key on the keyboard.
const ( KeyA Key = 1 + iota KeyB KeyC KeyD KeyE KeyF KeyG KeyH KeyI KeyJ KeyK KeyL KeyM KeyN KeyO KeyP KeyQ KeyR KeyS KeyT KeyU KeyV KeyW KeyX KeyY KeyZ Key0 Key1 Key2 Key3 Key4 Key5 Key6 Key7 Key8 Key9 KeyNum0 KeyNum1 KeyNum2 KeyNum3 KeyNum4 KeyNum5 KeyNum6 KeyNum7 KeyNum8 KeyNum9 KeyF1 KeyF2 KeyF3 KeyF4 KeyF5 KeyF6 KeyF7 KeyF8 KeyF9 KeyF10 KeyF11 KeyF12 KeyF13 KeyF14 KeyF15 KeyF16 KeyF17 KeyF18 KeyF19 KeyF20 KeyF21 KeyF22 KeyF23 KeyF24 KeyEnter KeyNumEnter KeyLeftControl KeyRightControl KeyLeftShift KeyRightShift KeyLeftAlt KeyRightAlt KeyLeft KeyRight KeyUp KeyDown KeyEscape KeySpace KeyBackspace KeyTab KeyHome KeyEnd KeyPageDown KeyPageUp KeyDelete KeyInsert KeyNumAdd KeyNumSubtract KeyNumMultiply KeyNumDivide KeyCapslock KeyPrint KeyPause )
These are all available keyboard keys.
type MouseButton ¶
type MouseButton int
MouseButton is one of the three buttons typically present on a mouse.
const ( LeftButton MouseButton = iota MiddleButton RightButton )
These are the possible values for MouseButton.
type MouseClick ¶
type MouseClick struct {
// X and Y are the screen position in pixels, relative to the drawing area.
// X goes from left to right, starting at 0 and Y goes from top to bottom
// starting at 0.
// This means that pixel 0,0 is the top-left pixel in the drawing area (not
// the title bar).
X, Y int
Button MouseButton
}
MouseClick is used to store mouse click events.
type UpdateFunction ¶
type UpdateFunction func(window Window)
UpdateFunction is used as a callback when creating a window. It is called at 60Hz and you do all your event handling and drawing in it.
type Window ¶
type Window interface {
// Close closes the window which will stop the update loop after the current
// frame (you will usually want to return from the update function after
// calling Close or another frame will be displayed).
Close()
// Size returns the window's size in pixels.
Size() (width, height int)
// SetFullscreen toggles between the fixed-size window with title and border
// and going full screen on the monitor that the window is placed on when
// the call to SetFullscreen(true) occurs.
// Use Window.Size to get the new size after this.
// By default the window is not fullscreen. It always starts windowed.
SetFullscreen(f bool)
// ShowCursor set the OS' mouse cursor to visible or invisible. It defaults
// to visible if you do not call ShowCursor.
ShowCursor(show bool)
// WasKeyPressed reports whether the specified key was pressed at any time
// during the last frame. If the user presses a key and releases it in the
// same frame, this function stores that information and will return true.
// See the Key... constants for the available keys that can be queried.
// NOTE do not use this for text input, use Characters instead.
WasKeyPressed(key Key) bool
// IsKeyDown reports whether the specified key is being held down at the
// moment of calling this function.
// See the Key... constants for the available keys that can be queried.
IsKeyDown(key Key) bool
// Characters returns all pressed keys translated to characters that
// happened in the last frame. The runes in the string are ordered by the
// time that the keys were entered.
Characters() string
// IsMouseDown reports whether the specified button is down at the time of
// the function call
IsMouseDown(button MouseButton) bool
// Clicks returns all MouseClicks that occurred during the last frame.
Clicks() []MouseClick
// MousePositoin returns the current mouse position in pixels at the time of
// the function call. It is relative to the drawing area of the window.
MousePosition() (x, y int)
// MouseWheelY returns the aggregate vertical mouse wheel rotation during
// the last frame. A value of 1 typically corresponds to one tick of the
// wheel. A positive value means the wheel was rotated forward, away from
// the user, a negative value means the wheel was rotated backward towards
// the user.
MouseWheelY() float64
// MouseWheelX returns the aggregate horizontal mouse wheel rotation during
// the last frame. A value of 1 typically corresponds to one tick of the
// wheel. A positive value means the wheel was rotated right, a negative
// value means the wheel was rotated left.
MouseWheelX() float64
// DrawPoint draws a single point at the given screen position in pixels.
DrawPoint(x, y int, color Color)
// DrawLine draws a one pixel wide line from the first point to the second
// (inclusive).
DrawLine(fromX, fromY, toX, toY int, color Color)
// DrawRect draws a one pixel wide rectangle outline.
DrawRect(x, y, width, height int, color Color)
// FillRect draws a filled rect.
FillRect(x, y, width, height int, color Color)
// DrawEllipse draws a one pixel wide ellipse. The top-left corner of the
// surrounding rectangle is given by x and y, the horizontal and vertical
// diameters are given by width and height.
DrawEllipse(x, y, width, height int, color Color)
// FillEllipse behaves like DrawEllipse but fills the ellipse with the color
// instaed of only drawing the outline.
FillEllipse(x, y, width, height int, color Color)
DrawTriangle(x0, y0, x1, y1, x2, y2 int, color Color)
FillTriangle(x0, y0, x1, y1, x2, y2 int, color Color)
// DrawImageFile draws the untransformed image at the give position. If the
// image file is not found or has the wrong format an error is returned.
DrawImageFile(path string, x, y int) error
// DrawImageFileTo draws the image to the given screen rectangle, possibly
// scaling it in either direction, and rotates it around the rectangles
// center point by the given angle. The rotation is clockwise.
// If the image file is not found or has the wrong format an error is
// returned.
DrawImageFileTo(path string, x, y, w, h, rotationCWDeg int) error
// DrawImageFileRotated draws the image with its top-left corner at the
// given coordinates but roatated clockwise about the given angle in degrees
// around its center. This means its top-left corner will only actually be
// at the given location if the rotation is 0.
// If the image file is not found or has the wrong format an error is
// returned.
DrawImageFileRotated(path string, x, y, rotationCWDeg int) error
// DrawImageFilePart lets you specify the source and destination rectangle
// for the image file to be drawn. The image is rotated about its center by
// the given angle in degrees, clockwise. You may flip the image by
// specifying a negative width or height. E.g. to flip in x direction,
// instead of
//
// DrawImageFilePart("x.png", 0, 0, 100, 100, 0, 0, 100, 100, 0)
//
// you would do
//
// DrawImageFilePart("x.png", 100, 0, -100, 100, 0, 0, 100, 100, 0)
//
// swapping the source rectangle's left and right positions.
//
// If the image file is not found or has the wrong format an error is
// returned.
DrawImageFilePart(
path string,
sourceX, sourceY, sourceWidth, sourceHeight int,
destX, destY, destWidth, destHeight int,
rotationCWDeg int,
) error
// GetTextSize returns the size the given text would have when being drawn.
GetTextSize(text string) (w, h int)
// GetScaledTextSize returns the size the given text would have when being
// drawn at the given scale.
GetScaledTextSize(text string, scale float32) (w, h int)
// DrawText draws a text string. New line characters ('\n') are not drawn
// but force a line break and the next character is drawn on the line below
// starting again at x.
DrawText(text string, x, y int, color Color)
// DrawScaledText behaves as DrawText, but the text is scaled. If scale = 1
// this behaves exactly like DrawText, scales > 1 make the text bigger,
// scales < 1 shrink it. Scales <= 0 will draw no text at all.
DrawScaledText(text string, x, y int, scale float32, color Color)
// PlaySoundFile only plays WAV sounds. If the file is not found or has the
// wrong format an error is returned.
PlaySoundFile(path string) error
}
Window provides functions to draw simple primitives and images, handle keyboard and mouse events and play sounds. All drawing functions that have width and height as input expect those to be positive. Objects with negative width or height will silently be ignored and not drawn.
Source Files
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