78 lines
2.2 KiB
Go
78 lines
2.2 KiB
Go
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// Provides access to the drawable primitives.
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package ui
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// A drawable context. Each context is allocated part of the screen and provides methods for
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// drawing within it's context.
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type DrawContext struct {
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// The left and top position of the context.
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X, Y int
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// The width and height position of the context.
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W, H int
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// The current driver
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driver Driver
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// The current foregound and background attributes
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fa, ba Attribute
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}
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// Returns a new subcontext. The sub-context must be an area within the current context.
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func (dc *DrawContext) NewSubContext(offsetX, offsetY, width, height int) *DrawContext {
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return &DrawContext{
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X: intMax(dc.X + offsetX, dc.X),
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Y: intMax(dc.Y + offsetY, dc.Y),
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W: intMax(width, 0),
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H: intMax(height, 0),
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driver: dc.driver,
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}
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}
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// Sets the foreground attribute
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func (dc *DrawContext) SetFgAttr(attr Attribute) {
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dc.fa = attr
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}
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// Sets the background attribute
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func (dc *DrawContext) SetBgAttr(attr Attribute) {
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dc.ba = attr
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}
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// Draws a horizontal rule with a specific rune.
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func (dc *DrawContext) HorizRule(y int, ch rune) {
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for x := 0; x < dc.W; x++ {
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dc.DrawRune(x, y, ch)
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}
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}
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// Prints a string at a specific offset. This will be bounded by the size of the drawing context.
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func (dc *DrawContext) Print(x, y int, str string) {
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for _, ch := range str {
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dc.DrawRune(x, y, ch)
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x++
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}
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}
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// Prints a right-justified string at a specific offset. This will be bounded by the size of the drawing context.
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func (dc *DrawContext) PrintRight(x, y int, str string) {
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l := len(str)
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dc.Print(x - l, y, str)
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}
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// Draws a rune at a local point X, Y with the current foreground and background attributes
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func (dc *DrawContext) DrawRune(x, y int, ch rune) {
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if rx, ry, isWithinContext := dc.localPointToRealPoint(x, y); isWithinContext {
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dc.driver.SetCell(rx, ry, ch, dc.fa, dc.ba)
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}
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}
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// Converts a local point to a real point. If the point is within the context, also returns true
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func (dc *DrawContext) localPointToRealPoint(x, y int) (int, int, bool) {
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rx, ry := x + dc.X, y + dc.Y
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return rx, ry, (rx >= dc.X) && (ry >= dc.Y) && (rx < dc.X + dc.W) && (ry < dc.Y + dc.H)
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}
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