139 lines
3.1 KiB
Go
139 lines
3.1 KiB
Go
package basic
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import "image"
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import "image/color"
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import "git.tebibyte.media/sashakoshka/tomo"
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// Core is a struct that implements some core functionality common to most
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// widgets. It is possible to embed this directly into a struct, but this is not
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// reccomended as it exposes internal functionality.
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type Core struct {
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*image.RGBA
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parent tomo.Element
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drawCallback func (region tomo.Image)
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minimumSizeChangeCallback func (width, height int)
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metrics struct {
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minimumWidth int
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minimumHeight int
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}
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}
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// Core creates a new element core.
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func NewCore (parent tomo.Element) (core Core) {
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core = Core { parent: parent }
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return
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}
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func (core Core) ColorModel () (model color.Model) {
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return color.RGBAModel
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}
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func (core Core) At (x, y int) (pixel color.Color) {
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if core.RGBA == nil { return color.RGBA { } }
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pixel = core.RGBA.At(x, y)
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return
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}
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func (core Core) RGBAAt (x, y int) (pixel color.RGBA) {
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if core.RGBA == nil { return color.RGBA { } }
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pixel = core.RGBA.RGBAAt(x, y)
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return
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}
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func (core Core) Bounds () (bounds image.Rectangle) {
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if core.RGBA != nil { bounds = core.RGBA.Bounds() }
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return
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}
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func (core *Core) SetDrawCallback (draw func (region tomo.Image)) {
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core.drawCallback = draw
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}
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func (core *Core) SetMinimumSizeChangeCallback (
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notify func (width, height int),
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) {
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core.minimumSizeChangeCallback = notify
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}
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func (core Core) HasImage () (has bool) {
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has = core.RGBA != nil
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return
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}
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func (core Core) PushRegion (bounds image.Rectangle) {
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if core.drawCallback != nil {
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core.drawCallback(core.SubImage(bounds).
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(*image.RGBA))
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}
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}
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func (core Core) PushAll () {
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core.PushRegion(core.Bounds())
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}
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func (core *Core) AllocateCanvas (width, height int) {
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width, height, _ = core.ConstrainSize(width, height)
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core.RGBA = image.NewRGBA(image.Rect (0, 0, width, height))
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}
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func (core Core) MinimumWidth () (minimum int) {
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minimum = core.metrics.minimumWidth
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return
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}
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func (core Core) MinimumHeight () (minimum int) {
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minimum = core.metrics.minimumHeight
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return
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}
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func (core *Core) SetMinimumSize (width, height int) {
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if width != core.metrics.minimumWidth ||
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height != core.metrics.minimumHeight {
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core.metrics.minimumWidth = width
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core.metrics.minimumHeight = height
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if core.minimumSizeChangeCallback != nil {
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core.minimumSizeChangeCallback(width, height)
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}
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// if there is an image buffer, and the current size is less
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// than this new minimum size, send core.parent a resize event.
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if core.HasImage() {
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bounds := core.Bounds()
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imageWidth,
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imageHeight,
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constrained := core.ConstrainSize (
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bounds.Dx(),
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bounds.Dy())
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if constrained {
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core.parent.Handle (tomo.EventResize {
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Width: imageWidth,
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Height: imageHeight,
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})
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}
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}
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}
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}
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func (core Core) ConstrainSize (
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inWidth, inHeight int,
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) (
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outWidth, outHeight int,
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constrained bool,
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) {
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outWidth = inWidth
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outHeight = inHeight
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if outWidth < core.metrics.minimumWidth {
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outWidth = core.metrics.minimumWidth
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constrained = true
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}
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if outHeight < core.metrics.minimumHeight {
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outHeight = core.metrics.minimumHeight
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constrained = true
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}
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return
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}
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