Progress bars

... And also the Do function works now

elements/basic/progressbar.go

@@ -0,0 +1,56 @@
+package basic
+
+import "image"
+import "git.tebibyte.media/sashakoshka/tomo/theme"
+import "git.tebibyte.media/sashakoshka/tomo/artist"
+import "git.tebibyte.media/sashakoshka/tomo/elements/core"
+
+// ProgressBar displays a visual indication of how far along a task is.
+type ProgressBar struct {
+	*core.Core
+	core core.CoreControl
+	progress float64
+}
+
+// NewProgressBar creates a new progress bar displaying the given progress
+// level.
+func NewProgressBar (progress float64) (element *ProgressBar) {
+	element = &ProgressBar { progress: progress }
+	element.Core, element.core = core.NewCore(element)
+	element.core.SetMinimumSize(theme.Padding() * 2, theme.Padding() * 2)
+	return
+}
+
+// Resize resizes the progress bar.
+func (element *ProgressBar) Resize (width, height int) {
+	element.core.AllocateCanvas(width, height)
+	element.draw()
+	return
+}
+
+// SetProgress sets the progress level of the bar.
+func (element *ProgressBar) SetProgress (progress float64) {
+	if progress == element.progress { return }
+	element.progress = progress
+	if element.core.HasImage() {
+		element.draw()
+		element.core.PushAll()
+	}
+}
+
+func (element *ProgressBar) draw () {
+	bounds := element.core.Bounds()
+
+	artist.FillRectangle (
+		element.core,
+		theme.SunkenPattern(),
+		bounds)
+	meterBounds := image.Rect (
+		bounds.Min.X + 2, bounds.Min.Y + 2,
+		bounds.Min.X - 1 + int(float64(bounds.Dx()) * element.progress),
+		bounds.Dy() - 1)
+	artist.FillRectangle (
+		element.core,
+		theme.AccentPattern(),
+		meterBounds)
+}