shithub: mycel

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fast scroll

--- a/browser/browser.go

+++ b/browser/browser.go

@@ -100,13 +100,6 @@

 	edit := &duit.Edit{

 		Font: Style.Font(),

 	}

-	/*edit.Keys = func(k rune, m draw.Mouse) (e duit.Event) {

-		//log.Printf("k=%v (c %v    p %v)", k, unicode.IsControl(k), unicode.IsPrint(k))

-		if unicode.IsPrint(k) {

-			e.Consumed = true

-		}

-		return

-	}*/

 	formatted := ""

 	lines := strings.Split(s, "\n")

 	for _, line := range lines {

--- a/browser/scroll.go

+++ b/browser/scroll.go

@@ -136,7 +136,7 @@

 		if ui.Kid.R.Dx() == 0 || ui.Kid.R.Dy() == 0 {

 			return

 		}

-		ui.img, err = dui.Display.AllocImage(ui.Kid.R, draw.ARGB32, false, dui.BackgroundColor)

+		ui.img, err = dui.Display.AllocImage(ui.drawRect(), draw.ARGB32, false, dui.BackgroundColor)

 		if duitError(dui, err, "allocimage") {

 			return

 		}

@@ -152,6 +152,29 @@

 		ui.Kid.Draw = duit.Clean

 	}

 	img.Draw(ui.childR.Add(orig), ui.img, nil, image.Pt(0, ui.Offset))

+}

+

+// Allocate only an image buffer of view size ui.r

+// - which is translated by scroll offset ui.Offset - instead

+// of whole Kid view size ui.Kid.R which leads to much

+// faster render times sometimes. Add same size rectangles

+// above/below to decrease flickering.

+func (ui *Scroll) drawRect() image.Rectangle {

+	if 2*ui.r.Dy() > ui.Kid.R.Dy() {

+		return ui.Kid.R

+	}

+	r := image.Rectangle{

+		Min: ui.r.Min,

+		Max: image.Point{

+			ui.r.Max.X,

+			2*ui.r.Max.Y,

+		},

+	}

+	r = r.Add(image.Point{X:0, Y:ui.Offset})

+	if r.Min.Y > ui.Offset {

+		r.Min.Y -= ui.Offset

+	}

+	return r

 }

 func (ui *Scroll) scroll(delta int) bool {