Example #1
0
func drawParagraph(ctx *nanovgo.Context, x, y, width, height, mx, my float32) {
	text := "This is longer chunk of text.\n  \n  Would have used lorem ipsum but she    was busy jumping over the lazy dog with the fox and all the men who came to the aid of the party."

	ctx.Save()
	defer ctx.Restore()

	ctx.SetFontSize(18.0)
	ctx.SetFontFace("sans")
	ctx.SetTextAlign(nanovgo.AlignLeft | nanovgo.AlignTop)
	_, _, lineh := ctx.TextMetrics()
	// The text break API can be used to fill a large buffer of rows,
	// or to iterate over the text just few lines (or just one) at a time.
	// The "next" variable of the last returned item tells where to continue.
	runes := []rune(text)

	var gx, gy float32
	var gutter int
	lnum := 0

	for _, row := range ctx.TextBreakLinesRune(runes, width) {
		hit := mx > x && mx < (x+width) && my >= y && my < (y+lineh)

		ctx.BeginPath()
		var alpha uint8
		if hit {
			alpha = 64
		} else {
			alpha = 16
		}
		ctx.SetFillColor(nanovgo.RGBA(255, 255, 255, alpha))
		ctx.Rect(x, y, row.Width, lineh)
		ctx.Fill()

		ctx.SetFillColor(nanovgo.RGBA(255, 255, 255, 255))
		ctx.TextRune(x, y, runes[row.StartIndex:row.EndIndex])

		if hit {
			var caretX float32
			if mx < x+row.Width/2 {
				caretX = x
			} else {
				caretX = x + row.Width
			}
			px := x
			lineRune := runes[row.StartIndex:row.EndIndex]
			glyphs := ctx.TextGlyphPositionsRune(x, y, lineRune)
			for j, glyph := range glyphs {
				x0 := glyph.X
				var x1 float32
				if j+1 < len(glyphs) {
					x1 = glyphs[j+1].X
				} else {
					x1 = x + row.Width
				}
				gx = x0*0.3 + x1*0.7
				if mx >= px && mx < gx {
					caretX = glyph.X
				}
				px = gx
			}
			ctx.BeginPath()
			ctx.SetFillColor(nanovgo.RGBA(255, 192, 0, 255))
			ctx.Rect(caretX, y, 1, lineh)
			ctx.Fill()

			gutter = lnum + 1
			gx = x - 10
			gy = y + lineh/2
		}
		lnum++
		y += lineh
	}

	if gutter > 0 {
		txt := strconv.Itoa(gutter)

		ctx.SetFontSize(13.0)
		ctx.SetTextAlign(nanovgo.AlignRight | nanovgo.AlignMiddle)

		_, bounds := ctx.TextBounds(gx, gy, txt)

		ctx.BeginPath()
		ctx.SetFillColor(nanovgo.RGBA(255, 192, 0, 255))
		ctx.RoundedRect(
			float32(int(bounds[0]-4)),
			float32(int(bounds[1]-2)),
			float32(int(bounds[2]-bounds[0])+8),
			float32(int(bounds[3]-bounds[1])+4),
			float32(int(bounds[3]-bounds[1])+4)/2.0-1.0)
		ctx.Fill()

		ctx.SetFillColor(nanovgo.RGBA(32, 32, 32, 255))
		ctx.Text(gx, gy, txt)
	}

	y += 20.0

	ctx.SetFontSize(13.0)
	ctx.SetTextAlign(nanovgo.AlignLeft | nanovgo.AlignTop)
	ctx.SetTextLineHeight(1.2)

	bounds := ctx.TextBoxBounds(x, y, 150, "Hover your mouse over the text to see calculated caret position.")

	// Fade the tooltip out when close to it.
	gx = absF((mx - (bounds[0]+bounds[2])*0.5) / (bounds[0] - bounds[2]))
	gy = absF((my - (bounds[1]+bounds[3])*0.5) / (bounds[1] - bounds[3]))
	a := maxF(gx, gy) - 0.5
	a = clampF(a, 0, 1)
	ctx.SetGlobalAlpha(a)

	ctx.BeginPath()
	ctx.SetFillColor(nanovgo.RGBA(220, 220, 220, 255))
	ctx.RoundedRect(bounds[0]-2, bounds[1]-2, float32(int(bounds[2]-bounds[0])+4), float32(int(bounds[3]-bounds[1])+4), 3)
	px := float32(int((bounds[2] + bounds[0]) / 2))
	ctx.MoveTo(px, bounds[1]-10)
	ctx.LineTo(px+7, bounds[1]+1)
	ctx.LineTo(px-7, bounds[1]+1)
	ctx.Fill()

	ctx.SetFillColor(nanovgo.RGBA(0, 0, 0, 220))
	ctx.TextBox(x, y, 150, "Hover your mouse over the text to see calculated caret position.")
}