Golang Context.TextGlyphPositionsRune方法代碼示例

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)
//.........這裏部分代碼省略.........

func (t *TextBox) Draw(self Widget, ctx *nanovgo.Context) {
	t.WidgetImplement.Draw(self, ctx)

	x := float32(t.x)
	y := float32(t.y)
	w := float32(t.w)
	h := float32(t.h)

	bg := nanovgo.BoxGradient(x+1, y+2, w-2, h-2, 3, 4, nanovgo.MONO(255, 32), nanovgo.MONO(32, 32))
	fg1 := nanovgo.BoxGradient(x+1, y+2, w-2, h-2, 3, 4, nanovgo.MONO(150, 32), nanovgo.MONO(32, 32))
	fg2 := nanovgo.BoxGradient(x+1, y+2, w-2, h-2, 3, 4, nanovgo.RGBA(255, 0, 0, 100), nanovgo.RGBA(255, 0, 0, 50))

	ctx.BeginPath()
	ctx.RoundedRect(x+1, y+2, w-2, h-2, 3)
	if t.editable && t.Focused() {
		if t.validFormat {
			ctx.SetFillPaint(fg1)
		} else {
			ctx.SetFillPaint(fg2)
		}
	} else {
		ctx.SetFillPaint(bg)
	}

	ctx.Fill()

	ctx.BeginPath()
	ctx.RoundedRect(x+0.5, y+0.5, w-1, h-1, 2.5)
	ctx.SetStrokeColor(nanovgo.MONO(0, 48))
	ctx.Stroke()

	ctx.SetFontSize(float32(t.FontSize()))
	ctx.SetFontFace(t.Font())
	drawPosX := x
	drawPosY := y + h*0.5 + 1

	xSpacing := h * 0.3
	var unitWidth float32

	if t.unitImage > 0 {
		iw, ih, _ := ctx.ImageSize(t.unitImage)
		unitHeight := float32(ih) * 0.4
		unitWidth = float32(iw) * unitHeight / float32(h)
		imgPaint := nanovgo.ImagePattern(x+w-xSpacing-unitWidth, drawPosY-unitHeight*0.5,
			unitWidth, unitHeight, 0, t.unitImage, toF(t.enabled, 0.7, 0.35))
		ctx.BeginPath()
		ctx.Rect(x+w-xSpacing-unitWidth, drawPosY-unitHeight*0.5, unitWidth, unitHeight)
		ctx.SetFillPaint(imgPaint)
		ctx.Fill()
		unitWidth += 2
	} else if t.units != "" {
		unitWidth, _ = ctx.TextBounds(0, 0, t.units)
		ctx.SetFillColor(nanovgo.MONO(255, toB(t.enabled, 64, 32)))
		ctx.SetTextAlign(nanovgo.AlignRight | nanovgo.AlignMiddle)
		ctx.Text(x+w-xSpacing, drawPosY, t.units)
	}

	switch t.alignment {
	case TextLeft:
		ctx.SetTextAlign(nanovgo.AlignLeft | nanovgo.AlignMiddle)
		drawPosX += xSpacing
	case TextRight:
		ctx.SetTextAlign(nanovgo.AlignRight | nanovgo.AlignMiddle)
		drawPosX += w - unitWidth - xSpacing
	case TextCenter:
		ctx.SetTextAlign(nanovgo.AlignCenter | nanovgo.AlignMiddle)
		drawPosX += w * 0.5
	}
	if t.enabled {
		ctx.SetFillColor(t.theme.TextColor)
	} else {
		ctx.SetFillColor(t.theme.DisabledTextColor)
	}
	// clip visible text area
	clipX := x + xSpacing - 1
	clipY := y + 1.0
	clipWidth := w - unitWidth - 2.0*xSpacing + 2.0
	clipHeight := h - 3.0
	ctx.Scissor(clipX, clipY, clipWidth, clipHeight)
	oldDrawPosX := drawPosX
	drawPosX += t.textOffset

	if t.committed {
		ctx.Text(drawPosX, drawPosY, t.value)
	} else {
		text := t.editingText()
		textString := string(text)
		_, bounds := ctx.TextBounds(drawPosX, drawPosY, textString)
		lineH := bounds[3] - bounds[1]
		// find cursor positions
		glyphs := ctx.TextGlyphPositionsRune(drawPosX, drawPosY, text)
		t.updateCursor(ctx, bounds[2], glyphs)

		// compute text offset
		prevCPos := toI(t.cursorPos > 0, t.cursorPos-1, 0)
		nextCPos := toI(t.cursorPos < len(glyphs), t.cursorPos+1, len(glyphs))
		prevCX := t.textIndex2Position(prevCPos, bounds[2], glyphs)
		nextCX := t.textIndex2Position(nextCPos, bounds[2], glyphs)

		if nextCX > clipX+clipWidth {
//.........這裏部分代碼省略.........